new hasher

* prepare v1 protos

* add in protos

* prepare beacon proposer

* stubs

* builds

* gaz

* build

* rem

* ssz

Co-authored-by: prylabs-bulldozer[bot] <58059840+prylabs-bulldozer[bot]@users.noreply.github.com>

WORKSPACE

@@ -183,7 +183,7 @@ load("@io_bazel_rules_go//go:deps.bzl", "go_register_toolchains", "go_rules_depe
 go_rules_dependencies()
 
 go_register_toolchains(
-    go_version = "1.16.4",
+    go_version = "1.17.6",
     nogo = "@//:nogo",
 )
 
@@ -222,7 +222,7 @@ filegroup(
     url = "https://github.com/eth-clients/slashing-protection-interchange-tests/archive/b8413ca42dc92308019d0d4db52c87e9e125c4e9.tar.gz",
 )
 
-consensus_spec_version = "v1.1.8"
+consensus_spec_version = "v1.1.9"
 
 bls_test_version = "v0.1.1"
 
@@ -238,7 +238,7 @@ filegroup(
     visibility = ["//visibility:public"],
 )
     """,
-    sha256 = "e4d2b7830e85734442d7172887dcd4edc0985d6256bafedb3353ab477a1433c0",
+    sha256 = "207d9c326ba4fa1f34bab7b6169201c32f2611755db030909a3405873445e0ba",
     url = "https://github.com/ethereum/consensus-spec-tests/releases/download/%s/general.tar.gz" % consensus_spec_version,
 )
 
@@ -254,7 +254,7 @@ filegroup(
     visibility = ["//visibility:public"],
 )
     """,
-    sha256 = "4a88d01ad12260220ab5c8efdeec6534bac48a47f29ba4f7977ea14c9d07b0fe",
+    sha256 = "a3995b39f412db236b2f1db909f288218da53cb53b9923b71dda9d144d68f40a",
     url = "https://github.com/ethereum/consensus-spec-tests/releases/download/%s/minimal.tar.gz" % consensus_spec_version,
 )
 
@@ -270,7 +270,7 @@ filegroup(
     visibility = ["//visibility:public"],
 )
     """,
-    sha256 = "0033fe107d9d2adb8d4fcb60dfb1c43fc5a54f0af970525c962124221757c266",
+    sha256 = "76cea7a4c8e32d458ad456b54bfbb30bc772481a91954a4cd97e229aa3023b1d",
     url = "https://github.com/ethereum/consensus-spec-tests/releases/download/%s/mainnet.tar.gz" % consensus_spec_version,
 )
 
@@ -285,7 +285,7 @@ filegroup(
     visibility = ["//visibility:public"],
 )
     """,
-    sha256 = "3fc3b8809d140a1ab61350fbd410f33add2851a63829d874dcb620babba603de",
+    sha256 = "0fc429684775f943250dce1f9c485ac25e26c6395d7f585c8d1317becec2ace7",
     strip_prefix = "consensus-specs-" + consensus_spec_version[1:],
     url = "https://github.com/ethereum/consensus-specs/archive/refs/tags/%s.tar.gz" % consensus_spec_version,
 )
@@ -349,9 +349,9 @@ filegroup(
     visibility = ["//visibility:public"],
 )
 """,
-    sha256 = "f196fe4367c2d2d01d36565c0dc6eecfa4f03adba1fc03a61d62953fce606e1f",
+    sha256 = "4797a7e594a5b1f4c1c8080701613f3ee451b01ec0861499ea7d9b60877a6b23",
     urls = [
-        "https://github.com/prysmaticlabs/prysm-web-ui/releases/download/v1.0.2/prysm-web-ui.tar.gz",
+        "https://github.com/prysmaticlabs/prysm-web-ui/releases/download/v1.0.3/prysm-web-ui.tar.gz",
     ],
 )
 

api/gateway/apimiddleware/api_middleware.go

@@ -3,6 +3,7 @@ package apimiddleware
 import (
 	"net/http"
 	"reflect"
+	"time"
 
 	"github.com/gorilla/mux"
 )
@@ -14,6 +15,7 @@ import (
 type ApiProxyMiddleware struct {
 	GatewayAddress  string
 	EndpointCreator EndpointFactory
+	Timeout         time.Duration
 	router          *mux.Router
 }
 
@@ -120,7 +122,7 @@ func (m *ApiProxyMiddleware) WithMiddleware(path string) http.HandlerFunc {
 			WriteError(w, errJson, nil)
 			return
 		}
-		grpcResp, errJson := ProxyRequest(req)
+		grpcResp, errJson := m.ProxyRequest(req)
 		if errJson != nil {
 			WriteError(w, errJson, nil)
 			return

api/gateway/apimiddleware/process_request.go

@@ -5,10 +5,10 @@ import (
 	"encoding/json"
 	"io"
 	"io/ioutil"
+	"net"
 	"net/http"
 	"strconv"
 	"strings"
-	"time"
 
 	"github.com/pkg/errors"
 	"github.com/prysmaticlabs/prysm/api/grpc"
@@ -75,11 +75,14 @@ func (m *ApiProxyMiddleware) PrepareRequestForProxying(endpoint Endpoint, req *h
 }
 
 // ProxyRequest proxies the request to grpc-gateway.
-func ProxyRequest(req *http.Request) (*http.Response, ErrorJson) {
+func (m *ApiProxyMiddleware) ProxyRequest(req *http.Request) (*http.Response, ErrorJson) {
 	// We do not use http.DefaultClient because it does not have any timeout.
-	netClient := &http.Client{Timeout: time.Minute * 2}
+	netClient := &http.Client{Timeout: m.Timeout}
 	grpcResp, err := netClient.Do(req)
 	if err != nil {
+		if err, ok := err.(net.Error); ok && err.Timeout() {
+			return nil, TimeoutError()
+		}
 		return nil, InternalServerErrorWithMessage(err, "could not proxy request")
 	}
 	if grpcResp == nil {
@@ -111,9 +114,14 @@ func HandleGrpcResponseError(errJson ErrorJson, resp *http.Response, respBody []
 				w.Header().Set(h, v)
 			}
 		}
-		// Set code to HTTP code because unmarshalled body contained gRPC code.
-		errJson.SetCode(resp.StatusCode)
-		WriteError(w, errJson, resp.Header)
+		// Handle gRPC timeout.
+		if resp.StatusCode == http.StatusGatewayTimeout {
+			WriteError(w, TimeoutError(), resp.Header)
+		} else {
+			// Set code to HTTP code because unmarshalled body contained gRPC code.
+			errJson.SetCode(resp.StatusCode)
+			WriteError(w, errJson, resp.Header)
+		}
 	}
 	return responseHasError, nil
 }

api/gateway/apimiddleware/structs.go

@@ -41,6 +41,13 @@ func InternalServerError(err error) *DefaultErrorJson {
 	}
 }
 
+func TimeoutError() *DefaultErrorJson {
+	return &DefaultErrorJson{
+		Message: "Request timeout",
+		Code:    http.StatusRequestTimeout,
+	}
+}
+
 // StatusCode returns the error's underlying error code.
 func (e *DefaultErrorJson) StatusCode() int {
 	return e.Code

api/gateway/gateway.go

@@ -52,6 +52,7 @@ type config struct {
 	muxHandler                   MuxHandler
 	pbHandlers                   []*PbMux
 	router                       *mux.Router
+	timeout                      time.Duration
 }
 
 // Gateway is the gRPC gateway to serve HTTP JSON traffic as a proxy and forward it to the gRPC server.
@@ -248,6 +249,7 @@ func (g *Gateway) registerApiMiddleware() {
 	g.proxy = &apimiddleware.ApiProxyMiddleware{
 		GatewayAddress:  g.cfg.gatewayAddr,
 		EndpointCreator: g.cfg.apiMiddlewareEndpointFactory,
+		Timeout:         g.cfg.timeout,
 	}
 	log.Info("Starting API middleware")
 	g.proxy.Run(g.cfg.router)

api/gateway/options.go

@@ -1,7 +1,10 @@
 package gateway
 
 import (
+	"time"
+
 	"github.com/gorilla/mux"
+	gwruntime "github.com/grpc-ecosystem/grpc-gateway/v2/runtime"
 	"github.com/prysmaticlabs/prysm/api/gateway/apimiddleware"
 )
 
@@ -79,3 +82,12 @@ func WithApiMiddleware(endpointFactory apimiddleware.EndpointFactory) Option {
 		return nil
 	}
 }
+
+// WithTimeout allows changing the timeout value for API calls.
+func WithTimeout(seconds uint64) Option {
+	return func(g *Gateway) error {
+		g.cfg.timeout = time.Second * time.Duration(seconds)
+		gwruntime.DefaultContextTimeout = time.Second * time.Duration(seconds)
+		return nil
+	}
+}

async/multilock_test.go

@@ -110,9 +110,8 @@ func TestLockUnlock_CleansUnused(t *testing.T) {
 		lock := NewMultilock("dog", "cat", "owl")
 		lock.Lock()
 		assert.Equal(t, 3, len(locks.list))
-		defer lock.Unlock()
+		lock.Unlock()
 
-		<-time.After(100 * time.Millisecond)
 		wg.Done()
 	}()
 	wg.Wait()

beacon-chain/blockchain/BUILD.bazel

@@ -7,11 +7,11 @@ go_library(
         "error.go",
         "head.go",
         "head_sync_committee_info.go",
-        "info.go",
         "init_sync_process_block.go",
         "log.go",
         "metrics.go",
         "new_slot.go",
+        "optimistic_sync.go",
         "options.go",
         "pow_block.go",
         "process_attestation.go",
@@ -38,6 +38,7 @@ go_library(
         "//beacon-chain/cache:go_default_library",
         "//beacon-chain/cache/depositcache:go_default_library",
         "//beacon-chain/core/altair:go_default_library",
+        "//beacon-chain/core/blocks:go_default_library",
         "//beacon-chain/core/epoch/precompute:go_default_library",
         "//beacon-chain/core/feed:go_default_library",
         "//beacon-chain/core/feed/state:go_default_library",
@@ -48,12 +49,14 @@ go_library(
         "//beacon-chain/db:go_default_library",
         "//beacon-chain/db/filters:go_default_library",
         "//beacon-chain/forkchoice:go_default_library",
+        "//beacon-chain/forkchoice/doubly-linked-tree:go_default_library",
         "//beacon-chain/forkchoice/protoarray:go_default_library",
         "//beacon-chain/operations/attestations:go_default_library",
         "//beacon-chain/operations/slashings:go_default_library",
         "//beacon-chain/operations/voluntaryexits:go_default_library",
         "//beacon-chain/p2p:go_default_library",
         "//beacon-chain/powchain:go_default_library",
+        "//beacon-chain/powchain/engine-api-client/v1:go_default_library",
         "//beacon-chain/state:go_default_library",
         "//beacon-chain/state/stategen:go_default_library",
         "//cmd/beacon-chain/flags:go_default_library",
@@ -63,6 +66,7 @@ go_library(
         "//crypto/bls:go_default_library",
         "//encoding/bytesutil:go_default_library",
         "//monitoring/tracing:go_default_library",
+        "//proto/engine/v1:go_default_library",
         "//proto/eth/v1:go_default_library",
         "//proto/prysm/v1alpha1:go_default_library",
         "//proto/prysm/v1alpha1/attestation:go_default_library",
@@ -70,7 +74,8 @@ go_library(
         "//runtime/version:go_default_library",
         "//time:go_default_library",
         "//time/slots:go_default_library",
-        "@com_github_emicklei_dot//:go_default_library",
+        "@com_github_ethereum_go_ethereum//common:go_default_library",
+        "@com_github_ethereum_go_ethereum//common/hexutil:go_default_library",
         "@com_github_holiman_uint256//:go_default_library",
         "@com_github_pkg_errors//:go_default_library",
         "@com_github_prometheus_client_golang//prometheus:go_default_library",
@@ -98,11 +103,12 @@ go_test(
         "checktags_test.go",
         "head_sync_committee_info_test.go",
         "head_test.go",
-        "info_test.go",
         "init_test.go",
         "log_test.go",
         "metrics_test.go",
+        "mock_engine_test.go",
         "mock_test.go",
+        "optimistic_sync_test.go",
         "pow_block_test.go",
         "process_attestation_test.go",
         "process_block_test.go",

beacon-chain/blockchain/chain_info.go

@@ -6,13 +6,14 @@ import (
 
 	types "github.com/prysmaticlabs/eth2-types"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
-	"github.com/prysmaticlabs/prysm/beacon-chain/forkchoice/protoarray"
+	"github.com/prysmaticlabs/prysm/beacon-chain/forkchoice"
 	"github.com/prysmaticlabs/prysm/beacon-chain/state"
 	fieldparams "github.com/prysmaticlabs/prysm/config/fieldparams"
 	"github.com/prysmaticlabs/prysm/config/params"
 	"github.com/prysmaticlabs/prysm/encoding/bytesutil"
 	ethpb "github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1"
 	"github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1/block"
+	"github.com/prysmaticlabs/prysm/time/slots"
 	"go.opencensus.io/trace"
 )
 
@@ -36,7 +37,7 @@ type TimeFetcher interface {
 
 // GenesisFetcher retrieves the Ethereum consensus data related to its genesis.
 type GenesisFetcher interface {
-	GenesisValidatorRoot() [32]byte
+	GenesisValidatorsRoot() [32]byte
 }
 
 // HeadFetcher defines a common interface for methods in blockchain service which
@@ -48,15 +49,16 @@ type HeadFetcher interface {
 	HeadState(ctx context.Context) (state.BeaconState, error)
 	HeadValidatorsIndices(ctx context.Context, epoch types.Epoch) ([]types.ValidatorIndex, error)
 	HeadSeed(ctx context.Context, epoch types.Epoch) ([32]byte, error)
-	HeadGenesisValidatorRoot() [32]byte
+	HeadGenesisValidatorsRoot() [32]byte
 	HeadETH1Data() *ethpb.Eth1Data
 	HeadPublicKeyToValidatorIndex(pubKey [fieldparams.BLSPubkeyLength]byte) (types.ValidatorIndex, bool)
 	HeadValidatorIndexToPublicKey(ctx context.Context, index types.ValidatorIndex) ([fieldparams.BLSPubkeyLength]byte, error)
-	ProtoArrayStore() *protoarray.Store
 	ChainHeads() ([][32]byte, []types.Slot)
 	IsOptimistic(ctx context.Context) (bool, error)
+	IsOptimisticForRoot(ctx context.Context, root [32]byte) (bool, error)
 	HeadSyncCommitteeFetcher
 	HeadDomainFetcher
+	ForkChoicer() forkchoice.ForkChoicer
 }
 
 // ForkFetcher retrieves the current fork information of the Ethereum beacon chain.
@@ -213,8 +215,8 @@ func (s *Service) HeadSeed(ctx context.Context, epoch types.Epoch) ([32]byte, er
 	return helpers.Seed(s.headState(ctx), epoch, params.BeaconConfig().DomainBeaconAttester)
 }
 
-// HeadGenesisValidatorRoot returns genesis validator root of the head state.
-func (s *Service) HeadGenesisValidatorRoot() [32]byte {
+// HeadGenesisValidatorsRoot returns genesis validators root of the head state.
+func (s *Service) HeadGenesisValidatorsRoot() [32]byte {
 	s.headLock.RLock()
 	defer s.headLock.RUnlock()
 
@@ -222,7 +224,7 @@ func (s *Service) HeadGenesisValidatorRoot() [32]byte {
 		return [32]byte{}
 	}
 
-	return s.headGenesisValidatorRoot()
+	return s.headGenesisValidatorsRoot()
 }
 
 // HeadETH1Data returns the eth1data of the current head state.
@@ -236,26 +238,21 @@ func (s *Service) HeadETH1Data() *ethpb.Eth1Data {
 	return s.head.state.Eth1Data()
 }
 
-// ProtoArrayStore returns the proto array store object.
-func (s *Service) ProtoArrayStore() *protoarray.Store {
-	return s.cfg.ForkChoiceStore.Store()
-}
-
 // GenesisTime returns the genesis time of beacon chain.
 func (s *Service) GenesisTime() time.Time {
 	return s.genesisTime
 }
 
-// GenesisValidatorRoot returns the genesis validator
+// GenesisValidatorsRoot returns the genesis validator
 // root of the chain.
-func (s *Service) GenesisValidatorRoot() [32]byte {
+func (s *Service) GenesisValidatorsRoot() [32]byte {
 	s.headLock.RLock()
 	defer s.headLock.RUnlock()
 
 	if !s.hasHeadState() {
 		return [32]byte{}
 	}
-	return bytesutil.ToBytes32(s.head.state.GenesisValidatorRoot())
+	return bytesutil.ToBytes32(s.head.state.GenesisValidatorsRoot())
 }
 
 // CurrentFork retrieves the latest fork information of the beacon chain.
@@ -286,23 +283,7 @@ func (s *Service) IsCanonical(ctx context.Context, blockRoot [32]byte) (bool, er
 // ChainHeads returns all possible chain heads (leaves of fork choice tree).
 // Heads roots and heads slots are returned.
 func (s *Service) ChainHeads() ([][32]byte, []types.Slot) {
-	nodes := s.ProtoArrayStore().Nodes()
-
-	// Deliberate choice to not preallocate space for below.
-	// Heads cant be more than 2-3 in the worst case where pre-allocation will be 64 to begin with.
-	headsRoots := make([][32]byte, 0)
-	headsSlots := make([]types.Slot, 0)
-
-	nonExistentNode := ^uint64(0)
-	for _, node := range nodes {
-		// Possible heads have no children.
-		if node.BestDescendant() == nonExistentNode && node.BestChild() == nonExistentNode {
-			headsRoots = append(headsRoots, node.Root())
-			headsSlots = append(headsSlots, node.Slot())
-		}
-	}
-
-	return headsRoots, headsSlots
+	return s.cfg.ForkChoiceStore.Tips()
 }
 
 // HeadPublicKeyToValidatorIndex returns the validator index of the `pubkey` in current head state.
@@ -329,14 +310,34 @@ func (s *Service) HeadValidatorIndexToPublicKey(_ context.Context, index types.V
 	return v.PublicKey(), nil
 }
 
+// ForkChoicer returns the forkchoice interface
+func (s *Service) ForkChoicer() forkchoice.ForkChoicer {
+	return s.cfg.ForkChoiceStore
+}
+
 // IsOptimistic returns true if the current head is optimistic.
 func (s *Service) IsOptimistic(ctx context.Context) (bool, error) {
 	s.headLock.RLock()
 	defer s.headLock.RUnlock()
-	return s.cfg.ForkChoiceStore.Optimistic(ctx, s.head.root, s.head.slot)
+	if slots.ToEpoch(s.CurrentSlot()) < params.BeaconConfig().BellatrixForkEpoch {
+		return false, nil
+	}
+
+	return s.cfg.ForkChoiceStore.IsOptimistic(ctx, s.head.root)
+}
+
+// IsOptimisticForRoot takes the root and slot as aguments instead of the current head
+// and returns true if it is optimistic.
+func (s *Service) IsOptimisticForRoot(ctx context.Context, root [32]byte) (bool, error) {
+	return s.cfg.ForkChoiceStore.IsOptimistic(ctx, root)
 }
 
 // SetGenesisTime sets the genesis time of beacon chain.
 func (s *Service) SetGenesisTime(t time.Time) {
 	s.genesisTime = t
 }
+
+// ForkChoiceStore returns the fork choice store in the service
+func (s *Service) ForkChoiceStore() forkchoice.ForkChoicer {
+	return s.cfg.ForkChoiceStore
+}

beacon-chain/blockchain/chain_info_test.go

@@ -8,6 +8,7 @@ import (
 	types "github.com/prysmaticlabs/eth2-types"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
 	testDB "github.com/prysmaticlabs/prysm/beacon-chain/db/testing"
+	doublylinkedtree "github.com/prysmaticlabs/prysm/beacon-chain/forkchoice/doubly-linked-tree"
 	"github.com/prysmaticlabs/prysm/beacon-chain/forkchoice/protoarray"
 	v1 "github.com/prysmaticlabs/prysm/beacon-chain/state/v1"
 	fieldparams "github.com/prysmaticlabs/prysm/config/fieldparams"
@@ -40,6 +41,12 @@ func TestHeadRoot_Nil(t *testing.T) {
 	assert.DeepEqual(t, params.BeaconConfig().ZeroHash[:], headRoot, "Incorrect pre chain start value")
 }
 
+func TestService_ForkChoiceStore(t *testing.T) {
+	c := &Service{cfg: &config{ForkChoiceStore: doublylinkedtree.New(0, 0)}}
+	p := c.ForkChoiceStore()
+	require.Equal(t, 0, int(p.FinalizedEpoch()))
+}
+
 func TestFinalizedCheckpt_CanRetrieve(t *testing.T) {
 	beaconDB := testDB.SetupDB(t)
 
@@ -185,15 +192,15 @@ func TestCurrentFork_NilHeadSTate(t *testing.T) {
 	}
 }
 
-func TestGenesisValidatorRoot_CanRetrieve(t *testing.T) {
+func TestGenesisValidatorsRoot_CanRetrieve(t *testing.T) {
 	// Should not panic if head state is nil.
 	c := &Service{}
-	assert.Equal(t, [32]byte{}, c.GenesisValidatorRoot(), "Did not get correct genesis validator root")
+	assert.Equal(t, [32]byte{}, c.GenesisValidatorsRoot(), "Did not get correct genesis validators root")
 
 	s, err := v1.InitializeFromProto(&ethpb.BeaconState{GenesisValidatorsRoot: []byte{'a'}})
 	require.NoError(t, err)
 	c.head = &head{state: s}
-	assert.Equal(t, [32]byte{'a'}, c.GenesisValidatorRoot(), "Did not get correct genesis validator root")
+	assert.Equal(t, [32]byte{'a'}, c.GenesisValidatorsRoot(), "Did not get correct genesis validators root")
 }
 
 func TestHeadETH1Data_Nil(t *testing.T) {
@@ -265,39 +272,52 @@ func TestService_HeadSeed(t *testing.T) {
 	require.DeepEqual(t, seed, root)
 }
 
-func TestService_HeadGenesisValidatorRoot(t *testing.T) {
+func TestService_HeadGenesisValidatorsRoot(t *testing.T) {
 	s, _ := util.DeterministicGenesisState(t, 1)
 	c := &Service{}
 
 	c.head = &head{}
-	root := c.HeadGenesisValidatorRoot()
+	root := c.HeadGenesisValidatorsRoot()
 	require.Equal(t, [32]byte{}, root)
 
 	c.head = &head{state: s}
-	root = c.HeadGenesisValidatorRoot()
-	require.DeepEqual(t, root[:], s.GenesisValidatorRoot())
+	root = c.HeadGenesisValidatorsRoot()
+	require.DeepEqual(t, root[:], s.GenesisValidatorsRoot())
 }
-
-func TestService_ProtoArrayStore(t *testing.T) {
-	c := &Service{cfg: &config{ForkChoiceStore: protoarray.New(0, 0, [32]byte{})}}
-	p := c.ProtoArrayStore()
-	require.Equal(t, 0, int(p.FinalizedEpoch()))
-}
-
-func TestService_ChainHeads(t *testing.T) {
+func TestService_ChainHeads_ProtoArray(t *testing.T) {
 	ctx := context.Background()
-	c := &Service{cfg: &config{ForkChoiceStore: protoarray.New(0, 0, [32]byte{})}}
-	require.NoError(t, c.cfg.ForkChoiceStore.ProcessBlock(ctx, 100, [32]byte{'a'}, [32]byte{}, [32]byte{}, 0, 0))
-	require.NoError(t, c.cfg.ForkChoiceStore.ProcessBlock(ctx, 101, [32]byte{'b'}, [32]byte{'a'}, [32]byte{}, 0, 0))
-	require.NoError(t, c.cfg.ForkChoiceStore.ProcessBlock(ctx, 102, [32]byte{'c'}, [32]byte{'b'}, [32]byte{}, 0, 0))
-	require.NoError(t, c.cfg.ForkChoiceStore.ProcessBlock(ctx, 103, [32]byte{'d'}, [32]byte{}, [32]byte{}, 0, 0))
-	require.NoError(t, c.cfg.ForkChoiceStore.ProcessBlock(ctx, 104, [32]byte{'e'}, [32]byte{'b'}, [32]byte{}, 0, 0))
+	c := &Service{cfg: &config{ForkChoiceStore: protoarray.New(0, 0,
+		params.BeaconConfig().ZeroHash)}}
+	require.NoError(t, c.cfg.ForkChoiceStore.ProcessBlock(ctx, 100, [32]byte{'a'}, [32]byte{}, 0, 0, false))
+	require.NoError(t, c.cfg.ForkChoiceStore.ProcessBlock(ctx, 101, [32]byte{'b'}, [32]byte{'a'}, 0, 0, false))
+	require.NoError(t, c.cfg.ForkChoiceStore.ProcessBlock(ctx, 102, [32]byte{'c'}, [32]byte{'b'}, 0, 0, false))
+	require.NoError(t, c.cfg.ForkChoiceStore.ProcessBlock(ctx, 103, [32]byte{'d'}, [32]byte{}, 0, 0, false))
+	require.NoError(t, c.cfg.ForkChoiceStore.ProcessBlock(ctx, 104, [32]byte{'e'}, [32]byte{'b'}, 0, 0, false))
 
 	roots, slots := c.ChainHeads()
 	require.DeepEqual(t, [][32]byte{{'c'}, {'d'}, {'e'}}, roots)
 	require.DeepEqual(t, []types.Slot{102, 103, 104}, slots)
 }
 
+func TestService_ChainHeads_DoublyLinkedTree(t *testing.T) {
+	ctx := context.Background()
+	c := &Service{cfg: &config{ForkChoiceStore: doublylinkedtree.New(0, 0)}}
+	require.NoError(t, c.cfg.ForkChoiceStore.ProcessBlock(ctx, 100, [32]byte{'a'}, [32]byte{}, 0, 0, false))
+	require.NoError(t, c.cfg.ForkChoiceStore.ProcessBlock(ctx, 101, [32]byte{'b'}, [32]byte{'a'}, 0, 0, false))
+	require.NoError(t, c.cfg.ForkChoiceStore.ProcessBlock(ctx, 102, [32]byte{'c'}, [32]byte{'b'}, 0, 0, false))
+	require.NoError(t, c.cfg.ForkChoiceStore.ProcessBlock(ctx, 103, [32]byte{'d'}, [32]byte{}, 0, 0, false))
+	require.NoError(t, c.cfg.ForkChoiceStore.ProcessBlock(ctx, 104, [32]byte{'e'}, [32]byte{'b'}, 0, 0, false))
+
+	roots, slots := c.ChainHeads()
+	require.Equal(t, 3, len(roots))
+	rootMap := map[[32]byte]types.Slot{[32]byte{'c'}: 102, [32]byte{'d'}: 103, [32]byte{'e'}: 104}
+	for i, root := range roots {
+		slot, ok := rootMap[root]
+		require.Equal(t, true, ok)
+		require.Equal(t, slot, slots[i])
+	}
+}
+
 func TestService_HeadPublicKeyToValidatorIndex(t *testing.T) {
 	s, _ := util.DeterministicGenesisState(t, 10)
 	c := &Service{}
@@ -356,13 +376,64 @@ func TestService_HeadValidatorIndexToPublicKeyNil(t *testing.T) {
 	require.Equal(t, [fieldparams.BLSPubkeyLength]byte{}, p)
 }
 
-func TestService_IsOptimistic(t *testing.T) {
+func TestService_IsOptimistic_ProtoArray(t *testing.T) {
+	params.SetupTestConfigCleanup(t)
+	cfg := params.BeaconConfig()
+	cfg.BellatrixForkEpoch = 0
+	params.OverrideBeaconConfig(cfg)
+
 	ctx := context.Background()
 	c := &Service{cfg: &config{ForkChoiceStore: protoarray.New(0, 0, [32]byte{})}, head: &head{slot: 101, root: [32]byte{'b'}}}
-	require.NoError(t, c.cfg.ForkChoiceStore.ProcessBlock(ctx, 100, [32]byte{'a'}, [32]byte{}, [32]byte{}, 0, 0))
-	require.NoError(t, c.cfg.ForkChoiceStore.ProcessBlock(ctx, 101, [32]byte{'b'}, [32]byte{'a'}, [32]byte{}, 0, 0))
+	require.NoError(t, c.cfg.ForkChoiceStore.ProcessBlock(ctx, 100, [32]byte{'a'}, [32]byte{}, 0, 0, true))
+	require.NoError(t, c.cfg.ForkChoiceStore.ProcessBlock(ctx, 101, [32]byte{'b'}, [32]byte{'a'}, 0, 0, true))
 
 	opt, err := c.IsOptimistic(ctx)
 	require.NoError(t, err)
 	require.Equal(t, true, opt)
 }
+
+func TestService_IsOptimistic_DoublyLinkedTree(t *testing.T) {
+	params.SetupTestConfigCleanup(t)
+	cfg := params.BeaconConfig()
+	cfg.BellatrixForkEpoch = 0
+	params.OverrideBeaconConfig(cfg)
+
+	ctx := context.Background()
+	c := &Service{cfg: &config{ForkChoiceStore: doublylinkedtree.New(0, 0)}, head: &head{slot: 101, root: [32]byte{'b'}}}
+	require.NoError(t, c.cfg.ForkChoiceStore.ProcessBlock(ctx, 100, [32]byte{'a'}, [32]byte{}, 0, 0, true))
+	require.NoError(t, c.cfg.ForkChoiceStore.ProcessBlock(ctx, 101, [32]byte{'b'}, [32]byte{'a'}, 0, 0, true))
+
+	opt, err := c.IsOptimistic(ctx)
+	require.NoError(t, err)
+	require.Equal(t, true, opt)
+}
+
+func TestService_IsOptimisticBeforeBellatrix(t *testing.T) {
+	ctx := context.Background()
+	c := &Service{genesisTime: time.Now()}
+	opt, err := c.IsOptimistic(ctx)
+	require.NoError(t, err)
+	require.Equal(t, false, opt)
+}
+
+func TestService_IsOptimisticForRoot_ProtoArray(t *testing.T) {
+	ctx := context.Background()
+	c := &Service{cfg: &config{ForkChoiceStore: protoarray.New(0, 0, [32]byte{})}, head: &head{slot: 101, root: [32]byte{'b'}}}
+	require.NoError(t, c.cfg.ForkChoiceStore.ProcessBlock(ctx, 100, [32]byte{'a'}, [32]byte{}, 0, 0, true))
+	require.NoError(t, c.cfg.ForkChoiceStore.ProcessBlock(ctx, 101, [32]byte{'b'}, [32]byte{'a'}, 0, 0, true))
+
+	opt, err := c.IsOptimisticForRoot(ctx, [32]byte{'a'})
+	require.NoError(t, err)
+	require.Equal(t, true, opt)
+}
+
+func TestService_IsOptimisticForRoot_DoublyLinkedTree(t *testing.T) {
+	ctx := context.Background()
+	c := &Service{cfg: &config{ForkChoiceStore: doublylinkedtree.New(0, 0)}, head: &head{slot: 101, root: [32]byte{'b'}}}
+	require.NoError(t, c.cfg.ForkChoiceStore.ProcessBlock(ctx, 100, [32]byte{'a'}, [32]byte{}, 0, 0, true))
+	require.NoError(t, c.cfg.ForkChoiceStore.ProcessBlock(ctx, 101, [32]byte{'b'}, [32]byte{'a'}, 0, 0, true))
+
+	opt, err := c.IsOptimisticForRoot(ctx, [32]byte{'a'})
+	require.NoError(t, err)
+	require.Equal(t, true, opt)
+}

beacon-chain/blockchain/head.go

@@ -10,6 +10,7 @@ import (
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/feed"
 	statefeed "github.com/prysmaticlabs/prysm/beacon-chain/core/feed/state"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
+	doublylinkedtree "github.com/prysmaticlabs/prysm/beacon-chain/forkchoice/doubly-linked-tree"
 	"github.com/prysmaticlabs/prysm/beacon-chain/forkchoice/protoarray"
 	"github.com/prysmaticlabs/prysm/beacon-chain/state"
 	"github.com/prysmaticlabs/prysm/config/features"
@@ -77,8 +78,13 @@ func (s *Service) updateHead(ctx context.Context, balances []uint64) error {
 		if err != nil {
 			return err
 		}
-		s.cfg.ForkChoiceStore = protoarray.New(j.Epoch, f.Epoch, bytesutil.ToBytes32(f.Root))
-		if err := s.insertBlockToForkChoiceStore(ctx, jb.Block(), headStartRoot, f, j); err != nil {
+		if features.Get().EnableForkChoiceDoublyLinkedTree {
+			s.cfg.ForkChoiceStore = doublylinkedtree.New(j.Epoch, f.Epoch)
+		} else {
+			s.cfg.ForkChoiceStore = protoarray.New(j.Epoch, f.Epoch, bytesutil.ToBytes32(f.Root))
+		}
+		// TODO(10261) send optimistic status
+		if err := s.insertBlockToForkChoiceStore(ctx, jb.Block(), headStartRoot, f, j, false /* optimistic status */); err != nil {
 			return err
 		}
 	}
@@ -265,10 +271,10 @@ func (s *Service) headState(ctx context.Context) state.BeaconState {
 	return s.head.state.Copy()
 }
 
-// This returns the genesis validator root of the head state.
+// This returns the genesis validators root of the head state.
 // This is a lock free version.
-func (s *Service) headGenesisValidatorRoot() [32]byte {
-	return bytesutil.ToBytes32(s.head.state.GenesisValidatorRoot())
+func (s *Service) headGenesisValidatorsRoot() [32]byte {
+	return bytesutil.ToBytes32(s.head.state.GenesisValidatorsRoot())
 }
 
 // This returns the validator referenced by the provided index in

beacon-chain/blockchain/head_sync_committee_info.go

@@ -130,7 +130,7 @@ func (s *Service) domainWithHeadState(ctx context.Context, slot types.Slot, doma
 	if err != nil {
 		return nil, err
 	}
-	return signing.Domain(headState.Fork(), slots.ToEpoch(headState.Slot()), domain, headState.GenesisValidatorRoot())
+	return signing.Domain(headState.Fork(), slots.ToEpoch(headState.Slot()), domain, headState.GenesisValidatorsRoot())
 }
 
 // returns the head state that is advanced up to `slot`. It utilizes the cache `syncCommitteeHeadState` by retrieving using `slot` as key.

beacon-chain/blockchain/head_sync_committee_info_test.go

@@ -122,7 +122,7 @@ func TestService_HeadSyncCommitteeDomain(t *testing.T) {
 	c := &Service{}
 	c.head = &head{state: s}
 
-	wanted, err := signing.Domain(s.Fork(), slots.ToEpoch(s.Slot()), params.BeaconConfig().DomainSyncCommittee, s.GenesisValidatorRoot())
+	wanted, err := signing.Domain(s.Fork(), slots.ToEpoch(s.Slot()), params.BeaconConfig().DomainSyncCommittee, s.GenesisValidatorsRoot())
 	require.NoError(t, err)
 
 	d, err := c.HeadSyncCommitteeDomain(context.Background(), 0)
@@ -136,7 +136,7 @@ func TestService_HeadSyncContributionProofDomain(t *testing.T) {
 	c := &Service{}
 	c.head = &head{state: s}
 
-	wanted, err := signing.Domain(s.Fork(), slots.ToEpoch(s.Slot()), params.BeaconConfig().DomainContributionAndProof, s.GenesisValidatorRoot())
+	wanted, err := signing.Domain(s.Fork(), slots.ToEpoch(s.Slot()), params.BeaconConfig().DomainContributionAndProof, s.GenesisValidatorsRoot())
 	require.NoError(t, err)
 
 	d, err := c.HeadSyncContributionProofDomain(context.Background(), 0)
@@ -150,7 +150,7 @@ func TestService_HeadSyncSelectionProofDomain(t *testing.T) {
 	c := &Service{}
 	c.head = &head{state: s}
 
-	wanted, err := signing.Domain(s.Fork(), slots.ToEpoch(s.Slot()), params.BeaconConfig().DomainSyncCommitteeSelectionProof, s.GenesisValidatorRoot())
+	wanted, err := signing.Domain(s.Fork(), slots.ToEpoch(s.Slot()), params.BeaconConfig().DomainSyncCommitteeSelectionProof, s.GenesisValidatorsRoot())
 	require.NoError(t, err)
 
 	d, err := c.HeadSyncSelectionProofDomain(context.Background(), 0)

beacon-chain/blockchain/info.go

@@ -1,99 +0,0 @@
-package blockchain
-
-import (
-	"encoding/hex"
-	"fmt"
-	"net/http"
-
-	"github.com/emicklei/dot"
-	"github.com/prysmaticlabs/prysm/config/params"
-)
-
-const template = `<html>
-<head>
-    <script src="//cdnjs.cloudflare.com/ajax/libs/viz.js/2.1.2/viz.js"></script>
-    <script src="//cdnjs.cloudflare.com/ajax/libs/viz.js/2.1.2/full.render.js"></script>
-<body>
-    <script type="application/javascript">
-        var graph = ` + "`%s`;" + `
-        var viz = new Viz();
-        viz.renderSVGElement(graph) // reading the graph.
-            .then(function(element) {
-                document.body.appendChild(element); // appends to document.
-            })
-            .catch(error => {
-                // Create a new Viz instance (@see Caveats page for more info)
-                viz = new Viz();
-                // Possibly display the error
-                console.error(error);
-            });
-    </script>
-</head>
-</body>
-</html>`
-
-// TreeHandler is a handler to serve /tree page in metrics.
-func (s *Service) TreeHandler(w http.ResponseWriter, r *http.Request) {
-	headState, err := s.HeadState(r.Context())
-	if err != nil {
-		log.WithError(err).Error("Could not get head state")
-		return
-	}
-	if headState == nil || headState.IsNil() {
-		if _, err := w.Write([]byte("Unavailable during initial syncing")); err != nil {
-			log.WithError(err).Error("Failed to render p2p info page")
-		}
-	}
-
-	nodes := s.cfg.ForkChoiceStore.Nodes()
-
-	graph := dot.NewGraph(dot.Directed)
-	graph.Attr("rankdir", "RL")
-	graph.Attr("labeljust", "l")
-
-	dotNodes := make([]*dot.Node, len(nodes))
-	avgBalance := uint64(averageBalance(headState.Balances()))
-
-	for i := len(nodes) - 1; i >= 0; i-- {
-		// Construct label for each node.
-		slot := fmt.Sprintf("%d", nodes[i].Slot())
-		weight := fmt.Sprintf("%d", nodes[i].Weight()/1e9) // Convert unit Gwei to unit ETH.
-		votes := fmt.Sprintf("%d", nodes[i].Weight()/1e9/avgBalance)
-		index := fmt.Sprintf("%d", i)
-		g := nodes[i].Graffiti()
-		graffiti := hex.EncodeToString(g[:8])
-		label := "slot: " + slot + "\n votes: " + votes + "\n weight: " + weight + "\n graffiti: " + graffiti
-		var dotN dot.Node
-		if nodes[i].Parent() != ^uint64(0) {
-			dotN = graph.Node(index).Box().Attr("label", label)
-		}
-
-		if nodes[i].Slot() == s.HeadSlot() &&
-			nodes[i].BestDescendant() == ^uint64(0) &&
-			nodes[i].Parent() != ^uint64(0) {
-			dotN = dotN.Attr("color", "green")
-		}
-
-		dotNodes[i] = &dotN
-	}
-
-	for i := len(nodes) - 1; i >= 0; i-- {
-		if nodes[i].Parent() != ^uint64(0) && nodes[i].Parent() < uint64(len(dotNodes)) {
-			graph.Edge(*dotNodes[i], *dotNodes[nodes[i].Parent()])
-		}
-	}
-
-	w.WriteHeader(http.StatusOK)
-	w.Header().Set("Content-Type", "text/html")
-	if _, err := fmt.Fprintf(w, template, graph.String()); err != nil {
-		log.WithError(err).Error("Failed to render p2p info page")
-	}
-}
-
-func averageBalance(balances []uint64) float64 {
-	total := uint64(0)
-	for i := 0; i < len(balances); i++ {
-		total += balances[i]
-	}
-	return float64(total) / float64(len(balances)) / float64(params.BeaconConfig().GweiPerEth)
-}

beacon-chain/blockchain/info_test.go

@@ -1,50 +0,0 @@
-package blockchain
-
-import (
-	"context"
-	"net/http"
-	"net/http/httptest"
-	"testing"
-
-	testDB "github.com/prysmaticlabs/prysm/beacon-chain/db/testing"
-	"github.com/prysmaticlabs/prysm/beacon-chain/forkchoice/protoarray"
-	"github.com/prysmaticlabs/prysm/beacon-chain/state/stategen"
-	"github.com/prysmaticlabs/prysm/config/params"
-	"github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1/wrapper"
-	"github.com/prysmaticlabs/prysm/testing/assert"
-	"github.com/prysmaticlabs/prysm/testing/require"
-	"github.com/prysmaticlabs/prysm/testing/util"
-)
-
-func TestService_TreeHandler(t *testing.T) {
-	req, err := http.NewRequest("GET", "/tree", nil)
-	require.NoError(t, err)
-
-	ctx := context.Background()
-	beaconDB := testDB.SetupDB(t)
-	headState, err := util.NewBeaconState()
-	require.NoError(t, err)
-	require.NoError(t, headState.SetBalances([]uint64{params.BeaconConfig().GweiPerEth}))
-	fcs := protoarray.New(
-		0, // justifiedEpoch
-		0, // finalizedEpoch
-		[32]byte{'a'},
-	)
-	opts := []Option{
-		WithDatabase(beaconDB),
-		WithStateGen(stategen.New(beaconDB)),
-		WithForkChoiceStore(fcs),
-	}
-	s, err := NewService(ctx, opts...)
-	require.NoError(t, err)
-	require.NoError(t, s.cfg.ForkChoiceStore.ProcessBlock(ctx, 0, [32]byte{'a'}, [32]byte{'g'}, [32]byte{'c'}, 0, 0))
-	require.NoError(t, s.cfg.ForkChoiceStore.ProcessBlock(ctx, 1, [32]byte{'b'}, [32]byte{'a'}, [32]byte{'c'}, 0, 0))
-	s.setHead([32]byte{'a'}, wrapper.WrappedPhase0SignedBeaconBlock(util.NewBeaconBlock()), headState)
-
-	rr := httptest.NewRecorder()
-	handler := http.HandlerFunc(s.TreeHandler)
-
-	handler.ServeHTTP(rr, req)
-
-	assert.Equal(t, http.StatusOK, rr.Code)
-}

beacon-chain/blockchain/mock_engine_test.go

@@ -0,0 +1,49 @@
+package blockchain
+
+import (
+	"context"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/pkg/errors"
+	enginev1 "github.com/prysmaticlabs/prysm/proto/engine/v1"
+)
+
+type mockEngineService struct {
+	newPayloadError error
+	forkchoiceError error
+	blks            map[[32]byte]*enginev1.ExecutionBlock
+}
+
+func (m *mockEngineService) NewPayload(context.Context, *enginev1.ExecutionPayload) ([]byte, error) {
+	return nil, m.newPayloadError
+}
+
+func (m *mockEngineService) ForkchoiceUpdated(context.Context, *enginev1.ForkchoiceState, *enginev1.PayloadAttributes) (*enginev1.PayloadIDBytes, []byte, error) {
+	return nil, nil, m.forkchoiceError
+}
+
+func (*mockEngineService) GetPayloadV1(
+	_ context.Context, _ enginev1.PayloadIDBytes,
+) *enginev1.ExecutionPayload {
+	return nil
+}
+
+func (*mockEngineService) GetPayload(context.Context, [8]byte) (*enginev1.ExecutionPayload, error) {
+	return nil, nil
+}
+
+func (*mockEngineService) ExchangeTransitionConfiguration(context.Context, *enginev1.TransitionConfiguration) error {
+	return nil
+}
+
+func (*mockEngineService) LatestExecutionBlock(context.Context) (*enginev1.ExecutionBlock, error) {
+	return nil, nil
+}
+
+func (m *mockEngineService) ExecutionBlockByHash(_ context.Context, hash common.Hash) (*enginev1.ExecutionBlock, error) {
+	blk, ok := m.blks[common.BytesToHash(hash.Bytes())]
+	if !ok {
+		return nil, errors.New("block not found")
+	}
+	return blk, nil
+}

beacon-chain/blockchain/new_slot_test.go

@@ -25,11 +25,11 @@ func TestService_newSlot(t *testing.T) {
 	}
 	ctx := context.Background()
 
-	require.NoError(t, fcs.ProcessBlock(ctx, 0, [32]byte{}, [32]byte{}, [32]byte{}, 0, 0))        // genesis
-	require.NoError(t, fcs.ProcessBlock(ctx, 32, [32]byte{'a'}, [32]byte{}, [32]byte{}, 0, 0))    // finalized
-	require.NoError(t, fcs.ProcessBlock(ctx, 64, [32]byte{'b'}, [32]byte{'a'}, [32]byte{}, 0, 0)) // justified
-	require.NoError(t, fcs.ProcessBlock(ctx, 96, [32]byte{'c'}, [32]byte{'a'}, [32]byte{}, 0, 0)) // best justified
-	require.NoError(t, fcs.ProcessBlock(ctx, 97, [32]byte{'d'}, [32]byte{}, [32]byte{}, 0, 0))    // bad
+	require.NoError(t, fcs.ProcessBlock(ctx, 0, [32]byte{}, [32]byte{}, 0, 0, false))        // genesis
+	require.NoError(t, fcs.ProcessBlock(ctx, 32, [32]byte{'a'}, [32]byte{}, 0, 0, false))    // finalized
+	require.NoError(t, fcs.ProcessBlock(ctx, 64, [32]byte{'b'}, [32]byte{'a'}, 0, 0, false)) // justified
+	require.NoError(t, fcs.ProcessBlock(ctx, 96, [32]byte{'c'}, [32]byte{'a'}, 0, 0, false)) // best justified
+	require.NoError(t, fcs.ProcessBlock(ctx, 97, [32]byte{'d'}, [32]byte{}, 0, 0, false))    // bad
 
 	type args struct {
 		slot          types.Slot

beacon-chain/blockchain/optimistic_sync.go

@@ -0,0 +1,160 @@
+package blockchain
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/pkg/errors"
+	"github.com/prysmaticlabs/prysm/beacon-chain/core/blocks"
+	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
+	v1 "github.com/prysmaticlabs/prysm/beacon-chain/powchain/engine-api-client/v1"
+	"github.com/prysmaticlabs/prysm/beacon-chain/state"
+	"github.com/prysmaticlabs/prysm/config/params"
+	"github.com/prysmaticlabs/prysm/encoding/bytesutil"
+	enginev1 "github.com/prysmaticlabs/prysm/proto/engine/v1"
+	ethpb "github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1"
+	"github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1/block"
+	"github.com/prysmaticlabs/prysm/runtime/version"
+	"github.com/sirupsen/logrus"
+)
+
+// notifyForkchoiceUpdate signals execution engine the fork choice updates. Execution engine should:
+// 1. Re-organizes the execution payload chain and corresponding state to make head_block_hash the head.
+// 2. Applies finality to the execution state: it irreversibly persists the chain of all execution payloads and corresponding state, up to and including finalized_block_hash.
+func (s *Service) notifyForkchoiceUpdate(ctx context.Context, headBlk block.BeaconBlock, finalizedRoot [32]byte) (*enginev1.PayloadIDBytes, error) {
+	if headBlk == nil || headBlk.IsNil() || headBlk.Body().IsNil() {
+		return nil, errors.New("nil head block")
+	}
+	// Must not call fork choice updated until the transition conditions are met on the Pow network.
+	if isPreBellatrix(headBlk.Version()) {
+		return nil, nil
+	}
+	isExecutionBlk, err := blocks.ExecutionBlock(headBlk.Body())
+	if err != nil {
+		return nil, errors.Wrap(err, "could not determine if block is execution block")
+	}
+	if !isExecutionBlk {
+		return nil, nil
+	}
+	headPayload, err := headBlk.Body().ExecutionPayload()
+	if err != nil {
+		return nil, errors.Wrap(err, "could not get execution payload")
+	}
+	finalizedBlock, err := s.cfg.BeaconDB.Block(ctx, s.ensureRootNotZeros(finalizedRoot))
+	if err != nil {
+		return nil, errors.Wrap(err, "could not get finalized block")
+	}
+	var finalizedHash []byte
+	if isPreBellatrix(finalizedBlock.Block().Version()) {
+		finalizedHash = params.BeaconConfig().ZeroHash[:]
+	} else {
+		payload, err := finalizedBlock.Block().Body().ExecutionPayload()
+		if err != nil {
+			return nil, errors.Wrap(err, "could not get finalized block execution payload")
+		}
+		finalizedHash = payload.BlockHash
+	}
+
+	fcs := &enginev1.ForkchoiceState{
+		HeadBlockHash:      headPayload.BlockHash,
+		SafeBlockHash:      headPayload.BlockHash,
+		FinalizedBlockHash: finalizedHash,
+	}
+
+	// payload attribute is only required when requesting payload, here we are just updating fork choice, so it is nil.
+	payloadID, _, err := s.cfg.ExecutionEngineCaller.ForkchoiceUpdated(ctx, fcs, nil /*payload attribute*/)
+	if err != nil {
+		switch err {
+		case v1.ErrAcceptedSyncingPayloadStatus:
+			log.WithFields(logrus.Fields{
+				"headSlot":      headBlk.Slot(),
+				"headHash":      fmt.Sprintf("%#x", bytesutil.Trunc(headPayload.BlockHash)),
+				"finalizedHash": fmt.Sprintf("%#x", bytesutil.Trunc(finalizedHash)),
+			}).Info("Called fork choice updated with optimistic block")
+			return payloadID, nil
+		default:
+			return nil, errors.Wrap(err, "could not notify forkchoice update from execution engine")
+		}
+	}
+	return payloadID, nil
+}
+
+// notifyForkchoiceUpdate signals execution engine on a new payload
+func (s *Service) notifyNewPayload(ctx context.Context, preStateVersion int, header *ethpb.ExecutionPayloadHeader, postState state.BeaconState, blk block.SignedBeaconBlock) error {
+	if postState == nil {
+		return errors.New("pre and post states must not be nil")
+	}
+	// Execution payload is only supported in Bellatrix and beyond.
+	if isPreBellatrix(postState.Version()) {
+		return nil
+	}
+	if err := helpers.BeaconBlockIsNil(blk); err != nil {
+		return err
+	}
+	body := blk.Block().Body()
+	enabled, err := blocks.ExecutionEnabled(postState, blk.Block().Body())
+	if err != nil {
+		return errors.Wrap(err, "could not determine if execution is enabled")
+	}
+	if !enabled {
+		return nil
+	}
+	payload, err := body.ExecutionPayload()
+	if err != nil {
+		return errors.Wrap(err, "could not get execution payload")
+	}
+	_, err = s.cfg.ExecutionEngineCaller.NewPayload(ctx, payload)
+	if err != nil {
+		switch err {
+		case v1.ErrAcceptedSyncingPayloadStatus:
+			log.WithFields(logrus.Fields{
+				"slot":      postState.Slot(),
+				"blockHash": fmt.Sprintf("%#x", bytesutil.Trunc(payload.BlockHash)),
+			}).Info("Called new payload with optimistic block")
+			return nil
+		default:
+			return errors.Wrap(err, "could not validate execution payload from execution engine")
+		}
+	}
+
+	// During the transition event, the transition block should be verified for sanity.
+	if isPreBellatrix(preStateVersion) {
+		return nil
+	}
+	atTransition, err := blocks.IsMergeTransitionBlockUsingPayloadHeader(header, body)
+	if err != nil {
+		return errors.Wrap(err, "could not check if merge block is terminal")
+	}
+	if !atTransition {
+		return nil
+	}
+	return s.validateMergeBlock(ctx, blk)
+}
+
+// isPreBellatrix returns true if input version is before bellatrix fork.
+func isPreBellatrix(v int) bool {
+	return v == version.Phase0 || v == version.Altair
+}
+
+// optimisticCandidateBlock returns true if this block can be optimistically synced.
+//
+// Spec pseudocode definition:
+// def is_optimistic_candidate_block(opt_store: OptimisticStore, current_slot: Slot, block: BeaconBlock) -> bool:
+//     justified_root = opt_store.block_states[opt_store.head_block_root].current_justified_checkpoint.root
+//     justified_is_execution_block = is_execution_block(opt_store.blocks[justified_root])
+//     block_is_deep = block.slot + SAFE_SLOTS_TO_IMPORT_OPTIMISTICALLY <= current_slot
+//     return justified_is_execution_block or block_is_deep
+func (s *Service) optimisticCandidateBlock(ctx context.Context, blk block.BeaconBlock) (bool, error) {
+	if blk.Slot()+params.BeaconConfig().SafeSlotsToImportOptimistically <= s.CurrentSlot() {
+		return true, nil
+	}
+	j := s.store.JustifiedCheckpt()
+	if j == nil {
+		return false, errNilJustifiedInStore
+	}
+	jBlock, err := s.cfg.BeaconDB.Block(ctx, bytesutil.ToBytes32(j.Root))
+	if err != nil {
+		return false, err
+	}
+	return blocks.ExecutionBlock(jBlock.Block().Body())
+}

beacon-chain/blockchain/optimistic_sync_test.go

@@ -0,0 +1,450 @@
+package blockchain
+
+import (
+	"context"
+	"testing"
+	"time"
+
+	testDB "github.com/prysmaticlabs/prysm/beacon-chain/db/testing"
+	"github.com/prysmaticlabs/prysm/beacon-chain/forkchoice/protoarray"
+	engine "github.com/prysmaticlabs/prysm/beacon-chain/powchain/engine-api-client/v1"
+	"github.com/prysmaticlabs/prysm/beacon-chain/state"
+	"github.com/prysmaticlabs/prysm/beacon-chain/state/stategen"
+	fieldparams "github.com/prysmaticlabs/prysm/config/fieldparams"
+	"github.com/prysmaticlabs/prysm/config/params"
+	"github.com/prysmaticlabs/prysm/encoding/bytesutil"
+	v1 "github.com/prysmaticlabs/prysm/proto/engine/v1"
+	ethpb "github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1"
+	"github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1/block"
+	"github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1/wrapper"
+	"github.com/prysmaticlabs/prysm/runtime/version"
+	"github.com/prysmaticlabs/prysm/testing/require"
+	"github.com/prysmaticlabs/prysm/testing/util"
+	"github.com/prysmaticlabs/prysm/time/slots"
+)
+
+func Test_NotifyForkchoiceUpdate(t *testing.T) {
+	ctx := context.Background()
+	beaconDB := testDB.SetupDB(t)
+	altairBlk, err := wrapper.WrappedSignedBeaconBlock(util.NewBeaconBlockAltair())
+	require.NoError(t, err)
+	altairBlkRoot, err := altairBlk.Block().HashTreeRoot()
+	require.NoError(t, err)
+	bellatrixBlk, err := wrapper.WrappedSignedBeaconBlock(util.NewBeaconBlockBellatrix())
+	require.NoError(t, err)
+	bellatrixBlkRoot, err := bellatrixBlk.Block().HashTreeRoot()
+	require.NoError(t, err)
+	require.NoError(t, beaconDB.SaveBlock(ctx, altairBlk))
+	require.NoError(t, beaconDB.SaveBlock(ctx, bellatrixBlk))
+
+	fcs := protoarray.New(0, 0, [32]byte{'a'})
+	opts := []Option{
+		WithDatabase(beaconDB),
+		WithStateGen(stategen.New(beaconDB)),
+		WithForkChoiceStore(fcs),
+	}
+	service, err := NewService(ctx, opts...)
+	require.NoError(t, err)
+
+	tests := []struct {
+		name             string
+		blk              block.BeaconBlock
+		finalizedRoot    [32]byte
+		newForkchoiceErr error
+		errString        string
+	}{
+		{
+			name:      "nil block",
+			errString: "nil head block",
+		},
+		{
+			name: "phase0 block",
+			blk: func() block.BeaconBlock {
+				b, err := wrapper.WrappedBeaconBlock(&ethpb.BeaconBlock{Body: &ethpb.BeaconBlockBody{}})
+				require.NoError(t, err)
+				return b
+			}(),
+		},
+		{
+			name: "altair block",
+			blk: func() block.BeaconBlock {
+				b, err := wrapper.WrappedBeaconBlock(&ethpb.BeaconBlockAltair{Body: &ethpb.BeaconBlockBodyAltair{}})
+				require.NoError(t, err)
+				return b
+			}(),
+		},
+		{
+			name: "not execution block",
+			blk: func() block.BeaconBlock {
+				b, err := wrapper.WrappedBeaconBlock(&ethpb.BeaconBlockBellatrix{
+					Body: &ethpb.BeaconBlockBodyBellatrix{
+						ExecutionPayload: &v1.ExecutionPayload{
+							ParentHash:    make([]byte, fieldparams.RootLength),
+							FeeRecipient:  make([]byte, fieldparams.FeeRecipientLength),
+							StateRoot:     make([]byte, fieldparams.RootLength),
+							ReceiptsRoot:  make([]byte, fieldparams.RootLength),
+							LogsBloom:     make([]byte, fieldparams.LogsBloomLength),
+							PrevRandao:    make([]byte, fieldparams.RootLength),
+							BaseFeePerGas: make([]byte, fieldparams.RootLength),
+							BlockHash:     make([]byte, fieldparams.RootLength),
+						},
+					},
+				})
+				require.NoError(t, err)
+				return b
+			}(),
+		},
+		{
+			name: "happy case: finalized root is altair block",
+			blk: func() block.BeaconBlock {
+				b, err := wrapper.WrappedBeaconBlock(&ethpb.BeaconBlockBellatrix{
+					Body: &ethpb.BeaconBlockBodyBellatrix{
+						ExecutionPayload: &v1.ExecutionPayload{},
+					},
+				})
+				require.NoError(t, err)
+				return b
+			}(),
+			finalizedRoot: altairBlkRoot,
+		},
+		{
+			name: "happy case: finalized root is bellatrix block",
+			blk: func() block.BeaconBlock {
+				b, err := wrapper.WrappedBeaconBlock(&ethpb.BeaconBlockBellatrix{
+					Body: &ethpb.BeaconBlockBodyBellatrix{
+						ExecutionPayload: &v1.ExecutionPayload{},
+					},
+				})
+				require.NoError(t, err)
+				return b
+			}(),
+			finalizedRoot: bellatrixBlkRoot,
+		},
+		{
+			name: "forkchoice updated with optimistic block",
+			blk: func() block.BeaconBlock {
+				b, err := wrapper.WrappedBeaconBlock(&ethpb.BeaconBlockBellatrix{
+					Body: &ethpb.BeaconBlockBodyBellatrix{
+						ExecutionPayload: &v1.ExecutionPayload{},
+					},
+				})
+				require.NoError(t, err)
+				return b
+			}(),
+			newForkchoiceErr: engine.ErrAcceptedSyncingPayloadStatus,
+			finalizedRoot:    bellatrixBlkRoot,
+		},
+		{
+			name: "forkchoice updated with invalid block",
+			blk: func() block.BeaconBlock {
+				b, err := wrapper.WrappedBeaconBlock(&ethpb.BeaconBlockBellatrix{
+					Body: &ethpb.BeaconBlockBodyBellatrix{
+						ExecutionPayload: &v1.ExecutionPayload{},
+					},
+				})
+				require.NoError(t, err)
+				return b
+			}(),
+			newForkchoiceErr: engine.ErrInvalidPayloadStatus,
+			finalizedRoot:    bellatrixBlkRoot,
+			errString:        "could not notify forkchoice update from execution engine: payload status is INVALID",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			engine := &mockEngineService{forkchoiceError: tt.newForkchoiceErr}
+			service.cfg.ExecutionEngineCaller = engine
+			_, err := service.notifyForkchoiceUpdate(ctx, tt.blk, tt.finalizedRoot)
+			if tt.errString != "" {
+				require.ErrorContains(t, tt.errString, err)
+			} else {
+				require.NoError(t, err)
+			}
+		})
+	}
+}
+
+func Test_NotifyNewPayload(t *testing.T) {
+	cfg := params.BeaconConfig()
+	cfg.TerminalTotalDifficulty = "2"
+	params.OverrideBeaconConfig(cfg)
+
+	ctx := context.Background()
+	beaconDB := testDB.SetupDB(t)
+	fcs := protoarray.New(0, 0, [32]byte{'a'})
+	opts := []Option{
+		WithDatabase(beaconDB),
+		WithStateGen(stategen.New(beaconDB)),
+		WithForkChoiceStore(fcs),
+	}
+	phase0State, _ := util.DeterministicGenesisState(t, 1)
+	altairState, _ := util.DeterministicGenesisStateAltair(t, 1)
+	bellatrixState, _ := util.DeterministicGenesisStateBellatrix(t, 2)
+	blk := &ethpb.SignedBeaconBlockBellatrix{
+		Block: &ethpb.BeaconBlockBellatrix{
+			Body: &ethpb.BeaconBlockBodyBellatrix{
+				ExecutionPayload: &v1.ExecutionPayload{},
+			},
+		},
+	}
+	bellatrixBlk, err := wrapper.WrappedSignedBeaconBlock(blk)
+	require.NoError(t, err)
+	service, err := NewService(ctx, opts...)
+	require.NoError(t, err)
+
+	tests := []struct {
+		name          string
+		preState      state.BeaconState
+		postState     state.BeaconState
+		blk           block.SignedBeaconBlock
+		newPayloadErr error
+		errString     string
+	}{
+		{
+			name:      "phase 0 post state",
+			postState: phase0State,
+			preState:  phase0State,
+		},
+		{
+			name:      "altair post state",
+			postState: altairState,
+			preState:  altairState,
+		},
+		{
+			name:      "nil post state",
+			preState:  phase0State,
+			errString: "pre and post states must not be nil",
+		},
+		{
+			name:      "nil beacon block",
+			postState: bellatrixState,
+			preState:  bellatrixState,
+			errString: "signed beacon block can't be nil",
+		},
+		{
+			name:          "new payload with optimistic block",
+			postState:     bellatrixState,
+			preState:      bellatrixState,
+			blk:           bellatrixBlk,
+			newPayloadErr: engine.ErrAcceptedSyncingPayloadStatus,
+		},
+		{
+			name:          "new payload with invalid block",
+			postState:     bellatrixState,
+			preState:      bellatrixState,
+			blk:           bellatrixBlk,
+			newPayloadErr: engine.ErrInvalidPayloadStatus,
+			errString:     "could not validate execution payload from execution engine: payload status is INVALID",
+		},
+		{
+			name:      "altair pre state",
+			postState: bellatrixState,
+			preState:  altairState,
+			blk:       bellatrixBlk,
+		},
+		{
+			name:      "could not get merge block",
+			postState: bellatrixState,
+			preState:  bellatrixState,
+			blk:       bellatrixBlk,
+			errString: "could not get merge block parent hash and total difficulty",
+		},
+		{
+			name:      "not at merge transition",
+			postState: bellatrixState,
+			preState:  bellatrixState,
+			blk: func() block.SignedBeaconBlock {
+				blk := &ethpb.SignedBeaconBlockBellatrix{
+					Block: &ethpb.BeaconBlockBellatrix{
+						Body: &ethpb.BeaconBlockBodyBellatrix{
+							ExecutionPayload: &v1.ExecutionPayload{
+								ParentHash:    make([]byte, fieldparams.RootLength),
+								FeeRecipient:  make([]byte, fieldparams.FeeRecipientLength),
+								StateRoot:     make([]byte, fieldparams.RootLength),
+								ReceiptsRoot:  make([]byte, fieldparams.RootLength),
+								LogsBloom:     make([]byte, fieldparams.LogsBloomLength),
+								PrevRandao:    make([]byte, fieldparams.RootLength),
+								BaseFeePerGas: make([]byte, fieldparams.RootLength),
+								BlockHash:     make([]byte, fieldparams.RootLength),
+							},
+						},
+					},
+				}
+				b, err := wrapper.WrappedSignedBeaconBlock(blk)
+				require.NoError(t, err)
+				return b
+			}(),
+		},
+		{
+			name:      "could not get merge block",
+			postState: bellatrixState,
+			preState:  bellatrixState,
+			blk:       bellatrixBlk,
+			errString: "could not get merge block parent hash and total difficulty",
+		},
+		{
+			name:      "happy case",
+			postState: bellatrixState,
+			preState:  bellatrixState,
+			blk: func() block.SignedBeaconBlock {
+				blk := &ethpb.SignedBeaconBlockBellatrix{
+					Block: &ethpb.BeaconBlockBellatrix{
+						Body: &ethpb.BeaconBlockBodyBellatrix{
+							ExecutionPayload: &v1.ExecutionPayload{
+								ParentHash: bytesutil.PadTo([]byte{'a'}, fieldparams.RootLength),
+							},
+						},
+					},
+				}
+				b, err := wrapper.WrappedSignedBeaconBlock(blk)
+				require.NoError(t, err)
+				return b
+			}(),
+		},
+	}
+	for _, tt := range tests {
+		engine := &mockEngineService{newPayloadError: tt.newPayloadErr, blks: map[[32]byte]*v1.ExecutionBlock{}}
+		engine.blks[[32]byte{'a'}] = &v1.ExecutionBlock{
+			ParentHash:      bytesutil.PadTo([]byte{'b'}, fieldparams.RootLength),
+			TotalDifficulty: "0x2",
+		}
+		engine.blks[[32]byte{'b'}] = &v1.ExecutionBlock{
+			ParentHash:      bytesutil.PadTo([]byte{'3'}, fieldparams.RootLength),
+			TotalDifficulty: "0x1",
+		}
+		service.cfg.ExecutionEngineCaller = engine
+		var payload *ethpb.ExecutionPayloadHeader
+		if tt.preState.Version() == version.Bellatrix {
+			payload, err = tt.preState.LatestExecutionPayloadHeader()
+			require.NoError(t, err)
+		}
+		err := service.notifyNewPayload(ctx, tt.preState.Version(), payload, tt.postState, tt.blk)
+		if tt.errString != "" {
+			require.ErrorContains(t, tt.errString, err)
+		} else {
+			require.NoError(t, err)
+		}
+	}
+}
+
+func Test_IsOptimisticCandidateBlock(t *testing.T) {
+	params.SetupTestConfigCleanup(t)
+	params.OverrideBeaconConfig(params.MainnetConfig())
+
+	ctx := context.Background()
+	beaconDB := testDB.SetupDB(t)
+	fcs := protoarray.New(0, 0, [32]byte{'a'})
+	opts := []Option{
+		WithDatabase(beaconDB),
+		WithStateGen(stategen.New(beaconDB)),
+		WithForkChoiceStore(fcs),
+	}
+
+	service, err := NewService(ctx, opts...)
+	require.NoError(t, err)
+
+	params.BeaconConfig().SafeSlotsToImportOptimistically = 128
+	service.genesisTime = time.Now().Add(-time.Second * 12 * 2 * 128)
+
+	tests := []struct {
+		name      string
+		blk       block.BeaconBlock
+		justified block.SignedBeaconBlock
+		want      bool
+	}{
+		{
+			name: "deep block",
+			blk: func(tt *testing.T) block.BeaconBlock {
+				blk := util.NewBeaconBlockBellatrix()
+				blk.Block.Slot = 1
+				wr, err := wrapper.WrappedBellatrixBeaconBlock(blk.Block)
+				require.NoError(tt, err)
+				return wr
+			}(t),
+			justified: func(tt *testing.T) block.SignedBeaconBlock {
+				blk := util.NewBeaconBlockBellatrix()
+				blk.Block.Slot = 32
+				wr, err := wrapper.WrappedBellatrixSignedBeaconBlock(blk)
+				require.NoError(tt, err)
+				return wr
+			}(t),
+			want: true,
+		},
+		{
+			name: "shallow block, Altair justified chkpt",
+			blk: func(tt *testing.T) block.BeaconBlock {
+				blk := util.NewBeaconBlockAltair()
+				blk.Block.Slot = 200
+				wr, err := wrapper.WrappedAltairBeaconBlock(blk.Block)
+				require.NoError(tt, err)
+				return wr
+			}(t),
+			justified: func(tt *testing.T) block.SignedBeaconBlock {
+				blk := util.NewBeaconBlockAltair()
+				blk.Block.Slot = 32
+				wr, err := wrapper.WrappedAltairSignedBeaconBlock(blk)
+				require.NoError(tt, err)
+				return wr
+			}(t),
+			want: false,
+		},
+		{
+			name: "shallow block, Bellatrix justified chkpt without execution",
+			blk: func(tt *testing.T) block.BeaconBlock {
+				blk := util.NewBeaconBlockBellatrix()
+				blk.Block.Slot = 200
+				wr, err := wrapper.WrappedBellatrixBeaconBlock(blk.Block)
+				require.NoError(tt, err)
+				return wr
+			}(t),
+			justified: func(tt *testing.T) block.SignedBeaconBlock {
+				blk := util.NewBeaconBlockBellatrix()
+				blk.Block.Slot = 32
+				wr, err := wrapper.WrappedBellatrixSignedBeaconBlock(blk)
+				require.NoError(tt, err)
+				return wr
+			}(t),
+			want: false,
+		},
+		{
+			name: "shallow block, execution enabled justified chkpt",
+			blk: func(tt *testing.T) block.BeaconBlock {
+				blk := util.NewBeaconBlockBellatrix()
+				blk.Block.Slot = 200
+				wr, err := wrapper.WrappedBellatrixBeaconBlock(blk.Block)
+				require.NoError(tt, err)
+				return wr
+			}(t),
+			justified: func(tt *testing.T) block.SignedBeaconBlock {
+				blk := util.NewBeaconBlockBellatrix()
+				blk.Block.Slot = 32
+				blk.Block.Body.ExecutionPayload.ParentHash = bytesutil.PadTo([]byte{'a'}, fieldparams.RootLength)
+				blk.Block.Body.ExecutionPayload.FeeRecipient = bytesutil.PadTo([]byte{'a'}, fieldparams.FeeRecipientLength)
+				blk.Block.Body.ExecutionPayload.StateRoot = bytesutil.PadTo([]byte{'a'}, fieldparams.RootLength)
+				blk.Block.Body.ExecutionPayload.ReceiptsRoot = bytesutil.PadTo([]byte{'a'}, fieldparams.RootLength)
+				blk.Block.Body.ExecutionPayload.LogsBloom = bytesutil.PadTo([]byte{'a'}, fieldparams.LogsBloomLength)
+				blk.Block.Body.ExecutionPayload.PrevRandao = bytesutil.PadTo([]byte{'a'}, fieldparams.RootLength)
+				blk.Block.Body.ExecutionPayload.BaseFeePerGas = bytesutil.PadTo([]byte{'a'}, fieldparams.RootLength)
+				blk.Block.Body.ExecutionPayload.BlockHash = bytesutil.PadTo([]byte{'a'}, fieldparams.RootLength)
+				wr, err := wrapper.WrappedBellatrixSignedBeaconBlock(blk)
+				require.NoError(tt, err)
+				return wr
+			}(t),
+			want: true,
+		},
+	}
+	for _, tt := range tests {
+		jroot, err := tt.justified.Block().HashTreeRoot()
+		require.NoError(t, err)
+		require.NoError(t, service.cfg.BeaconDB.SaveBlock(ctx, tt.justified))
+		service.store.SetJustifiedCheckpt(
+			&ethpb.Checkpoint{
+				Root:  jroot[:],
+				Epoch: slots.ToEpoch(tt.justified.Block().Slot()),
+			})
+		candidate, err := service.optimisticCandidateBlock(ctx, tt.blk)
+		require.NoError(t, err)
+		require.Equal(t, tt.want, candidate, tt.name)
+	}
+}

beacon-chain/blockchain/options.go

@@ -11,6 +11,7 @@ import (
 	"github.com/prysmaticlabs/prysm/beacon-chain/operations/voluntaryexits"
 	"github.com/prysmaticlabs/prysm/beacon-chain/p2p"
 	"github.com/prysmaticlabs/prysm/beacon-chain/powchain"
+	enginev1 "github.com/prysmaticlabs/prysm/beacon-chain/powchain/engine-api-client/v1"
 	"github.com/prysmaticlabs/prysm/beacon-chain/state"
 	"github.com/prysmaticlabs/prysm/beacon-chain/state/stategen"
 	ethpb "github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1"
@@ -50,6 +51,14 @@ func WithChainStartFetcher(f powchain.ChainStartFetcher) Option {
 	}
 }
 
+// WithExecutionEngineCaller to call execution engine.
+func WithExecutionEngineCaller(c enginev1.Caller) Option {
+	return func(s *Service) error {
+		s.cfg.ExecutionEngineCaller = c
+		return nil
+	}
+}
+
 // WithDepositCache for deposit lifecycle after chain inclusion.
 func WithDepositCache(c *depositcache.DepositCache) Option {
 	return func(s *Service) error {

beacon-chain/blockchain/pow_block.go

@@ -1,19 +1,141 @@
 package blockchain
 
 import (
+	"bytes"
+	"context"
+	"fmt"
+	"math/big"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/common/hexutil"
 	"github.com/holiman/uint256"
+	"github.com/pkg/errors"
+	types "github.com/prysmaticlabs/eth2-types"
+	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
 	"github.com/prysmaticlabs/prysm/config/params"
+	"github.com/prysmaticlabs/prysm/encoding/bytesutil"
+	enginev1 "github.com/prysmaticlabs/prysm/proto/engine/v1"
+	"github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1/block"
+	"github.com/prysmaticlabs/prysm/time/slots"
+	"github.com/sirupsen/logrus"
 )
 
-// validates terminal pow block by comparing own total difficulty with parent's total difficulty.
+// validateMergeBlock validates terminal block hash in the event of manual overrides before checking for total difficulty.
+//
+// def validate_merge_block(block: BeaconBlock) -> None:
+//    if TERMINAL_BLOCK_HASH != Hash32():
+//        # If `TERMINAL_BLOCK_HASH` is used as an override, the activation epoch must be reached.
+//        assert compute_epoch_at_slot(block.slot) >= TERMINAL_BLOCK_HASH_ACTIVATION_EPOCH
+//        assert block.body.execution_payload.parent_hash == TERMINAL_BLOCK_HASH
+//        return
+//
+//    pow_block = get_pow_block(block.body.execution_payload.parent_hash)
+//    # Check if `pow_block` is available
+//    assert pow_block is not None
+//    pow_parent = get_pow_block(pow_block.parent_hash)
+//    # Check if `pow_parent` is available
+//    assert pow_parent is not None
+//    # Check if `pow_block` is a valid terminal PoW block
+//    assert is_valid_terminal_pow_block(pow_block, pow_parent)
+func (s *Service) validateMergeBlock(ctx context.Context, b block.SignedBeaconBlock) error {
+	if err := helpers.BeaconBlockIsNil(b); err != nil {
+		return err
+	}
+	payload, err := b.Block().Body().ExecutionPayload()
+	if err != nil {
+		return err
+	}
+	if payload == nil {
+		return errors.New("nil execution payload")
+	}
+	if err := validateTerminalBlockHash(b.Block().Slot(), payload); err != nil {
+		return errors.Wrap(err, "could not validate terminal block hash")
+	}
+	mergeBlockParentHash, mergeBlockTD, err := s.getBlkParentHashAndTD(ctx, payload.ParentHash)
+	if err != nil {
+		return errors.Wrap(err, "could not get merge block parent hash and total difficulty")
+	}
+	_, mergeBlockParentTD, err := s.getBlkParentHashAndTD(ctx, mergeBlockParentHash)
+	if err != nil {
+		return errors.Wrap(err, "could not get merge parent block total difficulty")
+	}
+	valid, err := validateTerminalBlockDifficulties(mergeBlockTD, mergeBlockParentTD)
+	if err != nil {
+		return err
+	}
+	if !valid {
+		return fmt.Errorf("invalid TTD, configTTD: %s, currentTTD: %s, parentTTD: %s",
+			params.BeaconConfig().TerminalTotalDifficulty, mergeBlockTD, mergeBlockParentTD)
+	}
+
+	log.WithFields(logrus.Fields{
+		"slot":                            b.Block().Slot(),
+		"mergeBlockHash":                  common.BytesToHash(payload.ParentHash).String(),
+		"mergeBlockParentHash":            common.BytesToHash(mergeBlockParentHash).String(),
+		"terminalTotalDifficulty":         params.BeaconConfig().TerminalTotalDifficulty,
+		"mergeBlockTotalDifficulty":       mergeBlockTD,
+		"mergeBlockParentTotalDifficulty": mergeBlockParentTD,
+	}).Info("Validated terminal block")
+
+	return nil
+}
+
+// getBlkParentHashAndTD retrieves the parent hash and total difficulty of the given block.
+func (s *Service) getBlkParentHashAndTD(ctx context.Context, blkHash []byte) ([]byte, *uint256.Int, error) {
+	blk, err := s.cfg.ExecutionEngineCaller.ExecutionBlockByHash(ctx, common.BytesToHash(blkHash))
+	if err != nil {
+		return nil, nil, errors.Wrap(err, "could not get pow block")
+	}
+	if blk == nil {
+		return nil, nil, errors.New("pow block is nil")
+	}
+	blkTDBig, err := hexutil.DecodeBig(blk.TotalDifficulty)
+	if err != nil {
+		return nil, nil, errors.Wrap(err, "could not decode merge block total difficulty")
+	}
+	blkTDUint256, overflows := uint256.FromBig(blkTDBig)
+	if overflows {
+		return nil, nil, errors.New("total difficulty overflows")
+	}
+	return blk.ParentHash, blkTDUint256, nil
+}
+
+// validateTerminalBlockHash validates if the merge block is a valid terminal PoW block.
+// spec code:
+// if TERMINAL_BLOCK_HASH != Hash32():
+//        # If `TERMINAL_BLOCK_HASH` is used as an override, the activation epoch must be reached.
+//        assert compute_epoch_at_slot(block.slot) >= TERMINAL_BLOCK_HASH_ACTIVATION_EPOCH
+//        assert block.body.execution_payload.parent_hash == TERMINAL_BLOCK_HASH
+//        return
+func validateTerminalBlockHash(blkSlot types.Slot, payload *enginev1.ExecutionPayload) error {
+	if bytesutil.ToBytes32(params.BeaconConfig().TerminalBlockHash.Bytes()) == [32]byte{} {
+		return nil
+	}
+	if params.BeaconConfig().TerminalBlockHashActivationEpoch > slots.ToEpoch(blkSlot) {
+		return errors.New("terminal block hash activation epoch not reached")
+	}
+	if !bytes.Equal(payload.ParentHash, params.BeaconConfig().TerminalBlockHash.Bytes()) {
+		return errors.New("parent hash does not match terminal block hash")
+	}
+	return nil
+}
+
+// validateTerminalBlockDifficulties validates terminal pow block by comparing own total difficulty with parent's total difficulty.
 //
 // def is_valid_terminal_pow_block(block: PowBlock, parent: PowBlock) -> bool:
 //    is_total_difficulty_reached = block.total_difficulty >= TERMINAL_TOTAL_DIFFICULTY
 //    is_parent_total_difficulty_valid = parent.total_difficulty < TERMINAL_TOTAL_DIFFICULTY
 //    return is_total_difficulty_reached and is_parent_total_difficulty_valid
-func validTerminalPowBlock(currentDifficulty *uint256.Int, parentDifficulty *uint256.Int) bool {
-	ttd := uint256.NewInt(params.BeaconConfig().TerminalTotalDifficulty)
+func validateTerminalBlockDifficulties(currentDifficulty *uint256.Int, parentDifficulty *uint256.Int) (bool, error) {
+	b, ok := new(big.Int).SetString(params.BeaconConfig().TerminalTotalDifficulty, 10)
+	if !ok {
+		return false, errors.New("failed to parse terminal total difficulty")
+	}
+	ttd, of := uint256.FromBig(b)
+	if of {
+		return false, errors.New("overflow terminal total difficulty")
+	}
 	totalDifficultyReached := currentDifficulty.Cmp(ttd) >= 0
 	parentTotalDifficultyValid := ttd.Cmp(parentDifficulty) > 0
-	return totalDifficultyReached && parentTotalDifficultyValid
+	return totalDifficultyReached && parentTotalDifficultyValid, nil
 }

beacon-chain/blockchain/pow_block_test.go

@@ -1,10 +1,22 @@
 package blockchain
 
 import (
+	"context"
+	"fmt"
+	"math/big"
 	"testing"
 
 	"github.com/holiman/uint256"
+	testDB "github.com/prysmaticlabs/prysm/beacon-chain/db/testing"
+	"github.com/prysmaticlabs/prysm/beacon-chain/forkchoice/protoarray"
+	"github.com/prysmaticlabs/prysm/beacon-chain/state/stategen"
+	fieldparams "github.com/prysmaticlabs/prysm/config/fieldparams"
 	"github.com/prysmaticlabs/prysm/config/params"
+	"github.com/prysmaticlabs/prysm/encoding/bytesutil"
+	enginev1 "github.com/prysmaticlabs/prysm/proto/engine/v1"
+	ethpb "github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1"
+	"github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1/wrapper"
+	"github.com/prysmaticlabs/prysm/testing/require"
 )
 
 func Test_validTerminalPowBlock(t *testing.T) {
@@ -61,11 +73,138 @@ func Test_validTerminalPowBlock(t *testing.T) {
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
 			cfg := params.BeaconConfig()
-			cfg.TerminalTotalDifficulty = tt.ttd
+			cfg.TerminalTotalDifficulty = fmt.Sprint(tt.ttd)
 			params.OverrideBeaconConfig(cfg)
-			if got := validTerminalPowBlock(tt.currentDifficulty, tt.parentDifficulty); got != tt.want {
-				t.Errorf("validTerminalPowBlock() = %v, want %v", got, tt.want)
+			got, err := validateTerminalBlockDifficulties(tt.currentDifficulty, tt.parentDifficulty)
+			require.NoError(t, err)
+			if got != tt.want {
+				t.Errorf("validateTerminalBlockDifficulties() = %v, want %v", got, tt.want)
 			}
 		})
 	}
 }
+
+func Test_validTerminalPowBlockSpecConfig(t *testing.T) {
+	cfg := params.BeaconConfig()
+	cfg.TerminalTotalDifficulty = "115792089237316195423570985008687907853269984665640564039457584007913129638912"
+	params.OverrideBeaconConfig(cfg)
+
+	i, _ := new(big.Int).SetString("115792089237316195423570985008687907853269984665640564039457584007913129638912", 10)
+	current, of := uint256.FromBig(i)
+	require.Equal(t, of, false)
+	i, _ = new(big.Int).SetString("115792089237316195423570985008687907853269984665640564039457584007913129638911", 10)
+	parent, of := uint256.FromBig(i)
+	require.Equal(t, of, false)
+
+	got, err := validateTerminalBlockDifficulties(current, parent)
+	require.NoError(t, err)
+	require.Equal(t, true, got)
+}
+
+func Test_validateMergeBlock(t *testing.T) {
+	cfg := params.BeaconConfig()
+	cfg.TerminalTotalDifficulty = "2"
+	params.OverrideBeaconConfig(cfg)
+
+	ctx := context.Background()
+	beaconDB := testDB.SetupDB(t)
+	fcs := protoarray.New(0, 0, [32]byte{'a'})
+	opts := []Option{
+		WithDatabase(beaconDB),
+		WithStateGen(stategen.New(beaconDB)),
+		WithForkChoiceStore(fcs),
+	}
+	service, err := NewService(ctx, opts...)
+	require.NoError(t, err)
+
+	engine := &mockEngineService{blks: map[[32]byte]*enginev1.ExecutionBlock{}}
+	service.cfg.ExecutionEngineCaller = engine
+	engine.blks[[32]byte{'a'}] = &enginev1.ExecutionBlock{
+		ParentHash:      bytesutil.PadTo([]byte{'b'}, fieldparams.RootLength),
+		TotalDifficulty: "0x2",
+	}
+	engine.blks[[32]byte{'b'}] = &enginev1.ExecutionBlock{
+		ParentHash:      bytesutil.PadTo([]byte{'3'}, fieldparams.RootLength),
+		TotalDifficulty: "0x1",
+	}
+	blk := &ethpb.SignedBeaconBlockBellatrix{
+		Block: &ethpb.BeaconBlockBellatrix{
+			Slot: 1,
+			Body: &ethpb.BeaconBlockBodyBellatrix{
+				ExecutionPayload: &enginev1.ExecutionPayload{
+					ParentHash: bytesutil.PadTo([]byte{'a'}, fieldparams.RootLength),
+				},
+			},
+		},
+	}
+	b, err := wrapper.WrappedSignedBeaconBlock(blk)
+	require.NoError(t, err)
+	require.NoError(t, service.validateMergeBlock(ctx, b))
+
+	cfg.TerminalTotalDifficulty = "1"
+	params.OverrideBeaconConfig(cfg)
+	require.ErrorContains(t, "invalid TTD, configTTD: 1, currentTTD: 2, parentTTD: 1", service.validateMergeBlock(ctx, b))
+}
+
+func Test_getBlkParentHashAndTD(t *testing.T) {
+	ctx := context.Background()
+	beaconDB := testDB.SetupDB(t)
+	fcs := protoarray.New(0, 0, [32]byte{'a'})
+	opts := []Option{
+		WithDatabase(beaconDB),
+		WithStateGen(stategen.New(beaconDB)),
+		WithForkChoiceStore(fcs),
+	}
+	service, err := NewService(ctx, opts...)
+	require.NoError(t, err)
+
+	engine := &mockEngineService{blks: map[[32]byte]*enginev1.ExecutionBlock{}}
+	service.cfg.ExecutionEngineCaller = engine
+	h := [32]byte{'a'}
+	p := [32]byte{'b'}
+	td := "0x1"
+	engine.blks[h] = &enginev1.ExecutionBlock{
+		ParentHash:      p[:],
+		TotalDifficulty: td,
+	}
+	parentHash, totalDifficulty, err := service.getBlkParentHashAndTD(ctx, h[:])
+	require.NoError(t, err)
+	require.Equal(t, p, bytesutil.ToBytes32(parentHash))
+	require.Equal(t, td, totalDifficulty.String())
+
+	_, _, err = service.getBlkParentHashAndTD(ctx, []byte{'c'})
+	require.ErrorContains(t, "could not get pow block: block not found", err)
+
+	engine.blks[h] = nil
+	_, _, err = service.getBlkParentHashAndTD(ctx, h[:])
+	require.ErrorContains(t, "pow block is nil", err)
+
+	engine.blks[h] = &enginev1.ExecutionBlock{
+		ParentHash:      p[:],
+		TotalDifficulty: "1",
+	}
+	_, _, err = service.getBlkParentHashAndTD(ctx, h[:])
+	require.ErrorContains(t, "could not decode merge block total difficulty: hex string without 0x prefix", err)
+
+	engine.blks[h] = &enginev1.ExecutionBlock{
+		ParentHash:      p[:],
+		TotalDifficulty: "0XFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF",
+	}
+	_, _, err = service.getBlkParentHashAndTD(ctx, h[:])
+	require.ErrorContains(t, "could not decode merge block total difficulty: hex number > 256 bits", err)
+}
+
+func Test_validateTerminalBlockHash(t *testing.T) {
+	require.NoError(t, validateTerminalBlockHash(1, &enginev1.ExecutionPayload{}))
+
+	cfg := params.BeaconConfig()
+	cfg.TerminalBlockHash = [32]byte{0x01}
+	params.OverrideBeaconConfig(cfg)
+	require.ErrorContains(t, "terminal block hash activation epoch not reached", validateTerminalBlockHash(1, &enginev1.ExecutionPayload{}))
+
+	cfg.TerminalBlockHashActivationEpoch = 0
+	params.OverrideBeaconConfig(cfg)
+	require.ErrorContains(t, "parent hash does not match terminal block hash", validateTerminalBlockHash(1, &enginev1.ExecutionPayload{}))
+
+	require.NoError(t, validateTerminalBlockHash(1, &enginev1.ExecutionPayload{ParentHash: cfg.TerminalBlockHash.Bytes()}))
+}

beacon-chain/blockchain/process_attestation_test.go

@@ -8,6 +8,7 @@ import (
 	types "github.com/prysmaticlabs/eth2-types"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/transition"
 	testDB "github.com/prysmaticlabs/prysm/beacon-chain/db/testing"
+	doublylinkedtree "github.com/prysmaticlabs/prysm/beacon-chain/forkchoice/doubly-linked-tree"
 	"github.com/prysmaticlabs/prysm/beacon-chain/forkchoice/protoarray"
 	"github.com/prysmaticlabs/prysm/beacon-chain/state/stategen"
 	fieldparams "github.com/prysmaticlabs/prysm/config/fieldparams"
@@ -21,7 +22,7 @@ import (
 	"github.com/prysmaticlabs/prysm/time/slots"
 )
 
-func TestStore_OnAttestation_ErrorConditions(t *testing.T) {
+func TestStore_OnAttestation_ErrorConditions_ProtoArray(t *testing.T) {
 	ctx := context.Background()
 	beaconDB := testDB.SetupDB(t)
 
@@ -127,7 +128,113 @@ func TestStore_OnAttestation_ErrorConditions(t *testing.T) {
 	}
 }
 
-func TestStore_OnAttestation_Ok(t *testing.T) {
+func TestStore_OnAttestation_ErrorConditions_DoublyLinkedTree(t *testing.T) {
+	ctx := context.Background()
+	beaconDB := testDB.SetupDB(t)
+
+	opts := []Option{
+		WithDatabase(beaconDB),
+		WithForkChoiceStore(doublylinkedtree.New(0, 0)),
+		WithStateGen(stategen.New(beaconDB)),
+	}
+	service, err := NewService(ctx, opts...)
+	require.NoError(t, err)
+
+	_, err = blockTree1(t, beaconDB, []byte{'g'})
+	require.NoError(t, err)
+
+	BlkWithOutState := util.NewBeaconBlock()
+	BlkWithOutState.Block.Slot = 0
+	require.NoError(t, beaconDB.SaveBlock(ctx, wrapper.WrappedPhase0SignedBeaconBlock(BlkWithOutState)))
+	BlkWithOutStateRoot, err := BlkWithOutState.Block.HashTreeRoot()
+	require.NoError(t, err)
+
+	BlkWithStateBadAtt := util.NewBeaconBlock()
+	BlkWithStateBadAtt.Block.Slot = 1
+	require.NoError(t, beaconDB.SaveBlock(ctx, wrapper.WrappedPhase0SignedBeaconBlock(BlkWithStateBadAtt)))
+	BlkWithStateBadAttRoot, err := BlkWithStateBadAtt.Block.HashTreeRoot()
+	require.NoError(t, err)
+
+	s, err := util.NewBeaconState()
+	require.NoError(t, err)
+	require.NoError(t, s.SetSlot(100*params.BeaconConfig().SlotsPerEpoch))
+	require.NoError(t, service.cfg.BeaconDB.SaveState(ctx, s, BlkWithStateBadAttRoot))
+
+	BlkWithValidState := util.NewBeaconBlock()
+	BlkWithValidState.Block.Slot = 2
+	require.NoError(t, beaconDB.SaveBlock(ctx, wrapper.WrappedPhase0SignedBeaconBlock(BlkWithValidState)))
+
+	BlkWithValidStateRoot, err := BlkWithValidState.Block.HashTreeRoot()
+	require.NoError(t, err)
+	s, err = util.NewBeaconState()
+	require.NoError(t, err)
+	err = s.SetFork(&ethpb.Fork{
+		Epoch:           0,
+		CurrentVersion:  params.BeaconConfig().GenesisForkVersion,
+		PreviousVersion: params.BeaconConfig().GenesisForkVersion,
+	})
+	require.NoError(t, err)
+	require.NoError(t, service.cfg.BeaconDB.SaveState(ctx, s, BlkWithValidStateRoot))
+
+	tests := []struct {
+		name      string
+		a         *ethpb.Attestation
+		wantedErr string
+	}{
+		{
+			name:      "attestation's data slot not aligned with target vote",
+			a:         util.HydrateAttestation(&ethpb.Attestation{Data: &ethpb.AttestationData{Slot: params.BeaconConfig().SlotsPerEpoch, Target: &ethpb.Checkpoint{Root: make([]byte, 32)}}}),
+			wantedErr: "slot 32 does not match target epoch 0",
+		},
+		{
+			name:      "no pre state for attestations's target block",
+			a:         util.HydrateAttestation(&ethpb.Attestation{Data: &ethpb.AttestationData{Target: &ethpb.Checkpoint{Root: BlkWithOutStateRoot[:]}}}),
+			wantedErr: "could not get pre state for epoch 0",
+		},
+		{
+			name: "process attestation doesn't match current epoch",
+			a: util.HydrateAttestation(&ethpb.Attestation{Data: &ethpb.AttestationData{Slot: 100 * params.BeaconConfig().SlotsPerEpoch, Target: &ethpb.Checkpoint{Epoch: 100,
+				Root: BlkWithStateBadAttRoot[:]}}}),
+			wantedErr: "target epoch 100 does not match current epoch",
+		},
+		{
+			name:      "process nil attestation",
+			a:         nil,
+			wantedErr: "attestation can't be nil",
+		},
+		{
+			name:      "process nil field (a.Data) in attestation",
+			a:         &ethpb.Attestation{},
+			wantedErr: "attestation's data can't be nil",
+		},
+		{
+			name: "process nil field (a.Target) in attestation",
+			a: &ethpb.Attestation{
+				Data: &ethpb.AttestationData{
+					BeaconBlockRoot: make([]byte, fieldparams.RootLength),
+					Target:          nil,
+					Source:          &ethpb.Checkpoint{Root: make([]byte, fieldparams.RootLength)},
+				},
+				AggregationBits: make([]byte, 1),
+				Signature:       make([]byte, 96),
+			},
+			wantedErr: "attestation's target can't be nil",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			err := service.OnAttestation(ctx, tt.a)
+			if tt.wantedErr != "" {
+				assert.ErrorContains(t, tt.wantedErr, err)
+			} else {
+				assert.NoError(t, err)
+			}
+		})
+	}
+}
+
+func TestStore_OnAttestation_Ok_ProtoArray(t *testing.T) {
 	ctx := context.Background()
 	beaconDB := testDB.SetupDB(t)
 
@@ -149,7 +256,33 @@ func TestStore_OnAttestation_Ok(t *testing.T) {
 	copied, err = transition.ProcessSlots(ctx, copied, 1)
 	require.NoError(t, err)
 	require.NoError(t, service.cfg.BeaconDB.SaveState(ctx, copied, tRoot))
-	require.NoError(t, service.cfg.ForkChoiceStore.ProcessBlock(ctx, 0, tRoot, tRoot, tRoot, 1, 1))
+	require.NoError(t, service.cfg.ForkChoiceStore.ProcessBlock(ctx, 0, tRoot, tRoot, 1, 1, false))
+	require.NoError(t, service.OnAttestation(ctx, att[0]))
+}
+
+func TestStore_OnAttestation_Ok_DoublyLinkedTree(t *testing.T) {
+	ctx := context.Background()
+	beaconDB := testDB.SetupDB(t)
+
+	fcs := doublylinkedtree.New(0, 0)
+	opts := []Option{
+		WithDatabase(beaconDB),
+		WithStateGen(stategen.New(beaconDB)),
+		WithForkChoiceStore(fcs),
+	}
+	service, err := NewService(ctx, opts...)
+	require.NoError(t, err)
+	genesisState, pks := util.DeterministicGenesisState(t, 64)
+	service.SetGenesisTime(time.Unix(time.Now().Unix()-int64(params.BeaconConfig().SecondsPerSlot), 0))
+	require.NoError(t, service.saveGenesisData(ctx, genesisState))
+	att, err := util.GenerateAttestations(genesisState, pks, 1, 0, false)
+	require.NoError(t, err)
+	tRoot := bytesutil.ToBytes32(att[0].Data.Target.Root)
+	copied := genesisState.Copy()
+	copied, err = transition.ProcessSlots(ctx, copied, 1)
+	require.NoError(t, err)
+	require.NoError(t, service.cfg.BeaconDB.SaveState(ctx, copied, tRoot))
+	require.NoError(t, service.cfg.ForkChoiceStore.ProcessBlock(ctx, 0, tRoot, tRoot, 1, 1, false))
 	require.NoError(t, service.OnAttestation(ctx, att[0]))
 }
 
@@ -330,7 +463,7 @@ func TestVerifyBeaconBlock_OK(t *testing.T) {
 	assert.NoError(t, service.verifyBeaconBlock(ctx, d), "Did not receive the wanted error")
 }
 
-func TestVerifyFinalizedConsistency_InconsistentRoot(t *testing.T) {
+func TestVerifyFinalizedConsistency_InconsistentRoot_ProtoArray(t *testing.T) {
 	ctx := context.Background()
 	beaconDB := testDB.SetupDB(t)
 
@@ -361,6 +494,37 @@ func TestVerifyFinalizedConsistency_InconsistentRoot(t *testing.T) {
 	require.ErrorContains(t, "Root and finalized store are not consistent", err)
 }
 
+func TestVerifyFinalizedConsistency_InconsistentRoot_DoublyLinkedTree(t *testing.T) {
+	ctx := context.Background()
+	beaconDB := testDB.SetupDB(t)
+
+	fcs := doublylinkedtree.New(0, 0)
+	opts := []Option{
+		WithDatabase(beaconDB),
+		WithStateGen(stategen.New(beaconDB)),
+		WithForkChoiceStore(fcs),
+	}
+	service, err := NewService(ctx, opts...)
+	require.NoError(t, err)
+
+	b32 := util.NewBeaconBlock()
+	b32.Block.Slot = 32
+	require.NoError(t, service.cfg.BeaconDB.SaveBlock(ctx, wrapper.WrappedPhase0SignedBeaconBlock(b32)))
+	r32, err := b32.Block.HashTreeRoot()
+	require.NoError(t, err)
+
+	service.store.SetFinalizedCheckpt(&ethpb.Checkpoint{Epoch: 1})
+	b33 := util.NewBeaconBlock()
+	b33.Block.Slot = 33
+	b33.Block.ParentRoot = r32[:]
+	require.NoError(t, service.cfg.BeaconDB.SaveBlock(ctx, wrapper.WrappedPhase0SignedBeaconBlock(b33)))
+	r33, err := b33.Block.HashTreeRoot()
+	require.NoError(t, err)
+
+	err = service.VerifyFinalizedConsistency(context.Background(), r33[:])
+	require.ErrorContains(t, "Root and finalized store are not consistent", err)
+}
+
 func TestVerifyFinalizedConsistency_OK(t *testing.T) {
 	ctx := context.Background()
 
@@ -407,8 +571,8 @@ func TestVerifyFinalizedConsistency_IsCanonical(t *testing.T) {
 	r33, err := b33.Block.HashTreeRoot()
 	require.NoError(t, err)
 
-	require.NoError(t, service.cfg.ForkChoiceStore.ProcessBlock(ctx, b32.Block.Slot, r32, [32]byte{}, [32]byte{}, 0, 0))
-	require.NoError(t, service.cfg.ForkChoiceStore.ProcessBlock(ctx, b33.Block.Slot, r33, r32, [32]byte{}, 0, 0))
+	require.NoError(t, service.cfg.ForkChoiceStore.ProcessBlock(ctx, b32.Block.Slot, r32, [32]byte{}, 0, 0, false))
+	require.NoError(t, service.cfg.ForkChoiceStore.ProcessBlock(ctx, b33.Block.Slot, r33, r32, 0, 0, false))
 
 	_, err = service.cfg.ForkChoiceStore.Head(ctx, 0, r32, []uint64{}, 0)
 	require.NoError(t, err)

beacon-chain/blockchain/process_block.go

@@ -21,6 +21,7 @@ import (
 	ethpb "github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1"
 	"github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1/attestation"
 	"github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1/block"
+	"github.com/prysmaticlabs/prysm/runtime/version"
 	"github.com/prysmaticlabs/prysm/time/slots"
 	"go.opencensus.io/trace"
 )
@@ -98,10 +99,17 @@ func (s *Service) onBlock(ctx context.Context, signed block.SignedBeaconBlock, b
 		return err
 	}
 
+	preStateVersion, preStateHeader, err := getStateVersionAndPayload(preState)
+	if err != nil {
+		return err
+	}
 	postState, err := transition.ExecuteStateTransition(ctx, preState, signed)
 	if err != nil {
 		return err
 	}
+	if err := s.notifyNewPayload(ctx, preStateVersion, preStateHeader, postState, signed); err != nil {
+		return errors.Wrap(err, "could not verify new payload")
+	}
 
 	// We add a proposer score boost to fork choice for the block root if applicable, right after
 	// running a successful state transition for the block.
@@ -111,7 +119,8 @@ func (s *Service) onBlock(ctx context.Context, signed block.SignedBeaconBlock, b
 		return err
 	}
 
-	if err := s.savePostStateInfo(ctx, blockRoot, signed, postState, false /* reg sync */); err != nil {
+	// TODO(10261) Check optimistic status
+	if err := s.savePostStateInfo(ctx, blockRoot, signed, postState, false /* reg sync */, false /*optimistic sync*/); err != nil {
 		return err
 	}
 
@@ -174,6 +183,9 @@ func (s *Service) onBlock(ctx context.Context, signed block.SignedBeaconBlock, b
 	if err := s.updateHead(ctx, balances); err != nil {
 		log.WithError(err).Warn("Could not update head")
 	}
+	if _, err := s.notifyForkchoiceUpdate(ctx, s.headBlock().Block(), bytesutil.ToBytes32(finalized.Root)); err != nil {
+		return err
+	}
 
 	if err := s.pruneCanonicalAttsFromPool(ctx, blockRoot, signed); err != nil {
 		return err
@@ -246,6 +258,21 @@ func (s *Service) onBlock(ctx context.Context, signed block.SignedBeaconBlock, b
 	return s.handleEpochBoundary(ctx, postState)
 }
 
+func getStateVersionAndPayload(preState state.BeaconState) (int, *ethpb.ExecutionPayloadHeader, error) {
+	var preStateHeader *ethpb.ExecutionPayloadHeader
+	var err error
+	preStateVersion := preState.Version()
+	switch preStateVersion {
+	case version.Phase0, version.Altair:
+	default:
+		preStateHeader, err = preState.LatestExecutionPayloadHeader()
+		if err != nil {
+			return 0, nil, err
+		}
+	}
+	return preStateVersion, preStateHeader, nil
+}
+
 func (s *Service) onBlockBatch(ctx context.Context, blks []block.SignedBeaconBlock,
 	blockRoots [][32]byte) ([]*ethpb.Checkpoint, []*ethpb.Checkpoint, error) {
 	ctx, span := trace.StartSpan(ctx, "blockChain.onBlockBatch")
@@ -323,13 +350,14 @@ func (s *Service) onBlockBatch(ctx context.Context, blks []block.SignedBeaconBlo
 // handles a block after the block's batch has been verified, where we can save blocks
 // their state summaries and split them off to relative hot/cold storage.
 func (s *Service) handleBlockAfterBatchVerify(ctx context.Context, signed block.SignedBeaconBlock,
-	blockRoot [32]byte, fCheckpoint, jCheckpoint *ethpb.Checkpoint) error {
+	blockRoot [32]byte, fCheckpoint, jCheckpoint *ethpb.Checkpoint, optimistic bool) error {
 	b := signed.Block()
 
 	s.saveInitSyncBlock(blockRoot, signed)
-	if err := s.insertBlockToForkChoiceStore(ctx, b, blockRoot, fCheckpoint, jCheckpoint); err != nil {
+	if err := s.insertBlockToForkChoiceStore(ctx, b, blockRoot, fCheckpoint, jCheckpoint, optimistic); err != nil {
 		return err
 	}
+
 	if err := s.cfg.BeaconDB.SaveStateSummary(ctx, &ethpb.StateSummary{
 		Slot: signed.Block().Slot(),
 		Root: blockRoot[:],
@@ -414,13 +442,13 @@ func (s *Service) handleEpochBoundary(ctx context.Context, postState state.Beaco
 // This feeds in the block and block's attestations to fork choice store. It's allows fork choice store
 // to gain information on the most current chain.
 func (s *Service) insertBlockAndAttestationsToForkChoiceStore(ctx context.Context, blk block.BeaconBlock, root [32]byte,
-	st state.BeaconState) error {
+	st state.BeaconState, optimistic bool) error {
 	ctx, span := trace.StartSpan(ctx, "blockChain.insertBlockAndAttestationsToForkChoiceStore")
 	defer span.End()
 
 	fCheckpoint := st.FinalizedCheckpoint()
 	jCheckpoint := st.CurrentJustifiedCheckpoint()
-	if err := s.insertBlockToForkChoiceStore(ctx, blk, root, fCheckpoint, jCheckpoint); err != nil {
+	if err := s.insertBlockToForkChoiceStore(ctx, blk, root, fCheckpoint, jCheckpoint, optimistic); err != nil {
 		return err
 	}
 	// Feed in block's attestations to fork choice store.
@@ -439,15 +467,16 @@ func (s *Service) insertBlockAndAttestationsToForkChoiceStore(ctx context.Contex
 }
 
 func (s *Service) insertBlockToForkChoiceStore(ctx context.Context, blk block.BeaconBlock,
-	root [32]byte, fCheckpoint, jCheckpoint *ethpb.Checkpoint) error {
+	root [32]byte, fCheckpoint, jCheckpoint *ethpb.Checkpoint, optimistic bool) error {
+	//TODO(10261) check if the blocks are optimistic or not when filling fork choice
 	if err := s.fillInForkChoiceMissingBlocks(ctx, blk, fCheckpoint, jCheckpoint); err != nil {
 		return err
 	}
 	// Feed in block to fork choice store.
 	if err := s.cfg.ForkChoiceStore.ProcessBlock(ctx,
-		blk.Slot(), root, bytesutil.ToBytes32(blk.ParentRoot()), bytesutil.ToBytes32(blk.Body().Graffiti()),
+		blk.Slot(), root, bytesutil.ToBytes32(blk.ParentRoot()),
 		jCheckpoint.Epoch,
-		fCheckpoint.Epoch); err != nil {
+		fCheckpoint.Epoch, optimistic); err != nil {
 		return errors.Wrap(err, "could not process block for proto array fork choice")
 	}
 	return nil
@@ -455,7 +484,7 @@ func (s *Service) insertBlockToForkChoiceStore(ctx context.Context, blk block.Be
 
 // This saves post state info to DB or cache. This also saves post state info to fork choice store.
 // Post state info consists of processed block and state. Do not call this method unless the block and state are verified.
-func (s *Service) savePostStateInfo(ctx context.Context, r [32]byte, b block.SignedBeaconBlock, st state.BeaconState, initSync bool) error {
+func (s *Service) savePostStateInfo(ctx context.Context, r [32]byte, b block.SignedBeaconBlock, st state.BeaconState, initSync bool, optimistic bool) error {
 	ctx, span := trace.StartSpan(ctx, "blockChain.savePostStateInfo")
 	defer span.End()
 	if initSync {
@@ -466,7 +495,7 @@ func (s *Service) savePostStateInfo(ctx context.Context, r [32]byte, b block.Sig
 	if err := s.cfg.StateGen.SaveState(ctx, r, st); err != nil {
 		return errors.Wrap(err, "could not save state")
 	}
-	if err := s.insertBlockAndAttestationsToForkChoiceStore(ctx, b.Block(), r, st); err != nil {
+	if err := s.insertBlockAndAttestationsToForkChoiceStore(ctx, b.Block(), r, st, optimistic); err != nil {
 		return errors.Wrapf(err, "could not insert block %d to fork choice store", b.Block().Slot())
 	}
 	return nil

beacon-chain/blockchain/process_block_helpers.go

@@ -113,7 +113,7 @@ func (s *Service) VerifyBlkDescendant(ctx context.Context, root [32]byte) error
 	}
 
 	if !bytes.Equal(bFinalizedRoot, fRoot[:]) {
-		err := fmt.Errorf("block %#x is not a descendent of the current finalized block slot %d, %#x != %#x",
+		err := fmt.Errorf("block %#x is not a descendant of the current finalized block slot %d, %#x != %#x",
 			bytesutil.Trunc(root[:]), finalizedBlk.Slot(), bytesutil.Trunc(bFinalizedRoot),
 			bytesutil.Trunc(fRoot[:]))
 		tracing.AnnotateError(span, err)
@@ -367,9 +367,9 @@ func (s *Service) fillInForkChoiceMissingBlocks(ctx context.Context, blk block.B
 		b := pendingNodes[i]
 		r := pendingRoots[i]
 		if err := s.cfg.ForkChoiceStore.ProcessBlock(ctx,
-			b.Slot(), r, bytesutil.ToBytes32(b.ParentRoot()), bytesutil.ToBytes32(b.Body().Graffiti()),
+			b.Slot(), r, bytesutil.ToBytes32(b.ParentRoot()),
 			jCheckpoint.Epoch,
-			fCheckpoint.Epoch); err != nil {
+			fCheckpoint.Epoch, false /* optimistic status */); err != nil {
 			return errors.Wrap(err, "could not process block for proto array fork choice")
 		}
 	}

beacon-chain/blockchain/process_block_test.go

@@ -16,6 +16,7 @@ import (
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/transition"
 	"github.com/prysmaticlabs/prysm/beacon-chain/db"
 	testDB "github.com/prysmaticlabs/prysm/beacon-chain/db/testing"
+	doublylinkedtree "github.com/prysmaticlabs/prysm/beacon-chain/forkchoice/doubly-linked-tree"
 	"github.com/prysmaticlabs/prysm/beacon-chain/forkchoice/protoarray"
 	"github.com/prysmaticlabs/prysm/beacon-chain/state"
 	"github.com/prysmaticlabs/prysm/beacon-chain/state/stategen"
@@ -27,13 +28,14 @@ import (
 	ethpb "github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1"
 	"github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1/block"
 	"github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1/wrapper"
+	"github.com/prysmaticlabs/prysm/runtime/version"
 	"github.com/prysmaticlabs/prysm/testing/assert"
 	"github.com/prysmaticlabs/prysm/testing/require"
 	"github.com/prysmaticlabs/prysm/testing/util"
 	prysmTime "github.com/prysmaticlabs/prysm/time"
 )
 
-func TestStore_OnBlock(t *testing.T) {
+func TestStore_OnBlock_ProtoArray(t *testing.T) {
 	ctx := context.Background()
 
 	beaconDB := testDB.SetupDB(t)
@@ -100,7 +102,7 @@ func TestStore_OnBlock(t *testing.T) {
 				return b
 			}(),
 			s:             st.Copy(),
-			wantErrString: "is not a descendent of the current finalized block",
+			wantErrString: "is not a descendant of the current finalized block",
 		},
 		{
 			name: "same slot as finalized block",
@@ -130,7 +132,104 @@ func TestStore_OnBlock(t *testing.T) {
 	}
 }
 
-func TestStore_OnBlockBatch(t *testing.T) {
+func TestStore_OnBlock_DoublyLinkedTree(t *testing.T) {
+	ctx := context.Background()
+
+	beaconDB := testDB.SetupDB(t)
+	fcs := doublylinkedtree.New(0, 0)
+	opts := []Option{
+		WithDatabase(beaconDB),
+		WithStateGen(stategen.New(beaconDB)),
+		WithForkChoiceStore(fcs),
+	}
+
+	service, err := NewService(ctx, opts...)
+	require.NoError(t, err)
+	genesisStateRoot := [32]byte{}
+	genesis := blocks.NewGenesisBlock(genesisStateRoot[:])
+	assert.NoError(t, beaconDB.SaveBlock(ctx, wrapper.WrappedPhase0SignedBeaconBlock(genesis)))
+	validGenesisRoot, err := genesis.Block.HashTreeRoot()
+	require.NoError(t, err)
+	st, err := util.NewBeaconState()
+	require.NoError(t, err)
+	require.NoError(t, service.cfg.BeaconDB.SaveState(ctx, st.Copy(), validGenesisRoot))
+	roots, err := blockTree1(t, beaconDB, validGenesisRoot[:])
+	require.NoError(t, err)
+	random := util.NewBeaconBlock()
+	random.Block.Slot = 1
+	random.Block.ParentRoot = validGenesisRoot[:]
+	assert.NoError(t, beaconDB.SaveBlock(ctx, wrapper.WrappedPhase0SignedBeaconBlock(random)))
+	randomParentRoot, err := random.Block.HashTreeRoot()
+	assert.NoError(t, err)
+	require.NoError(t, service.cfg.BeaconDB.SaveStateSummary(ctx, &ethpb.StateSummary{Slot: st.Slot(), Root: randomParentRoot[:]}))
+	require.NoError(t, service.cfg.BeaconDB.SaveState(ctx, st.Copy(), randomParentRoot))
+	randomParentRoot2 := roots[1]
+	require.NoError(t, service.cfg.BeaconDB.SaveStateSummary(ctx, &ethpb.StateSummary{Slot: st.Slot(), Root: randomParentRoot2}))
+	require.NoError(t, service.cfg.BeaconDB.SaveState(ctx, st.Copy(), bytesutil.ToBytes32(randomParentRoot2)))
+
+	tests := []struct {
+		name          string
+		blk           *ethpb.SignedBeaconBlock
+		s             state.BeaconState
+		time          uint64
+		wantErrString string
+	}{
+		{
+			name:          "parent block root does not have a state",
+			blk:           util.NewBeaconBlock(),
+			s:             st.Copy(),
+			wantErrString: "could not reconstruct parent state",
+		},
+		{
+			name: "block is from the future",
+			blk: func() *ethpb.SignedBeaconBlock {
+				b := util.NewBeaconBlock()
+				b.Block.ParentRoot = randomParentRoot2
+				b.Block.Slot = params.BeaconConfig().FarFutureSlot
+				return b
+			}(),
+			s:             st.Copy(),
+			wantErrString: "is in the far distant future",
+		},
+		{
+			name: "could not get finalized block",
+			blk: func() *ethpb.SignedBeaconBlock {
+				b := util.NewBeaconBlock()
+				b.Block.ParentRoot = randomParentRoot[:]
+				return b
+			}(),
+			s:             st.Copy(),
+			wantErrString: "is not a descendant of the current finalized block",
+		},
+		{
+			name: "same slot as finalized block",
+			blk: func() *ethpb.SignedBeaconBlock {
+				b := util.NewBeaconBlock()
+				b.Block.Slot = 0
+				b.Block.ParentRoot = randomParentRoot2
+				return b
+			}(),
+			s:             st.Copy(),
+			wantErrString: "block is equal or earlier than finalized block, slot 0 < slot 0",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			service.store.SetJustifiedCheckpt(&ethpb.Checkpoint{Root: validGenesisRoot[:]})
+			service.store.SetBestJustifiedCheckpt(&ethpb.Checkpoint{Root: validGenesisRoot[:]})
+			service.store.SetFinalizedCheckpt(&ethpb.Checkpoint{Root: roots[0]})
+			service.store.SetPrevFinalizedCheckpt(&ethpb.Checkpoint{Root: validGenesisRoot[:]})
+
+			root, err := tt.blk.Block.HashTreeRoot()
+			assert.NoError(t, err)
+			err = service.onBlock(ctx, wrapper.WrappedPhase0SignedBeaconBlock(tt.blk), root)
+			assert.ErrorContains(t, tt.wantErrString, err)
+		})
+	}
+}
+
+func TestStore_OnBlockBatch_ProtoArray(t *testing.T) {
 	ctx := context.Background()
 	beaconDB := testDB.SetupDB(t)
 
@@ -182,6 +281,58 @@ func TestStore_OnBlockBatch(t *testing.T) {
 	require.NoError(t, err)
 }
 
+func TestStore_OnBlockBatch_DoublyLinkedTree(t *testing.T) {
+	ctx := context.Background()
+	beaconDB := testDB.SetupDB(t)
+
+	opts := []Option{
+		WithDatabase(beaconDB),
+		WithStateGen(stategen.New(beaconDB)),
+	}
+	service, err := NewService(ctx, opts...)
+	require.NoError(t, err)
+
+	genesisStateRoot := [32]byte{}
+	genesis := blocks.NewGenesisBlock(genesisStateRoot[:])
+	assert.NoError(t, beaconDB.SaveBlock(ctx, wrapper.WrappedPhase0SignedBeaconBlock(genesis)))
+	gRoot, err := genesis.Block.HashTreeRoot()
+	require.NoError(t, err)
+	service.store.SetFinalizedCheckpt(&ethpb.Checkpoint{Root: gRoot[:]})
+
+	service.cfg.ForkChoiceStore = doublylinkedtree.New(0, 0)
+	service.saveInitSyncBlock(gRoot, wrapper.WrappedPhase0SignedBeaconBlock(genesis))
+
+	st, keys := util.DeterministicGenesisState(t, 64)
+
+	bState := st.Copy()
+
+	var blks []block.SignedBeaconBlock
+	var blkRoots [][32]byte
+	var firstState state.BeaconState
+	for i := 1; i < 10; i++ {
+		b, err := util.GenerateFullBlock(bState, keys, util.DefaultBlockGenConfig(), types.Slot(i))
+		require.NoError(t, err)
+		bState, err = transition.ExecuteStateTransition(ctx, bState, wrapper.WrappedPhase0SignedBeaconBlock(b))
+		require.NoError(t, err)
+		if i == 1 {
+			firstState = bState.Copy()
+		}
+		root, err := b.Block.HashTreeRoot()
+		require.NoError(t, err)
+		service.saveInitSyncBlock(root, wrapper.WrappedPhase0SignedBeaconBlock(b))
+		blks = append(blks, wrapper.WrappedPhase0SignedBeaconBlock(b))
+		blkRoots = append(blkRoots, root)
+	}
+
+	rBlock, err := blks[0].PbPhase0Block()
+	assert.NoError(t, err)
+	rBlock.Block.ParentRoot = gRoot[:]
+	require.NoError(t, beaconDB.SaveBlock(context.Background(), blks[0]))
+	require.NoError(t, service.cfg.StateGen.SaveState(ctx, blkRoots[0], firstState))
+	_, _, err = service.onBlockBatch(ctx, blks[1:], blkRoots[1:])
+	require.NoError(t, err)
+}
+
 func TestRemoveStateSinceLastFinalized_EmptyStartSlot(t *testing.T) {
 	ctx := context.Background()
 	params.SetupTestConfigCleanup(t)
@@ -215,7 +366,7 @@ func TestRemoveStateSinceLastFinalized_EmptyStartSlot(t *testing.T) {
 	assert.Equal(t, true, update, "Should be able to update justified")
 }
 
-func TestShouldUpdateJustified_ReturnFalse(t *testing.T) {
+func TestShouldUpdateJustified_ReturnFalse_ProtoArray(t *testing.T) {
 	ctx := context.Background()
 	params.SetupTestConfigCleanup(t)
 	params.OverrideBeaconConfig(params.MinimalSpecConfig())
@@ -244,7 +395,36 @@ func TestShouldUpdateJustified_ReturnFalse(t *testing.T) {
 	assert.Equal(t, false, update, "Should not be able to update justified, received true")
 }
 
-func TestCachedPreState_CanGetFromStateSummary(t *testing.T) {
+func TestShouldUpdateJustified_ReturnFalse_DoublyLinkedTree(t *testing.T) {
+	ctx := context.Background()
+	params.SetupTestConfigCleanup(t)
+	params.OverrideBeaconConfig(params.MinimalSpecConfig())
+
+	opts := testServiceOptsWithDB(t)
+	service, err := NewService(ctx, opts...)
+	require.NoError(t, err)
+	service.cfg.ForkChoiceStore = doublylinkedtree.New(0, 0)
+	lastJustifiedBlk := util.NewBeaconBlock()
+	lastJustifiedBlk.Block.ParentRoot = bytesutil.PadTo([]byte{'G'}, 32)
+	lastJustifiedRoot, err := lastJustifiedBlk.Block.HashTreeRoot()
+	require.NoError(t, err)
+	newJustifiedBlk := util.NewBeaconBlock()
+	newJustifiedBlk.Block.ParentRoot = bytesutil.PadTo(lastJustifiedRoot[:], 32)
+	newJustifiedRoot, err := newJustifiedBlk.Block.HashTreeRoot()
+	require.NoError(t, err)
+	require.NoError(t, service.cfg.BeaconDB.SaveBlock(ctx, wrapper.WrappedPhase0SignedBeaconBlock(newJustifiedBlk)))
+	require.NoError(t, service.cfg.BeaconDB.SaveBlock(ctx, wrapper.WrappedPhase0SignedBeaconBlock(lastJustifiedBlk)))
+
+	diff := params.BeaconConfig().SlotsPerEpoch.Sub(1).Mul(params.BeaconConfig().SecondsPerSlot)
+	service.genesisTime = time.Unix(time.Now().Unix()-int64(diff), 0)
+	service.store.SetJustifiedCheckpt(&ethpb.Checkpoint{Root: lastJustifiedRoot[:]})
+
+	update, err := service.shouldUpdateCurrentJustified(ctx, &ethpb.Checkpoint{Root: newJustifiedRoot[:]})
+	require.NoError(t, err)
+	assert.Equal(t, false, update, "Should not be able to update justified, received true")
+}
+
+func TestCachedPreState_CanGetFromStateSummary_ProtoArray(t *testing.T) {
 	ctx := context.Background()
 	beaconDB := testDB.SetupDB(t)
 
@@ -275,6 +455,37 @@ func TestCachedPreState_CanGetFromStateSummary(t *testing.T) {
 	require.NoError(t, service.verifyBlkPreState(ctx, wrapper.WrappedPhase0BeaconBlock(b.Block)))
 }
 
+func TestCachedPreState_CanGetFromStateSummary_DoublyLinkedTree(t *testing.T) {
+	ctx := context.Background()
+	beaconDB := testDB.SetupDB(t)
+
+	opts := []Option{
+		WithDatabase(beaconDB),
+		WithStateGen(stategen.New(beaconDB)),
+	}
+	service, err := NewService(ctx, opts...)
+	require.NoError(t, err)
+
+	s, err := v1.InitializeFromProto(&ethpb.BeaconState{Slot: 1, GenesisValidatorsRoot: params.BeaconConfig().ZeroHash[:]})
+	require.NoError(t, err)
+
+	genesisStateRoot := [32]byte{}
+	genesis := blocks.NewGenesisBlock(genesisStateRoot[:])
+	assert.NoError(t, beaconDB.SaveBlock(ctx, wrapper.WrappedPhase0SignedBeaconBlock(genesis)))
+	gRoot, err := genesis.Block.HashTreeRoot()
+	require.NoError(t, err)
+	service.store.SetFinalizedCheckpt(&ethpb.Checkpoint{Root: gRoot[:]})
+	service.cfg.ForkChoiceStore = doublylinkedtree.New(0, 0)
+	service.saveInitSyncBlock(gRoot, wrapper.WrappedPhase0SignedBeaconBlock(genesis))
+
+	b := util.NewBeaconBlock()
+	b.Block.Slot = 1
+	b.Block.ParentRoot = gRoot[:]
+	require.NoError(t, service.cfg.BeaconDB.SaveStateSummary(ctx, &ethpb.StateSummary{Slot: 1, Root: gRoot[:]}))
+	require.NoError(t, service.cfg.StateGen.SaveState(ctx, gRoot, s))
+	require.NoError(t, service.verifyBlkPreState(ctx, wrapper.WrappedPhase0BeaconBlock(b.Block)))
+}
+
 func TestCachedPreState_CanGetFromDB(t *testing.T) {
 	ctx := context.Background()
 	beaconDB := testDB.SetupDB(t)
@@ -347,7 +558,7 @@ func TestUpdateJustified_CouldUpdateBest(t *testing.T) {
 	assert.Equal(t, types.Epoch(2), service.store.BestJustifiedCheckpt().Epoch, "Incorrect justified epoch in service")
 }
 
-func TestFillForkChoiceMissingBlocks_CanSave(t *testing.T) {
+func TestFillForkChoiceMissingBlocks_CanSave_ProtoArray(t *testing.T) {
 	ctx := context.Background()
 	beaconDB := testDB.SetupDB(t)
 
@@ -382,13 +593,54 @@ func TestFillForkChoiceMissingBlocks_CanSave(t *testing.T) {
 	require.NoError(t, err)
 
 	// 5 nodes from the block tree 1. B0 - B3 - B4 - B6 - B8
-	assert.Equal(t, 5, len(service.cfg.ForkChoiceStore.Nodes()), "Miss match nodes")
+	assert.Equal(t, 5, service.cfg.ForkChoiceStore.NodeCount(), "Miss match nodes")
 	assert.Equal(t, true, service.cfg.ForkChoiceStore.HasNode(bytesutil.ToBytes32(roots[4])), "Didn't save node")
 	assert.Equal(t, true, service.cfg.ForkChoiceStore.HasNode(bytesutil.ToBytes32(roots[6])), "Didn't save node")
 	assert.Equal(t, true, service.cfg.ForkChoiceStore.HasNode(bytesutil.ToBytes32(roots[8])), "Didn't save node")
 }
 
-func TestFillForkChoiceMissingBlocks_RootsMatch(t *testing.T) {
+func TestFillForkChoiceMissingBlocks_CanSave_DoublyLinkedTree(t *testing.T) {
+	ctx := context.Background()
+	beaconDB := testDB.SetupDB(t)
+
+	opts := []Option{
+		WithDatabase(beaconDB),
+		WithStateGen(stategen.New(beaconDB)),
+	}
+	service, err := NewService(ctx, opts...)
+	require.NoError(t, err)
+	service.cfg.ForkChoiceStore = doublylinkedtree.New(0, 0)
+	service.store.SetFinalizedCheckpt(&ethpb.Checkpoint{Root: make([]byte, 32)})
+
+	genesisStateRoot := [32]byte{}
+	genesis := blocks.NewGenesisBlock(genesisStateRoot[:])
+	require.NoError(t, beaconDB.SaveBlock(ctx, wrapper.WrappedPhase0SignedBeaconBlock(genesis)))
+	validGenesisRoot, err := genesis.Block.HashTreeRoot()
+	require.NoError(t, err)
+	st, err := util.NewBeaconState()
+	require.NoError(t, err)
+
+	require.NoError(t, service.cfg.BeaconDB.SaveState(ctx, st.Copy(), validGenesisRoot))
+	roots, err := blockTree1(t, beaconDB, validGenesisRoot[:])
+	require.NoError(t, err)
+
+	beaconState, _ := util.DeterministicGenesisState(t, 32)
+	block := util.NewBeaconBlock()
+	block.Block.Slot = 9
+	block.Block.ParentRoot = roots[8]
+
+	err = service.fillInForkChoiceMissingBlocks(
+		context.Background(), wrapper.WrappedPhase0SignedBeaconBlock(block).Block(), beaconState.FinalizedCheckpoint(), beaconState.CurrentJustifiedCheckpoint())
+	require.NoError(t, err)
+
+	// 5 nodes from the block tree 1. B0 - B3 - B4 - B6 - B8
+	assert.Equal(t, 5, service.cfg.ForkChoiceStore.NodeCount(), "Miss match nodes")
+	assert.Equal(t, true, service.cfg.ForkChoiceStore.HasNode(bytesutil.ToBytes32(roots[4])), "Didn't save node")
+	assert.Equal(t, true, service.cfg.ForkChoiceStore.HasNode(bytesutil.ToBytes32(roots[6])), "Didn't save node")
+	assert.Equal(t, true, service.cfg.ForkChoiceStore.HasNode(bytesutil.ToBytes32(roots[8])), "Didn't save node")
+}
+
+func TestFillForkChoiceMissingBlocks_RootsMatch_ProtoArray(t *testing.T) {
 	ctx := context.Background()
 	beaconDB := testDB.SetupDB(t)
 
@@ -423,7 +675,7 @@ func TestFillForkChoiceMissingBlocks_RootsMatch(t *testing.T) {
 	require.NoError(t, err)
 
 	// 5 nodes from the block tree 1. B0 - B3 - B4 - B6 - B8
-	assert.Equal(t, 5, len(service.cfg.ForkChoiceStore.Nodes()), "Miss match nodes")
+	assert.Equal(t, 5, service.cfg.ForkChoiceStore.NodeCount(), "Miss match nodes")
 	// Ensure all roots and their respective blocks exist.
 	wantedRoots := [][]byte{roots[0], roots[3], roots[4], roots[6], roots[8]}
 	for i, rt := range wantedRoots {
@@ -432,7 +684,51 @@ func TestFillForkChoiceMissingBlocks_RootsMatch(t *testing.T) {
 	}
 }
 
-func TestFillForkChoiceMissingBlocks_FilterFinalized(t *testing.T) {
+func TestFillForkChoiceMissingBlocks_RootsMatch_DoublyLinkedTree(t *testing.T) {
+	ctx := context.Background()
+	beaconDB := testDB.SetupDB(t)
+
+	opts := []Option{
+		WithDatabase(beaconDB),
+		WithStateGen(stategen.New(beaconDB)),
+	}
+	service, err := NewService(ctx, opts...)
+	require.NoError(t, err)
+	service.cfg.ForkChoiceStore = doublylinkedtree.New(0, 0)
+	service.store.SetFinalizedCheckpt(&ethpb.Checkpoint{Root: make([]byte, 32)})
+
+	genesisStateRoot := [32]byte{}
+	genesis := blocks.NewGenesisBlock(genesisStateRoot[:])
+	require.NoError(t, beaconDB.SaveBlock(ctx, wrapper.WrappedPhase0SignedBeaconBlock(genesis)))
+	validGenesisRoot, err := genesis.Block.HashTreeRoot()
+	require.NoError(t, err)
+	st, err := util.NewBeaconState()
+	require.NoError(t, err)
+
+	require.NoError(t, service.cfg.BeaconDB.SaveState(ctx, st.Copy(), validGenesisRoot))
+	roots, err := blockTree1(t, beaconDB, validGenesisRoot[:])
+	require.NoError(t, err)
+
+	beaconState, _ := util.DeterministicGenesisState(t, 32)
+	block := util.NewBeaconBlock()
+	block.Block.Slot = 9
+	block.Block.ParentRoot = roots[8]
+
+	err = service.fillInForkChoiceMissingBlocks(
+		context.Background(), wrapper.WrappedPhase0SignedBeaconBlock(block).Block(), beaconState.FinalizedCheckpoint(), beaconState.CurrentJustifiedCheckpoint())
+	require.NoError(t, err)
+
+	// 5 nodes from the block tree 1. B0 - B3 - B4 - B6 - B8
+	assert.Equal(t, 5, service.cfg.ForkChoiceStore.NodeCount(), "Miss match nodes")
+	// Ensure all roots and their respective blocks exist.
+	wantedRoots := [][]byte{roots[0], roots[3], roots[4], roots[6], roots[8]}
+	for i, rt := range wantedRoots {
+		assert.Equal(t, true, service.cfg.ForkChoiceStore.HasNode(bytesutil.ToBytes32(rt)), fmt.Sprintf("Didn't save node: %d", i))
+		assert.Equal(t, true, service.cfg.BeaconDB.HasBlock(context.Background(), bytesutil.ToBytes32(rt)))
+	}
+}
+
+func TestFillForkChoiceMissingBlocks_FilterFinalized_ProtoArray(t *testing.T) {
 	ctx := context.Background()
 	beaconDB := testDB.SetupDB(t)
 
@@ -479,7 +775,60 @@ func TestFillForkChoiceMissingBlocks_FilterFinalized(t *testing.T) {
 	require.NoError(t, err)
 
 	// There should be 2 nodes, block 65 and block 64.
-	assert.Equal(t, 2, len(service.cfg.ForkChoiceStore.Nodes()), "Miss match nodes")
+	assert.Equal(t, 2, service.cfg.ForkChoiceStore.NodeCount(), "Miss match nodes")
+
+	// Block with slot 63 should be in fork choice because it's less than finalized epoch 1.
+	assert.Equal(t, true, service.cfg.ForkChoiceStore.HasNode(r63), "Didn't save node")
+}
+
+func TestFillForkChoiceMissingBlocks_FilterFinalized_DoublyLinkedTree(t *testing.T) {
+	ctx := context.Background()
+	beaconDB := testDB.SetupDB(t)
+
+	opts := []Option{
+		WithDatabase(beaconDB),
+		WithStateGen(stategen.New(beaconDB)),
+	}
+	service, err := NewService(ctx, opts...)
+	require.NoError(t, err)
+	service.cfg.ForkChoiceStore = doublylinkedtree.New(0, 0)
+	// Set finalized epoch to 1.
+	service.store.SetFinalizedCheckpt(&ethpb.Checkpoint{Epoch: 1})
+
+	genesisStateRoot := [32]byte{}
+	genesis := blocks.NewGenesisBlock(genesisStateRoot[:])
+	assert.NoError(t, beaconDB.SaveBlock(ctx, wrapper.WrappedPhase0SignedBeaconBlock(genesis)))
+	validGenesisRoot, err := genesis.Block.HashTreeRoot()
+	assert.NoError(t, err)
+	st, err := util.NewBeaconState()
+	require.NoError(t, err)
+
+	require.NoError(t, service.cfg.BeaconDB.SaveState(ctx, st.Copy(), validGenesisRoot))
+
+	// Define a tree branch, slot 63 <- 64 <- 65
+	b63 := util.NewBeaconBlock()
+	b63.Block.Slot = 63
+	require.NoError(t, service.cfg.BeaconDB.SaveBlock(ctx, wrapper.WrappedPhase0SignedBeaconBlock(b63)))
+	r63, err := b63.Block.HashTreeRoot()
+	require.NoError(t, err)
+	b64 := util.NewBeaconBlock()
+	b64.Block.Slot = 64
+	b64.Block.ParentRoot = r63[:]
+	require.NoError(t, service.cfg.BeaconDB.SaveBlock(ctx, wrapper.WrappedPhase0SignedBeaconBlock(b64)))
+	r64, err := b64.Block.HashTreeRoot()
+	require.NoError(t, err)
+	b65 := util.NewBeaconBlock()
+	b65.Block.Slot = 65
+	b65.Block.ParentRoot = r64[:]
+	require.NoError(t, service.cfg.BeaconDB.SaveBlock(ctx, wrapper.WrappedPhase0SignedBeaconBlock(b65)))
+
+	beaconState, _ := util.DeterministicGenesisState(t, 32)
+	err = service.fillInForkChoiceMissingBlocks(
+		context.Background(), wrapper.WrappedPhase0SignedBeaconBlock(b65).Block(), beaconState.FinalizedCheckpoint(), beaconState.CurrentJustifiedCheckpoint())
+	require.NoError(t, err)
+
+	// There should be 2 nodes, block 65 and block 64.
+	assert.Equal(t, 2, service.cfg.ForkChoiceStore.NodeCount(), "Miss match nodes")
 
 	// Block with slot 63 should be in fork choice because it's less than finalized epoch 1.
 	assert.Equal(t, true, service.cfg.ForkChoiceStore.HasNode(r63), "Didn't save node")
@@ -668,7 +1017,7 @@ func TestAncestor_CanUseForkchoice(t *testing.T) {
 		beaconBlock.Block.ParentRoot = bytesutil.PadTo(b.Block.ParentRoot, 32)
 		r, err := b.Block.HashTreeRoot()
 		require.NoError(t, err)
-		require.NoError(t, service.cfg.ForkChoiceStore.ProcessBlock(context.Background(), b.Block.Slot, r, bytesutil.ToBytes32(b.Block.ParentRoot), [32]byte{}, 0, 0)) // Saves blocks to fork choice store.
+		require.NoError(t, service.cfg.ForkChoiceStore.ProcessBlock(context.Background(), b.Block.Slot, r, bytesutil.ToBytes32(b.Block.ParentRoot), 0, 0, false)) // Saves blocks to fork choice store.
 	}
 
 	r, err := service.ancestor(context.Background(), r200[:], 150)
@@ -713,7 +1062,7 @@ func TestAncestor_CanUseDB(t *testing.T) {
 		require.NoError(t, beaconDB.SaveBlock(context.Background(), wrapper.WrappedPhase0SignedBeaconBlock(beaconBlock))) // Saves blocks to DB.
 	}
 
-	require.NoError(t, service.cfg.ForkChoiceStore.ProcessBlock(context.Background(), 200, r200, r200, [32]byte{}, 0, 0))
+	require.NoError(t, service.cfg.ForkChoiceStore.ProcessBlock(context.Background(), 200, r200, r200, 0, 0, false))
 
 	r, err := service.ancestor(context.Background(), r200[:], 150)
 	require.NoError(t, err)
@@ -789,7 +1138,7 @@ func TestVerifyBlkDescendant(t *testing.T) {
 				finalizedRoot: r1,
 				parentRoot:    r,
 			},
-			wantedErr: "is not a descendent of the current finalized block slot",
+			wantedErr: "is not a descendant of the current finalized block slot",
 		},
 		{
 			name: "is descendant",
@@ -913,6 +1262,48 @@ func TestOnBlock_CanFinalize(t *testing.T) {
 	require.Equal(t, f.Epoch, service.FinalizedCheckpt().Epoch)
 }
 
+func TestOnBlock_CallNewPayloadAndForkchoiceUpdated(t *testing.T) {
+	params.SetupTestConfigCleanup(t)
+	config := params.BeaconConfig()
+	config.AltairForkEpoch = 1
+	config.BellatrixForkEpoch = 2
+	params.OverrideBeaconConfig(config)
+
+	ctx := context.Background()
+	beaconDB := testDB.SetupDB(t)
+	fcs := protoarray.New(0, 0, [32]byte{'a'})
+	depositCache, err := depositcache.New()
+	require.NoError(t, err)
+	opts := []Option{
+		WithDatabase(beaconDB),
+		WithStateGen(stategen.New(beaconDB)),
+		WithForkChoiceStore(fcs),
+		WithDepositCache(depositCache),
+		WithStateNotifier(&mock.MockStateNotifier{}),
+	}
+	service, err := NewService(ctx, opts...)
+	require.NoError(t, err)
+
+	gs, keys := util.DeterministicGenesisState(t, 32)
+	require.NoError(t, service.saveGenesisData(ctx, gs))
+	gBlk, err := service.cfg.BeaconDB.GenesisBlock(ctx)
+	require.NoError(t, err)
+	gRoot, err := gBlk.Block().HashTreeRoot()
+	require.NoError(t, err)
+	service.store.SetFinalizedCheckpt(&ethpb.Checkpoint{Root: gRoot[:]})
+
+	testState := gs.Copy()
+	for i := types.Slot(1); i < params.BeaconConfig().SlotsPerEpoch; i++ {
+		blk, err := util.GenerateFullBlock(testState, keys, util.DefaultBlockGenConfig(), i)
+		require.NoError(t, err)
+		r, err := blk.Block.HashTreeRoot()
+		require.NoError(t, err)
+		require.NoError(t, service.onBlock(ctx, wrapper.WrappedPhase0SignedBeaconBlock(blk), r))
+		testState, err = service.cfg.StateGen.StateByRoot(ctx, r)
+		require.NoError(t, err)
+	}
+}
+
 func TestInsertFinalizedDeposits(t *testing.T) {
 	ctx := context.Background()
 	opts := testServiceOptsWithDB(t)
@@ -996,3 +1387,53 @@ func TestRemoveBlockAttestationsInPool_NonCanonical(t *testing.T) {
 	require.NoError(t, service.pruneCanonicalAttsFromPool(ctx, r, wrapper.WrappedPhase0SignedBeaconBlock(b)))
 	require.Equal(t, 1, service.cfg.AttPool.AggregatedAttestationCount())
 }
+
+func Test_getStateVersionAndPayload(t *testing.T) {
+	tests := []struct {
+		name    string
+		st      state.BeaconState
+		version int
+		header  *ethpb.ExecutionPayloadHeader
+	}{
+		{
+			name: "phase 0 state",
+			st: func() state.BeaconState {
+				s, _ := util.DeterministicGenesisState(t, 1)
+				return s
+			}(),
+			version: version.Phase0,
+			header:  (*ethpb.ExecutionPayloadHeader)(nil),
+		},
+		{
+			name: "altair state",
+			st: func() state.BeaconState {
+				s, _ := util.DeterministicGenesisStateAltair(t, 1)
+				return s
+			}(),
+			version: version.Altair,
+			header:  (*ethpb.ExecutionPayloadHeader)(nil),
+		},
+		{
+			name: "bellatrix state",
+			st: func() state.BeaconState {
+				s, _ := util.DeterministicGenesisStateBellatrix(t, 1)
+				require.NoError(t, s.SetLatestExecutionPayloadHeader(&ethpb.ExecutionPayloadHeader{
+					BlockNumber: 1,
+				}))
+				return s
+			}(),
+			version: version.Bellatrix,
+			header: &ethpb.ExecutionPayloadHeader{
+				BlockNumber: 1,
+			},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			version, header, err := getStateVersionAndPayload(tt.st)
+			require.NoError(t, err)
+			require.Equal(t, tt.version, version)
+			require.DeepEqual(t, tt.header, header)
+		})
+	}
+}

beacon-chain/blockchain/receive_attestation_test.go

@@ -111,7 +111,7 @@ func TestProcessAttestations_Ok(t *testing.T) {
 	copied, err = transition.ProcessSlots(ctx, copied, 1)
 	require.NoError(t, err)
 	require.NoError(t, service.cfg.BeaconDB.SaveState(ctx, copied, tRoot))
-	require.NoError(t, service.cfg.ForkChoiceStore.ProcessBlock(ctx, 0, tRoot, tRoot, tRoot, 1, 1))
+	require.NoError(t, service.cfg.ForkChoiceStore.ProcessBlock(ctx, 0, tRoot, tRoot, 1, 1, false))
 	require.NoError(t, service.cfg.AttPool.SaveForkchoiceAttestations(atts))
 	service.processAttestations(ctx)
 	require.Equal(t, 0, len(service.cfg.AttPool.ForkchoiceAttestations()))

beacon-chain/blockchain/receive_block.go

@@ -86,7 +86,8 @@ func (s *Service) ReceiveBlockBatch(ctx context.Context, blocks []block.SignedBe
 
 	for i, b := range blocks {
 		blockCopy := b.Copy()
-		if err = s.handleBlockAfterBatchVerify(ctx, blockCopy, blkRoots[i], fCheckpoints[i], jCheckpoints[i]); err != nil {
+		// TODO(10261) check optimistic status
+		if err = s.handleBlockAfterBatchVerify(ctx, blockCopy, blkRoots[i], fCheckpoints[i], jCheckpoints[i], false /*optimistic status*/); err != nil {
 			tracing.AnnotateError(span, err)
 			return err
 		}

beacon-chain/blockchain/receive_block_test.go

@@ -192,7 +192,7 @@ func TestService_ReceiveBlockUpdateHead(t *testing.T) {
 		t.Errorf("Received %d state notifications, expected at least 1", recvd)
 	}
 	// Verify fork choice has processed the block. (Genesis block and the new block)
-	assert.Equal(t, 2, len(s.cfg.ForkChoiceStore.Nodes()))
+	assert.Equal(t, 2, s.cfg.ForkChoiceStore.NodeCount())
 }
 
 func TestService_ReceiveBlockBatch(t *testing.T) {

beacon-chain/blockchain/service.go

@@ -21,15 +21,18 @@ import (
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/transition"
 	"github.com/prysmaticlabs/prysm/beacon-chain/db"
 	f "github.com/prysmaticlabs/prysm/beacon-chain/forkchoice"
+	doublylinkedtree "github.com/prysmaticlabs/prysm/beacon-chain/forkchoice/doubly-linked-tree"
 	"github.com/prysmaticlabs/prysm/beacon-chain/forkchoice/protoarray"
 	"github.com/prysmaticlabs/prysm/beacon-chain/operations/attestations"
 	"github.com/prysmaticlabs/prysm/beacon-chain/operations/slashings"
 	"github.com/prysmaticlabs/prysm/beacon-chain/operations/voluntaryexits"
 	"github.com/prysmaticlabs/prysm/beacon-chain/p2p"
 	"github.com/prysmaticlabs/prysm/beacon-chain/powchain"
+	enginev1 "github.com/prysmaticlabs/prysm/beacon-chain/powchain/engine-api-client/v1"
 	"github.com/prysmaticlabs/prysm/beacon-chain/state"
 	"github.com/prysmaticlabs/prysm/beacon-chain/state/stategen"
 	"github.com/prysmaticlabs/prysm/cmd/beacon-chain/flags"
+	"github.com/prysmaticlabs/prysm/config/features"
 	"github.com/prysmaticlabs/prysm/config/params"
 	"github.com/prysmaticlabs/prysm/encoding/bytesutil"
 	ethpb "github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1"
@@ -82,7 +85,9 @@ type config struct {
 	StateGen                *stategen.State
 	SlasherAttestationsFeed *event.Feed
 	WeakSubjectivityCheckpt *ethpb.Checkpoint
+	BlockFetcher            powchain.POWBlockFetcher
 	FinalizedStateAtStartUp state.BeaconState
+	ExecutionEngineCaller   enginev1.Caller
 }
 
 // NewService instantiates a new block service instance that will
@@ -130,6 +135,7 @@ func (s *Service) Start() {
 			log.Fatal(err)
 		}
 	}
+	s.spawnProcessAttestationsRoutine(s.cfg.StateNotifier.StateFeed())
 }
 
 // Stop the blockchain service's main event loop and associated goroutines.
@@ -184,7 +190,12 @@ func (s *Service) startFromSavedState(saved state.BeaconState) error {
 	}
 	s.store = store.New(justified, finalized)
 
-	store := protoarray.New(justified.Epoch, finalized.Epoch, bytesutil.ToBytes32(finalized.Root))
+	var store f.ForkChoicer
+	if features.Get().EnableForkChoiceDoublyLinkedTree {
+		store = doublylinkedtree.New(justified.Epoch, finalized.Epoch)
+	} else {
+		store = protoarray.New(justified.Epoch, finalized.Epoch, bytesutil.ToBytes32(finalized.Root))
+	}
 	s.cfg.ForkChoiceStore = store
 
 	ss, err := slots.EpochStart(finalized.Epoch)
@@ -213,12 +224,10 @@ func (s *Service) startFromSavedState(saved state.BeaconState) error {
 		Type: statefeed.Initialized,
 		Data: &statefeed.InitializedData{
 			StartTime:             s.genesisTime,
-			GenesisValidatorsRoot: saved.GenesisValidatorRoot(),
+			GenesisValidatorsRoot: saved.GenesisValidatorsRoot(),
 		},
 	})
 
-	s.spawnProcessAttestationsRoutine(s.cfg.StateNotifier.StateFeed())
-
 	return nil
 }
 
@@ -327,7 +336,6 @@ func (s *Service) startFromPOWChain() error {
 		stateChannel := make(chan *feed.Event, 1)
 		stateSub := s.cfg.StateNotifier.StateFeed().Subscribe(stateChannel)
 		defer stateSub.Unsubscribe()
-		s.spawnProcessAttestationsRoutine(s.cfg.StateNotifier.StateFeed())
 		for {
 			select {
 			case event := <-stateChannel:
@@ -375,7 +383,7 @@ func (s *Service) onPowchainStart(ctx context.Context, genesisTime time.Time) {
 		Type: statefeed.Initialized,
 		Data: &statefeed.InitializedData{
 			StartTime:             genesisTime,
-			GenesisValidatorsRoot: initializedState.GenesisValidatorRoot(),
+			GenesisValidatorsRoot: initializedState.GenesisValidatorsRoot(),
 		},
 	})
 }
@@ -445,9 +453,8 @@ func (s *Service) saveGenesisData(ctx context.Context, genesisState state.Beacon
 		genesisBlk.Block().Slot(),
 		genesisBlkRoot,
 		params.BeaconConfig().ZeroHash,
-		[32]byte{},
 		genesisCheckpoint.Epoch,
-		genesisCheckpoint.Epoch); err != nil {
+		genesisCheckpoint.Epoch, false /* optimistic status */); err != nil {
 		log.Fatalf("Could not process genesis block for fork choice: %v", err)
 	}
 

beacon-chain/blockchain/service_test.go

@@ -19,6 +19,7 @@ import (
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/transition"
 	"github.com/prysmaticlabs/prysm/beacon-chain/db"
 	testDB "github.com/prysmaticlabs/prysm/beacon-chain/db/testing"
+	doublylinkedtree "github.com/prysmaticlabs/prysm/beacon-chain/forkchoice/doubly-linked-tree"
 	"github.com/prysmaticlabs/prysm/beacon-chain/forkchoice/protoarray"
 	"github.com/prysmaticlabs/prysm/beacon-chain/operations/attestations"
 	"github.com/prysmaticlabs/prysm/beacon-chain/p2p"
@@ -278,7 +279,7 @@ func TestChainService_InitializeChainInfo(t *testing.T) {
 	headState, err := util.NewBeaconState()
 	require.NoError(t, err)
 	require.NoError(t, headState.SetSlot(finalizedSlot))
-	require.NoError(t, headState.SetGenesisValidatorRoot(params.BeaconConfig().ZeroHash[:]))
+	require.NoError(t, headState.SetGenesisValidatorsRoot(params.BeaconConfig().ZeroHash[:]))
 	headRoot, err := headBlock.Block.HashTreeRoot()
 	require.NoError(t, err)
 	require.NoError(t, beaconDB.SaveState(ctx, headState, headRoot))
@@ -322,7 +323,7 @@ func TestChainService_InitializeChainInfo_SetHeadAtGenesis(t *testing.T) {
 	headState, err := util.NewBeaconState()
 	require.NoError(t, err)
 	require.NoError(t, headState.SetSlot(finalizedSlot))
-	require.NoError(t, headState.SetGenesisValidatorRoot(params.BeaconConfig().ZeroHash[:]))
+	require.NoError(t, headState.SetGenesisValidatorsRoot(params.BeaconConfig().ZeroHash[:]))
 	headRoot, err := headBlock.Block.HashTreeRoot()
 	require.NoError(t, err)
 	require.NoError(t, beaconDB.SaveState(ctx, headState, headRoot))
@@ -378,7 +379,7 @@ func TestChainService_InitializeChainInfo_HeadSync(t *testing.T) {
 	headState, err := util.NewBeaconState()
 	require.NoError(t, err)
 	require.NoError(t, headState.SetSlot(headBlock.Block.Slot))
-	require.NoError(t, headState.SetGenesisValidatorRoot(params.BeaconConfig().ZeroHash[:]))
+	require.NoError(t, headState.SetGenesisValidatorsRoot(params.BeaconConfig().ZeroHash[:]))
 	require.NoError(t, beaconDB.SaveState(ctx, headState, genesisRoot))
 	require.NoError(t, beaconDB.SaveState(ctx, headState, finalizedRoot))
 	require.NoError(t, beaconDB.SaveState(ctx, headState, headRoot))
@@ -446,7 +447,7 @@ func TestChainService_SaveHeadNoDB(t *testing.T) {
 	}
 }
 
-func TestHasBlock_ForkChoiceAndDB(t *testing.T) {
+func TestHasBlock_ForkChoiceAndDB_ProtoArray(t *testing.T) {
 	ctx := context.Background()
 	beaconDB := testDB.SetupDB(t)
 	s := &Service{
@@ -459,7 +460,26 @@ func TestHasBlock_ForkChoiceAndDB(t *testing.T) {
 	require.NoError(t, err)
 	beaconState, err := util.NewBeaconState()
 	require.NoError(t, err)
-	require.NoError(t, s.insertBlockAndAttestationsToForkChoiceStore(ctx, wrapper.WrappedPhase0SignedBeaconBlock(block).Block(), r, beaconState))
+	require.NoError(t, s.insertBlockAndAttestationsToForkChoiceStore(ctx, wrapper.WrappedPhase0SignedBeaconBlock(block).Block(), r, beaconState, false))
+
+	assert.Equal(t, false, s.hasBlock(ctx, [32]byte{}), "Should not have block")
+	assert.Equal(t, true, s.hasBlock(ctx, r), "Should have block")
+}
+
+func TestHasBlock_ForkChoiceAndDB_DoublyLinkedTree(t *testing.T) {
+	ctx := context.Background()
+	beaconDB := testDB.SetupDB(t)
+	s := &Service{
+		cfg:   &config{ForkChoiceStore: doublylinkedtree.New(0, 0), BeaconDB: beaconDB},
+		store: &store.Store{},
+	}
+	s.store.SetFinalizedCheckpt(&ethpb.Checkpoint{Epoch: 0, Root: params.BeaconConfig().ZeroHash[:]})
+	block := util.NewBeaconBlock()
+	r, err := block.Block.HashTreeRoot()
+	require.NoError(t, err)
+	beaconState, err := util.NewBeaconState()
+	require.NoError(t, err)
+	require.NoError(t, s.insertBlockAndAttestationsToForkChoiceStore(ctx, wrapper.WrappedPhase0SignedBeaconBlock(block).Block(), r, beaconState, false))
 
 	assert.Equal(t, false, s.hasBlock(ctx, [32]byte{}), "Should not have block")
 	assert.Equal(t, true, s.hasBlock(ctx, r), "Should have block")
@@ -513,7 +533,7 @@ func BenchmarkHasBlockDB(b *testing.B) {
 	}
 }
 
-func BenchmarkHasBlockForkChoiceStore(b *testing.B) {
+func BenchmarkHasBlockForkChoiceStore_ProtoArray(b *testing.B) {
 	ctx := context.Background()
 	beaconDB := testDB.SetupDB(b)
 	s := &Service{
@@ -527,7 +547,28 @@ func BenchmarkHasBlockForkChoiceStore(b *testing.B) {
 	bs := &ethpb.BeaconState{FinalizedCheckpoint: &ethpb.Checkpoint{Root: make([]byte, 32)}, CurrentJustifiedCheckpoint: &ethpb.Checkpoint{Root: make([]byte, 32)}}
 	beaconState, err := v1.InitializeFromProto(bs)
 	require.NoError(b, err)
-	require.NoError(b, s.insertBlockAndAttestationsToForkChoiceStore(ctx, wrapper.WrappedPhase0SignedBeaconBlock(block).Block(), r, beaconState))
+	require.NoError(b, s.insertBlockAndAttestationsToForkChoiceStore(ctx, wrapper.WrappedPhase0SignedBeaconBlock(block).Block(), r, beaconState, false))
+
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		require.Equal(b, true, s.cfg.ForkChoiceStore.HasNode(r), "Block is not in fork choice store")
+	}
+}
+func BenchmarkHasBlockForkChoiceStore_DoublyLinkedTree(b *testing.B) {
+	ctx := context.Background()
+	beaconDB := testDB.SetupDB(b)
+	s := &Service{
+		cfg:   &config{ForkChoiceStore: doublylinkedtree.New(0, 0), BeaconDB: beaconDB},
+		store: &store.Store{},
+	}
+	s.store.SetFinalizedCheckpt(&ethpb.Checkpoint{Epoch: 0, Root: params.BeaconConfig().ZeroHash[:]})
+	block := &ethpb.SignedBeaconBlock{Block: &ethpb.BeaconBlock{Body: &ethpb.BeaconBlockBody{}}}
+	r, err := block.Block.HashTreeRoot()
+	require.NoError(b, err)
+	bs := &ethpb.BeaconState{FinalizedCheckpoint: &ethpb.Checkpoint{Root: make([]byte, 32)}, CurrentJustifiedCheckpoint: &ethpb.Checkpoint{Root: make([]byte, 32)}}
+	beaconState, err := v1.InitializeFromProto(bs)
+	require.NoError(b, err)
+	require.NoError(b, s.insertBlockAndAttestationsToForkChoiceStore(ctx, wrapper.WrappedPhase0SignedBeaconBlock(block).Block(), r, beaconState, false))
 
 	b.ResetTimer()
 	for i := 0; i < b.N; i++ {

beacon-chain/blockchain/testing/BUILD.bazel

@@ -18,9 +18,8 @@ go_library(
         "//beacon-chain/core/feed/state:go_default_library",
         "//beacon-chain/core/helpers:go_default_library",
         "//beacon-chain/db:go_default_library",
-        "//beacon-chain/forkchoice/protoarray:go_default_library",
+        "//beacon-chain/forkchoice:go_default_library",
         "//beacon-chain/state:go_default_library",
-        "//beacon-chain/state/v1:go_default_library",
         "//config/fieldparams:go_default_library",
         "//config/params:go_default_library",
         "//encoding/bytesutil:go_default_library",

beacon-chain/blockchain/testing/mock.go

@@ -18,9 +18,8 @@ import (
 	statefeed "github.com/prysmaticlabs/prysm/beacon-chain/core/feed/state"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
 	"github.com/prysmaticlabs/prysm/beacon-chain/db"
-	"github.com/prysmaticlabs/prysm/beacon-chain/forkchoice/protoarray"
+	"github.com/prysmaticlabs/prysm/beacon-chain/forkchoice"
 	"github.com/prysmaticlabs/prysm/beacon-chain/state"
-	v1 "github.com/prysmaticlabs/prysm/beacon-chain/state/v1"
 	fieldparams "github.com/prysmaticlabs/prysm/config/fieldparams"
 	"github.com/prysmaticlabs/prysm/config/params"
 	"github.com/prysmaticlabs/prysm/encoding/bytesutil"
@@ -29,36 +28,44 @@ import (
 	"github.com/sirupsen/logrus"
 )
 
+var ErrNilState = errors.New("nil state")
+
 // ChainService defines the mock interface for testing
 type ChainService struct {
-	State                       state.BeaconState
-	Root                        []byte
-	Block                       block.SignedBeaconBlock
+	Optimistic                  bool
+	ValidAttestation            bool
+	ValidatorsRoot              [32]byte
+	PublicKey                   [fieldparams.BLSPubkeyLength]byte
 	FinalizedCheckPoint         *ethpb.Checkpoint
 	CurrentJustifiedCheckPoint  *ethpb.Checkpoint
 	PreviousJustifiedCheckPoint *ethpb.Checkpoint
-	BlocksReceived              []block.SignedBeaconBlock
+	Slot                        *types.Slot // Pointer because 0 is a useful value, so checking against it can be incorrect.
 	Balance                     *precompute.Balance
-	Genesis                     time.Time
-	ValidatorsRoot              [32]byte
 	CanonicalRoots              map[[32]byte]bool
 	Fork                        *ethpb.Fork
 	ETH1Data                    *ethpb.Eth1Data
+	InitSyncBlockRoots          map[[32]byte]bool
 	DB                          db.Database
+	State                       state.BeaconState
+	Block                       block.SignedBeaconBlock
+	VerifyBlkDescendantErr      error
 	stateNotifier               statefeed.Notifier
+	BlocksReceived              []block.SignedBeaconBlock
+	SyncCommitteeIndices        []types.CommitteeIndex
 	blockNotifier               blockfeed.Notifier
 	opNotifier                  opfeed.Notifier
-	ValidAttestation            bool
-	ForkChoiceStore             *protoarray.Store
-	VerifyBlkDescendantErr      error
-	Slot                        *types.Slot // Pointer because 0 is a useful value, so checking against it can be incorrect.
-	SyncCommitteeIndices        []types.CommitteeIndex
+	Root                        []byte
 	SyncCommitteeDomain         []byte
 	SyncSelectionProofDomain    []byte
 	SyncContributionProofDomain []byte
-	PublicKey                   [fieldparams.BLSPubkeyLength]byte
 	SyncCommitteePubkeys        [][]byte
-	InitSyncBlockRoots          map[[32]byte]bool
+	Genesis                     time.Time
+	ForkChoiceStore             forkchoice.ForkChoicer
+}
+
+// ForkChoicer mocks the same method in the chain service
+func (s *ChainService) ForkChoicer() forkchoice.ForkChoicer {
+	return s.ForkChoiceStore
 }
 
 // StateNotifier mocks the same method in the chain service.
@@ -159,7 +166,7 @@ func (mon *MockOperationNotifier) OperationFeed() *event.Feed {
 // ReceiveBlockInitialSync mocks ReceiveBlockInitialSync method in chain service.
 func (s *ChainService) ReceiveBlockInitialSync(ctx context.Context, block block.SignedBeaconBlock, _ [32]byte) error {
 	if s.State == nil {
-		s.State = &v1.BeaconState{}
+		return ErrNilState
 	}
 	if !bytes.Equal(s.Root, block.Block().ParentRoot()) {
 		return errors.Errorf("wanted %#x but got %#x", s.Root, block.Block().ParentRoot())
@@ -186,7 +193,7 @@ func (s *ChainService) ReceiveBlockInitialSync(ctx context.Context, block block.
 // ReceiveBlockBatch processes blocks in batches from initial-sync.
 func (s *ChainService) ReceiveBlockBatch(ctx context.Context, blks []block.SignedBeaconBlock, _ [][32]byte) error {
 	if s.State == nil {
-		s.State = &v1.BeaconState{}
+		return ErrNilState
 	}
 	for _, block := range blks {
 		if !bytes.Equal(s.Root, block.Block().ParentRoot()) {
@@ -215,7 +222,7 @@ func (s *ChainService) ReceiveBlockBatch(ctx context.Context, blks []block.Signe
 // ReceiveBlock mocks ReceiveBlock method in chain service.
 func (s *ChainService) ReceiveBlock(ctx context.Context, block block.SignedBeaconBlock, _ [32]byte) error {
 	if s.State == nil {
-		s.State = &v1.BeaconState{}
+		return ErrNilState
 	}
 	if !bytes.Equal(s.Root, block.Block().ParentRoot()) {
 		return errors.Errorf("wanted %#x but got %#x", s.Root, block.Block().ParentRoot())
@@ -318,18 +325,13 @@ func (s *ChainService) HeadETH1Data() *ethpb.Eth1Data {
 	return s.ETH1Data
 }
 
-// ProtoArrayStore mocks the same method in the chain service.
-func (s *ChainService) ProtoArrayStore() *protoarray.Store {
-	return s.ForkChoiceStore
-}
-
 // GenesisTime mocks the same method in the chain service.
 func (s *ChainService) GenesisTime() time.Time {
 	return s.Genesis
 }
 
-// GenesisValidatorRoot mocks the same method in the chain service.
-func (s *ChainService) GenesisValidatorRoot() [32]byte {
+// GenesisValidatorsRoot mocks the same method in the chain service.
+func (s *ChainService) GenesisValidatorsRoot() [32]byte {
 	return s.ValidatorsRoot
 }
 
@@ -369,8 +371,8 @@ func (s *ChainService) HasInitSyncBlock(rt [32]byte) bool {
 	return s.InitSyncBlockRoots[rt]
 }
 
-// HeadGenesisValidatorRoot mocks HeadGenesisValidatorRoot method in chain service.
-func (_ *ChainService) HeadGenesisValidatorRoot() [32]byte {
+// HeadGenesisValidatorsRoot mocks HeadGenesisValidatorsRoot method in chain service.
+func (_ *ChainService) HeadGenesisValidatorsRoot() [32]byte {
 	return [32]byte{}
 }
 
@@ -441,5 +443,10 @@ func (s *ChainService) HeadSyncContributionProofDomain(_ context.Context, _ type
 
 // IsOptimistic mocks the same method in the chain service.
 func (s *ChainService) IsOptimistic(_ context.Context) (bool, error) {
-	return false, nil
+	return s.Optimistic, nil
+}
+
+// IsOptimisticForRoot mocks the same method in the chain service.
+func (s *ChainService) IsOptimisticForRoot(_ context.Context, _ [32]byte) (bool, error) {
+	return s.Optimistic, nil
 }

beacon-chain/cache/BUILD.bazel

@@ -30,7 +30,6 @@ go_library(
     ],
     deps = [
         "//beacon-chain/state:go_default_library",
-        "//beacon-chain/state/v1:go_default_library",
         "//cache/lru:go_default_library",
         "//config/features:go_default_library",
         "//config/params:go_default_library",

beacon-chain/cache/sync_committee_head_state.go

@@ -6,7 +6,6 @@ import (
 	lru "github.com/hashicorp/golang-lru"
 	types "github.com/prysmaticlabs/eth2-types"
 	"github.com/prysmaticlabs/prysm/beacon-chain/state"
-	v1 "github.com/prysmaticlabs/prysm/beacon-chain/state/v1"
 	lruwrpr "github.com/prysmaticlabs/prysm/cache/lru"
 	"github.com/prysmaticlabs/prysm/runtime/version"
 )
@@ -33,8 +32,7 @@ func (c *SyncCommitteeHeadStateCache) Put(slot types.Slot, st state.BeaconState)
 		return ErrNilValueProvided
 	}
 
-	_, ok := st.(*v1.BeaconState)
-	if ok {
+	if st.Version() == version.Phase0 {
 		return ErrIncorrectType
 	}
 

beacon-chain/core/altair/block.go

@@ -102,7 +102,7 @@ func FilterSyncCommitteeVotes(s state.BeaconStateAltair, sync *ethpb.SyncAggrega
 // VerifySyncCommitteeSig verifies sync committee signature `syncSig` is valid with respect to public keys `syncKeys`.
 func VerifySyncCommitteeSig(s state.BeaconStateAltair, syncKeys []bls.PublicKey, syncSig []byte) error {
 	ps := slots.PrevSlot(s.Slot())
-	d, err := signing.Domain(s.Fork(), slots.ToEpoch(ps), params.BeaconConfig().DomainSyncCommittee, s.GenesisValidatorRoot())
+	d, err := signing.Domain(s.Fork(), slots.ToEpoch(ps), params.BeaconConfig().DomainSyncCommittee, s.GenesisValidatorsRoot())
 	if err != nil {
 		return err
 	}

beacon-chain/core/altair/sync_committee_test.go

@@ -8,7 +8,9 @@ import (
 	types "github.com/prysmaticlabs/eth2-types"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/altair"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
+	"github.com/prysmaticlabs/prysm/beacon-chain/state"
 	stateAltair "github.com/prysmaticlabs/prysm/beacon-chain/state/v2"
+	v2 "github.com/prysmaticlabs/prysm/beacon-chain/state/v2"
 	"github.com/prysmaticlabs/prysm/config/params"
 	"github.com/prysmaticlabs/prysm/crypto/bls"
 	ethpb "github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1"
@@ -18,7 +20,7 @@ import (
 )
 
 func TestSyncCommitteeIndices_CanGet(t *testing.T) {
-	getState := func(t *testing.T, count uint64) *stateAltair.BeaconState {
+	getState := func(t *testing.T, count uint64) state.BeaconStateAltair {
 		validators := make([]*ethpb.Validator, count)
 		for i := 0; i < len(validators); i++ {
 			validators[i] = &ethpb.Validator{
@@ -35,7 +37,7 @@ func TestSyncCommitteeIndices_CanGet(t *testing.T) {
 	}
 
 	type args struct {
-		state *stateAltair.BeaconState
+		state state.BeaconStateAltair
 		epoch types.Epoch
 	}
 	tests := []struct {
@@ -45,9 +47,9 @@ func TestSyncCommitteeIndices_CanGet(t *testing.T) {
 		errString string
 	}{
 		{
-			name: "nil state",
+			name: "nil inner state",
 			args: args{
-				state: nil,
+				state: &v2.BeaconState{},
 			},
 			wantErr:   true,
 			errString: "nil inner state",
@@ -93,7 +95,7 @@ func TestSyncCommitteeIndices_CanGet(t *testing.T) {
 
 func TestSyncCommitteeIndices_DifferentPeriods(t *testing.T) {
 	helpers.ClearCache()
-	getState := func(t *testing.T, count uint64) *stateAltair.BeaconState {
+	getState := func(t *testing.T, count uint64) state.BeaconStateAltair {
 		validators := make([]*ethpb.Validator, count)
 		for i := 0; i < len(validators); i++ {
 			validators[i] = &ethpb.Validator{
@@ -127,7 +129,7 @@ func TestSyncCommitteeIndices_DifferentPeriods(t *testing.T) {
 }
 
 func TestSyncCommittee_CanGet(t *testing.T) {
-	getState := func(t *testing.T, count uint64) *stateAltair.BeaconState {
+	getState := func(t *testing.T, count uint64) state.BeaconStateAltair {
 		validators := make([]*ethpb.Validator, count)
 		for i := 0; i < len(validators); i++ {
 			blsKey, err := bls.RandKey()
@@ -147,7 +149,7 @@ func TestSyncCommittee_CanGet(t *testing.T) {
 	}
 
 	type args struct {
-		state *stateAltair.BeaconState
+		state state.BeaconStateAltair
 		epoch types.Epoch
 	}
 	tests := []struct {
@@ -157,9 +159,9 @@ func TestSyncCommittee_CanGet(t *testing.T) {
 		errString string
 	}{
 		{
-			name: "nil state",
+			name: "nil inner state",
 			args: args{
-				state: nil,
+				state: &v2.BeaconState{},
 			},
 			wantErr:   true,
 			errString: "nil inner state",
@@ -382,7 +384,7 @@ func Test_ValidateSyncMessageTime(t *testing.T) {
 	}
 }
 
-func getState(t *testing.T, count uint64) *stateAltair.BeaconState {
+func getState(t *testing.T, count uint64) state.BeaconStateAltair {
 	validators := make([]*ethpb.Validator, count)
 	for i := 0; i < len(validators); i++ {
 		blsKey, err := bls.RandKey()

beacon-chain/core/altair/upgrade.go

@@ -68,7 +68,7 @@ func UpgradeToAltair(ctx context.Context, state state.BeaconState) (state.Beacon
 	numValidators := state.NumValidators()
 	s := &ethpb.BeaconStateAltair{
 		GenesisTime:           state.GenesisTime(),
-		GenesisValidatorsRoot: state.GenesisValidatorRoot(),
+		GenesisValidatorsRoot: state.GenesisValidatorsRoot(),
 		Slot:                  state.Slot(),
 		Fork: &ethpb.Fork{
 			PreviousVersion: state.Fork().CurrentVersion,
@@ -137,7 +137,7 @@ func UpgradeToAltair(ctx context.Context, state state.BeaconState) (state.Beacon
 //        for index in get_attesting_indices(state, data, attestation.aggregation_bits):
 //            for flag_index in participation_flag_indices:
 //                epoch_participation[index] = add_flag(epoch_participation[index], flag_index)
-func TranslateParticipation(ctx context.Context, state *statealtair.BeaconState, atts []*ethpb.PendingAttestation) (*statealtair.BeaconState, error) {
+func TranslateParticipation(ctx context.Context, state state.BeaconStateAltair, atts []*ethpb.PendingAttestation) (state.BeaconStateAltair, error) {
 	epochParticipation, err := state.PreviousEpochParticipation()
 	if err != nil {
 		return nil, err

beacon-chain/core/altair/upgrade_test.go

@@ -9,7 +9,6 @@ import (
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/altair"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/time"
-	stateAltair "github.com/prysmaticlabs/prysm/beacon-chain/state/v2"
 	"github.com/prysmaticlabs/prysm/config/params"
 	ethpb "github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1"
 	"github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1/attestation"
@@ -20,12 +19,10 @@ import (
 func TestTranslateParticipation(t *testing.T) {
 	ctx := context.Background()
 	s, _ := util.DeterministicGenesisStateAltair(t, 64)
-	st, ok := s.(*stateAltair.BeaconState)
-	require.Equal(t, true, ok)
-	require.NoError(t, st.SetSlot(st.Slot()+params.BeaconConfig().MinAttestationInclusionDelay))
+	require.NoError(t, s.SetSlot(s.Slot()+params.BeaconConfig().MinAttestationInclusionDelay))
 
 	var err error
-	newState, err := altair.TranslateParticipation(ctx, st, nil)
+	newState, err := altair.TranslateParticipation(ctx, s, nil)
 	require.NoError(t, err)
 	participation, err := newState.PreviousEpochParticipation()
 	require.NoError(t, err)
@@ -56,7 +53,7 @@ func TestTranslateParticipation(t *testing.T) {
 	require.NoError(t, err)
 	require.DeepNotSSZEqual(t, make([]byte, 64), participation)
 
-	committee, err := helpers.BeaconCommitteeFromState(ctx, st, pendingAtts[0].Data.Slot, pendingAtts[0].Data.CommitteeIndex)
+	committee, err := helpers.BeaconCommitteeFromState(ctx, s, pendingAtts[0].Data.Slot, pendingAtts[0].Data.CommitteeIndex)
 	require.NoError(t, err)
 	indices, err := attestation.AttestingIndices(pendingAtts[0].AggregationBits, committee)
 	require.NoError(t, err)
@@ -80,7 +77,7 @@ func TestUpgradeToAltair(t *testing.T) {
 	require.NoError(t, err)
 
 	require.Equal(t, preForkState.GenesisTime(), aState.GenesisTime())
-	require.DeepSSZEqual(t, preForkState.GenesisValidatorRoot(), aState.GenesisValidatorRoot())
+	require.DeepSSZEqual(t, preForkState.GenesisValidatorsRoot(), aState.GenesisValidatorsRoot())
 	require.Equal(t, preForkState.Slot(), aState.Slot())
 	require.DeepSSZEqual(t, preForkState.LatestBlockHeader(), aState.LatestBlockHeader())
 	require.DeepSSZEqual(t, preForkState.BlockRoots(), aState.BlockRoots())

beacon-chain/core/blocks/BUILD.bazel

@@ -98,6 +98,7 @@ go_test(
         "//proto/prysm/v1alpha1/attestation/aggregation:go_default_library",
         "//proto/prysm/v1alpha1/attestation/aggregation/attestations:go_default_library",
         "//proto/prysm/v1alpha1/wrapper:go_default_library",
+        "//runtime/version:go_default_library",
         "//testing/assert:go_default_library",
         "//testing/require:go_default_library",
         "//testing/util:go_default_library",

beacon-chain/core/blocks/attestation.go

@@ -208,7 +208,7 @@ func VerifyIndexedAttestation(ctx context.Context, beaconState state.ReadOnlyBea
 		beaconState.Fork(),
 		indexedAtt.Data.Target.Epoch,
 		params.BeaconConfig().DomainBeaconAttester,
-		beaconState.GenesisValidatorRoot(),
+		beaconState.GenesisValidatorsRoot(),
 	)
 	if err != nil {
 		return err

beacon-chain/core/blocks/attestation_test.go

@@ -337,7 +337,9 @@ func TestValidateIndexedAttestation_AboveMaxLength(t *testing.T) {
 	}
 
 	want := "validator indices count exceeds MAX_VALIDATORS_PER_COMMITTEE"
-	err := blocks.VerifyIndexedAttestation(context.Background(), &v1.BeaconState{}, indexedAtt1)
+	st, err := v1.InitializeFromProtoUnsafe(&ethpb.BeaconState{})
+	require.NoError(t, err)
+	err = blocks.VerifyIndexedAttestation(context.Background(), st, indexedAtt1)
 	assert.ErrorContains(t, want, err)
 }
 
@@ -415,7 +417,7 @@ func TestVerifyAttestations_HandlesPlannedFork(t *testing.T) {
 			Slot: 1,
 		},
 	})
-	prevDomain, err := signing.Domain(st.Fork(), st.Fork().Epoch-1, params.BeaconConfig().DomainBeaconAttester, st.GenesisValidatorRoot())
+	prevDomain, err := signing.Domain(st.Fork(), st.Fork().Epoch-1, params.BeaconConfig().DomainBeaconAttester, st.GenesisValidatorsRoot())
 	require.NoError(t, err)
 	root, err := signing.ComputeSigningRoot(att1.Data, prevDomain)
 	require.NoError(t, err)
@@ -435,7 +437,7 @@ func TestVerifyAttestations_HandlesPlannedFork(t *testing.T) {
 			CommitteeIndex: 1,
 		},
 	})
-	currDomain, err := signing.Domain(st.Fork(), st.Fork().Epoch, params.BeaconConfig().DomainBeaconAttester, st.GenesisValidatorRoot())
+	currDomain, err := signing.Domain(st.Fork(), st.Fork().Epoch, params.BeaconConfig().DomainBeaconAttester, st.GenesisValidatorsRoot())
 	require.NoError(t, err)
 	root, err = signing.ComputeSigningRoot(att2.Data, currDomain)
 	require.NoError(t, err)
@@ -474,7 +476,7 @@ func TestRetrieveAttestationSignatureSet_VerifiesMultipleAttestations(t *testing
 			Slot: 1,
 		},
 	})
-	domain, err := signing.Domain(st.Fork(), st.Fork().Epoch, params.BeaconConfig().DomainBeaconAttester, st.GenesisValidatorRoot())
+	domain, err := signing.Domain(st.Fork(), st.Fork().Epoch, params.BeaconConfig().DomainBeaconAttester, st.GenesisValidatorsRoot())
 	require.NoError(t, err)
 	root, err := signing.ComputeSigningRoot(att1.Data, domain)
 	require.NoError(t, err)
@@ -538,7 +540,7 @@ func TestRetrieveAttestationSignatureSet_AcrossFork(t *testing.T) {
 			Slot: 1,
 		},
 	})
-	domain, err := signing.Domain(st.Fork(), st.Fork().Epoch, params.BeaconConfig().DomainBeaconAttester, st.GenesisValidatorRoot())
+	domain, err := signing.Domain(st.Fork(), st.Fork().Epoch, params.BeaconConfig().DomainBeaconAttester, st.GenesisValidatorsRoot())
 	require.NoError(t, err)
 	root, err := signing.ComputeSigningRoot(att1.Data, domain)
 	require.NoError(t, err)

beacon-chain/core/blocks/attester_slashing_test.go

@@ -108,7 +108,7 @@ func TestProcessAttesterSlashings_AppliesCorrectStatus(t *testing.T) {
 		},
 		AttestingIndices: []uint64{0, 1},
 	})
-	domain, err := signing.Domain(beaconState.Fork(), 0, params.BeaconConfig().DomainBeaconAttester, beaconState.GenesisValidatorRoot())
+	domain, err := signing.Domain(beaconState.Fork(), 0, params.BeaconConfig().DomainBeaconAttester, beaconState.GenesisValidatorsRoot())
 	require.NoError(t, err)
 	signingRoot, err := signing.ComputeSigningRoot(att1.Data, domain)
 	assert.NoError(t, err, "Could not get signing root of beacon block header")
@@ -177,7 +177,7 @@ func TestProcessAttesterSlashings_AppliesCorrectStatusAltair(t *testing.T) {
 		},
 		AttestingIndices: []uint64{0, 1},
 	})
-	domain, err := signing.Domain(beaconState.Fork(), 0, params.BeaconConfig().DomainBeaconAttester, beaconState.GenesisValidatorRoot())
+	domain, err := signing.Domain(beaconState.Fork(), 0, params.BeaconConfig().DomainBeaconAttester, beaconState.GenesisValidatorsRoot())
 	require.NoError(t, err)
 	signingRoot, err := signing.ComputeSigningRoot(att1.Data, domain)
 	assert.NoError(t, err, "Could not get signing root of beacon block header")
@@ -246,7 +246,7 @@ func TestProcessAttesterSlashings_AppliesCorrectStatusBellatrix(t *testing.T) {
 		},
 		AttestingIndices: []uint64{0, 1},
 	})
-	domain, err := signing.Domain(beaconState.Fork(), 0, params.BeaconConfig().DomainBeaconAttester, beaconState.GenesisValidatorRoot())
+	domain, err := signing.Domain(beaconState.Fork(), 0, params.BeaconConfig().DomainBeaconAttester, beaconState.GenesisValidatorsRoot())
 	require.NoError(t, err)
 	signingRoot, err := signing.ComputeSigningRoot(att1.Data, domain)
 	assert.NoError(t, err, "Could not get signing root of beacon block header")

beacon-chain/core/blocks/block_operations_fuzz_test.go

@@ -74,7 +74,8 @@ func TestFuzzverifyDepositDataSigningRoot_10000(_ *testing.T) {
 func TestFuzzProcessEth1DataInBlock_10000(t *testing.T) {
 	fuzzer := fuzz.NewWithSeed(0)
 	e := &ethpb.Eth1Data{}
-	state := &v1.BeaconState{}
+	state, err := v1.InitializeFromProtoUnsafe(&ethpb.BeaconState{})
+	require.NoError(t, err)
 	for i := 0; i < 10000; i++ {
 		fuzzer.Fuzz(state)
 		fuzzer.Fuzz(e)

beacon-chain/core/blocks/block_regression_test.go

@@ -44,7 +44,7 @@ func TestProcessAttesterSlashings_RegressionSlashableIndices(t *testing.T) {
 		AttestingIndices: setA,
 		Signature:        make([]byte, 96),
 	}
-	domain, err := signing.Domain(beaconState.Fork(), 0, params.BeaconConfig().DomainBeaconAttester, beaconState.GenesisValidatorRoot())
+	domain, err := signing.Domain(beaconState.Fork(), 0, params.BeaconConfig().DomainBeaconAttester, beaconState.GenesisValidatorsRoot())
 	require.NoError(t, err)
 	signingRoot, err := signing.ComputeSigningRoot(att1.Data, domain)
 	require.NoError(t, err, "Could not get signing root of beacon block header")

beacon-chain/core/blocks/eth1_data_test.go

@@ -11,6 +11,7 @@ import (
 	"github.com/prysmaticlabs/prysm/config/params"
 	"github.com/prysmaticlabs/prysm/encoding/bytesutil"
 	ethpb "github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1"
+	"github.com/prysmaticlabs/prysm/runtime/version"
 	"github.com/prysmaticlabs/prysm/testing/assert"
 	"github.com/prysmaticlabs/prysm/testing/require"
 	"github.com/prysmaticlabs/prysm/testing/util"
@@ -175,12 +176,10 @@ func TestProcessEth1Data_SetsCorrectly(t *testing.T) {
 	}
 
 	period := uint64(params.BeaconConfig().SlotsPerEpoch.Mul(uint64(params.BeaconConfig().EpochsPerEth1VotingPeriod)))
-	var ok bool
 	for i := uint64(0); i < period; i++ {
 		processedState, err := blocks.ProcessEth1DataInBlock(context.Background(), beaconState, b.Block.Body.Eth1Data)
 		require.NoError(t, err)
-		beaconState, ok = processedState.(*v1.BeaconState)
-		require.Equal(t, true, ok)
+		require.Equal(t, true, processedState.Version() == version.Phase0)
 	}
 
 	newETH1DataVotes := beaconState.Eth1DataVotes()

beacon-chain/core/blocks/exit.go

@@ -57,7 +57,7 @@ func ProcessVoluntaryExits(
 		if err != nil {
 			return nil, err
 		}
-		if err := VerifyExitAndSignature(val, beaconState.Slot(), beaconState.Fork(), exit, beaconState.GenesisValidatorRoot()); err != nil {
+		if err := VerifyExitAndSignature(val, beaconState.Slot(), beaconState.Fork(), exit, beaconState.GenesisValidatorsRoot()); err != nil {
 			return nil, errors.Wrapf(err, "could not verify exit %d", idx)
 		}
 		beaconState, err = v.InitiateValidatorExit(ctx, beaconState, exit.Exit.ValidatorIndex)

beacon-chain/core/blocks/payload.go

@@ -2,6 +2,7 @@ package blocks
 
 import (
 	"bytes"
+	"strings"
 
 	"github.com/pkg/errors"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
@@ -16,13 +17,15 @@ import (
 	"github.com/prysmaticlabs/prysm/time/slots"
 )
 
-// MergeComplete returns true if the transition to Bellatrix has completed.
+// MergeTransitionComplete returns true if the transition to Bellatrix has completed.
 // Meaning the payload header in beacon state is not `ExecutionPayloadHeader()` (i.e. not empty).
 //
 // Spec code:
-// def is_merge_complete(state: BeaconState) -> bool:
+// def is_merge_transition_complete(state: BeaconState) -> bool:
 //    return state.latest_execution_payload_header != ExecutionPayloadHeader()
-func MergeComplete(st state.BeaconState) (bool, error) {
+//
+// Deprecated: Use `IsMergeTransitionBlockUsingPayloadHeader` instead.
+func MergeTransitionComplete(st state.BeaconState) (bool, error) {
 	h, err := st.LatestExecutionPayloadHeader()
 	if err != nil {
 		return false, err
@@ -31,15 +34,15 @@ func MergeComplete(st state.BeaconState) (bool, error) {
 	return !isEmptyHeader(h), nil
 }
 
-// IsMergeBlock returns true if the input block is the terminal merge block.
+// MergeTransitionBlock returns true if the input block is the terminal merge block.
 // Meaning the header in beacon state is  `ExecutionPayloadHeader()` (i.e. empty).
 // And the input block has a non-empty header.
 //
 // Spec code:
-// def is_merge_block(state: BeaconState, body: BeaconBlockBody) -> bool:
-//    return not is_merge_complete(state) and body.execution_payload != ExecutionPayload()
-func IsMergeBlock(st state.BeaconState, blk block.BeaconBlockBody) (bool, error) {
-	mergeComplete, err := MergeComplete(st)
+// def is_merge_transition_block(state: BeaconState, body: BeaconBlockBody) -> bool:
+//    return not is_merge_transition_complete(state) and body.execution_payload != ExecutionPayload()
+func MergeTransitionBlock(st state.BeaconState, body block.BeaconBlockBody) (bool, error) {
+	mergeComplete, err := MergeTransitionComplete(st)
 	if err != nil {
 		return false, err
 	}
@@ -47,8 +50,30 @@ func IsMergeBlock(st state.BeaconState, blk block.BeaconBlockBody) (bool, error)
 		return false, err
 	}
 
-	payload, err := blk.ExecutionPayload()
+	return ExecutionBlock(body)
+}
+
+// IsMergeTransitionBlockUsingPayloadHeader returns true if the input block is the terminal merge block.
+// Terminal merge block must be associated with an empty payload header.
+// This is an optimized version of MergeTransitionComplete where beacon state is not required as an argument.
+func IsMergeTransitionBlockUsingPayloadHeader(h *ethpb.ExecutionPayloadHeader, body block.BeaconBlockBody) (bool, error) {
+	if !isEmptyHeader(h) {
+		return false, nil
+	}
+	return ExecutionBlock(body)
+}
+
+// ExecutionBlock returns whether the block has a non-empty ExecutionPayload.
+//
+// Spec code:
+// def is_execution_block(block: BeaconBlock) -> bool:
+//     return block.body.execution_payload != ExecutionPayload()
+func ExecutionBlock(body block.BeaconBlockBody) (bool, error) {
+	payload, err := body.ExecutionPayload()
 	if err != nil {
+		if strings.HasPrefix(err.Error(), "ExecutionPayload is not supported in") {
+			return false, nil
+		}
 		return false, err
 	}
 	return !isEmptyPayload(payload), nil
@@ -60,15 +85,15 @@ func IsMergeBlock(st state.BeaconState, blk block.BeaconBlockBody) (bool, error)
 // Spec code:
 // def is_execution_enabled(state: BeaconState, body: BeaconBlockBody) -> bool:
 //    return is_merge_block(state, body) or is_merge_complete(state)
-func ExecutionEnabled(st state.BeaconState, blk block.BeaconBlockBody) (bool, error) {
-	mergeBlock, err := IsMergeBlock(st, blk)
+func ExecutionEnabled(st state.BeaconState, body block.BeaconBlockBody) (bool, error) {
+	mergeBlock, err := MergeTransitionBlock(st, body)
 	if err != nil {
 		return false, err
 	}
 	if mergeBlock {
 		return true, nil
 	}
-	return MergeComplete(st)
+	return MergeTransitionComplete(st)
 }
 
 // ValidatePayloadWhenMergeCompletes validates if payload is valid versus input beacon state.
@@ -79,7 +104,7 @@ func ExecutionEnabled(st state.BeaconState, blk block.BeaconBlockBody) (bool, er
 //    if is_merge_complete(state):
 //        assert payload.parent_hash == state.latest_execution_payload_header.block_hash
 func ValidatePayloadWhenMergeCompletes(st state.BeaconState, payload *enginev1.ExecutionPayload) error {
-	complete, err := MergeComplete(st)
+	complete, err := MergeTransitionComplete(st)
 	if err != nil {
 		return err
 	}
@@ -111,8 +136,8 @@ func ValidatePayload(st state.BeaconState, payload *enginev1.ExecutionPayload) e
 		return err
 	}
 
-	if !bytes.Equal(payload.Random, random) {
-		return errors.New("incorrect random")
+	if !bytes.Equal(payload.PrevRandao, random) {
+		return errors.New("incorrect prev randao")
 	}
 	t, err := slots.ToTime(st.GenesisTime(), st.Slot())
 	if err != nil {
@@ -188,7 +213,7 @@ func PayloadToHeader(payload *enginev1.ExecutionPayload) (*ethpb.ExecutionPayloa
 		StateRoot:        bytesutil.SafeCopyBytes(payload.StateRoot),
 		ReceiptRoot:      bytesutil.SafeCopyBytes(payload.ReceiptsRoot),
 		LogsBloom:        bytesutil.SafeCopyBytes(payload.LogsBloom),
-		Random:           bytesutil.SafeCopyBytes(payload.Random),
+		PrevRandao:       bytesutil.SafeCopyBytes(payload.PrevRandao),
 		BlockNumber:      payload.BlockNumber,
 		GasLimit:         payload.GasLimit,
 		GasUsed:          payload.GasUsed,
@@ -216,7 +241,7 @@ func isEmptyPayload(p *enginev1.ExecutionPayload) bool {
 	if !bytes.Equal(p.LogsBloom, make([]byte, fieldparams.LogsBloomLength)) {
 		return false
 	}
-	if !bytes.Equal(p.Random, make([]byte, fieldparams.RootLength)) {
+	if !bytes.Equal(p.PrevRandao, make([]byte, fieldparams.RootLength)) {
 		return false
 	}
 	if !bytes.Equal(p.BaseFeePerGas, make([]byte, fieldparams.RootLength)) {
@@ -262,7 +287,7 @@ func isEmptyHeader(h *ethpb.ExecutionPayloadHeader) bool {
 	if !bytes.Equal(h.LogsBloom, make([]byte, fieldparams.LogsBloomLength)) {
 		return false
 	}
-	if !bytes.Equal(h.Random, make([]byte, fieldparams.RootLength)) {
+	if !bytes.Equal(h.PrevRandao, make([]byte, fieldparams.RootLength)) {
 		return false
 	}
 	if !bytes.Equal(h.BaseFeePerGas, make([]byte, fieldparams.RootLength)) {

beacon-chain/core/blocks/payload_test.go

@@ -78,7 +78,7 @@ func Test_MergeComplete(t *testing.T) {
 			name: "has random",
 			payload: func() *ethpb.ExecutionPayloadHeader {
 				h := emptyPayloadHeader()
-				h.Random = bytesutil.PadTo([]byte{'a'}, fieldparams.RootLength)
+				h.PrevRandao = bytesutil.PadTo([]byte{'a'}, fieldparams.RootLength)
 				return h
 			}(),
 			want: true,
@@ -160,7 +160,7 @@ func Test_MergeComplete(t *testing.T) {
 		t.Run(tt.name, func(t *testing.T) {
 			st, _ := util.DeterministicGenesisStateBellatrix(t, 1)
 			require.NoError(t, st.SetLatestExecutionPayloadHeader(tt.payload))
-			got, err := blocks.MergeComplete(st)
+			got, err := blocks.MergeTransitionComplete(st)
 			require.NoError(t, err)
 			if got != tt.want {
 				t.Errorf("mergeComplete() got = %v, want %v", got, tt.want)
@@ -246,7 +246,7 @@ func Test_MergeBlock(t *testing.T) {
 			name: "empty header, payload has random",
 			payload: func() *enginev1.ExecutionPayload {
 				p := emptyPayload()
-				p.Random = bytesutil.PadTo([]byte{'a'}, fieldparams.RootLength)
+				p.PrevRandao = bytesutil.PadTo([]byte{'a'}, fieldparams.RootLength)
 				return p
 			}(),
 			header: emptyPayloadHeader(),
@@ -341,15 +341,228 @@ func Test_MergeBlock(t *testing.T) {
 			blk.Block.Body.ExecutionPayload = tt.payload
 			body, err := wrapper.WrappedBellatrixBeaconBlockBody(blk.Block.Body)
 			require.NoError(t, err)
-			got, err := blocks.IsMergeBlock(st, body)
+			got, err := blocks.MergeTransitionBlock(st, body)
 			require.NoError(t, err)
 			if got != tt.want {
-				t.Errorf("IsMergeBlock() got = %v, want %v", got, tt.want)
+				t.Errorf("MergeTransitionBlock() got = %v, want %v", got, tt.want)
 			}
 		})
 	}
 }
 
+func Test_IsMergeTransitionBlockUsingPayloadHeader(t *testing.T) {
+	tests := []struct {
+		name    string
+		payload *enginev1.ExecutionPayload
+		header  *ethpb.ExecutionPayloadHeader
+		want    bool
+	}{
+		{
+			name:    "empty header, empty payload",
+			payload: emptyPayload(),
+			header:  emptyPayloadHeader(),
+			want:    false,
+		},
+		{
+			name:    "non-empty header, empty payload",
+			payload: emptyPayload(),
+			header: func() *ethpb.ExecutionPayloadHeader {
+				h := emptyPayloadHeader()
+				h.ParentHash = bytesutil.PadTo([]byte{'a'}, fieldparams.RootLength)
+				return h
+			}(),
+			want: false,
+		},
+		{
+			name: "empty header, payload has parent hash",
+			payload: func() *enginev1.ExecutionPayload {
+				p := emptyPayload()
+				p.ParentHash = bytesutil.PadTo([]byte{'a'}, fieldparams.RootLength)
+				return p
+			}(),
+			header: emptyPayloadHeader(),
+			want:   true,
+		},
+		{
+			name: "empty header, payload has fee recipient",
+			payload: func() *enginev1.ExecutionPayload {
+				p := emptyPayload()
+				p.FeeRecipient = bytesutil.PadTo([]byte{'a'}, fieldparams.FeeRecipientLength)
+				return p
+			}(),
+			header: emptyPayloadHeader(),
+			want:   true,
+		},
+		{
+			name: "empty header, payload has state root",
+			payload: func() *enginev1.ExecutionPayload {
+				p := emptyPayload()
+				p.StateRoot = bytesutil.PadTo([]byte{'a'}, fieldparams.RootLength)
+				return p
+			}(),
+			header: emptyPayloadHeader(),
+			want:   true,
+		},
+		{
+			name: "empty header, payload has receipt root",
+			payload: func() *enginev1.ExecutionPayload {
+				p := emptyPayload()
+				p.ReceiptsRoot = bytesutil.PadTo([]byte{'a'}, fieldparams.RootLength)
+				return p
+			}(),
+			header: emptyPayloadHeader(),
+			want:   true,
+		},
+		{
+			name: "empty header, payload has logs bloom",
+			payload: func() *enginev1.ExecutionPayload {
+				p := emptyPayload()
+				p.LogsBloom = bytesutil.PadTo([]byte{'a'}, fieldparams.LogsBloomLength)
+				return p
+			}(),
+			header: emptyPayloadHeader(),
+			want:   true,
+		},
+		{
+			name: "empty header, payload has random",
+			payload: func() *enginev1.ExecutionPayload {
+				p := emptyPayload()
+				p.PrevRandao = bytesutil.PadTo([]byte{'a'}, fieldparams.RootLength)
+				return p
+			}(),
+			header: emptyPayloadHeader(),
+			want:   true,
+		},
+		{
+			name: "empty header, payload has base fee",
+			payload: func() *enginev1.ExecutionPayload {
+				p := emptyPayload()
+				p.BaseFeePerGas = bytesutil.PadTo([]byte{'a'}, fieldparams.RootLength)
+				return p
+			}(),
+			header: emptyPayloadHeader(),
+			want:   true,
+		},
+		{
+			name: "empty header, payload has block hash",
+			payload: func() *enginev1.ExecutionPayload {
+				p := emptyPayload()
+				p.BlockHash = bytesutil.PadTo([]byte{'a'}, fieldparams.RootLength)
+				return p
+			}(),
+			header: emptyPayloadHeader(),
+			want:   true,
+		},
+		{
+			name: "empty header, payload has tx",
+			payload: func() *enginev1.ExecutionPayload {
+				p := emptyPayload()
+				p.Transactions = [][]byte{{'a'}}
+				return p
+			}(),
+			header: emptyPayloadHeader(),
+			want:   true,
+		},
+		{
+			name: "empty header, payload has extra data",
+			payload: func() *enginev1.ExecutionPayload {
+				p := emptyPayload()
+				p.ExtraData = bytesutil.PadTo([]byte{'a'}, fieldparams.RootLength)
+				return p
+			}(),
+			header: emptyPayloadHeader(),
+			want:   true,
+		},
+		{
+			name: "empty header, payload has block number",
+			payload: func() *enginev1.ExecutionPayload {
+				p := emptyPayload()
+				p.BlockNumber = 1
+				return p
+			}(),
+			header: emptyPayloadHeader(),
+			want:   true,
+		},
+		{
+			name: "empty header, payload has gas limit",
+			payload: func() *enginev1.ExecutionPayload {
+				p := emptyPayload()
+				p.GasLimit = 1
+				return p
+			}(),
+			header: emptyPayloadHeader(),
+			want:   true,
+		},
+		{
+			name: "empty header, payload has gas used",
+			payload: func() *enginev1.ExecutionPayload {
+				p := emptyPayload()
+				p.GasUsed = 1
+				return p
+			}(),
+			header: emptyPayloadHeader(),
+			want:   true,
+		},
+		{
+			name: "empty header, payload has timestamp",
+			payload: func() *enginev1.ExecutionPayload {
+				p := emptyPayload()
+				p.Timestamp = 1
+				return p
+			}(),
+			header: emptyPayloadHeader(),
+			want:   true,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			blk := util.NewBeaconBlockBellatrix()
+			blk.Block.Body.ExecutionPayload = tt.payload
+			body, err := wrapper.WrappedBellatrixBeaconBlockBody(blk.Block.Body)
+			require.NoError(t, err)
+			got, err := blocks.IsMergeTransitionBlockUsingPayloadHeader(tt.header, body)
+			require.NoError(t, err)
+			if got != tt.want {
+				t.Errorf("MergeTransitionBlock() got = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
+
+func Test_IsExecutionBlock(t *testing.T) {
+	tests := []struct {
+		name    string
+		payload *enginev1.ExecutionPayload
+		want    bool
+	}{
+		{
+			name:    "empty payload",
+			payload: emptyPayload(),
+			want:    false,
+		},
+		{
+			name: "non-empty payload",
+			payload: func() *enginev1.ExecutionPayload {
+				p := emptyPayload()
+				p.ParentHash = bytesutil.PadTo([]byte{'a'}, fieldparams.RootLength)
+				return p
+			}(),
+			want: true,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			blk := util.NewBeaconBlockBellatrix()
+			blk.Block.Body.ExecutionPayload = tt.payload
+			wrappedBlock, err := wrapper.WrappedBellatrixBeaconBlock(blk.Block)
+			require.NoError(t, err)
+			got, err := blocks.ExecutionBlock(wrappedBlock.Body())
+			require.NoError(t, err)
+			require.Equal(t, tt.want, got)
+		})
+	}
+}
+
 func Test_ExecutionEnabled(t *testing.T) {
 	tests := []struct {
 		name    string
@@ -486,21 +699,21 @@ func Test_ValidatePayload(t *testing.T) {
 			name: "validate passes",
 			payload: func() *enginev1.ExecutionPayload {
 				h := emptyPayload()
-				h.Random = random
+				h.PrevRandao = random
 				h.Timestamp = uint64(ts.Unix())
 				return h
 			}(), err: nil,
 		},
 		{
-			name:    "incorrect random",
+			name:    "incorrect prev randao",
 			payload: emptyPayload(),
-			err:     errors.New("incorrect random"),
+			err:     errors.New("incorrect prev randao"),
 		},
 		{
 			name: "incorrect timestamp",
 			payload: func() *enginev1.ExecutionPayload {
 				h := emptyPayload()
-				h.Random = random
+				h.PrevRandao = random
 				h.Timestamp = 1
 				return h
 			}(),
@@ -534,21 +747,21 @@ func Test_ProcessPayload(t *testing.T) {
 			name: "process passes",
 			payload: func() *enginev1.ExecutionPayload {
 				h := emptyPayload()
-				h.Random = random
+				h.PrevRandao = random
 				h.Timestamp = uint64(ts.Unix())
 				return h
 			}(), err: nil,
 		},
 		{
-			name:    "incorrect random",
+			name:    "incorrect prev randao",
 			payload: emptyPayload(),
-			err:     errors.New("incorrect random"),
+			err:     errors.New("incorrect prev randao"),
 		},
 		{
 			name: "incorrect timestamp",
 			payload: func() *enginev1.ExecutionPayload {
 				h := emptyPayload()
-				h.Random = random
+				h.PrevRandao = random
 				h.Timestamp = 1
 				return h
 			}(),
@@ -587,7 +800,7 @@ func Test_PayloadToHeader(t *testing.T) {
 	p.StateRoot = b
 	p.ReceiptsRoot = b
 	p.LogsBloom = b
-	p.Random = b
+	p.PrevRandao = b
 	p.ExtraData = b
 	p.BaseFeePerGas = b
 	p.BlockHash = b
@@ -601,7 +814,7 @@ func Test_PayloadToHeader(t *testing.T) {
 	require.DeepSSZEqual(t, h.StateRoot, make([]byte, fieldparams.RootLength))
 	require.DeepSSZEqual(t, h.ReceiptRoot, make([]byte, fieldparams.RootLength))
 	require.DeepSSZEqual(t, h.LogsBloom, make([]byte, fieldparams.LogsBloomLength))
-	require.DeepSSZEqual(t, h.Random, make([]byte, fieldparams.RootLength))
+	require.DeepSSZEqual(t, h.PrevRandao, make([]byte, fieldparams.RootLength))
 	require.DeepSSZEqual(t, h.ExtraData, make([]byte, 0))
 	require.DeepSSZEqual(t, h.BaseFeePerGas, make([]byte, fieldparams.RootLength))
 	require.DeepSSZEqual(t, h.BlockHash, make([]byte, fieldparams.RootLength))
@@ -617,7 +830,7 @@ func BenchmarkBellatrixComplete(b *testing.B) {
 
 	b.ResetTimer()
 	for i := 0; i < b.N; i++ {
-		_, err := blocks.MergeComplete(st)
+		_, err := blocks.MergeTransitionComplete(st)
 		require.NoError(b, err)
 	}
 }
@@ -629,7 +842,7 @@ func emptyPayloadHeader() *ethpb.ExecutionPayloadHeader {
 		StateRoot:        make([]byte, fieldparams.RootLength),
 		ReceiptRoot:      make([]byte, fieldparams.RootLength),
 		LogsBloom:        make([]byte, fieldparams.LogsBloomLength),
-		Random:           make([]byte, fieldparams.RootLength),
+		PrevRandao:       make([]byte, fieldparams.RootLength),
 		BaseFeePerGas:    make([]byte, fieldparams.RootLength),
 		BlockHash:        make([]byte, fieldparams.RootLength),
 		TransactionsRoot: make([]byte, fieldparams.RootLength),
@@ -644,7 +857,7 @@ func emptyPayload() *enginev1.ExecutionPayload {
 		StateRoot:     make([]byte, fieldparams.RootLength),
 		ReceiptsRoot:  make([]byte, fieldparams.RootLength),
 		LogsBloom:     make([]byte, fieldparams.LogsBloomLength),
-		Random:        make([]byte, fieldparams.RootLength),
+		PrevRandao:    make([]byte, fieldparams.RootLength),
 		BaseFeePerGas: make([]byte, fieldparams.RootLength),
 		BlockHash:     make([]byte, fieldparams.RootLength),
 		Transactions:  make([][]byte, 0),

beacon-chain/core/blocks/proposer_slashing_test.go

@@ -378,7 +378,7 @@ func TestVerifyProposerSlashing(t *testing.T) {
 		t.Run(tt.name, func(t *testing.T) {
 
 			sk := sks[tt.args.slashing.Header_1.Header.ProposerIndex]
-			d, err := signing.Domain(tt.args.beaconState.Fork(), slots.ToEpoch(tt.args.slashing.Header_1.Header.Slot), params.BeaconConfig().DomainBeaconProposer, tt.args.beaconState.GenesisValidatorRoot())
+			d, err := signing.Domain(tt.args.beaconState.Fork(), slots.ToEpoch(tt.args.slashing.Header_1.Header.Slot), params.BeaconConfig().DomainBeaconProposer, tt.args.beaconState.GenesisValidatorsRoot())
 			require.NoError(t, err)
 			if tt.args.slashing.Header_1.Signature == nil {
 				sr, err := signing.ComputeSigningRoot(tt.args.slashing.Header_1.Header, d)

beacon-chain/core/blocks/randao_test.go

@@ -26,7 +26,7 @@ func TestProcessRandao_IncorrectProposerFailsVerification(t *testing.T) {
 	epoch := types.Epoch(0)
 	buf := make([]byte, 32)
 	binary.LittleEndian.PutUint64(buf, uint64(epoch))
-	domain, err := signing.Domain(beaconState.Fork(), epoch, params.BeaconConfig().DomainRandao, beaconState.GenesisValidatorRoot())
+	domain, err := signing.Domain(beaconState.Fork(), epoch, params.BeaconConfig().DomainRandao, beaconState.GenesisValidatorsRoot())
 	require.NoError(t, err)
 	root, err := (&ethpb.SigningData{ObjectRoot: buf, Domain: domain}).HashTreeRoot()
 	require.NoError(t, err)

beacon-chain/core/blocks/signature.go

@@ -68,7 +68,7 @@ func VerifyBlockSignature(beaconState state.ReadOnlyBeaconState,
 	sig []byte,
 	rootFunc func() ([32]byte, error)) error {
 	currentEpoch := slots.ToEpoch(beaconState.Slot())
-	domain, err := signing.Domain(beaconState.Fork(), currentEpoch, params.BeaconConfig().DomainBeaconProposer, beaconState.GenesisValidatorRoot())
+	domain, err := signing.Domain(beaconState.Fork(), currentEpoch, params.BeaconConfig().DomainBeaconProposer, beaconState.GenesisValidatorsRoot())
 	if err != nil {
 		return err
 	}
@@ -83,7 +83,7 @@ func VerifyBlockSignature(beaconState state.ReadOnlyBeaconState,
 // VerifyBlockHeaderSignature verifies the proposer signature of a beacon block header.
 func VerifyBlockHeaderSignature(beaconState state.BeaconState, header *ethpb.SignedBeaconBlockHeader) error {
 	currentEpoch := slots.ToEpoch(beaconState.Slot())
-	domain, err := signing.Domain(beaconState.Fork(), currentEpoch, params.BeaconConfig().DomainBeaconProposer, beaconState.GenesisValidatorRoot())
+	domain, err := signing.Domain(beaconState.Fork(), currentEpoch, params.BeaconConfig().DomainBeaconProposer, beaconState.GenesisValidatorsRoot())
 	if err != nil {
 		return err
 	}
@@ -104,7 +104,7 @@ func VerifyBlockSignatureUsingCurrentFork(beaconState state.ReadOnlyBeaconState,
 	if err != nil {
 		return err
 	}
-	domain, err := signing.Domain(fork, currentEpoch, params.BeaconConfig().DomainBeaconProposer, beaconState.GenesisValidatorRoot())
+	domain, err := signing.Domain(fork, currentEpoch, params.BeaconConfig().DomainBeaconProposer, beaconState.GenesisValidatorsRoot())
 	if err != nil {
 		return err
 	}
@@ -122,7 +122,7 @@ func BlockSignatureBatch(beaconState state.ReadOnlyBeaconState,
 	sig []byte,
 	rootFunc func() ([32]byte, error)) (*bls.SignatureBatch, error) {
 	currentEpoch := slots.ToEpoch(beaconState.Slot())
-	domain, err := signing.Domain(beaconState.Fork(), currentEpoch, params.BeaconConfig().DomainBeaconProposer, beaconState.GenesisValidatorRoot())
+	domain, err := signing.Domain(beaconState.Fork(), currentEpoch, params.BeaconConfig().DomainBeaconProposer, beaconState.GenesisValidatorsRoot())
 	if err != nil {
 		return nil, err
 	}
@@ -164,7 +164,7 @@ func randaoSigningData(ctx context.Context, beaconState state.ReadOnlyBeaconStat
 	buf := make([]byte, 32)
 	binary.LittleEndian.PutUint64(buf, uint64(currentEpoch))
 
-	domain, err := signing.Domain(beaconState.Fork(), currentEpoch, params.BeaconConfig().DomainRandao, beaconState.GenesisValidatorRoot())
+	domain, err := signing.Domain(beaconState.Fork(), currentEpoch, params.BeaconConfig().DomainRandao, beaconState.GenesisValidatorsRoot())
 	if err != nil {
 		return nil, nil, nil, err
 	}
@@ -231,7 +231,7 @@ func AttestationSignatureBatch(ctx context.Context, beaconState state.ReadOnlyBe
 	}
 
 	fork := beaconState.Fork()
-	gvr := beaconState.GenesisValidatorRoot()
+	gvr := beaconState.GenesisValidatorsRoot()
 	dt := params.BeaconConfig().DomainBeaconAttester
 
 	// Split attestations by fork. Note: the signature domain will differ based on the fork.

beacon-chain/core/blocks/signature_test.go

@@ -41,7 +41,7 @@ func TestVerifyBlockHeaderSignature(t *testing.T) {
 		beaconState.Fork(),
 		0,
 		params.BeaconConfig().DomainBeaconProposer,
-		beaconState.GenesisValidatorRoot(),
+		beaconState.GenesisValidatorsRoot(),
 	)
 	require.NoError(t, err)
 	htr, err := blockHeader.Header.HashTreeRoot()
@@ -77,7 +77,7 @@ func TestVerifyBlockSignatureUsingCurrentFork(t *testing.T) {
 		CurrentVersion:  params.BeaconConfig().AltairForkVersion,
 		PreviousVersion: params.BeaconConfig().GenesisForkVersion,
 	}
-	domain, err := signing.Domain(fData, 100, params.BeaconConfig().DomainBeaconProposer, bState.GenesisValidatorRoot())
+	domain, err := signing.Domain(fData, 100, params.BeaconConfig().DomainBeaconProposer, bState.GenesisValidatorsRoot())
 	assert.NoError(t, err)
 	rt, err := signing.ComputeSigningRoot(altairBlk.Block, domain)
 	assert.NoError(t, err)

beacon-chain/core/epoch/precompute/reward_penalty_test.go

@@ -16,6 +16,7 @@ import (
 	"github.com/prysmaticlabs/prysm/config/params"
 	"github.com/prysmaticlabs/prysm/math"
 	ethpb "github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1"
+	"github.com/prysmaticlabs/prysm/runtime/version"
 	"github.com/prysmaticlabs/prysm/testing/assert"
 	"github.com/prysmaticlabs/prysm/testing/require"
 )
@@ -47,8 +48,7 @@ func TestProcessRewardsAndPenaltiesPrecompute(t *testing.T) {
 
 	processedState, err := ProcessRewardsAndPenaltiesPrecompute(beaconState, bp, vp, AttestationsDelta, ProposersDelta)
 	require.NoError(t, err)
-	beaconState, ok := processedState.(*v1.BeaconState)
-	require.Equal(t, true, ok)
+	require.Equal(t, true, processedState.Version() == version.Phase0)
 
 	// Indices that voted everything except for head, lost a bit money
 	wanted := uint64(31999810265)

beacon-chain/core/execution/upgrade.go

@@ -38,7 +38,7 @@ func UpgradeToBellatrix(ctx context.Context, state state.BeaconState) (state.Bea
 
 	s := &ethpb.BeaconStateBellatrix{
 		GenesisTime:           state.GenesisTime(),
-		GenesisValidatorsRoot: state.GenesisValidatorRoot(),
+		GenesisValidatorsRoot: state.GenesisValidatorsRoot(),
 		Slot:                  state.Slot(),
 		Fork: &ethpb.Fork{
 			PreviousVersion: state.Fork().CurrentVersion,
@@ -71,7 +71,7 @@ func UpgradeToBellatrix(ctx context.Context, state state.BeaconState) (state.Bea
 			StateRoot:        make([]byte, 32),
 			ReceiptRoot:      make([]byte, 32),
 			LogsBloom:        make([]byte, 256),
-			Random:           make([]byte, 32),
+			PrevRandao:       make([]byte, 32),
 			BlockNumber:      0,
 			GasLimit:         0,
 			GasUsed:          0,

beacon-chain/core/execution/upgrade_test.go

@@ -19,7 +19,7 @@ func TestUpgradeToBellatrix(t *testing.T) {
 	require.NoError(t, err)
 
 	require.Equal(t, preForkState.GenesisTime(), mSt.GenesisTime())
-	require.DeepSSZEqual(t, preForkState.GenesisValidatorRoot(), mSt.GenesisValidatorRoot())
+	require.DeepSSZEqual(t, preForkState.GenesisValidatorsRoot(), mSt.GenesisValidatorsRoot())
 	require.Equal(t, preForkState.Slot(), mSt.Slot())
 	require.DeepSSZEqual(t, preForkState.LatestBlockHeader(), mSt.LatestBlockHeader())
 	require.DeepSSZEqual(t, preForkState.BlockRoots(), mSt.BlockRoots())
@@ -67,7 +67,7 @@ func TestUpgradeToBellatrix(t *testing.T) {
 		StateRoot:        make([]byte, 32),
 		ReceiptRoot:      make([]byte, 32),
 		LogsBloom:        make([]byte, 256),
-		Random:           make([]byte, 32),
+		PrevRandao:       make([]byte, 32),
 		BlockNumber:      0,
 		GasLimit:         0,
 		GasUsed:          0,

beacon-chain/core/helpers/block.go

@@ -11,18 +11,22 @@ import (
 	"github.com/prysmaticlabs/prysm/time/slots"
 )
 
+var ErrNilSignedBeaconBlock = errors.New("signed beacon block can't be nil")
+var ErrNilBeaconBlock = errors.New("beacon block can't be nil")
+var ErrNilBeaconBlockBody = errors.New("beacon block body can't be nil")
+
 // BeaconBlockIsNil checks if any composite field of input signed beacon block is nil.
 // Access to these nil fields will result in run time panic,
 // it is recommended to run these checks as first line of defense.
 func BeaconBlockIsNil(b block.SignedBeaconBlock) error {
 	if b == nil || b.IsNil() {
-		return errors.New("signed beacon block can't be nil")
+		return ErrNilSignedBeaconBlock
 	}
 	if b.Block().IsNil() {
-		return errors.New("beacon block can't be nil")
+		return ErrNilBeaconBlock
 	}
 	if b.Block().Body().IsNil() {
-		return errors.New("beacon block body can't be nil")
+		return ErrNilBeaconBlockBody
 	}
 	return nil
 }

beacon-chain/core/signing/signing_root.go

@@ -23,7 +23,7 @@ var ErrSigFailedToVerify = errors.New("signature did not verify")
 
 // ComputeDomainAndSign computes the domain and signing root and sign it using the passed in private key.
 func ComputeDomainAndSign(st state.ReadOnlyBeaconState, epoch types.Epoch, obj fssz.HashRoot, domain [4]byte, key bls.SecretKey) ([]byte, error) {
-	d, err := Domain(st.Fork(), epoch, domain, st.GenesisValidatorRoot())
+	d, err := Domain(st.Fork(), epoch, domain, st.GenesisValidatorsRoot())
 	if err != nil {
 		return nil, err
 	}
@@ -69,7 +69,7 @@ func ComputeDomainVerifySigningRoot(st state.ReadOnlyBeaconState, index types.Va
 	if err != nil {
 		return err
 	}
-	d, err := Domain(st.Fork(), epoch, domain, st.GenesisValidatorRoot())
+	d, err := Domain(st.Fork(), epoch, domain, st.GenesisValidatorsRoot())
 	if err != nil {
 		return err
 	}
@@ -219,7 +219,7 @@ func computeForkDataRoot(version, root []byte) ([32]byte, error) {
 	return r, nil
 }
 
-// ComputeForkDigest returns the fork for the current version and genesis validator root
+// ComputeForkDigest returns the fork for the current version and genesis validators root
 //
 // Spec pseudocode definition:
 //	def compute_fork_digest(current_version: Version, genesis_validators_root: Root) -> ForkDigest:

beacon-chain/core/transition/bellatrix_transition_no_verify_sig_test.go

@@ -244,7 +244,7 @@ func createFullBellatrixBlockWithOperations(t *testing.T) (state.BeaconState,
 					StateRoot:     make([]byte, fieldparams.RootLength),
 					ReceiptsRoot:  make([]byte, fieldparams.RootLength),
 					LogsBloom:     make([]byte, fieldparams.LogsBloomLength),
-					Random:        make([]byte, fieldparams.RootLength),
+					PrevRandao:    make([]byte, fieldparams.RootLength),
 					BaseFeePerGas: make([]byte, fieldparams.RootLength),
 					BlockHash:     make([]byte, fieldparams.RootLength),
 					Transactions:  make([][]byte, 0),

beacon-chain/core/transition/skip_slot_cache_test.go

@@ -10,6 +10,7 @@ import (
 	v1 "github.com/prysmaticlabs/prysm/beacon-chain/state/v1"
 	"github.com/prysmaticlabs/prysm/config/params"
 	"github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1/wrapper"
+	"github.com/prysmaticlabs/prysm/runtime/version"
 	"github.com/prysmaticlabs/prysm/testing/assert"
 	"github.com/prysmaticlabs/prysm/testing/require"
 	"github.com/prysmaticlabs/prysm/testing/util"
@@ -33,8 +34,7 @@ func TestSkipSlotCache_OK(t *testing.T) {
 	require.NoError(t, err)
 	executedState, err := transition.ExecuteStateTransition(context.Background(), originalState, wrapper.WrappedPhase0SignedBeaconBlock(blk))
 	require.NoError(t, err, "Could not run state transition")
-	originalState, ok := executedState.(*v1.BeaconState)
-	require.Equal(t, true, ok)
+	require.Equal(t, true, executedState.Version() == version.Phase0)
 	bState, err = transition.ExecuteStateTransition(context.Background(), bState, wrapper.WrappedPhase0SignedBeaconBlock(blk))
 	require.NoError(t, err, "Could not process state transition")
 
@@ -59,8 +59,7 @@ func TestSkipSlotCache_ConcurrentMixup(t *testing.T) {
 	require.NoError(t, err)
 	executedState, err := transition.ExecuteStateTransition(context.Background(), originalState, wrapper.WrappedPhase0SignedBeaconBlock(blk))
 	require.NoError(t, err, "Could not run state transition")
-	originalState, ok := executedState.(*v1.BeaconState)
-	require.Equal(t, true, ok)
+	require.Equal(t, true, executedState.Version() == version.Phase0)
 
 	// Create two shallow but different forks
 	var s1, s0 state.BeaconState

beacon-chain/core/transition/state_fuzz_test.go

@@ -7,6 +7,7 @@ import (
 	fuzz "github.com/google/gofuzz"
 	v1 "github.com/prysmaticlabs/prysm/beacon-chain/state/v1"
 	ethpb "github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1"
+	"github.com/prysmaticlabs/prysm/testing/require"
 )
 
 func TestGenesisBeaconState_1000(t *testing.T) {
@@ -37,7 +38,8 @@ func TestOptimizedGenesisBeaconState_1000(t *testing.T) {
 	fuzzer := fuzz.NewWithSeed(0)
 	fuzzer.NilChance(0.1)
 	var genesisTime uint64
-	preState := &v1.BeaconState{}
+	preState, err := v1.InitializeFromProtoUnsafe(&ethpb.BeaconState{})
+	require.NoError(t, err)
 	eth1Data := &ethpb.Eth1Data{}
 	for i := 0; i < 1000; i++ {
 		fuzzer.Fuzz(&genesisTime)

beacon-chain/core/transition/transition_fuzz_test.go

@@ -10,13 +10,15 @@ import (
 	v1 "github.com/prysmaticlabs/prysm/beacon-chain/state/v1"
 	ethpb "github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1"
 	"github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1/wrapper"
+	"github.com/prysmaticlabs/prysm/testing/require"
 )
 
 func TestFuzzExecuteStateTransition_1000(t *testing.T) {
 	SkipSlotCache.Disable()
 	defer SkipSlotCache.Enable()
 	ctx := context.Background()
-	state := &v1.BeaconState{}
+	state, err := v1.InitializeFromProtoUnsafe(&ethpb.BeaconState{})
+	require.NoError(t, err)
 	sb := &ethpb.SignedBeaconBlock{}
 	fuzzer := fuzz.NewWithSeed(0)
 	fuzzer.NilChance(0.1)
@@ -34,7 +36,8 @@ func TestFuzzCalculateStateRoot_1000(t *testing.T) {
 	SkipSlotCache.Disable()
 	defer SkipSlotCache.Enable()
 	ctx := context.Background()
-	state := &v1.BeaconState{}
+	state, err := v1.InitializeFromProtoUnsafe(&ethpb.BeaconState{})
+	require.NoError(t, err)
 	sb := &ethpb.SignedBeaconBlock{}
 	fuzzer := fuzz.NewWithSeed(0)
 	fuzzer.NilChance(0.1)
@@ -52,7 +55,8 @@ func TestFuzzProcessSlot_1000(t *testing.T) {
 	SkipSlotCache.Disable()
 	defer SkipSlotCache.Enable()
 	ctx := context.Background()
-	state := &v1.BeaconState{}
+	state, err := v1.InitializeFromProtoUnsafe(&ethpb.BeaconState{})
+	require.NoError(t, err)
 	fuzzer := fuzz.NewWithSeed(0)
 	fuzzer.NilChance(0.1)
 	for i := 0; i < 1000; i++ {
@@ -68,7 +72,8 @@ func TestFuzzProcessSlots_1000(t *testing.T) {
 	SkipSlotCache.Disable()
 	defer SkipSlotCache.Enable()
 	ctx := context.Background()
-	state := &v1.BeaconState{}
+	state, err := v1.InitializeFromProtoUnsafe(&ethpb.BeaconState{})
+	require.NoError(t, err)
 	slot := types.Slot(0)
 	fuzzer := fuzz.NewWithSeed(0)
 	fuzzer.NilChance(0.1)
@@ -86,7 +91,8 @@ func TestFuzzprocessOperationsNoVerify_1000(t *testing.T) {
 	SkipSlotCache.Disable()
 	defer SkipSlotCache.Enable()
 	ctx := context.Background()
-	state := &v1.BeaconState{}
+	state, err := v1.InitializeFromProtoUnsafe(&ethpb.BeaconState{})
+	require.NoError(t, err)
 	bb := &ethpb.SignedBeaconBlock{}
 	fuzzer := fuzz.NewWithSeed(0)
 	fuzzer.NilChance(0.1)
@@ -100,10 +106,11 @@ func TestFuzzprocessOperationsNoVerify_1000(t *testing.T) {
 	}
 }
 
-func TestFuzzverifyOperationLengths_10000(_ *testing.T) {
+func TestFuzzverifyOperationLengths_10000(t *testing.T) {
 	SkipSlotCache.Disable()
 	defer SkipSlotCache.Enable()
-	state := &v1.BeaconState{}
+	state, err := v1.InitializeFromProtoUnsafe(&ethpb.BeaconState{})
+	require.NoError(t, err)
 	bb := &ethpb.SignedBeaconBlock{}
 	fuzzer := fuzz.NewWithSeed(0)
 	fuzzer.NilChance(0.1)
@@ -115,10 +122,11 @@ func TestFuzzverifyOperationLengths_10000(_ *testing.T) {
 	}
 }
 
-func TestFuzzCanProcessEpoch_10000(_ *testing.T) {
+func TestFuzzCanProcessEpoch_10000(t *testing.T) {
 	SkipSlotCache.Disable()
 	defer SkipSlotCache.Enable()
-	state := &v1.BeaconState{}
+	state, err := v1.InitializeFromProtoUnsafe(&ethpb.BeaconState{})
+	require.NoError(t, err)
 	fuzzer := fuzz.NewWithSeed(0)
 	fuzzer.NilChance(0.1)
 	for i := 0; i < 10000; i++ {
@@ -131,7 +139,8 @@ func TestFuzzProcessEpochPrecompute_1000(t *testing.T) {
 	SkipSlotCache.Disable()
 	defer SkipSlotCache.Enable()
 	ctx := context.Background()
-	state := &v1.BeaconState{}
+	state, err := v1.InitializeFromProtoUnsafe(&ethpb.BeaconState{})
+	require.NoError(t, err)
 	fuzzer := fuzz.NewWithSeed(0)
 	fuzzer.NilChance(0.1)
 	for i := 0; i < 1000; i++ {
@@ -147,7 +156,8 @@ func TestFuzzProcessBlockForStateRoot_1000(t *testing.T) {
 	SkipSlotCache.Disable()
 	defer SkipSlotCache.Enable()
 	ctx := context.Background()
-	state := &v1.BeaconState{}
+	state, err := v1.InitializeFromProtoUnsafe(&ethpb.BeaconState{})
+	require.NoError(t, err)
 	sb := &ethpb.SignedBeaconBlock{}
 	fuzzer := fuzz.NewWithSeed(0)
 	fuzzer.NilChance(0.1)

beacon-chain/core/transition/transition_no_verify_sig.go

@@ -137,16 +137,6 @@ func CalculateStateRoot(
 	if err != nil {
 		return [32]byte{}, errors.Wrap(err, "could not process block")
 	}
-	if signed.Version() == version.Altair || signed.Version() == version.Bellatrix {
-		sa, err := signed.Block().Body().SyncAggregate()
-		if err != nil {
-			return [32]byte{}, err
-		}
-		state, err = altair.ProcessSyncAggregate(ctx, state, sa)
-		if err != nil {
-			return [32]byte{}, err
-		}
-	}
 
 	return state.HashTreeRoot(ctx)
 }
@@ -183,16 +173,6 @@ func ProcessBlockNoVerifyAnySig(
 	if err != nil {
 		return nil, nil, err
 	}
-	if signed.Version() == version.Altair || signed.Version() == version.Bellatrix {
-		sa, err := signed.Block().Body().SyncAggregate()
-		if err != nil {
-			return nil, nil, err
-		}
-		state, err = altair.ProcessSyncAggregate(ctx, state, sa)
-		if err != nil {
-			return nil, nil, err
-		}
-	}
 
 	bSet, err := b.BlockSignatureBatch(state, blk.ProposerIndex(), signed.Signature(), blk.HashTreeRoot)
 	if err != nil {
@@ -340,6 +320,19 @@ func ProcessBlockForStateRoot(
 		return nil, errors.Wrap(err, "could not process block operation")
 	}
 
+	if signed.Block().Version() == version.Phase0 {
+		return state, nil
+	}
+
+	sa, err := signed.Block().Body().SyncAggregate()
+	if err != nil {
+		return nil, errors.Wrap(err, "could not get sync aggregate from block")
+	}
+	state, err = altair.ProcessSyncAggregate(ctx, state, sa)
+	if err != nil {
+		return nil, errors.Wrap(err, "process_sync_aggregate failed")
+	}
+
 	return state, nil
 }
 

beacon-chain/core/transition/transition_test.go

@@ -253,7 +253,7 @@ func createFullBlockWithOperations(t *testing.T) (state.BeaconState,
 		},
 		AttestingIndices: []uint64{0, 1},
 	})
-	domain, err := signing.Domain(beaconState.Fork(), currentEpoch, params.BeaconConfig().DomainBeaconAttester, beaconState.GenesisValidatorRoot())
+	domain, err := signing.Domain(beaconState.Fork(), currentEpoch, params.BeaconConfig().DomainBeaconAttester, beaconState.GenesisValidatorsRoot())
 	require.NoError(t, err)
 	hashTreeRoot, err := signing.ComputeSigningRoot(att1.Data, domain)
 	require.NoError(t, err)
@@ -394,7 +394,9 @@ func TestProcessBlock_OverMaxProposerSlashings(t *testing.T) {
 	}
 	want := fmt.Sprintf("number of proposer slashings (%d) in block body exceeds allowed threshold of %d",
 		len(b.Block.Body.ProposerSlashings), params.BeaconConfig().MaxProposerSlashings)
-	_, err := transition.VerifyOperationLengths(context.Background(), &v1.BeaconState{}, wrapper.WrappedPhase0SignedBeaconBlock(b))
+	s, err := v1.InitializeFromProtoUnsafe(&ethpb.BeaconState{})
+	require.NoError(t, err)
+	_, err = transition.VerifyOperationLengths(context.Background(), s, wrapper.WrappedPhase0SignedBeaconBlock(b))
 	assert.ErrorContains(t, want, err)
 }
 
@@ -409,7 +411,9 @@ func TestProcessBlock_OverMaxAttesterSlashings(t *testing.T) {
 	}
 	want := fmt.Sprintf("number of attester slashings (%d) in block body exceeds allowed threshold of %d",
 		len(b.Block.Body.AttesterSlashings), params.BeaconConfig().MaxAttesterSlashings)
-	_, err := transition.VerifyOperationLengths(context.Background(), &v1.BeaconState{}, wrapper.WrappedPhase0SignedBeaconBlock(b))
+	s, err := v1.InitializeFromProtoUnsafe(&ethpb.BeaconState{})
+	require.NoError(t, err)
+	_, err = transition.VerifyOperationLengths(context.Background(), s, wrapper.WrappedPhase0SignedBeaconBlock(b))
 	assert.ErrorContains(t, want, err)
 }
 
@@ -423,7 +427,9 @@ func TestProcessBlock_OverMaxAttestations(t *testing.T) {
 	}
 	want := fmt.Sprintf("number of attestations (%d) in block body exceeds allowed threshold of %d",
 		len(b.Block.Body.Attestations), params.BeaconConfig().MaxAttestations)
-	_, err := transition.VerifyOperationLengths(context.Background(), &v1.BeaconState{}, wrapper.WrappedPhase0SignedBeaconBlock(b))
+	s, err := v1.InitializeFromProtoUnsafe(&ethpb.BeaconState{})
+	require.NoError(t, err)
+	_, err = transition.VerifyOperationLengths(context.Background(), s, wrapper.WrappedPhase0SignedBeaconBlock(b))
 	assert.ErrorContains(t, want, err)
 }
 
@@ -438,7 +444,9 @@ func TestProcessBlock_OverMaxVoluntaryExits(t *testing.T) {
 	}
 	want := fmt.Sprintf("number of voluntary exits (%d) in block body exceeds allowed threshold of %d",
 		len(b.Block.Body.VoluntaryExits), maxExits)
-	_, err := transition.VerifyOperationLengths(context.Background(), &v1.BeaconState{}, wrapper.WrappedPhase0SignedBeaconBlock(b))
+	s, err := v1.InitializeFromProtoUnsafe(&ethpb.BeaconState{})
+	require.NoError(t, err)
+	_, err = transition.VerifyOperationLengths(context.Background(), s, wrapper.WrappedPhase0SignedBeaconBlock(b))
 	assert.ErrorContains(t, want, err)
 }
 

beacon-chain/core/validators/BUILD.bazel

@@ -31,6 +31,7 @@ go_test(
         "//beacon-chain/state/v1:go_default_library",
         "//config/params:go_default_library",
         "//proto/prysm/v1alpha1:go_default_library",
+        "//runtime/version:go_default_library",
         "//testing/assert:go_default_library",
         "//testing/require:go_default_library",
         "@com_github_prysmaticlabs_eth2_types//:go_default_library",

beacon-chain/core/validators/validator_test.go

@@ -10,6 +10,7 @@ import (
 	v1 "github.com/prysmaticlabs/prysm/beacon-chain/state/v1"
 	"github.com/prysmaticlabs/prysm/config/params"
 	ethpb "github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1"
+	"github.com/prysmaticlabs/prysm/runtime/version"
 	"github.com/prysmaticlabs/prysm/testing/assert"
 	"github.com/prysmaticlabs/prysm/testing/require"
 )
@@ -129,8 +130,7 @@ func TestSlashValidator_OK(t *testing.T) {
 	cfg := params.BeaconConfig()
 	slashedState, err := SlashValidator(context.Background(), state, slashedIdx, cfg.MinSlashingPenaltyQuotient, cfg.ProposerRewardQuotient)
 	require.NoError(t, err, "Could not slash validator")
-	state, ok := slashedState.(*v1.BeaconState)
-	require.Equal(t, true, ok)
+	require.Equal(t, true, slashedState.Version() == version.Phase0)
 
 	v, err := state.ValidatorAtIndex(slashedIdx)
 	require.NoError(t, err)

beacon-chain/db/errors.go

@@ -7,3 +7,9 @@ import "github.com/prysmaticlabs/prysm/beacon-chain/db/kv"
 // i/o error. This variable copies the value in the kv package to the same scope as the Database interfaces,
 // so that it is available to code paths that do not interact directly with the kv package.
 var ErrNotFound = kv.ErrNotFound
+
+// ErrNotFoundState wraps ErrNotFound for an error specific to a state not being found in the database.
+var ErrNotFoundState = kv.ErrNotFoundState
+
+// ErrNotFoundOriginBlockRoot wraps ErrNotFound for an error specific to the origin block root.
+var ErrNotFoundOriginBlockRoot = kv.ErrNotFoundOriginBlockRoot

beacon-chain/db/iface/interface.go

@@ -32,6 +32,7 @@ type ReadOnlyDatabase interface {
 	HighestSlotBlocksBelow(ctx context.Context, slot types.Slot) ([]block.SignedBeaconBlock, error)
 	// State related methods.
 	State(ctx context.Context, blockRoot [32]byte) (state.BeaconState, error)
+	StateOrError(ctx context.Context, blockRoot [32]byte) (state.BeaconState, error)
 	GenesisState(ctx context.Context) (state.BeaconState, error)
 	HasState(ctx context.Context, blockRoot [32]byte) bool
 	StateSummary(ctx context.Context, blockRoot [32]byte) (*ethpb.StateSummary, error)
@@ -58,6 +59,7 @@ type NoHeadAccessDatabase interface {
 	ReadOnlyDatabase
 
 	// Block related methods.
+	DeleteBlock(ctx context.Context, root [32]byte) error
 	SaveBlock(ctx context.Context, block block.SignedBeaconBlock) error
 	SaveBlocks(ctx context.Context, blocks []block.SignedBeaconBlock) error
 	SaveGenesisBlockRoot(ctx context.Context, blockRoot [32]byte) error

beacon-chain/db/kv/BUILD.bazel

@@ -25,7 +25,6 @@ go_library(
         "state_summary.go",
         "state_summary_cache.go",
         "utils.go",
-        "validated_tips.go",
         "wss.go",
     ],
     importpath = "github.com/prysmaticlabs/prysm/beacon-chain/db/kv",
@@ -81,7 +80,6 @@ go_test(
         "checkpoint_test.go",
         "deposit_contract_test.go",
         "encoding_test.go",
-        "error_test.go",
         "finalized_block_roots_test.go",
         "genesis_test.go",
         "init_test.go",
@@ -93,7 +91,6 @@ go_test(
         "state_summary_test.go",
         "state_test.go",
         "utils_test.go",
-        "validated_tips_test.go",
     ],
     data = glob(["testdata/**"]),
     embed = [":go_default_library"],

beacon-chain/db/kv/blocks.go

@@ -204,6 +204,34 @@ func (s *Store) BlockRootsBySlot(ctx context.Context, slot types.Slot) (bool, []
 	return len(blockRoots) > 0, blockRoots, nil
 }
 
+// DeleteBlock from the db
+// This deletes the root entry from all buckets in the blocks DB
+// If the block is finalized this function returns an error
+func (s *Store) DeleteBlock(ctx context.Context, root [32]byte) error {
+	ctx, span := trace.StartSpan(ctx, "BeaconDB.DeleteBlock")
+	defer span.End()
+
+	if err := s.DeleteState(ctx, root); err != nil {
+		return errDeleteFinalized
+	}
+
+	return s.db.Update(func(tx *bolt.Tx) error {
+		bkt := tx.Bucket(finalizedBlockRootsIndexBucket)
+		if b := bkt.Get(root[:]); b != nil {
+			return errDeleteFinalized
+		}
+
+		if err := tx.Bucket(blocksBucket).Delete(root[:]); err != nil {
+			return err
+		}
+		if err := tx.Bucket(blockParentRootIndicesBucket).Delete(root[:]); err != nil {
+			return err
+		}
+		s.blockCache.Del(string(root[:]))
+		return nil
+	})
+}
+
 // SaveBlock to the db.
 func (s *Store) SaveBlock(ctx context.Context, signed block.SignedBeaconBlock) error {
 	ctx, span := trace.StartSpan(ctx, "BeaconDB.SaveBlock")

beacon-chain/db/kv/blocks_test.go

@@ -8,6 +8,7 @@ import (
 	"github.com/prysmaticlabs/prysm/beacon-chain/db/filters"
 	"github.com/prysmaticlabs/prysm/config/params"
 	"github.com/prysmaticlabs/prysm/encoding/bytesutil"
+	ethpb "github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1"
 	"github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1/block"
 	"github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1/wrapper"
 	"github.com/prysmaticlabs/prysm/testing/assert"
@@ -163,6 +164,44 @@ func TestStore_BlocksHandleInvalidEndSlot(t *testing.T) {
 	}
 }
 
+func TestStore_DeleteBlock(t *testing.T) {
+	slotsPerEpoch := uint64(params.BeaconConfig().SlotsPerEpoch)
+	db := setupDB(t)
+	ctx := context.Background()
+
+	require.NoError(t, db.SaveGenesisBlockRoot(ctx, genesisBlockRoot))
+	blks := makeBlocks(t, 0, slotsPerEpoch*4, genesisBlockRoot)
+	require.NoError(t, db.SaveBlocks(ctx, blks))
+
+	root, err := blks[slotsPerEpoch].Block().HashTreeRoot()
+	require.NoError(t, err)
+	cp := &ethpb.Checkpoint{
+		Epoch: 1,
+		Root:  root[:],
+	}
+	st, err := util.NewBeaconState()
+	require.NoError(t, err)
+	require.NoError(t, db.SaveState(ctx, st, root))
+	require.NoError(t, db.SaveFinalizedCheckpoint(ctx, cp))
+
+	root2, err := blks[4*slotsPerEpoch-2].Block().HashTreeRoot()
+	require.NoError(t, err)
+	b, err := db.Block(ctx, root2)
+	require.NoError(t, err)
+	require.NotNil(t, b)
+	require.NoError(t, db.DeleteBlock(ctx, root2))
+	st, err = db.State(ctx, root2)
+	require.NoError(t, err)
+	require.Equal(t, st, nil)
+
+	b, err = db.Block(ctx, root2)
+	require.NoError(t, err)
+	require.Equal(t, b, nil)
+
+	require.ErrorIs(t, db.DeleteBlock(ctx, root), errDeleteFinalized)
+
+}
+
 func TestStore_GenesisBlock(t *testing.T) {
 	db := setupDB(t)
 	ctx := context.Background()

beacon-chain/db/kv/error.go

@@ -1,46 +1,14 @@
 package kv
 
-import "errors"
+import "github.com/pkg/errors"
+
+// errDeleteFinalized is raised when we attempt to delete a finalized block/state
+var errDeleteFinalized = errors.New("cannot delete finalized block or state")
 
 // ErrNotFound can be used directly, or as a wrapped DBError, whenever a db method needs to
 // indicate that a value couldn't be found.
 var ErrNotFound = errors.New("not found in db")
+var ErrNotFoundState = errors.Wrap(ErrNotFound, "state not found")
 
 // ErrNotFoundOriginBlockRoot is an error specifically for the origin block root getter
-var ErrNotFoundOriginBlockRoot = WrapDBError(ErrNotFound, "OriginBlockRoot")
-
-// WrapDBError wraps an error in a DBError. See commentary on DBError for more context.
-func WrapDBError(e error, outer string) error {
-	return DBError{
-		Wraps: e,
-		Outer: errors.New(outer),
-	}
-}
-
-// DBError implements the Error method so that it can be asserted as an error.
-// The Unwrap method supports error wrapping, enabling it to be used with errors.Is/As.
-// The primary use case is to make it simple for database methods to return errors
-// that wrap ErrNotFound, allowing calling code to check for "not found" errors
-// like: `error.Is(err, ErrNotFound)`. This is intended to improve error handling
-// in db lookup methods that need to differentiate between a missing value and some
-// other database error. for more background see:
-// https://go.dev/blog/go1.13-errors
-type DBError struct {
-	Wraps error
-	Outer error
-}
-
-// Error satisfies the error interface, so that DBErrors can be used anywhere that
-// expects an `error`.
-func (e DBError) Error() string {
-	es := e.Outer.Error()
-	if e.Wraps != nil {
-		es += ": " + e.Wraps.Error()
-	}
-	return es
-}
-
-// Unwrap is used by the errors package Is and As methods.
-func (e DBError) Unwrap() error {
-	return e.Wraps
-}
+var ErrNotFoundOriginBlockRoot = errors.Wrap(ErrNotFound, "OriginBlockRoot")

beacon-chain/db/kv/error_test.go

@@ -1,24 +0,0 @@
-package kv
-
-import (
-	"errors"
-	"testing"
-)
-
-func TestWrappedSentinelError(t *testing.T) {
-	e := ErrNotFoundOriginBlockRoot
-	if !errors.Is(e, ErrNotFoundOriginBlockRoot) {
-		t.Error("expected that a copy of ErrNotFoundOriginBlockRoot would have an is-a relationship")
-	}
-
-	outer := errors.New("wrapped error")
-	e2 := DBError{Wraps: ErrNotFoundOriginBlockRoot, Outer: outer}
-	if !errors.Is(e2, ErrNotFoundOriginBlockRoot) {
-		t.Error("expected that errors.Is would know DBError wraps ErrNotFoundOriginBlockRoot")
-	}
-
-	// test that the innermost not found error is detected
-	if !errors.Is(e2, ErrNotFound) {
-		t.Error("expected that errors.Is would know ErrNotFoundOriginBlockRoot wraps ErrNotFound")
-	}
-}

beacon-chain/db/kv/kv.go

@@ -105,6 +105,8 @@ func NewKVStore(ctx context.Context, dirPath string, config *Config) (*Store, er
 		}
 	}
 	datafile := KVStoreDatafilePath(dirPath)
+	start := time.Now()
+	log.Infof("Opening Bolt DB at %s", datafile)
 	boltDB, err := bolt.Open(
 		datafile,
 		params.BeaconIoConfig().ReadWritePermissions,
@@ -114,29 +116,40 @@ func NewKVStore(ctx context.Context, dirPath string, config *Config) (*Store, er
 		},
 	)
 	if err != nil {
+		log.WithField("elapsed", time.Since(start)).Error("Failed to open Bolt DB")
 		if errors.Is(err, bolt.ErrTimeout) {
 			return nil, errors.New("cannot obtain database lock, database may be in use by another process")
 		}
 		return nil, err
 	}
+	log.WithField("elapsed", time.Since(start)).Info("Opened Bolt DB")
+
 	boltDB.AllocSize = boltAllocSize
+	start = time.Now()
+	log.Infof("Creating block cache...")
 	blockCache, err := ristretto.NewCache(&ristretto.Config{
 		NumCounters: 1000,           // number of keys to track frequency of (1000).
 		MaxCost:     BlockCacheSize, // maximum cost of cache (1000 Blocks).
 		BufferItems: 64,             // number of keys per Get buffer.
 	})
 	if err != nil {
+		log.WithField("elapsed", time.Since(start)).Error("Failed to create block cache")
 		return nil, err
 	}
+	log.WithField("elapsed", time.Since(start)).Info("Created block cache")
 
+	start = time.Now()
+	log.Infof("Creating validator cache...")
 	validatorCache, err := ristretto.NewCache(&ristretto.Config{
 		NumCounters: NumOfValidatorEntries, // number of entries in cache (2 Million).
 		MaxCost:     ValidatorEntryMaxCost, // maximum size of the cache (64Mb)
 		BufferItems: 64,                    // number of keys per Get buffer.
 	})
 	if err != nil {
+		log.WithField("elapsed", time.Since(start)).Error("Failed to to create validator cache")
 		return nil, err
 	}
+	log.WithField("elapsed", time.Since(start)).Info("Created validator cache")
 
 	kv := &Store{
 		db:                  boltDB,
@@ -146,7 +159,8 @@ func NewKVStore(ctx context.Context, dirPath string, config *Config) (*Store, er
 		stateSummaryCache:   newStateSummaryCache(),
 		ctx:                 ctx,
 	}
-
+	start = time.Now()
+	log.Infof("Updating DB and creating buckets...")
 	if err := kv.db.Update(func(tx *bolt.Tx) error {
 		return createBuckets(
 			tx,
@@ -179,8 +193,10 @@ func NewKVStore(ctx context.Context, dirPath string, config *Config) (*Store, er
 			migrationsBucket,
 		)
 	}); err != nil {
+		log.WithField("elapsed", time.Since(start)).Error("Failed to update db and create buckets")
 		return nil, err
 	}
+	log.WithField("elapsed", time.Since(start)).Info("Updated db and created buckets")
 
 	err = prometheus.Register(createBoltCollector(kv.db))
 

beacon-chain/db/kv/migration_state_validators_test.go

@@ -6,6 +6,7 @@ import (
 	"testing"
 
 	"github.com/golang/snappy"
+	"github.com/prysmaticlabs/prysm/beacon-chain/state"
 	v1 "github.com/prysmaticlabs/prysm/beacon-chain/state/v1"
 	v2 "github.com/prysmaticlabs/prysm/beacon-chain/state/v2"
 	"github.com/prysmaticlabs/prysm/config/features"
@@ -19,12 +20,12 @@ import (
 func Test_migrateStateValidators(t *testing.T) {
 	tests := []struct {
 		name  string
-		setup func(t *testing.T, dbStore *Store, state *v1.BeaconState, vals []*v1alpha1.Validator)
-		eval  func(t *testing.T, dbStore *Store, state *v1.BeaconState, vals []*v1alpha1.Validator)
+		setup func(t *testing.T, dbStore *Store, state state.BeaconState, vals []*v1alpha1.Validator)
+		eval  func(t *testing.T, dbStore *Store, state state.BeaconState, vals []*v1alpha1.Validator)
 	}{
 		{
 			name: "only runs once",
-			setup: func(t *testing.T, dbStore *Store, state *v1.BeaconState, vals []*v1alpha1.Validator) {
+			setup: func(t *testing.T, dbStore *Store, state state.BeaconState, vals []*v1alpha1.Validator) {
 				// create some new buckets that should be present for this migration
 				err := dbStore.db.Update(func(tx *bbolt.Tx) error {
 					_, err := tx.CreateBucketIfNotExists(stateValidatorsBucket)
@@ -35,7 +36,7 @@ func Test_migrateStateValidators(t *testing.T) {
 				})
 				assert.NoError(t, err)
 			},
-			eval: func(t *testing.T, dbStore *Store, state *v1.BeaconState, vals []*v1alpha1.Validator) {
+			eval: func(t *testing.T, dbStore *Store, state state.BeaconState, vals []*v1alpha1.Validator) {
 				// check if the migration is completed, per migration table.
 				err := dbStore.db.View(func(tx *bbolt.Tx) error {
 					migrationCompleteOrNot := tx.Bucket(migrationsBucket).Get(migrationStateValidatorsKey)
@@ -47,7 +48,7 @@ func Test_migrateStateValidators(t *testing.T) {
 		},
 		{
 			name: "once migrated, always enable flag",
-			setup: func(t *testing.T, dbStore *Store, state *v1.BeaconState, vals []*v1alpha1.Validator) {
+			setup: func(t *testing.T, dbStore *Store, state state.BeaconState, vals []*v1alpha1.Validator) {
 				// create some new buckets that should be present for this migration
 				err := dbStore.db.Update(func(tx *bbolt.Tx) error {
 					_, err := tx.CreateBucketIfNotExists(stateValidatorsBucket)
@@ -58,7 +59,7 @@ func Test_migrateStateValidators(t *testing.T) {
 				})
 				assert.NoError(t, err)
 			},
-			eval: func(t *testing.T, dbStore *Store, state *v1.BeaconState, vals []*v1alpha1.Validator) {
+			eval: func(t *testing.T, dbStore *Store, state state.BeaconState, vals []*v1alpha1.Validator) {
 				// disable the flag and see if the code mandates that flag.
 				resetCfg := features.InitWithReset(&features.Flags{
 					EnableHistoricalSpaceRepresentation: false,
@@ -111,7 +112,7 @@ func Test_migrateStateValidators(t *testing.T) {
 		},
 		{
 			name: "migrates validators and adds them to new buckets",
-			setup: func(t *testing.T, dbStore *Store, state *v1.BeaconState, vals []*v1alpha1.Validator) {
+			setup: func(t *testing.T, dbStore *Store, state state.BeaconState, vals []*v1alpha1.Validator) {
 				// create some new buckets that should be present for this migration
 				err := dbStore.db.Update(func(tx *bbolt.Tx) error {
 					_, err := tx.CreateBucketIfNotExists(stateValidatorsBucket)
@@ -122,7 +123,7 @@ func Test_migrateStateValidators(t *testing.T) {
 				})
 				assert.NoError(t, err)
 			},
-			eval: func(t *testing.T, dbStore *Store, state *v1.BeaconState, vals []*v1alpha1.Validator) {
+			eval: func(t *testing.T, dbStore *Store, state state.BeaconState, vals []*v1alpha1.Validator) {
 				// check whether the new buckets are present
 				err := dbStore.db.View(func(tx *bbolt.Tx) error {
 					valBkt := tx.Bucket(stateValidatorsBucket)
@@ -209,12 +210,12 @@ func Test_migrateStateValidators(t *testing.T) {
 func Test_migrateAltairStateValidators(t *testing.T) {
 	tests := []struct {
 		name  string
-		setup func(t *testing.T, dbStore *Store, state *v2.BeaconState, vals []*v1alpha1.Validator)
-		eval  func(t *testing.T, dbStore *Store, state *v2.BeaconState, vals []*v1alpha1.Validator)
+		setup func(t *testing.T, dbStore *Store, state state.BeaconStateAltair, vals []*v1alpha1.Validator)
+		eval  func(t *testing.T, dbStore *Store, state state.BeaconStateAltair, vals []*v1alpha1.Validator)
 	}{
 		{
 			name: "migrates validators and adds them to new buckets",
-			setup: func(t *testing.T, dbStore *Store, state *v2.BeaconState, vals []*v1alpha1.Validator) {
+			setup: func(t *testing.T, dbStore *Store, state state.BeaconStateAltair, vals []*v1alpha1.Validator) {
 				// create some new buckets that should be present for this migration
 				err := dbStore.db.Update(func(tx *bbolt.Tx) error {
 					_, err := tx.CreateBucketIfNotExists(stateValidatorsBucket)
@@ -225,7 +226,7 @@ func Test_migrateAltairStateValidators(t *testing.T) {
 				})
 				assert.NoError(t, err)
 			},
-			eval: func(t *testing.T, dbStore *Store, state *v2.BeaconState, vals []*v1alpha1.Validator) {
+			eval: func(t *testing.T, dbStore *Store, state state.BeaconStateAltair, vals []*v1alpha1.Validator) {
 				// check whether the new buckets are present
 				err := dbStore.db.View(func(tx *bbolt.Tx) error {
 					valBkt := tx.Bucket(stateValidatorsBucket)
@@ -300,9 +301,9 @@ func Test_migrateAltairStateValidators(t *testing.T) {
 			})
 			defer resetCfg()
 
-			tt.setup(t, dbStore, st.(*v2.BeaconState), vals)
+			tt.setup(t, dbStore, st, vals)
 			assert.NoError(t, migrateStateValidators(context.Background(), dbStore.db), "migrateArchivedIndex(tx) error")
-			tt.eval(t, dbStore, st.(*v2.BeaconState), vals)
+			tt.eval(t, dbStore, st, vals)
 		})
 	}
 }

beacon-chain/db/kv/state.go

@@ -3,6 +3,7 @@ package kv
 import (
 	"bytes"
 	"context"
+	"fmt"
 
 	"github.com/golang/snappy"
 	"github.com/pkg/errors"
@@ -46,6 +47,19 @@ func (s *Store) State(ctx context.Context, blockRoot [32]byte) (state.BeaconStat
 	return s.unmarshalState(ctx, enc, valEntries)
 }
 
+// StateOrError is just like State(), except it only returns a non-error response
+// if the requested state is found in the database.
+func (s *Store) StateOrError(ctx context.Context, blockRoot [32]byte) (state.BeaconState, error) {
+	st, err := s.State(ctx, blockRoot)
+	if err != nil {
+		return nil, err
+	}
+	if st == nil || st.IsNil() {
+		return nil, errors.Wrap(ErrNotFoundState, fmt.Sprintf("no state with blockroot=%#x", blockRoot))
+	}
+	return st, nil
+}
+
 // GenesisState returns the genesis state in beacon chain.
 func (s *Store) GenesisState(ctx context.Context) (state.BeaconState, error) {
 	ctx, span := trace.StartSpan(ctx, "BeaconDB.GenesisState")

beacon-chain/db/kv/state_test.go

@@ -21,6 +21,12 @@ import (
 	bolt "go.etcd.io/bbolt"
 )
 
+func TestStateNil(t *testing.T) {
+	db := setupDB(t)
+	_, err := db.StateOrError(context.Background(), [32]byte{})
+	require.ErrorIs(t, err, ErrNotFoundState)
+}
+
 func TestState_CanSaveRetrieve(t *testing.T) {
 	db := setupDB(t)
 

beacon-chain/db/kv/validated_tips.go

@@ -1,71 +0,0 @@
-package kv
-
-import (
-	"context"
-
-	types "github.com/prysmaticlabs/eth2-types"
-	"github.com/prysmaticlabs/prysm/encoding/bytesutil"
-	bolt "go.etcd.io/bbolt"
-	"go.opencensus.io/trace"
-)
-
-// ValidatedTips returns all the validated_tips that are present in the DB.
-func (s *Store) ValidatedTips(ctx context.Context) (map[[32]byte]types.Slot, error) {
-	ctx, span := trace.StartSpan(ctx, "BeaconDB.ValidatedTips")
-	defer span.End()
-
-	valTips := make(map[[32]byte]types.Slot, 1)
-	err := s.db.View(func(tx *bolt.Tx) error {
-		bkt := tx.Bucket(validatedTips)
-
-		c := bkt.Cursor()
-		for k, v := c.First(); k != nil; k, v = c.Next() {
-			if ctx.Err() != nil {
-				return ctx.Err()
-			}
-			valTips[bytesutil.ToBytes32(k)] = bytesutil.BytesToSlotBigEndian(v)
-		}
-		return nil
-	})
-	return valTips, err
-}
-
-// UpdateValidatedTips clears off all the old validated_tips from the DB and
-// adds the new tips that are provided.
-func (s *Store) UpdateValidatedTips(ctx context.Context, newVals map[[32]byte]types.Slot) error {
-	ctx, span := trace.StartSpan(ctx, "BeaconDB.UpdateValidatedTips")
-	defer span.End()
-
-	// Get the already existing tips.
-	oldVals, err := s.ValidatedTips(ctx)
-	if err != nil {
-		return err
-	}
-
-	updateErr := s.db.Update(func(tx *bolt.Tx) error {
-		bkt := tx.Bucket(validatedTips)
-
-		// Delete keys that are present and not in the new set.
-		for k := range oldVals {
-			if _, ok := newVals[k]; !ok {
-				deleteErr := bkt.Delete(k[:])
-				if deleteErr != nil {
-					return deleteErr
-				}
-
-			}
-		}
-
-		// Add keys not present already.
-		for k, v := range newVals {
-			if _, ok := oldVals[k]; !ok {
-				putErr := bkt.Put(k[:], bytesutil.SlotToBytesBigEndian(v))
-				if putErr != nil {
-					return putErr
-				}
-			}
-		}
-		return nil
-	})
-	return updateErr
-}

beacon-chain/db/kv/validated_tips_test.go

@@ -1,93 +0,0 @@
-package kv
-
-import (
-	"context"
-	"testing"
-
-	types "github.com/prysmaticlabs/eth2-types"
-	"github.com/prysmaticlabs/prysm/testing/require"
-)
-
-func TestTips_AddNewTips(t *testing.T) {
-	ctx := context.Background()
-	db := setupDB(t)
-
-	newTips := make(map[[32]byte]types.Slot)
-	newTips[[32]byte{'A'}] = types.Slot(1)
-	newTips[[32]byte{'B'}] = types.Slot(2)
-	newTips[[32]byte{'C'}] = types.Slot(3)
-
-	require.NoError(t, db.UpdateValidatedTips(ctx, newTips))
-
-	gotTips, err := db.ValidatedTips(ctx)
-	require.NoError(t, err)
-
-	require.Equal(t, true, areTipsSame(gotTips, newTips))
-}
-
-func TestTips_UpdateTipsWithoutOverlap(t *testing.T) {
-	ctx := context.Background()
-	db := setupDB(t)
-
-	oldTips := make(map[[32]byte]types.Slot)
-	oldTips[[32]byte{'A'}] = types.Slot(1)
-	oldTips[[32]byte{'B'}] = types.Slot(2)
-	oldTips[[32]byte{'C'}] = types.Slot(3)
-
-	require.NoError(t, db.UpdateValidatedTips(ctx, oldTips))
-
-	// create a new non-overlapping tips to add
-	newTips := make(map[[32]byte]types.Slot)
-	newTips[[32]byte{'D'}] = types.Slot(4)
-	newTips[[32]byte{'E'}] = types.Slot(5)
-	newTips[[32]byte{'F'}] = types.Slot(6)
-
-	require.NoError(t, db.UpdateValidatedTips(ctx, newTips))
-
-	gotTips, err := db.ValidatedTips(ctx)
-	require.NoError(t, err)
-
-	require.Equal(t, true, areTipsSame(gotTips, newTips))
-
-}
-
-func TestTips_UpdateTipsWithOverlap(t *testing.T) {
-	ctx := context.Background()
-	db := setupDB(t)
-
-	oldTips := make(map[[32]byte]types.Slot)
-	oldTips[[32]byte{'A'}] = types.Slot(1)
-	oldTips[[32]byte{'B'}] = types.Slot(2)
-	oldTips[[32]byte{'C'}] = types.Slot(3)
-	require.NoError(t, db.UpdateValidatedTips(ctx, oldTips))
-
-	// create a new overlapping tips to add
-	newTips := make(map[[32]byte]types.Slot)
-	newTips[[32]byte{'C'}] = types.Slot(3)
-	newTips[[32]byte{'D'}] = types.Slot(4)
-	newTips[[32]byte{'E'}] = types.Slot(5)
-	require.NoError(t, db.UpdateValidatedTips(ctx, newTips))
-
-	gotTips, err := db.ValidatedTips(ctx)
-	require.NoError(t, err)
-
-	require.Equal(t, true, areTipsSame(gotTips, newTips))
-
-}
-
-func areTipsSame(got map[[32]byte]types.Slot, required map[[32]byte]types.Slot) bool {
-	if len(got) != len(required) {
-		return false
-	}
-
-	for k, v := range got {
-		if val, ok := required[k]; ok {
-			if uint64(v) != uint64(val) {
-				return false
-			}
-		} else {
-			return false
-		}
-	}
-	return true
-}

beacon-chain/deterministic-genesis/service.go

@@ -120,11 +120,6 @@ func (_ *Service) AllDeposits(_ context.Context, _ *big.Int) []*ethpb.Deposit {
 	return []*ethpb.Deposit{}
 }
 
-// ChainStartDeposits mocks out the powchain functionality for interop.
-func (s *Service) ChainStartDeposits() []*ethpb.Deposit {
-	return s.chainStartDeposits
-}
-
 // ChainStartEth1Data mocks out the powchain functionality for interop.
 func (_ *Service) ChainStartEth1Data() *ethpb.Eth1Data {
 	return &ethpb.Eth1Data{}
@@ -132,7 +127,11 @@ func (_ *Service) ChainStartEth1Data() *ethpb.Eth1Data {
 
 // PreGenesisState returns an empty beacon state.
 func (_ *Service) PreGenesisState() state.BeaconState {
-	return &v1.BeaconState{}
+	s, err := v1.InitializeFromProto(&ethpb.BeaconState{})
+	if err != nil {
+		panic("could not initialize state")
+	}
+	return s
 }
 
 // ClearPreGenesisData --

beacon-chain/forkchoice/BUILD.bazel

@@ -12,7 +12,8 @@ go_library(
         "//testing/spectest:__subpackages__",
     ],
     deps = [
-        "//beacon-chain/forkchoice/protoarray:go_default_library",
+        "//config/fieldparams:go_default_library",
+        "//proto/prysm/v1alpha1:go_default_library",
         "@com_github_prysmaticlabs_eth2_types//:go_default_library",
     ],
 )

beacon-chain/forkchoice/doubly-linked-tree/BUILD.bazel

@@ -0,0 +1,55 @@
+load("@prysm//tools/go:def.bzl", "go_library", "go_test")
+
+go_library(
+    name = "go_default_library",
+    srcs = [
+        "doc.go",
+        "errors.go",
+        "forkchoice.go",
+        "metrics.go",
+        "node.go",
+        "optimistic_sync.go",
+        "proposer_boost.go",
+        "store.go",
+        "types.go",
+    ],
+    importpath = "github.com/prysmaticlabs/prysm/beacon-chain/forkchoice/doubly-linked-tree",
+    visibility = [
+        "//beacon-chain:__subpackages__",
+        "//testing/spectest:__subpackages__",
+    ],
+    deps = [
+        "//config/fieldparams:go_default_library",
+        "//config/params:go_default_library",
+        "//proto/prysm/v1alpha1:go_default_library",
+        "//time/slots:go_default_library",
+        "@com_github_pkg_errors//:go_default_library",
+        "@com_github_prometheus_client_golang//prometheus:go_default_library",
+        "@com_github_prometheus_client_golang//prometheus/promauto:go_default_library",
+        "@com_github_prysmaticlabs_eth2_types//:go_default_library",
+        "@io_opencensus_go//trace:go_default_library",
+    ],
+)
+
+go_test(
+    name = "go_default_test",
+    srcs = [
+        "ffg_update_test.go",
+        "forkchoice_test.go",
+        "no_vote_test.go",
+        "node_test.go",
+        "optimistic_sync_test.go",
+        "proposer_boost_test.go",
+        "store_test.go",
+        "vote_test.go",
+    ],
+    embed = [":go_default_library"],
+    deps = [
+        "//config/params:go_default_library",
+        "//crypto/hash:go_default_library",
+        "//encoding/bytesutil:go_default_library",
+        "//testing/assert:go_default_library",
+        "//testing/require:go_default_library",
+        "@com_github_prysmaticlabs_eth2_types//:go_default_library",
+    ],
+)

beacon-chain/forkchoice/doubly-linked-tree/doc.go

@@ -0,0 +1,4 @@
+/*
+Package doublylinkedtree implements eth2 LMD GHOST fork choice using the doubly linked proto array node structure.
+*/
+package doublylinkedtree

beacon-chain/forkchoice/doubly-linked-tree/errors.go

@@ -0,0 +1,10 @@
+package doublylinkedtree
+
+import "errors"
+
+var errNilNode = errors.New("invalid nil or unknown node")
+var errInvalidBalance = errors.New("invalid node balance")
+var errInvalidProposerBoostRoot = errors.New("invalid proposer boost root")
+var errUnknownFinalizedRoot = errors.New("unknown finalized root")
+var errUnknownJustifiedRoot = errors.New("unknown justified root")
+var errInvalidOptimisticStatus = errors.New("invalid optimistic status")

beacon-chain/forkchoice/doubly-linked-tree/ffg_update_test.go

@@ -0,0 +1,193 @@
+package doublylinkedtree
+
+import (
+	"context"
+	"testing"
+
+	types "github.com/prysmaticlabs/eth2-types"
+	"github.com/prysmaticlabs/prysm/config/params"
+	"github.com/prysmaticlabs/prysm/testing/assert"
+	"github.com/prysmaticlabs/prysm/testing/require"
+)
+
+func TestFFGUpdates_OneBranch(t *testing.T) {
+	balances := []uint64{1, 1}
+	f := setup(0, 0)
+
+	// The head should always start at the finalized block.
+	r, err := f.Head(context.Background(), 0, params.BeaconConfig().ZeroHash, balances, 0)
+	require.NoError(t, err)
+	assert.Equal(t, params.BeaconConfig().ZeroHash, r, "Incorrect head with genesis")
+
+	// Define the following tree:
+	//            0 <- justified: 0, finalized: 0
+	//            |
+	//            1 <- justified: 0, finalized: 0
+	//            |
+	//            2 <- justified: 1, finalized: 0
+	//            |
+	//            3 <- justified: 2, finalized: 1
+	require.NoError(t, f.ProcessBlock(context.Background(), 1, indexToHash(1), params.BeaconConfig().ZeroHash, 0, 0, false))
+	require.NoError(t, f.ProcessBlock(context.Background(), 2, indexToHash(2), indexToHash(1), 1, 0, false))
+	require.NoError(t, f.ProcessBlock(context.Background(), 3, indexToHash(3), indexToHash(2), 2, 1, false))
+
+	// With starting justified epoch at 0, the head should be 3:
+	//            0 <- start
+	//            |
+	//            1
+	//            |
+	//            2
+	//            |
+	//            3 <- head
+	r, err = f.Head(context.Background(), 0, params.BeaconConfig().ZeroHash, balances, 0)
+	require.NoError(t, err)
+	assert.Equal(t, indexToHash(3), r, "Incorrect head for with justified epoch at 0")
+
+	// With starting justified epoch at 1, the head should be 2:
+	//            0
+	//            |
+	//            1 <- start
+	//            |
+	//            2 <- head
+	//            |
+	//            3
+	r, err = f.Head(context.Background(), 1, indexToHash(2), balances, 0)
+	require.NoError(t, err)
+	assert.Equal(t, indexToHash(2), r, "Incorrect head with justified epoch at 1")
+
+	// With starting justified epoch at 2, the head should be 3:
+	//            0
+	//            |
+	//            1
+	//            |
+	//            2 <- start
+	//            |
+	//            3 <- head
+	r, err = f.Head(context.Background(), 2, indexToHash(3), balances, 1)
+	require.NoError(t, err)
+	assert.Equal(t, indexToHash(3), r, "Incorrect head with justified epoch at 2")
+}
+
+func TestFFGUpdates_TwoBranches(t *testing.T) {
+	balances := []uint64{1, 1}
+	f := setup(0, 0)
+
+	r, err := f.Head(context.Background(), 0, params.BeaconConfig().ZeroHash, balances, 0)
+	require.NoError(t, err)
+	assert.Equal(t, params.BeaconConfig().ZeroHash, r, "Incorrect head with genesis")
+
+	// Define the following tree:
+	//                                0
+	//                               / \
+	//  justified: 0, finalized: 0 -> 1   2 <- justified: 0, finalized: 0
+	//                              |   |
+	//  justified: 1, finalized: 0 -> 3   4 <- justified: 0, finalized: 0
+	//                              |   |
+	//  justified: 1, finalized: 0 -> 5   6 <- justified: 0, finalized: 0
+	//                              |   |
+	//  justified: 1, finalized: 0 -> 7   8 <- justified: 1, finalized: 0
+	//                              |   |
+	//  justified: 2, finalized: 0 -> 9  10 <- justified: 2, finalized: 0
+	// Left branch.
+	require.NoError(t, f.ProcessBlock(context.Background(), 1, indexToHash(1), params.BeaconConfig().ZeroHash, 0, 0, false))
+	require.NoError(t, f.ProcessBlock(context.Background(), 2, indexToHash(3), indexToHash(1), 1, 0, false))
+	require.NoError(t, f.ProcessBlock(context.Background(), 3, indexToHash(5), indexToHash(3), 1, 0, false))
+	require.NoError(t, f.ProcessBlock(context.Background(), 4, indexToHash(7), indexToHash(5), 1, 0, false))
+	require.NoError(t, f.ProcessBlock(context.Background(), 4, indexToHash(9), indexToHash(7), 2, 0, false))
+	// Right branch.
+	require.NoError(t, f.ProcessBlock(context.Background(), 1, indexToHash(2), params.BeaconConfig().ZeroHash, 0, 0, false))
+	require.NoError(t, f.ProcessBlock(context.Background(), 2, indexToHash(4), indexToHash(2), 0, 0, false))
+	require.NoError(t, f.ProcessBlock(context.Background(), 3, indexToHash(6), indexToHash(4), 0, 0, false))
+	require.NoError(t, f.ProcessBlock(context.Background(), 4, indexToHash(8), indexToHash(6), 1, 0, false))
+	require.NoError(t, f.ProcessBlock(context.Background(), 4, indexToHash(10), indexToHash(8), 2, 0, false))
+
+	// With start at 0, the head should be 10:
+	//           0  <-- start
+	//          / \
+	//         1   2
+	//         |   |
+	//         3   4
+	//         |   |
+	//         5   6
+	//         |   |
+	//         7   8
+	//         |   |
+	//         9  10 <-- head
+	r, err = f.Head(context.Background(), 0, params.BeaconConfig().ZeroHash, balances, 0)
+	require.NoError(t, err)
+	assert.Equal(t, indexToHash(10), r, "Incorrect head with justified epoch at 0")
+
+	// Add a vote to 1:
+	//                 0
+	//                / \
+	//    +1 vote -> 1   2
+	//               |   |
+	//               3   4
+	//               |   |
+	//               5   6
+	//               |   |
+	//               7   8
+	//               |   |
+	//               9  10
+	f.ProcessAttestation(context.Background(), []uint64{0}, indexToHash(1), 0)
+
+	// With the additional vote to the left branch, the head should be 9:
+	//           0  <-- start
+	//          / \
+	//         1   2
+	//         |   |
+	//         3   4
+	//         |   |
+	//         5   6
+	//         |   |
+	//         7   8
+	//         |   |
+	// head -> 9  10
+	r, err = f.Head(context.Background(), 0, params.BeaconConfig().ZeroHash, balances, 0)
+	require.NoError(t, err)
+	assert.Equal(t, indexToHash(9), r, "Incorrect head with justified epoch at 0")
+
+	// Add a vote to 2:
+	//                 0
+	//                / \
+	//               1   2 <- +1 vote
+	//               |   |
+	//               3   4
+	//               |   |
+	//               5   6
+	//               |   |
+	//               7   8
+	//               |   |
+	//               9  10
+	f.ProcessAttestation(context.Background(), []uint64{1}, indexToHash(2), 0)
+
+	// With the additional vote to the right branch, the head should be 10:
+	//           0  <-- start
+	//          / \
+	//         1   2
+	//         |   |
+	//         3   4
+	//         |   |
+	//         5   6
+	//         |   |
+	//         7   8
+	//         |   |
+	//         9  10 <-- head
+	r, err = f.Head(context.Background(), 0, params.BeaconConfig().ZeroHash, balances, 0)
+	require.NoError(t, err)
+	assert.Equal(t, indexToHash(10), r, "Incorrect head with justified epoch at 0")
+
+	r, err = f.Head(context.Background(), 1, indexToHash(1), balances, 0)
+	require.NoError(t, err)
+	assert.Equal(t, indexToHash(7), r, "Incorrect head with justified epoch at 0")
+}
+
+func setup(justifiedEpoch, finalizedEpoch types.Epoch) *ForkChoice {
+	ctx := context.Background()
+	f := New(justifiedEpoch, finalizedEpoch)
+	err := f.ProcessBlock(ctx, 0, params.BeaconConfig().ZeroHash, [32]byte{}, justifiedEpoch, finalizedEpoch, false)
+	if err != nil {
+		return nil
+	}
+	return f
+}

beacon-chain/forkchoice/doubly-linked-tree/forkchoice.go

@@ -0,0 +1,307 @@
+package doublylinkedtree
+
+import (
+	"context"
+
+	"github.com/pkg/errors"
+	types "github.com/prysmaticlabs/eth2-types"
+	fieldparams "github.com/prysmaticlabs/prysm/config/fieldparams"
+	"github.com/prysmaticlabs/prysm/config/params"
+	pbrpc "github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1"
+	"go.opencensus.io/trace"
+)
+
+// New initializes a new fork choice store.
+func New(justifiedEpoch, finalizedEpoch types.Epoch) *ForkChoice {
+	s := &Store{
+		justifiedEpoch:    justifiedEpoch,
+		finalizedEpoch:    finalizedEpoch,
+		proposerBoostRoot: [32]byte{},
+		nodeByRoot:        make(map[[fieldparams.RootLength]byte]*Node),
+		pruneThreshold:    defaultPruneThreshold,
+	}
+
+	b := make([]uint64, 0)
+	v := make([]Vote, 0)
+	return &ForkChoice{store: s, balances: b, votes: v}
+}
+
+// NodeCount returns the current number of nodes in the Store.
+func (f *ForkChoice) NodeCount() int {
+	f.store.nodesLock.RLock()
+	defer f.store.nodesLock.RUnlock()
+	return len(f.store.nodeByRoot)
+}
+
+// Head returns the head root from fork choice store.
+// It firsts computes validator's balance changes then recalculates block tree from leaves to root.
+func (f *ForkChoice) Head(
+	ctx context.Context,
+	justifiedEpoch types.Epoch,
+	justifiedRoot [32]byte,
+	justifiedStateBalances []uint64,
+	finalizedEpoch types.Epoch,
+) ([32]byte, error) {
+	ctx, span := trace.StartSpan(ctx, "doublyLinkedForkchoice.Head")
+	defer span.End()
+	f.votesLock.Lock()
+	defer f.votesLock.Unlock()
+
+	calledHeadCount.Inc()
+
+	// Using the write lock here because `applyWeightChanges` that gets called subsequently requires a write operation.
+	f.store.nodesLock.Lock()
+	defer f.store.nodesLock.Unlock()
+
+	f.store.updateCheckpoints(justifiedEpoch, finalizedEpoch)
+
+	if err := f.updateBalances(justifiedStateBalances); err != nil {
+		return [32]byte{}, errors.Wrap(err, "could not update balances")
+	}
+
+	if err := f.store.applyProposerBoostScore(justifiedStateBalances); err != nil {
+		return [32]byte{}, errors.Wrap(err, "could not apply proposer boost score")
+	}
+
+	if err := f.store.treeRootNode.applyWeightChanges(ctx); err != nil {
+		return [32]byte{}, errors.Wrap(err, "could not apply weight changes")
+	}
+
+	if err := f.store.treeRootNode.updateBestDescendant(ctx, justifiedEpoch, finalizedEpoch); err != nil {
+		return [32]byte{}, errors.Wrap(err, "could not update best descendant")
+	}
+
+	return f.store.head(ctx, justifiedRoot)
+}
+
+// ProcessAttestation processes attestation for vote accounting, it iterates around validator indices
+// and update their votes accordingly.
+func (f *ForkChoice) ProcessAttestation(ctx context.Context, validatorIndices []uint64, blockRoot [32]byte, targetEpoch types.Epoch) {
+	_, span := trace.StartSpan(ctx, "doublyLinkedForkchoice.ProcessAttestation")
+	defer span.End()
+	f.votesLock.Lock()
+	defer f.votesLock.Unlock()
+
+	for _, index := range validatorIndices {
+		// Validator indices will grow the vote cache.
+		for index >= uint64(len(f.votes)) {
+			f.votes = append(f.votes, Vote{currentRoot: params.BeaconConfig().ZeroHash, nextRoot: params.BeaconConfig().ZeroHash})
+		}
+
+		// Newly allocated vote if the root fields are untouched.
+		newVote := f.votes[index].nextRoot == params.BeaconConfig().ZeroHash &&
+			f.votes[index].currentRoot == params.BeaconConfig().ZeroHash
+
+		// Vote gets updated if it's newly allocated or high target epoch.
+		if newVote || targetEpoch > f.votes[index].nextEpoch {
+			f.votes[index].nextEpoch = targetEpoch
+			f.votes[index].nextRoot = blockRoot
+		}
+	}
+
+	processedAttestationCount.Inc()
+}
+
+// ProcessBlock processes a new block by inserting it to the fork choice store.
+func (f *ForkChoice) ProcessBlock(
+	ctx context.Context,
+	slot types.Slot,
+	blockRoot, parentRoot [fieldparams.RootLength]byte,
+	justifiedEpoch, finalizedEpoch types.Epoch, optimistic bool,
+) error {
+	ctx, span := trace.StartSpan(ctx, "doublyLinkedForkchoice.ProcessBlock")
+	defer span.End()
+
+	return f.store.insert(ctx, slot, blockRoot, parentRoot, justifiedEpoch, finalizedEpoch, optimistic)
+}
+
+// Prune prunes the fork choice store with the new finalized root. The store is only pruned if the input
+// root is different than the current store finalized root, and the number of the store has met prune threshold.
+func (f *ForkChoice) Prune(ctx context.Context, finalizedRoot [32]byte) error {
+	return f.store.prune(ctx, finalizedRoot)
+}
+
+// HasNode returns true if the node exists in fork choice store,
+// false else wise.
+func (f *ForkChoice) HasNode(root [32]byte) bool {
+	f.store.nodesLock.RLock()
+	defer f.store.nodesLock.RUnlock()
+
+	_, ok := f.store.nodeByRoot[root]
+	return ok
+}
+
+// HasParent returns true if the node parent exists in fork choice store,
+// false else wise.
+func (f *ForkChoice) HasParent(root [32]byte) bool {
+	f.store.nodesLock.RLock()
+	defer f.store.nodesLock.RUnlock()
+
+	node, ok := f.store.nodeByRoot[root]
+	if !ok || node == nil {
+		return false
+	}
+
+	return node.parent != nil
+}
+
+// IsCanonical returns true if the given root is part of the canonical chain.
+func (f *ForkChoice) IsCanonical(root [32]byte) bool {
+	f.store.nodesLock.RLock()
+	defer f.store.nodesLock.RUnlock()
+
+	node, ok := f.store.nodeByRoot[root]
+	if !ok || node == nil {
+		return false
+	}
+
+	if node.bestDescendant == nil {
+		if f.store.headNode.bestDescendant == nil {
+			return node == f.store.headNode
+		}
+		return node == f.store.headNode.bestDescendant
+	}
+	if f.store.headNode.bestDescendant == nil {
+		return node.bestDescendant == f.store.headNode
+	}
+	return node.bestDescendant == f.store.headNode.bestDescendant
+}
+
+// IsOptimistic returns true if the given root has been optimistically synced.
+func (f *ForkChoice) IsOptimistic(_ context.Context, root [32]byte) (bool, error) {
+	f.store.nodesLock.RLock()
+	defer f.store.nodesLock.RUnlock()
+
+	node, ok := f.store.nodeByRoot[root]
+	if !ok || node == nil {
+		return false, errNilNode
+	}
+
+	return node.optimistic, nil
+}
+
+// AncestorRoot returns the ancestor root of input block root at a given slot.
+func (f *ForkChoice) AncestorRoot(ctx context.Context, root [32]byte, slot types.Slot) ([]byte, error) {
+	ctx, span := trace.StartSpan(ctx, "protoArray.AncestorRoot")
+	defer span.End()
+
+	f.store.nodesLock.RLock()
+	defer f.store.nodesLock.RUnlock()
+
+	node, ok := f.store.nodeByRoot[root]
+	if !ok || node == nil {
+		return nil, errNilNode
+	}
+
+	n := node
+	for n != nil && n.slot > slot {
+		if ctx.Err() != nil {
+			return nil, ctx.Err()
+		}
+		n = n.parent
+	}
+
+	if n == nil {
+		return nil, errNilNode
+	}
+
+	return n.root[:], nil
+}
+
+// updateBalances updates the balances that directly voted for each block taking into account the
+// validators' latest votes.
+func (f *ForkChoice) updateBalances(newBalances []uint64) error {
+	for index, vote := range f.votes {
+		// Skip if validator has never voted for current root and next root (i.e. if the
+		// votes are zero hash aka genesis block), there's nothing to compute.
+		if vote.currentRoot == params.BeaconConfig().ZeroHash && vote.nextRoot == params.BeaconConfig().ZeroHash {
+			continue
+		}
+
+		oldBalance := uint64(0)
+		newBalance := uint64(0)
+		// If the validator index did not exist in `f.balances` or
+		// `newBalances` list above, the balance is just 0.
+		if index < len(f.balances) {
+			oldBalance = f.balances[index]
+		}
+		if index < len(newBalances) {
+			newBalance = newBalances[index]
+		}
+
+		// Update only if the validator's balance or vote has changed.
+		if vote.currentRoot != vote.nextRoot || oldBalance != newBalance {
+			// Ignore the vote if the root is not in fork choice
+			// store, that means we have not seen the block before.
+			nextNode, ok := f.store.nodeByRoot[vote.nextRoot]
+			if ok && vote.nextRoot != params.BeaconConfig().ZeroHash {
+				// Protection against nil node
+				if nextNode == nil {
+					return errNilNode
+				}
+				nextNode.balance += newBalance
+			}
+
+			currentNode, ok := f.store.nodeByRoot[vote.currentRoot]
+			if ok && vote.currentRoot != params.BeaconConfig().ZeroHash {
+				// Protection against nil node
+				if currentNode == nil {
+					return errNilNode
+				}
+				if currentNode.balance < oldBalance {
+					return errInvalidBalance
+				}
+				currentNode.balance -= oldBalance
+			}
+		}
+
+		// Rotate the validator vote.
+		f.votes[index].currentRoot = vote.nextRoot
+	}
+	f.balances = newBalances
+	return nil
+}
+
+// Tips returns a list of possible heads from fork choice store, it returns the
+// roots and the slots of the leaf nodes.
+func (f *ForkChoice) Tips() ([][32]byte, []types.Slot) {
+	return f.store.tips()
+}
+
+// ProposerBoost returns the proposerBoost of the store
+func (f *ForkChoice) ProposerBoost() [fieldparams.RootLength]byte {
+	return f.store.proposerBoost()
+}
+
+// SetOptimisticToValid sets the node with the given root as a fully validated node
+func (f *ForkChoice) SetOptimisticToValid(ctx context.Context, root [fieldparams.RootLength]byte) error {
+	f.store.nodesLock.Lock()
+	defer f.store.nodesLock.Unlock()
+	node, ok := f.store.nodeByRoot[root]
+	if !ok || node == nil {
+		return errNilNode
+	}
+	return node.setNodeAndParentValidated(ctx)
+}
+
+// JustifiedEpoch of fork choice store.
+func (f *ForkChoice) JustifiedEpoch() types.Epoch {
+	return f.store.justifiedEpoch
+}
+
+// FinalizedEpoch of fork choice store.
+func (f *ForkChoice) FinalizedEpoch() types.Epoch {
+	return f.store.finalizedEpoch
+}
+
+func (f *ForkChoice) ForkChoiceNodes() []*pbrpc.ForkChoiceNode {
+	f.store.nodesLock.RLock()
+	defer f.store.nodesLock.RUnlock()
+	ret := make([]*pbrpc.ForkChoiceNode, len(f.store.nodeByRoot))
+	return f.store.treeRootNode.rpcNodes(ret)
+}
+
+// SetOptimisticToInvalid removes a block with an invalid execution payload from fork choice store
+func (f *ForkChoice) SetOptimisticToInvalid(ctx context.Context, root [fieldparams.RootLength]byte) error {
+	return f.store.removeNode(ctx, root)
+}

beacon-chain/forkchoice/doubly-linked-tree/forkchoice_test.go

@@ -0,0 +1,168 @@
+package doublylinkedtree
+
+import (
+	"context"
+	"encoding/binary"
+	"testing"
+
+	"github.com/prysmaticlabs/prysm/config/params"
+	"github.com/prysmaticlabs/prysm/crypto/hash"
+	"github.com/prysmaticlabs/prysm/encoding/bytesutil"
+	"github.com/prysmaticlabs/prysm/testing/assert"
+	"github.com/prysmaticlabs/prysm/testing/require"
+)
+
+func TestForkChoice_UpdateBalancesPositiveChange(t *testing.T) {
+	f := setup(0, 0)
+	ctx := context.Background()
+	require.NoError(t, f.ProcessBlock(ctx, 1, indexToHash(1), params.BeaconConfig().ZeroHash, 0, 0, false))
+	require.NoError(t, f.ProcessBlock(ctx, 2, indexToHash(2), indexToHash(1), 0, 0, false))
+	require.NoError(t, f.ProcessBlock(ctx, 3, indexToHash(3), indexToHash(2), 0, 0, false))
+
+	f.votes = []Vote{
+		{indexToHash(1), indexToHash(1), 0},
+		{indexToHash(2), indexToHash(2), 0},
+		{indexToHash(3), indexToHash(3), 0},
+	}
+
+	// Each node gets one unique vote. The weight should look like 103 <- 102 <- 101 because
+	// they get propagated back.
+	require.NoError(t, f.updateBalances([]uint64{10, 20, 30}))
+	s := f.store
+	assert.Equal(t, uint64(10), s.nodeByRoot[indexToHash(1)].balance)
+	assert.Equal(t, uint64(20), s.nodeByRoot[indexToHash(2)].balance)
+	assert.Equal(t, uint64(30), s.nodeByRoot[indexToHash(3)].balance)
+}
+
+func TestForkChoice_UpdateBalancesNegativeChange(t *testing.T) {
+	f := setup(0, 0)
+	ctx := context.Background()
+	require.NoError(t, f.ProcessBlock(ctx, 1, indexToHash(1), params.BeaconConfig().ZeroHash, 0, 0, false))
+	require.NoError(t, f.ProcessBlock(ctx, 2, indexToHash(2), indexToHash(1), 0, 0, false))
+	require.NoError(t, f.ProcessBlock(ctx, 3, indexToHash(3), indexToHash(2), 0, 0, false))
+	s := f.store
+	s.nodeByRoot[indexToHash(1)].balance = 100
+	s.nodeByRoot[indexToHash(2)].balance = 100
+	s.nodeByRoot[indexToHash(3)].balance = 100
+
+	f.balances = []uint64{100, 100, 100}
+	f.votes = []Vote{
+		{indexToHash(1), indexToHash(1), 0},
+		{indexToHash(2), indexToHash(2), 0},
+		{indexToHash(3), indexToHash(3), 0},
+	}
+
+	require.NoError(t, f.updateBalances([]uint64{10, 20, 30}))
+	assert.Equal(t, uint64(10), s.nodeByRoot[indexToHash(1)].balance)
+	assert.Equal(t, uint64(20), s.nodeByRoot[indexToHash(2)].balance)
+	assert.Equal(t, uint64(30), s.nodeByRoot[indexToHash(3)].balance)
+}
+
+func TestForkChoice_IsCanonical(t *testing.T) {
+	f := setup(1, 1)
+	ctx := context.Background()
+	require.NoError(t, f.ProcessBlock(ctx, 1, indexToHash(1), params.BeaconConfig().ZeroHash, 1, 1, false))
+	require.NoError(t, f.ProcessBlock(ctx, 2, indexToHash(2), params.BeaconConfig().ZeroHash, 1, 1, false))
+	require.NoError(t, f.ProcessBlock(ctx, 3, indexToHash(3), indexToHash(1), 1, 1, false))
+	require.NoError(t, f.ProcessBlock(ctx, 4, indexToHash(4), indexToHash(2), 1, 1, false))
+	require.NoError(t, f.ProcessBlock(ctx, 5, indexToHash(5), indexToHash(4), 1, 1, false))
+	require.NoError(t, f.ProcessBlock(ctx, 6, indexToHash(6), indexToHash(5), 1, 1, false))
+
+	require.Equal(t, true, f.IsCanonical(params.BeaconConfig().ZeroHash))
+	require.Equal(t, false, f.IsCanonical(indexToHash(1)))
+	require.Equal(t, true, f.IsCanonical(indexToHash(2)))
+	require.Equal(t, false, f.IsCanonical(indexToHash(3)))
+	require.Equal(t, true, f.IsCanonical(indexToHash(4)))
+	require.Equal(t, true, f.IsCanonical(indexToHash(5)))
+	require.Equal(t, true, f.IsCanonical(indexToHash(6)))
+}
+
+func TestForkChoice_IsCanonicalReorg(t *testing.T) {
+	f := setup(1, 1)
+	ctx := context.Background()
+	require.NoError(t, f.ProcessBlock(ctx, 1, [32]byte{'1'}, params.BeaconConfig().ZeroHash, 1, 1, false))
+	require.NoError(t, f.ProcessBlock(ctx, 2, [32]byte{'2'}, params.BeaconConfig().ZeroHash, 1, 1, false))
+	require.NoError(t, f.ProcessBlock(ctx, 3, [32]byte{'3'}, [32]byte{'1'}, 1, 1, false))
+	require.NoError(t, f.ProcessBlock(ctx, 4, [32]byte{'4'}, [32]byte{'2'}, 1, 1, false))
+	require.NoError(t, f.ProcessBlock(ctx, 5, [32]byte{'5'}, [32]byte{'4'}, 1, 1, false))
+	require.NoError(t, f.ProcessBlock(ctx, 6, [32]byte{'6'}, [32]byte{'5'}, 1, 1, false))
+
+	f.store.nodesLock.Lock()
+	f.store.nodeByRoot[[32]byte{'3'}].balance = 10
+	require.NoError(t, f.store.treeRootNode.applyWeightChanges(ctx))
+	require.Equal(t, uint64(10), f.store.nodeByRoot[[32]byte{'1'}].weight)
+	require.Equal(t, uint64(0), f.store.nodeByRoot[[32]byte{'2'}].weight)
+
+	require.NoError(t, f.store.treeRootNode.updateBestDescendant(ctx, 1, 1))
+	require.DeepEqual(t, [32]byte{'3'}, f.store.treeRootNode.bestDescendant.root)
+	f.store.nodesLock.Unlock()
+
+	h, err := f.store.head(ctx, [32]byte{'1'})
+	require.NoError(t, err)
+	require.DeepEqual(t, [32]byte{'3'}, h)
+	require.DeepEqual(t, h, f.store.headNode.root)
+
+	require.Equal(t, true, f.IsCanonical(params.BeaconConfig().ZeroHash))
+	require.Equal(t, true, f.IsCanonical([32]byte{'1'}))
+	require.Equal(t, false, f.IsCanonical([32]byte{'2'}))
+	require.Equal(t, true, f.IsCanonical([32]byte{'3'}))
+	require.Equal(t, false, f.IsCanonical([32]byte{'4'}))
+	require.Equal(t, false, f.IsCanonical([32]byte{'5'}))
+	require.Equal(t, false, f.IsCanonical([32]byte{'6'}))
+}
+
+func TestForkChoice_AncestorRoot(t *testing.T) {
+	f := setup(1, 1)
+	ctx := context.Background()
+	require.NoError(t, f.ProcessBlock(ctx, 1, indexToHash(1), params.BeaconConfig().ZeroHash, 1, 1, false))
+	require.NoError(t, f.ProcessBlock(ctx, 2, indexToHash(2), indexToHash(1), 1, 1, false))
+	require.NoError(t, f.ProcessBlock(ctx, 5, indexToHash(3), indexToHash(2), 1, 1, false))
+	f.store.treeRootNode = f.store.nodeByRoot[indexToHash(1)]
+	f.store.treeRootNode.parent = nil
+
+	r, err := f.AncestorRoot(ctx, indexToHash(3), 6)
+	assert.NoError(t, err)
+	assert.Equal(t, bytesutil.ToBytes32(r), indexToHash(3))
+
+	_, err = f.AncestorRoot(ctx, indexToHash(3), 0)
+	assert.ErrorContains(t, errNilNode.Error(), err)
+
+	root, err := f.AncestorRoot(ctx, indexToHash(3), 5)
+	require.NoError(t, err)
+	hash3 := indexToHash(3)
+	require.DeepEqual(t, hash3[:], root)
+	root, err = f.AncestorRoot(ctx, indexToHash(3), 1)
+	require.NoError(t, err)
+	hash1 := indexToHash(1)
+	require.DeepEqual(t, hash1[:], root)
+}
+
+func TestForkChoice_AncestorEqualSlot(t *testing.T) {
+	f := setup(1, 1)
+	ctx := context.Background()
+	require.NoError(t, f.ProcessBlock(ctx, 100, [32]byte{'1'}, params.BeaconConfig().ZeroHash, 1, 1, false))
+	require.NoError(t, f.ProcessBlock(ctx, 101, [32]byte{'3'}, [32]byte{'1'}, 1, 1, false))
+
+	r, err := f.AncestorRoot(ctx, [32]byte{'3'}, 100)
+	require.NoError(t, err)
+	root := bytesutil.ToBytes32(r)
+	require.Equal(t, root, [32]byte{'1'})
+}
+
+func TestForkChoice_AncestorLowerSlot(t *testing.T) {
+	f := setup(1, 1)
+	ctx := context.Background()
+	require.NoError(t, f.ProcessBlock(ctx, 100, [32]byte{'1'}, params.BeaconConfig().ZeroHash, 1, 1, false))
+	require.NoError(t, f.ProcessBlock(ctx, 200, [32]byte{'3'}, [32]byte{'1'}, 1, 1, false))
+
+	r, err := f.AncestorRoot(ctx, [32]byte{'3'}, 150)
+	require.NoError(t, err)
+	root := bytesutil.ToBytes32(r)
+	require.Equal(t, root, [32]byte{'1'})
+}
+
+func indexToHash(i uint64) [32]byte {
+	var b [8]byte
+	binary.LittleEndian.PutUint64(b[:], i)
+	return hash.Hash(b[:])
+}

beacon-chain/forkchoice/doubly-linked-tree/metrics.go

@@ -0,0 +1,57 @@
+package doublylinkedtree
+
+import (
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/promauto"
+)
+
+var (
+	headSlotNumber = promauto.NewGauge(
+		prometheus.GaugeOpts{
+			Name: "doublylinkedtree_head_slot",
+			Help: "The slot number of the current head.",
+		},
+	)
+	nodeCount = promauto.NewGauge(
+		prometheus.GaugeOpts{
+			Name: "doublylinkedtree_node_count",
+			Help: "The number of nodes in the DAG array based store structure.",
+		},
+	)
+	headChangesCount = promauto.NewCounter(
+		prometheus.CounterOpts{
+			Name: "doublylinkedtree_head_changed_count",
+			Help: "The number of times head changes.",
+		},
+	)
+	calledHeadCount = promauto.NewCounter(
+		prometheus.CounterOpts{
+			Name: "doublylinkedtree_head_requested_count",
+			Help: "The number of times someone called head.",
+		},
+	)
+	processedBlockCount = promauto.NewCounter(
+		prometheus.CounterOpts{
+			Name: "doublylinkedtree_block_processed_count",
+			Help: "The number of times a block is processed for fork choice.",
+		},
+	)
+	processedAttestationCount = promauto.NewCounter(
+		prometheus.CounterOpts{
+			Name: "doublylinkedtree_attestation_processed_count",
+			Help: "The number of times an attestation is processed for fork choice.",
+		},
+	)
+	prunedCount = promauto.NewCounter(
+		prometheus.CounterOpts{
+			Name: "doublylinkedtree_pruned_count",
+			Help: "The number of times pruning happened.",
+		},
+	)
+	optimisticCount = promauto.NewCounter(
+		prometheus.CounterOpts{
+			Name: "doublylinkedtree_optimistic_count",
+			Help: "The number of blocks that have been optimistically synced.",
+		},
+	)
+)

beacon-chain/forkchoice/doubly-linked-tree/no_vote_test.go

@@ -0,0 +1,114 @@
+package doublylinkedtree
+
+import (
+	"context"
+	"testing"
+
+	"github.com/prysmaticlabs/prysm/config/params"
+	"github.com/prysmaticlabs/prysm/testing/assert"
+	"github.com/prysmaticlabs/prysm/testing/require"
+)
+
+func TestNoVote_CanFindHead(t *testing.T) {
+	balances := make([]uint64, 16)
+	f := setup(1, 1)
+
+	// The head should always start at the finalized block.
+	r, err := f.Head(context.Background(), 1, params.BeaconConfig().ZeroHash, balances, 1)
+	require.NoError(t, err)
+	if r != params.BeaconConfig().ZeroHash {
+		t.Errorf("Incorrect head with genesis")
+	}
+
+	// Insert block 2 into the tree and verify head is at 2:
+	//         0
+	//        /
+	//       2 <- head
+	require.NoError(t, f.ProcessBlock(context.Background(), 0, indexToHash(2), params.BeaconConfig().ZeroHash, 1, 1, false))
+	r, err = f.Head(context.Background(), 1, params.BeaconConfig().ZeroHash, balances, 1)
+	require.NoError(t, err)
+	assert.Equal(t, indexToHash(2), r, "Incorrect head for with justified epoch at 1")
+
+	// Insert block 1 into the tree and verify head is still at 2:
+	//            0
+	//           / \
+	//  head -> 2  1
+	require.NoError(t, f.ProcessBlock(context.Background(), 0, indexToHash(1), params.BeaconConfig().ZeroHash, 1, 1, false))
+	r, err = f.Head(context.Background(), 1, params.BeaconConfig().ZeroHash, balances, 1)
+	require.NoError(t, err)
+	assert.Equal(t, indexToHash(2), r, "Incorrect head for with justified epoch at 1")
+
+	// Insert block 3 into the tree and verify head is still at 2:
+	//            0
+	//           / \
+	//  head -> 2  1
+	//             |
+	//             3
+	require.NoError(t, f.ProcessBlock(context.Background(), 0, indexToHash(3), indexToHash(1), 1, 1, false))
+	r, err = f.Head(context.Background(), 1, params.BeaconConfig().ZeroHash, balances, 1)
+	require.NoError(t, err)
+	assert.Equal(t, indexToHash(2), r, "Incorrect head for with justified epoch at 1")
+
+	// Insert block 4 into the tree and verify head is at 4:
+	//            0
+	//           / \
+	//          2  1
+	//          |  |
+	//  head -> 4  3
+	require.NoError(t, f.ProcessBlock(context.Background(), 0, indexToHash(4), indexToHash(2), 1, 1, false))
+	r, err = f.Head(context.Background(), 1, params.BeaconConfig().ZeroHash, balances, 1)
+	require.NoError(t, err)
+	assert.Equal(t, indexToHash(4), r, "Incorrect head for with justified epoch at 1")
+
+	// Insert block 5 with justified epoch of 2, verify head is still at 4.
+	//            0
+	//           / \
+	//          2  1
+	//          |  |
+	//  head -> 4  3
+	//          |
+	//          5 <- justified epoch = 2
+	require.NoError(t, f.ProcessBlock(context.Background(), 0, indexToHash(5), indexToHash(4), 2, 1, false))
+	r, err = f.Head(context.Background(), 1, params.BeaconConfig().ZeroHash, balances, 1)
+	require.NoError(t, err)
+	assert.Equal(t, indexToHash(4), r, "Incorrect head for with justified epoch at 1")
+
+	// Verify there's an error when starting from a block with wrong justified epoch.
+	//            0
+	//           / \
+	//          2  1
+	//          |  |
+	//  head -> 4  3
+	//          |
+	//          5 <- starting from 5 with justified epoch 0 should error
+	_, err = f.Head(context.Background(), 1, indexToHash(5), balances, 1)
+	wanted := "head at slot 0 with weight 0 is not eligible, finalizedEpoch 1 != 1, justifiedEpoch 2 != 1"
+	require.ErrorContains(t, wanted, err)
+
+	// Set the justified epoch to 2 and start block to 5 to verify head is 5.
+	//            0
+	//           / \
+	//          2  1
+	//          |  |
+	//          4  3
+	//          |
+	//          5 <- head
+	r, err = f.Head(context.Background(), 2, indexToHash(5), balances, 1)
+	require.NoError(t, err)
+	assert.Equal(t, indexToHash(5), r, "Incorrect head for with justified epoch at 2")
+
+	// Insert block 6 with justified epoch of 2, verify head is at 6.
+	//            0
+	//           / \
+	//          2  1
+	//          |  |
+	//          4  3
+	//          |
+	//          5
+	//          |
+	//          6 <- head
+	require.NoError(t, f.ProcessBlock(context.Background(), 0, indexToHash(6), indexToHash(5), 2, 1, false))
+	r, err = f.Head(context.Background(), 2, indexToHash(5), balances, 1)
+	require.NoError(t, err)
+	assert.Equal(t, indexToHash(6), r, "Incorrect head for with justified epoch at 2")
+}

beacon-chain/forkchoice/doubly-linked-tree/node.go

@@ -0,0 +1,152 @@
+package doublylinkedtree
+
+import (
+	"bytes"
+	"context"
+
+	types "github.com/prysmaticlabs/eth2-types"
+	"github.com/prysmaticlabs/prysm/config/params"
+	pbrpc "github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1"
+)
+
+// depth returns the length of the path to the root of Fork Choice
+func (n *Node) depth() uint64 {
+	ret := uint64(0)
+	for node := n.parent; node != nil; node = node.parent {
+		ret += 1
+	}
+	return ret
+}
+
+// applyWeightChanges recomputes the weight of the node passed as an argument and all of its descendants,
+// using the current balance stored in each node. This function requires a lock
+// in Store.nodesLock
+func (n *Node) applyWeightChanges(ctx context.Context) error {
+	// Recursively calling the children to sum their weights.
+	childrenWeight := uint64(0)
+	for _, child := range n.children {
+		if ctx.Err() != nil {
+			return ctx.Err()
+		}
+		if err := child.applyWeightChanges(ctx); err != nil {
+			return err
+		}
+		childrenWeight += child.weight
+	}
+	if n.root == params.BeaconConfig().ZeroHash {
+		return nil
+	}
+	n.weight = n.balance + childrenWeight
+	return nil
+}
+
+// updateBestDescendant updates the best descendant of this node and its children.
+func (n *Node) updateBestDescendant(ctx context.Context, justifiedEpoch, finalizedEpoch types.Epoch) error {
+	if ctx.Err() != nil {
+		return ctx.Err()
+	}
+	if len(n.children) == 0 {
+		n.bestDescendant = nil
+		return nil
+	}
+
+	var bestChild *Node
+	bestWeight := uint64(0)
+	hasViableDescendant := false
+	for _, child := range n.children {
+		if child == nil {
+			return errNilNode
+		}
+		if err := child.updateBestDescendant(ctx, justifiedEpoch, finalizedEpoch); err != nil {
+			return err
+		}
+		childLeadsToViableHead := child.leadsToViableHead(justifiedEpoch, finalizedEpoch)
+		if childLeadsToViableHead && !hasViableDescendant {
+			// The child leads to a viable head, but the current
+			// parent's best child doesn't.
+			bestWeight = child.weight
+			bestChild = child
+			hasViableDescendant = true
+		} else if childLeadsToViableHead {
+			// If both are viable, compare their weights.
+			if child.weight == bestWeight {
+				// Tie-breaker of equal weights by root.
+				if bytes.Compare(child.root[:], bestChild.root[:]) > 0 {
+					bestChild = child
+				}
+			} else if child.weight > bestWeight {
+				bestChild = child
+				bestWeight = child.weight
+			}
+		}
+	}
+	if hasViableDescendant {
+		if bestChild.bestDescendant == nil {
+			n.bestDescendant = bestChild
+		} else {
+			n.bestDescendant = bestChild.bestDescendant
+		}
+	} else {
+		n.bestDescendant = nil
+	}
+	return nil
+}
+
+// viableForHead returns true if the node is viable to head.
+// Any node with different finalized or justified epoch than
+// the ones in fork choice store should not be viable to head.
+func (n *Node) viableForHead(justifiedEpoch, finalizedEpoch types.Epoch) bool {
+	justified := justifiedEpoch == n.justifiedEpoch || justifiedEpoch == 0
+	finalized := finalizedEpoch == n.finalizedEpoch || finalizedEpoch == 0
+
+	return justified && finalized
+}
+
+func (n *Node) leadsToViableHead(justifiedEpoch, finalizedEpoch types.Epoch) bool {
+	if n.bestDescendant == nil {
+		return n.viableForHead(justifiedEpoch, finalizedEpoch)
+	}
+	return n.bestDescendant.viableForHead(justifiedEpoch, finalizedEpoch)
+}
+
+// setNodeAndParentValidated sets the current node and the parent as validated (i.e. non-optimistic).
+func (n *Node) setNodeAndParentValidated(ctx context.Context) error {
+	if ctx.Err() != nil {
+		return ctx.Err()
+	}
+
+	if !n.optimistic || n.parent == nil {
+		return nil
+	}
+
+	n.optimistic = false
+	return n.parent.setNodeAndParentValidated(ctx)
+}
+
+// rpcNodes is used by the RPC Debug endpoint to return information
+// about all nodes in the fork choice store
+func (n *Node) rpcNodes(ret []*pbrpc.ForkChoiceNode) []*pbrpc.ForkChoiceNode {
+	for _, child := range n.children {
+		ret = child.rpcNodes(ret)
+	}
+	r := n.root
+	p := [32]byte{}
+	if n.parent != nil {
+		copy(p[:], n.parent.root[:])
+	}
+	b := [32]byte{}
+	if n.bestDescendant != nil {
+		copy(b[:], n.bestDescendant.root[:])
+	}
+	node := &pbrpc.ForkChoiceNode{
+		Slot:           n.slot,
+		Root:           r[:],
+		Parent:         p[:],
+		JustifiedEpoch: n.justifiedEpoch,
+		FinalizedEpoch: n.finalizedEpoch,
+		Weight:         n.weight,
+		BestDescendant: b[:],
+	}
+	ret = append(ret, node)
+	return ret
+}

beacon-chain/forkchoice/doubly-linked-tree/node_test.go

@@ -0,0 +1,204 @@
+package doublylinkedtree
+
+import (
+	"context"
+	"testing"
+
+	types "github.com/prysmaticlabs/eth2-types"
+	"github.com/prysmaticlabs/prysm/config/params"
+	"github.com/prysmaticlabs/prysm/testing/assert"
+	"github.com/prysmaticlabs/prysm/testing/require"
+)
+
+func TestNode_ApplyWeightChanges_PositiveChange(t *testing.T) {
+	f := setup(0, 0)
+	ctx := context.Background()
+	require.NoError(t, f.ProcessBlock(ctx, 1, indexToHash(1), params.BeaconConfig().ZeroHash, 0, 0, false))
+	require.NoError(t, f.ProcessBlock(ctx, 2, indexToHash(2), indexToHash(1), 0, 0, false))
+	require.NoError(t, f.ProcessBlock(ctx, 3, indexToHash(3), indexToHash(2), 0, 0, false))
+
+	// The updated balances of each node is 100
+	s := f.store
+
+	s.nodesLock.Lock()
+	defer s.nodesLock.Unlock()
+	s.nodeByRoot[indexToHash(1)].balance = 100
+	s.nodeByRoot[indexToHash(2)].balance = 100
+	s.nodeByRoot[indexToHash(3)].balance = 100
+
+	assert.NoError(t, s.treeRootNode.applyWeightChanges(ctx))
+
+	assert.Equal(t, uint64(300), s.nodeByRoot[indexToHash(1)].weight)
+	assert.Equal(t, uint64(200), s.nodeByRoot[indexToHash(2)].weight)
+	assert.Equal(t, uint64(100), s.nodeByRoot[indexToHash(3)].weight)
+}
+
+func TestNode_ApplyWeightChanges_NegativeChange(t *testing.T) {
+	f := setup(0, 0)
+	ctx := context.Background()
+	require.NoError(t, f.ProcessBlock(ctx, 1, indexToHash(1), params.BeaconConfig().ZeroHash, 0, 0, false))
+	require.NoError(t, f.ProcessBlock(ctx, 2, indexToHash(2), indexToHash(1), 0, 0, false))
+	require.NoError(t, f.ProcessBlock(ctx, 3, indexToHash(3), indexToHash(2), 0, 0, false))
+
+	// The updated balances of each node is 100
+	s := f.store
+	s.nodesLock.Lock()
+	defer s.nodesLock.Unlock()
+	s.nodeByRoot[indexToHash(1)].weight = 400
+	s.nodeByRoot[indexToHash(2)].weight = 400
+	s.nodeByRoot[indexToHash(3)].weight = 400
+
+	s.nodeByRoot[indexToHash(1)].balance = 100
+	s.nodeByRoot[indexToHash(2)].balance = 100
+	s.nodeByRoot[indexToHash(3)].balance = 100
+
+	assert.NoError(t, s.treeRootNode.applyWeightChanges(ctx))
+
+	assert.Equal(t, uint64(300), s.nodeByRoot[indexToHash(1)].weight)
+	assert.Equal(t, uint64(200), s.nodeByRoot[indexToHash(2)].weight)
+	assert.Equal(t, uint64(100), s.nodeByRoot[indexToHash(3)].weight)
+}
+
+func TestNode_UpdateBestDescendant_NonViableChild(t *testing.T) {
+	f := setup(1, 1)
+	ctx := context.Background()
+	// Input child is not viable.
+	require.NoError(t, f.ProcessBlock(ctx, 1, indexToHash(1), params.BeaconConfig().ZeroHash, 2, 3, false))
+
+	// Verify parent's best child and best descendant are `none`.
+	s := f.store
+	assert.Equal(t, 1, len(s.treeRootNode.children))
+	nilBestDescendant := s.treeRootNode.bestDescendant == nil
+	assert.Equal(t, true, nilBestDescendant)
+}
+
+func TestNode_UpdateBestDescendant_ViableChild(t *testing.T) {
+	f := setup(1, 1)
+	ctx := context.Background()
+	// Input child is best descendant
+	require.NoError(t, f.ProcessBlock(ctx, 1, indexToHash(1), params.BeaconConfig().ZeroHash, 1, 1, false))
+
+	s := f.store
+	assert.Equal(t, 1, len(s.treeRootNode.children))
+	assert.Equal(t, s.treeRootNode.children[0], s.treeRootNode.bestDescendant)
+}
+
+func TestNode_UpdateBestDescendant_HigherWeightChild(t *testing.T) {
+	f := setup(1, 1)
+	ctx := context.Background()
+	// Input child is best descendant
+	require.NoError(t, f.ProcessBlock(ctx, 1, indexToHash(1), params.BeaconConfig().ZeroHash, 1, 1, false))
+	require.NoError(t, f.ProcessBlock(ctx, 2, indexToHash(2), params.BeaconConfig().ZeroHash, 1, 1, false))
+
+	s := f.store
+	s.nodeByRoot[indexToHash(1)].weight = 100
+	s.nodeByRoot[indexToHash(2)].weight = 200
+	assert.NoError(t, s.treeRootNode.updateBestDescendant(ctx, 1, 1))
+
+	assert.Equal(t, 2, len(s.treeRootNode.children))
+	assert.Equal(t, s.treeRootNode.children[1], s.treeRootNode.bestDescendant)
+}
+
+func TestNode_UpdateBestDescendant_LowerWeightChild(t *testing.T) {
+	f := setup(1, 1)
+	ctx := context.Background()
+	// Input child is best descendant
+	require.NoError(t, f.ProcessBlock(ctx, 1, indexToHash(1), params.BeaconConfig().ZeroHash, 1, 1, false))
+	require.NoError(t, f.ProcessBlock(ctx, 2, indexToHash(2), params.BeaconConfig().ZeroHash, 1, 1, false))
+
+	s := f.store
+	s.nodeByRoot[indexToHash(1)].weight = 200
+	s.nodeByRoot[indexToHash(2)].weight = 100
+	assert.NoError(t, s.treeRootNode.updateBestDescendant(ctx, 1, 1))
+
+	assert.Equal(t, 2, len(s.treeRootNode.children))
+	assert.Equal(t, s.treeRootNode.children[0], s.treeRootNode.bestDescendant)
+}
+
+func TestNode_TestDepth(t *testing.T) {
+	f := setup(1, 1)
+	ctx := context.Background()
+	// Input child is best descendant
+	require.NoError(t, f.ProcessBlock(ctx, 1, indexToHash(1), params.BeaconConfig().ZeroHash, 1, 1, false))
+	require.NoError(t, f.ProcessBlock(ctx, 2, indexToHash(2), indexToHash(1), 1, 1, false))
+	require.NoError(t, f.ProcessBlock(ctx, 3, indexToHash(3), params.BeaconConfig().ZeroHash, 1, 1, false))
+
+	s := f.store
+	require.Equal(t, s.nodeByRoot[indexToHash(2)].depth(), uint64(2))
+	require.Equal(t, s.nodeByRoot[indexToHash(3)].depth(), uint64(1))
+}
+
+func TestNode_ViableForHead(t *testing.T) {
+	tests := []struct {
+		n              *Node
+		justifiedEpoch types.Epoch
+		finalizedEpoch types.Epoch
+		want           bool
+	}{
+		{&Node{}, 0, 0, true},
+		{&Node{}, 1, 0, false},
+		{&Node{}, 0, 1, false},
+		{&Node{finalizedEpoch: 1, justifiedEpoch: 1}, 1, 1, true},
+		{&Node{finalizedEpoch: 1, justifiedEpoch: 1}, 2, 2, false},
+		{&Node{finalizedEpoch: 3, justifiedEpoch: 4}, 4, 3, true},
+	}
+	for _, tc := range tests {
+		got := tc.n.viableForHead(tc.justifiedEpoch, tc.finalizedEpoch)
+		assert.Equal(t, tc.want, got)
+	}
+}
+
+func TestNode_LeadsToViableHead(t *testing.T) {
+	f := setup(4, 3)
+	ctx := context.Background()
+	require.NoError(t, f.ProcessBlock(ctx, 1, indexToHash(1), params.BeaconConfig().ZeroHash, 1, 1, false))
+	require.NoError(t, f.ProcessBlock(ctx, 2, indexToHash(2), params.BeaconConfig().ZeroHash, 1, 1, false))
+	require.NoError(t, f.ProcessBlock(ctx, 3, indexToHash(3), indexToHash(1), 1, 1, false))
+	require.NoError(t, f.ProcessBlock(ctx, 4, indexToHash(4), indexToHash(2), 1, 1, false))
+	require.NoError(t, f.ProcessBlock(ctx, 5, indexToHash(5), indexToHash(3), 4, 3, false))
+
+	require.Equal(t, true, f.store.treeRootNode.leadsToViableHead(4, 3))
+	require.Equal(t, true, f.store.nodeByRoot[indexToHash(5)].leadsToViableHead(4, 3))
+	require.Equal(t, false, f.store.nodeByRoot[indexToHash(2)].leadsToViableHead(4, 3))
+	require.Equal(t, false, f.store.nodeByRoot[indexToHash(4)].leadsToViableHead(4, 3))
+}
+
+func TestNode_SetFullyValidated(t *testing.T) {
+	f := setup(1, 1)
+	ctx := context.Background()
+	// insert blocks in the fork pattern (optimistic status in parenthesis)
+	//
+	// 0 (false) -- 1 (false) -- 2 (false) -- 3 (true) -- 4 (true)
+	//               \
+	//                 -- 5 (true)
+	//
+	require.NoError(t, f.ProcessBlock(ctx, 1, indexToHash(1), params.BeaconConfig().ZeroHash, 1, 1, false))
+	require.NoError(t, f.ProcessBlock(ctx, 2, indexToHash(2), indexToHash(1), 1, 1, false))
+	require.NoError(t, f.ProcessBlock(ctx, 3, indexToHash(3), indexToHash(2), 1, 1, true))
+	require.NoError(t, f.ProcessBlock(ctx, 4, indexToHash(4), indexToHash(3), 1, 1, true))
+	require.NoError(t, f.ProcessBlock(ctx, 5, indexToHash(5), indexToHash(1), 1, 1, true))
+
+	opt, err := f.IsOptimistic(ctx, indexToHash(5))
+	require.NoError(t, err)
+	require.Equal(t, true, opt)
+
+	opt, err = f.IsOptimistic(ctx, indexToHash(4))
+	require.NoError(t, err)
+	require.Equal(t, true, opt)
+
+	require.NoError(t, f.store.nodeByRoot[indexToHash(4)].setNodeAndParentValidated(ctx))
+
+	// block 5 should still be optimistic
+	opt, err = f.IsOptimistic(ctx, indexToHash(5))
+	require.NoError(t, err)
+	require.Equal(t, true, opt)
+
+	// block 4 and 3 should now be valid
+	opt, err = f.IsOptimistic(ctx, indexToHash(4))
+	require.NoError(t, err)
+	require.Equal(t, false, opt)
+
+	opt, err = f.IsOptimistic(ctx, indexToHash(3))
+	require.NoError(t, err)
+	require.Equal(t, false, opt)
+}

beacon-chain/forkchoice/doubly-linked-tree/optimistic_sync.go

@@ -0,0 +1,50 @@
+package doublylinkedtree
+
+import (
+	"context"
+)
+
+// removeNode removes the node with the given root and all of its children
+// from the Fork Choice Store.
+func (s *Store) removeNode(ctx context.Context, root [32]byte) error {
+	s.nodesLock.Lock()
+	defer s.nodesLock.Unlock()
+
+	node, ok := s.nodeByRoot[root]
+	if !ok || node == nil {
+		return errNilNode
+	}
+	if !node.optimistic || node.parent == nil {
+		return errInvalidOptimisticStatus
+	}
+	children := node.parent.children
+	if len(children) == 1 {
+		node.parent.children = []*Node{}
+	} else {
+		for i, n := range children {
+			if n == node {
+				if i != len(children)-1 {
+					children[i] = children[len(children)-1]
+				}
+				node.parent.children = children[:len(children)-2]
+				break
+			}
+		}
+	}
+	return s.removeNodeAndChildren(ctx, node)
+}
+
+// removeNodeAndChildren removes `node` and all of its descendant from the Store
+func (s *Store) removeNodeAndChildren(ctx context.Context, node *Node) error {
+	for _, child := range node.children {
+		if ctx.Err() != nil {
+			return ctx.Err()
+		}
+		if err := s.removeNodeAndChildren(ctx, child); err != nil {
+			return err
+		}
+	}
+
+	delete(s.nodeByRoot, node.root)
+	return nil
+}

beacon-chain/forkchoice/doubly-linked-tree/optimistic_sync_test.go

@@ -0,0 +1,70 @@
+package doublylinkedtree
+
+import (
+	"context"
+	"testing"
+
+	"github.com/prysmaticlabs/prysm/config/params"
+	"github.com/prysmaticlabs/prysm/testing/require"
+)
+
+// We test the algorithm to update a node from SYNCING to INVALID
+// We start with the same diagram as above:
+//
+//                E -- F
+//               /
+//         C -- D
+//        /      \
+//  A -- B        G -- H -- I
+//        \        \
+//         J        -- K -- L
+//
+// And every block in the Fork choice is optimistic.
+//
+func TestPruneInvalid(t *testing.T) {
+	tests := []struct {
+		root             [32]byte // the root of the new INVALID block
+		wantedNodeNumber int
+	}{
+		{
+			[32]byte{'j'},
+			12,
+		},
+		{
+			[32]byte{'c'},
+			4,
+		},
+		{
+			[32]byte{'i'},
+			12,
+		},
+		{
+			[32]byte{'h'},
+			11,
+		},
+		{
+			[32]byte{'g'},
+			8,
+		},
+	}
+	for _, tc := range tests {
+		ctx := context.Background()
+		f := setup(1, 1)
+
+		require.NoError(t, f.ProcessBlock(ctx, 100, [32]byte{'a'}, params.BeaconConfig().ZeroHash, 1, 1, true))
+		require.NoError(t, f.ProcessBlock(ctx, 101, [32]byte{'b'}, [32]byte{'a'}, 1, 1, true))
+		require.NoError(t, f.ProcessBlock(ctx, 102, [32]byte{'c'}, [32]byte{'b'}, 1, 1, true))
+		require.NoError(t, f.ProcessBlock(ctx, 102, [32]byte{'j'}, [32]byte{'b'}, 1, 1, true))
+		require.NoError(t, f.ProcessBlock(ctx, 103, [32]byte{'d'}, [32]byte{'c'}, 1, 1, true))
+		require.NoError(t, f.ProcessBlock(ctx, 104, [32]byte{'e'}, [32]byte{'d'}, 1, 1, true))
+		require.NoError(t, f.ProcessBlock(ctx, 104, [32]byte{'g'}, [32]byte{'d'}, 1, 1, true))
+		require.NoError(t, f.ProcessBlock(ctx, 105, [32]byte{'f'}, [32]byte{'e'}, 1, 1, true))
+		require.NoError(t, f.ProcessBlock(ctx, 105, [32]byte{'h'}, [32]byte{'g'}, 1, 1, true))
+		require.NoError(t, f.ProcessBlock(ctx, 105, [32]byte{'k'}, [32]byte{'g'}, 1, 1, true))
+		require.NoError(t, f.ProcessBlock(ctx, 106, [32]byte{'i'}, [32]byte{'h'}, 1, 1, true))
+		require.NoError(t, f.ProcessBlock(ctx, 106, [32]byte{'l'}, [32]byte{'k'}, 1, 1, true))
+
+		require.NoError(t, f.store.removeNode(context.Background(), tc.root))
+		require.Equal(t, tc.wantedNodeNumber, f.NodeCount())
+	}
+}

beacon-chain/forkchoice/doubly-linked-tree/proposer_boost.go

@@ -0,0 +1,73 @@
+package doublylinkedtree
+
+import (
+	"context"
+	"time"
+
+	"github.com/pkg/errors"
+	types "github.com/prysmaticlabs/eth2-types"
+	"github.com/prysmaticlabs/prysm/config/params"
+	"github.com/prysmaticlabs/prysm/time/slots"
+)
+
+// BoostProposerRoot sets the block root which should be boosted during
+// the LMD fork choice algorithm calculations. This is meant to reward timely,
+// proposed blocks which occur before a cutoff interval set to
+// SECONDS_PER_SLOT // INTERVALS_PER_SLOT.
+//
+//  time_into_slot = (store.time - store.genesis_time) % SECONDS_PER_SLOT
+//  is_before_attesting_interval = time_into_slot < SECONDS_PER_SLOT // INTERVALS_PER_SLOT
+//  if get_current_slot(store) == block.slot and is_before_attesting_interval:
+//      store.proposer_boost_root = hash_tree_root(block)
+func (f *ForkChoice) BoostProposerRoot(_ context.Context, blockSlot types.Slot, blockRoot [32]byte, genesisTime time.Time) error {
+	secondsPerSlot := params.BeaconConfig().SecondsPerSlot
+	timeIntoSlot := uint64(time.Since(genesisTime).Seconds()) % secondsPerSlot
+	isBeforeAttestingInterval := timeIntoSlot < secondsPerSlot/params.BeaconConfig().IntervalsPerSlot
+	currentSlot := slots.SinceGenesis(genesisTime)
+
+	// Only update the boosted proposer root to the incoming block root
+	// if the block is for the current, clock-based slot and the block was timely.
+	if currentSlot == blockSlot && isBeforeAttestingInterval {
+		f.store.proposerBoostLock.Lock()
+		f.store.proposerBoostRoot = blockRoot
+		f.store.proposerBoostLock.Unlock()
+	}
+	return nil
+}
+
+// ResetBoostedProposerRoot sets the value of the proposer boosted root to zeros.
+func (f *ForkChoice) ResetBoostedProposerRoot(_ context.Context) error {
+	f.store.proposerBoostLock.Lock()
+	f.store.proposerBoostRoot = [32]byte{}
+	f.store.proposerBoostLock.Unlock()
+	return nil
+}
+
+// Given a list of validator balances, we compute the proposer boost score
+// that should be given to a proposer based on their committee weight, derived from
+// the total active balances, the size of a committee, and a boost score constant.
+// IMPORTANT: The caller MUST pass in a list of validator balances where balances > 0 refer to active
+// validators while balances == 0 are for inactive validators.
+func computeProposerBoostScore(validatorBalances []uint64) (score uint64, err error) {
+	totalActiveBalance := uint64(0)
+	numActive := uint64(0)
+	for _, balance := range validatorBalances {
+		// We only consider balances > 0. The input slice should be constructed
+		// as balance > 0 for all active validators and 0 for inactive ones.
+		if balance == 0 {
+			continue
+		}
+		totalActiveBalance += balance
+		numActive += 1
+	}
+	if numActive == 0 {
+		// Should never happen.
+		err = errors.New("no active validators")
+		return
+	}
+	avgBalance := totalActiveBalance / numActive
+	committeeSize := numActive / uint64(params.BeaconConfig().SlotsPerEpoch)
+	committeeWeight := committeeSize * avgBalance
+	score = (committeeWeight * params.BeaconConfig().ProposerScoreBoost) / 100
+	return
+}

beacon-chain/forkchoice/doubly-linked-tree/proposer_boost_test.go

@@ -0,0 +1,491 @@
+package doublylinkedtree
+
+import (
+	"context"
+	"fmt"
+	"testing"
+	"time"
+
+	types "github.com/prysmaticlabs/eth2-types"
+	"github.com/prysmaticlabs/prysm/config/params"
+	"github.com/prysmaticlabs/prysm/testing/assert"
+	"github.com/prysmaticlabs/prysm/testing/require"
+)
+
+// Simple, ex-ante attack mitigation using proposer boost.
+// In a nutshell, an adversarial block proposer in slot n+1 keeps its proposal hidden.
+// The honest block proposer in slot n+2 will then propose an honest block. The
+// adversary can now use its committee members’ votes from both slots n+1 and n+2.
+// and release their withheld block of slot n+2 in an attempt to win fork choice.
+// If the honest proposal is boosted at slot n+2, it will win against this attacker.
+func TestForkChoice_BoostProposerRoot_PreventsExAnteAttack(t *testing.T) {
+	ctx := context.Background()
+	zeroHash := params.BeaconConfig().ZeroHash
+	balances := make([]uint64, 64) // 64 active validators.
+	for i := 0; i < len(balances); i++ {
+		balances[i] = 10
+	}
+	jEpoch, fEpoch := types.Epoch(0), types.Epoch(0)
+	t.Run("back-propagates boost score to ancestors after proposer boosting", func(t *testing.T) {
+		f := setup(jEpoch, fEpoch)
+
+		// The head should always start at the finalized block.
+		headRoot, err := f.Head(ctx, jEpoch, zeroHash, balances, fEpoch)
+		require.NoError(t, err)
+		assert.Equal(t, zeroHash, headRoot, "Incorrect head with genesis")
+
+		// Insert block at slot 1 into the tree and verify head is at that block:
+		//         0
+		//         |
+		//         1 <- HEAD
+		slot := types.Slot(1)
+		newRoot := indexToHash(1)
+		require.NoError(t,
+			f.ProcessBlock(
+				ctx,
+				slot,
+				newRoot,
+				headRoot,
+				jEpoch,
+				fEpoch,
+				true,
+			),
+		)
+		f.ProcessAttestation(ctx, []uint64{0}, newRoot, fEpoch)
+		headRoot, err = f.Head(ctx, jEpoch, zeroHash, balances, fEpoch)
+		require.NoError(t, err)
+		assert.Equal(t, newRoot, headRoot, "Incorrect head for justified epoch at slot 1")
+
+		// Insert block at slot 2 into the tree and verify head is at that block:
+		//         0
+		//         |
+		//         1
+		//         |
+		//         2 <- HEAD
+		slot = types.Slot(2)
+		newRoot = indexToHash(2)
+		require.NoError(t,
+			f.ProcessBlock(
+				ctx,
+				slot,
+				newRoot,
+				headRoot,
+				jEpoch,
+				fEpoch,
+				true,
+			),
+		)
+		f.ProcessAttestation(ctx, []uint64{1}, newRoot, fEpoch)
+		headRoot, err = f.Head(ctx, jEpoch, zeroHash, balances, fEpoch)
+		require.NoError(t, err)
+		assert.Equal(t, newRoot, headRoot, "Incorrect head for justified epoch at slot 2")
+
+		// Insert block at slot 3 into the tree and verify head is at that block:
+		//         0
+		//         |
+		//         1
+		//         |
+		//         2
+		//         |
+		//         3 <- HEAD
+		slot = types.Slot(3)
+		newRoot = indexToHash(3)
+		require.NoError(t,
+			f.ProcessBlock(
+				ctx,
+				slot,
+				newRoot,
+				headRoot,
+				jEpoch,
+				fEpoch,
+				true,
+			),
+		)
+		f.ProcessAttestation(ctx, []uint64{2}, newRoot, fEpoch)
+		headRoot, err = f.Head(ctx, jEpoch, zeroHash, balances, fEpoch)
+		require.NoError(t, err)
+		assert.Equal(t, newRoot, headRoot, "Incorrect head for justified epoch at slot 3")
+
+		// Insert a second block at slot 3 into the tree and boost its score.
+		//         0
+		//         |
+		//         1
+		//         |
+		//         2
+		//        / \
+		//       3   4 <- HEAD
+		slot = types.Slot(3)
+		newRoot = indexToHash(4)
+		require.NoError(t,
+			f.ProcessBlock(
+				ctx,
+				slot,
+				newRoot,
+				headRoot,
+				jEpoch,
+				fEpoch,
+				true,
+			),
+		)
+		f.ProcessAttestation(ctx, []uint64{3}, newRoot, fEpoch)
+		threeSlots := 3 * params.BeaconConfig().SecondsPerSlot
+		genesisTime := time.Now().Add(-time.Second * time.Duration(threeSlots))
+		require.NoError(t, f.BoostProposerRoot(ctx, slot, newRoot, genesisTime))
+		headRoot, err = f.Head(ctx, jEpoch, zeroHash, balances, fEpoch)
+		require.NoError(t, err)
+		assert.Equal(t, newRoot, headRoot, "Incorrect head for justified epoch at slot 3")
+
+		// Check the ancestor scores from the store.
+		require.Equal(t, 5, len(f.store.nodeByRoot))
+
+		// Expect nodes to have a boosted, back-propagated score.
+		// Ancestors have the added weights of their children. Genesis is a special exception at 0 weight,
+		require.Equal(t, f.store.treeRootNode.weight, uint64(0))
+
+		// Otherwise, assuming a block, A, that is not-genesis:
+		//
+		// A -> B -> C
+		//
+		//Where each one has a weight of 10 individually, the final weights will look like
+		//
+		// (A: 30) -> (B: 20) -> (C: 10)
+		//
+		// The boost adds 14 to the weight, so if C is boosted, we would have
+		//
+		// (A: 44) -> (B: 34) -> (C: 24)
+		//
+		// In this case, we have a small fork:
+		//
+		// (A: 54) -> (B: 44) -> (C: 34)
+		//                   \_->(D: 24)
+		//
+		// So B has its own weight, 10, and the sum of both C and D. That's why we see weight 54 in the
+		// middle instead of the normal progression of (44 -> 34 -> 24).
+		node1 := f.store.nodeByRoot[indexToHash(1)]
+		require.Equal(t, node1.weight, uint64(54))
+		node2 := f.store.nodeByRoot[indexToHash(2)]
+		require.Equal(t, node2.weight, uint64(44))
+		node3 := f.store.nodeByRoot[indexToHash(4)]
+		require.Equal(t, node3.weight, uint64(24))
+	})
+	t.Run("vanilla ex ante attack", func(t *testing.T) {
+		f := setup(jEpoch, fEpoch)
+
+		// The head should always start at the finalized block.
+		r, err := f.Head(ctx, jEpoch, zeroHash, balances, fEpoch)
+		require.NoError(t, err)
+		assert.Equal(t, zeroHash, r, "Incorrect head with genesis")
+
+		// Proposer from slot 1 does not reveal their block, B, at slot 1.
+		// Proposer at slot 2 does reveal their block, C, and it becomes the head.
+		// C builds on A, as proposer at slot 1 did not reveal B.
+		//         A
+		//        / \
+		//      (B?) \
+		//            \
+		//             C <- Slot 2 HEAD
+		honestBlockSlot := types.Slot(2)
+		honestBlock := indexToHash(2)
+		require.NoError(t,
+			f.ProcessBlock(
+				ctx,
+				honestBlockSlot,
+				honestBlock,
+				zeroHash,
+				jEpoch,
+				fEpoch,
+				true,
+			),
+		)
+		r, err = f.Head(ctx, jEpoch, zeroHash, balances, fEpoch)
+		require.NoError(t, err)
+		assert.Equal(t, honestBlock, r, "Incorrect head for justified epoch at slot 2")
+
+		maliciouslyWithheldBlockSlot := types.Slot(1)
+		maliciouslyWithheldBlock := indexToHash(1)
+		require.NoError(t,
+			f.ProcessBlock(
+				ctx,
+				maliciouslyWithheldBlockSlot,
+				maliciouslyWithheldBlock,
+				zeroHash,
+				jEpoch,
+				fEpoch,
+				true,
+			),
+		)
+
+		// Ensure the head is C, the honest block.
+		r, err = f.Head(ctx, jEpoch, zeroHash, balances, fEpoch)
+		require.NoError(t, err)
+		assert.Equal(t, honestBlock, r, "Incorrect head for justified epoch at slot 2")
+
+		// We boost the honest proposal at slot 2.
+		secondsPerSlot := time.Second * time.Duration(params.BeaconConfig().SecondsPerSlot)
+		genesis := time.Now().Add(-2 * secondsPerSlot)
+		require.NoError(t, f.BoostProposerRoot(ctx, honestBlockSlot, honestBlock, genesis))
+
+		// The maliciously withheld block has one vote.
+		votes := []uint64{1}
+		f.ProcessAttestation(ctx, votes, maliciouslyWithheldBlock, fEpoch)
+
+		// Ensure the head is STILL C, the honest block, as the honest block had proposer boost.
+		r, err = f.Head(ctx, jEpoch, zeroHash, balances, fEpoch)
+		require.NoError(t, err)
+		assert.Equal(t, honestBlock, r, "Incorrect head for justified epoch at slot 2")
+	})
+	t.Run("adversarial attestations > proposer boosting", func(t *testing.T) {
+		f := setup(jEpoch, fEpoch)
+
+		// The head should always start at the finalized block.
+		r, err := f.Head(ctx, jEpoch, zeroHash, balances, fEpoch)
+		require.NoError(t, err)
+		assert.Equal(t, zeroHash, r, "Incorrect head with genesis")
+
+		// Proposer from slot 1 does not reveal their block, B, at slot 1.
+		// Proposer at slot 2 does reveal their block, C, and it becomes the head.
+		// C builds on A, as proposer at slot 1 did not reveal B.
+		//         A
+		//        / \
+		//	    (B?) \
+		//            \
+		//             C <- Slot 2 HEAD
+		honestBlockSlot := types.Slot(2)
+		honestBlock := indexToHash(2)
+		require.NoError(t,
+			f.ProcessBlock(
+				ctx,
+				honestBlockSlot,
+				honestBlock,
+				zeroHash,
+				jEpoch,
+				fEpoch,
+				true,
+			),
+		)
+
+		// Ensure C is the head.
+		r, err = f.Head(ctx, jEpoch, zeroHash, balances, fEpoch)
+		require.NoError(t, err)
+		assert.Equal(t, honestBlock, r, "Incorrect head for justified epoch at slot 2")
+
+		maliciouslyWithheldBlockSlot := types.Slot(1)
+		maliciouslyWithheldBlock := indexToHash(1)
+		require.NoError(t,
+			f.ProcessBlock(
+				ctx,
+				maliciouslyWithheldBlockSlot,
+				maliciouslyWithheldBlock,
+				zeroHash,
+				jEpoch,
+				fEpoch,
+				true,
+			),
+		)
+
+		// Ensure C is still the head after the malicious proposer reveals their block.
+		r, err = f.Head(ctx, jEpoch, zeroHash, balances, fEpoch)
+		require.NoError(t, err)
+		assert.Equal(t, honestBlock, r, "Incorrect head for justified epoch at slot 2")
+
+		// We boost the honest proposal at slot 2.
+		secondsPerSlot := time.Second * time.Duration(params.BeaconConfig().SecondsPerSlot)
+		genesis := time.Now().Add(-2 * secondsPerSlot)
+		require.NoError(t, f.BoostProposerRoot(ctx, honestBlockSlot, honestBlock, genesis))
+
+		// An attestation is received for B that has more voting power than C with the proposer boost,
+		// allowing B to then become the head if their attestation has enough adversarial votes.
+		votes := []uint64{1, 2}
+		f.ProcessAttestation(ctx, votes, maliciouslyWithheldBlock, fEpoch)
+
+		// Expect the head to have switched to B.
+		r, err = f.Head(ctx, jEpoch, zeroHash, balances, fEpoch)
+		require.NoError(t, err)
+		assert.Equal(t, maliciouslyWithheldBlock, r, "Expected B to become the head")
+	})
+	t.Run("boosting necessary to sandwich attack", func(t *testing.T) {
+		// Boosting necessary to sandwich attack.
+		// Objects:
+		//	Block A - slot N
+		//	Block B (parent A) - slot N+1
+		//	Block C (parent A) - slot N+2
+		//	Block D (parent B) - slot N+3
+		//	Attestation_1 (Block C); size 1 - slot N+2 (honest)
+		// Steps:
+		//	Block A received at N — A is head
+		//	Block C received at N+2 — C is head
+		//	Block B received at N+2 — C is head
+		//	Attestation_1 received at N+3 — C is head
+		//	Block D received at N+3 — D is head
+		f := setup(jEpoch, fEpoch)
+		a := zeroHash
+
+		// The head should always start at the finalized block.
+		r, err := f.Head(ctx, jEpoch, zeroHash, balances, fEpoch)
+		require.NoError(t, err)
+		assert.Equal(t, zeroHash, r, "Incorrect head with genesis")
+
+		cSlot := types.Slot(2)
+		c := indexToHash(2)
+		require.NoError(t,
+			f.ProcessBlock(
+				ctx,
+				cSlot,
+				c,
+				a, // parent
+				jEpoch,
+				fEpoch,
+				true,
+			),
+		)
+
+		// Ensure C is the head.
+		r, err = f.Head(ctx, jEpoch, zeroHash, balances, fEpoch)
+		require.NoError(t, err)
+		assert.Equal(t, c, r, "Incorrect head for justified epoch at slot 2")
+
+		// We boost C.
+		secondsPerSlot := time.Second * time.Duration(params.BeaconConfig().SecondsPerSlot)
+		genesis := time.Now().Add(-2 * secondsPerSlot)
+		require.NoError(t, f.BoostProposerRoot(ctx, cSlot /* slot */, c, genesis))
+
+		bSlot := types.Slot(1)
+		b := indexToHash(1)
+		require.NoError(t,
+			f.ProcessBlock(
+				ctx,
+				bSlot,
+				b,
+				a, // parent
+				jEpoch,
+				fEpoch,
+				true,
+			),
+		)
+
+		// Ensure C is still the head.
+		r, err = f.Head(ctx, jEpoch, zeroHash, balances, fEpoch)
+		require.NoError(t, err)
+		assert.Equal(t, c, r, "Incorrect head for justified epoch at slot 2")
+
+		// An attestation for C is received at slot N+3.
+		votes := []uint64{1}
+		f.ProcessAttestation(ctx, votes, c, fEpoch)
+
+		// A block D, building on B, is received at slot N+3. It should not be able to win without boosting.
+		dSlot := types.Slot(3)
+		d := indexToHash(3)
+		require.NoError(t,
+			f.ProcessBlock(
+				ctx,
+				dSlot,
+				d,
+				b, // parent
+				jEpoch,
+				fEpoch,
+				true,
+			),
+		)
+
+		// D cannot win without a boost.
+		r, err = f.Head(ctx, jEpoch, zeroHash, balances, fEpoch)
+		require.NoError(t, err)
+		assert.Equal(t, c, r, "Expected C to remain the head")
+
+		// Block D receives the boost.
+		genesis = time.Now().Add(-3 * secondsPerSlot)
+		require.NoError(t, f.BoostProposerRoot(ctx, dSlot /* slot */, d, genesis))
+
+		// Ensure D becomes the head thanks to boosting.
+		r, err = f.Head(ctx, jEpoch, zeroHash, balances, fEpoch)
+		require.NoError(t, err)
+		assert.Equal(t, d, r, "Expected D to become the head")
+	})
+}
+
+func TestForkChoice_BoostProposerRoot(t *testing.T) {
+	params.SetupTestConfigCleanup(t)
+	cfg := params.BeaconConfig()
+	cfg.SecondsPerSlot = 6
+	cfg.IntervalsPerSlot = 3
+	params.OverrideBeaconConfig(cfg)
+	ctx := context.Background()
+
+	t.Run("does not boost block from different slot", func(t *testing.T) {
+		f := &ForkChoice{
+			store: &Store{},
+		}
+		// Genesis set to 1 slot ago.
+		genesis := time.Now().Add(-time.Duration(cfg.SecondsPerSlot) * time.Second)
+		blockRoot := [32]byte{'A'}
+
+		// Trying to boost a block from slot 0 should not work.
+		err := f.BoostProposerRoot(ctx, types.Slot(0), blockRoot, genesis)
+		require.NoError(t, err)
+		require.DeepEqual(t, [32]byte{}, f.store.proposerBoostRoot)
+	})
+	t.Run("does not boost untimely block from same slot", func(t *testing.T) {
+		f := &ForkChoice{
+			store: &Store{},
+		}
+		// Genesis set to 1 slot ago + X where X > attesting interval.
+		genesis := time.Now().Add(-time.Duration(cfg.SecondsPerSlot) * time.Second)
+		attestingInterval := time.Duration(cfg.SecondsPerSlot / cfg.IntervalsPerSlot)
+		greaterThanAttestingInterval := attestingInterval + 100*time.Millisecond
+		genesis = genesis.Add(-greaterThanAttestingInterval * time.Second)
+		blockRoot := [32]byte{'A'}
+
+		// Trying to boost a block from slot 1 that is untimely should not work.
+		err := f.BoostProposerRoot(ctx, types.Slot(1), blockRoot, genesis)
+		require.NoError(t, err)
+		require.DeepEqual(t, [32]byte{}, f.store.proposerBoostRoot)
+	})
+	t.Run("boosts perfectly timely block from same slot", func(t *testing.T) {
+		f := &ForkChoice{
+			store: &Store{},
+		}
+		// Genesis set to 1 slot ago + 0 seconds into the attesting interval.
+		genesis := time.Now().Add(-time.Duration(cfg.SecondsPerSlot) * time.Second)
+		fmt.Println(genesis)
+		blockRoot := [32]byte{'A'}
+
+		err := f.BoostProposerRoot(ctx, types.Slot(1), blockRoot, genesis)
+		require.NoError(t, err)
+		require.DeepEqual(t, [32]byte{'A'}, f.store.proposerBoostRoot)
+	})
+	t.Run("boosts timely block from same slot", func(t *testing.T) {
+		f := &ForkChoice{
+			store: &Store{},
+		}
+		// Genesis set to 1 slot ago + (attesting interval / 2).
+		genesis := time.Now().Add(-time.Duration(cfg.SecondsPerSlot) * time.Second)
+		blockRoot := [32]byte{'A'}
+		halfAttestingInterval := time.Second
+		genesis = genesis.Add(-halfAttestingInterval)
+
+		err := f.BoostProposerRoot(ctx, types.Slot(1), blockRoot, genesis)
+		require.NoError(t, err)
+		require.DeepEqual(t, [32]byte{'A'}, f.store.proposerBoostRoot)
+	})
+}
+
+func TestForkChoice_computeProposerBoostScore(t *testing.T) {
+	t.Run("nil justified balances throws error", func(t *testing.T) {
+		_, err := computeProposerBoostScore(nil)
+		require.ErrorContains(t, "no active validators", err)
+	})
+	t.Run("normal active balances computes score", func(t *testing.T) {
+		validatorBalances := make([]uint64, 64) // Num validators
+		for i := 0; i < len(validatorBalances); i++ {
+			validatorBalances[i] = 10
+		}
+		// Avg balance is 10, and the number of validators is 64.
+		// With a committee size of num validators (64) / slots per epoch (32) == 2.
+		// we then have a committee weight of avg balance * committee size = 10 * 2 = 20.
+		// The score then becomes 10 * PROPOSER_SCORE_BOOST // 100, which is
+		// 20 * 70 / 100 = 14.
+		score, err := computeProposerBoostScore(validatorBalances)
+		require.NoError(t, err)
+		require.Equal(t, uint64(14), score)
+	})
+}

beacon-chain/forkchoice/doubly-linked-tree/store.go

@@ -0,0 +1,223 @@
+package doublylinkedtree
+
+import (
+	"context"
+	"fmt"
+
+	types "github.com/prysmaticlabs/eth2-types"
+	fieldparams "github.com/prysmaticlabs/prysm/config/fieldparams"
+	"github.com/prysmaticlabs/prysm/config/params"
+	"go.opencensus.io/trace"
+)
+
+// This defines the minimal number of block nodes that can be in the tree
+// before getting pruned upon new finalization.
+const defaultPruneThreshold = 256
+
+// applyProposerBoostScore applies the current proposer boost scores to the
+// relevant nodes
+func (s *Store) applyProposerBoostScore(newBalances []uint64) error {
+	s.proposerBoostLock.Lock()
+	defer s.proposerBoostLock.Unlock()
+
+	proposerScore := uint64(0)
+	var err error
+	if s.previousProposerBoostRoot != params.BeaconConfig().ZeroHash {
+		previousNode, ok := s.nodeByRoot[s.previousProposerBoostRoot]
+		if !ok || previousNode == nil {
+			return errInvalidProposerBoostRoot
+		}
+		previousNode.balance -= s.previousProposerBoostScore
+	}
+
+	if s.proposerBoostRoot != params.BeaconConfig().ZeroHash {
+		currentNode, ok := s.nodeByRoot[s.proposerBoostRoot]
+		if !ok || currentNode == nil {
+			return errInvalidProposerBoostRoot
+		}
+		proposerScore, err = computeProposerBoostScore(newBalances)
+		if err != nil {
+			return err
+		}
+		currentNode.balance += proposerScore
+	}
+	s.previousProposerBoostRoot = s.proposerBoostRoot
+	s.previousProposerBoostScore = proposerScore
+	return nil
+}
+
+// ProposerBoost of fork choice store.
+func (s *Store) proposerBoost() [fieldparams.RootLength]byte {
+	s.proposerBoostLock.RLock()
+	defer s.proposerBoostLock.RUnlock()
+	return s.proposerBoostRoot
+}
+
+// PruneThreshold of fork choice store.
+func (s *Store) PruneThreshold() uint64 {
+	return s.pruneThreshold
+}
+
+// head starts from justified root and then follows the best descendant links
+// to find the best block for head. This function assumes a lock on s.nodesLock
+func (s *Store) head(ctx context.Context, justifiedRoot [32]byte) ([32]byte, error) {
+	_, span := trace.StartSpan(ctx, "doublyLinkedForkchoice.head")
+	defer span.End()
+
+	// JustifiedRoot has to be known
+	justifiedNode, ok := s.nodeByRoot[justifiedRoot]
+	if !ok || justifiedNode == nil {
+		return [32]byte{}, errUnknownJustifiedRoot
+	}
+
+	// If the justified node doesn't have a best descendant,
+	// the best node is itself.
+	bestDescendant := justifiedNode.bestDescendant
+	if bestDescendant == nil {
+		bestDescendant = justifiedNode
+	}
+
+	if !bestDescendant.viableForHead(s.justifiedEpoch, s.finalizedEpoch) {
+		return [32]byte{}, fmt.Errorf("head at slot %d with weight %d is not eligible, finalizedEpoch %d != %d, justifiedEpoch %d != %d",
+			bestDescendant.slot, bestDescendant.weight/10e9, bestDescendant.finalizedEpoch, s.finalizedEpoch, bestDescendant.justifiedEpoch, s.justifiedEpoch)
+	}
+
+	// Update metrics.
+	if bestDescendant != s.headNode {
+		headChangesCount.Inc()
+		headSlotNumber.Set(float64(bestDescendant.slot))
+		s.headNode = bestDescendant
+	}
+
+	return bestDescendant.root, nil
+}
+
+// insert registers a new block node to the fork choice store's node list.
+// It then updates the new node's parent with best child and descendant node.
+func (s *Store) insert(ctx context.Context,
+	slot types.Slot,
+	root, parentRoot [fieldparams.RootLength]byte,
+	justifiedEpoch, finalizedEpoch types.Epoch, optimistic bool) error {
+	_, span := trace.StartSpan(ctx, "doublyLinkedForkchoice.insert")
+	defer span.End()
+
+	s.nodesLock.Lock()
+	defer s.nodesLock.Unlock()
+
+	// Return if the block has been inserted into Store before.
+	if _, ok := s.nodeByRoot[root]; ok {
+		return nil
+	}
+
+	parent := s.nodeByRoot[parentRoot]
+
+	n := &Node{
+		slot:           slot,
+		root:           root,
+		parent:         parent,
+		justifiedEpoch: justifiedEpoch,
+		finalizedEpoch: finalizedEpoch,
+		optimistic:     optimistic,
+	}
+
+	s.nodeByRoot[root] = n
+	if parent != nil {
+		parent.children = append(parent.children, n)
+		if err := s.treeRootNode.updateBestDescendant(ctx, s.justifiedEpoch, s.finalizedEpoch); err != nil {
+			return err
+		}
+	}
+
+	if !optimistic {
+		if err := n.setNodeAndParentValidated(ctx); err != nil {
+			return err
+		}
+	} else {
+		optimisticCount.Inc()
+	}
+
+	// Set the node as root if the store was empty
+	if s.treeRootNode == nil {
+		s.treeRootNode = n
+		s.headNode = n
+	}
+
+	// Update metrics.
+	processedBlockCount.Inc()
+	nodeCount.Set(float64(len(s.nodeByRoot)))
+
+	return nil
+}
+
+// updateCheckpoints Update the justified / finalized epochs in store if necessary.
+func (s *Store) updateCheckpoints(justifiedEpoch, finalizedEpoch types.Epoch) {
+	s.justifiedEpoch = justifiedEpoch
+	s.finalizedEpoch = finalizedEpoch
+}
+
+// pruneFinalizedNodeByRootMap prunes the `nodeByRoot` map
+// starting from `node` down to the finalized Node or to a leaf of the Fork
+// choice store. This method assumes a lock on nodesLock.
+func (s *Store) pruneFinalizedNodeByRootMap(ctx context.Context, node, finalizedNode *Node) error {
+	if ctx.Err() != nil {
+		return ctx.Err()
+	}
+	if node == finalizedNode {
+		return nil
+	}
+	for _, child := range node.children {
+		if err := s.pruneFinalizedNodeByRootMap(ctx, child, finalizedNode); err != nil {
+			return err
+		}
+	}
+
+	delete(s.nodeByRoot, node.root)
+	return nil
+}
+
+// prune prunes the fork choice store with the new finalized root. The store is only pruned if the input
+// root is different than the current store finalized root, and the number of the store has met prune threshold.
+// This function does not prune for invalid optimistically synced nodes, it deals only with pruning upon finalization
+func (s *Store) prune(ctx context.Context, finalizedRoot [32]byte) error {
+	_, span := trace.StartSpan(ctx, "doublyLinkedForkchoice.Prune")
+	defer span.End()
+
+	s.nodesLock.Lock()
+	defer s.nodesLock.Unlock()
+
+	finalizedNode, ok := s.nodeByRoot[finalizedRoot]
+	if !ok || finalizedNode == nil {
+		return errUnknownFinalizedRoot
+	}
+
+	// The number of the nodes has not met the prune threshold.
+	// Pruning at small numbers incurs more cost than benefit.
+	if finalizedNode.depth() < s.pruneThreshold {
+		return nil
+	}
+
+	// Prune nodeByRoot starting from root
+	if err := s.pruneFinalizedNodeByRootMap(ctx, s.treeRootNode, finalizedNode); err != nil {
+		return err
+	}
+
+	finalizedNode.parent = nil
+	s.treeRootNode = finalizedNode
+
+	prunedCount.Inc()
+	return nil
+}
+
+// tips returns a list of possible heads from fork choice store, it returns the
+// roots and the slots of the leaf nodes.
+func (s *Store) tips() ([][32]byte, []types.Slot) {
+	var roots [][32]byte
+	var slots []types.Slot
+	for root, node := range s.nodeByRoot {
+		if len(node.children) == 0 {
+			roots = append(roots, root)
+			slots = append(slots, node.slot)
+		}
+	}
+	return roots, slots
+}

beacon-chain/forkchoice/doubly-linked-tree/store_test.go

@@ -0,0 +1,274 @@
+package doublylinkedtree
+
+import (
+	"context"
+	"testing"
+
+	types "github.com/prysmaticlabs/eth2-types"
+	"github.com/prysmaticlabs/prysm/config/params"
+	"github.com/prysmaticlabs/prysm/testing/assert"
+	"github.com/prysmaticlabs/prysm/testing/require"
+)
+
+func TestStore_PruneThreshold(t *testing.T) {
+	s := &Store{
+		pruneThreshold: defaultPruneThreshold,
+	}
+	if got := s.PruneThreshold(); got != defaultPruneThreshold {
+		t.Errorf("PruneThreshold() = %v, want %v", got, defaultPruneThreshold)
+	}
+}
+
+func TestStore_JustifiedEpoch(t *testing.T) {
+	j := types.Epoch(100)
+	f := setup(j, j)
+	require.Equal(t, j, f.JustifiedEpoch())
+}
+
+func TestStore_FinalizedEpoch(t *testing.T) {
+	j := types.Epoch(50)
+	f := setup(j, j)
+	require.Equal(t, j, f.FinalizedEpoch())
+}
+
+func TestStore_NodeCount(t *testing.T) {
+	f := setup(0, 0)
+	require.NoError(t, f.ProcessBlock(context.Background(), 1, indexToHash(1), params.BeaconConfig().ZeroHash, 0, 0, false))
+	require.Equal(t, 2, f.NodeCount())
+}
+
+func TestStore_NodeByRoot(t *testing.T) {
+	f := setup(0, 0)
+	require.NoError(t, f.ProcessBlock(context.Background(), 1, indexToHash(1), params.BeaconConfig().ZeroHash, 0, 0, false))
+	require.NoError(t, f.ProcessBlock(context.Background(), 2, indexToHash(2), indexToHash(1), 0, 0, false))
+	node0 := f.store.treeRootNode
+	node1 := node0.children[0]
+	node2 := node1.children[0]
+
+	expectedRoots := map[[32]byte]*Node{
+		params.BeaconConfig().ZeroHash: node0,
+		indexToHash(1):                 node1,
+		indexToHash(2):                 node2,
+	}
+
+	require.Equal(t, 3, f.NodeCount())
+	for root, node := range f.store.nodeByRoot {
+		v, ok := expectedRoots[root]
+		require.Equal(t, ok, true)
+		require.Equal(t, v, node)
+	}
+}
+
+func TestForkChoice_HasNode(t *testing.T) {
+	f := setup(0, 0)
+	require.NoError(t, f.ProcessBlock(context.Background(), 1, indexToHash(1), params.BeaconConfig().ZeroHash, 0, 0, false))
+	require.Equal(t, true, f.HasNode(indexToHash(1)))
+}
+
+func TestStore_Head_UnknownJustifiedRoot(t *testing.T) {
+	f := setup(0, 0)
+
+	_, err := f.store.head(context.Background(), [32]byte{'a'})
+	assert.ErrorContains(t, errUnknownJustifiedRoot.Error(), err)
+}
+
+func TestStore_Head_Itself(t *testing.T) {
+	f := setup(0, 0)
+	require.NoError(t, f.ProcessBlock(context.Background(), 1, indexToHash(1), params.BeaconConfig().ZeroHash, 0, 0, false))
+
+	// Since the justified node does not have a best descendant so the best node
+	// is itself.
+	h, err := f.store.head(context.Background(), indexToHash(1))
+	require.NoError(t, err)
+	assert.Equal(t, indexToHash(1), h)
+}
+
+func TestStore_Head_BestDescendant(t *testing.T) {
+	f := setup(0, 0)
+	require.NoError(t, f.ProcessBlock(context.Background(), 1, indexToHash(1), params.BeaconConfig().ZeroHash, 0, 0, false))
+	require.NoError(t, f.ProcessBlock(context.Background(), 2, indexToHash(2), indexToHash(1), 0, 0, false))
+	require.NoError(t, f.ProcessBlock(context.Background(), 3, indexToHash(3), indexToHash(1), 0, 0, false))
+	require.NoError(t, f.ProcessBlock(context.Background(), 4, indexToHash(4), indexToHash(2), 0, 0, false))
+	h, err := f.store.head(context.Background(), indexToHash(1))
+	require.NoError(t, err)
+	require.Equal(t, h, indexToHash(4))
+}
+
+func TestStore_UpdateBestDescendant_ContextCancelled(t *testing.T) {
+	ctx, cancel := context.WithCancel(context.Background())
+	f := setup(0, 0)
+	require.NoError(t, f.ProcessBlock(ctx, 1, indexToHash(1), params.BeaconConfig().ZeroHash, 0, 0, false))
+	cancel()
+	err := f.ProcessBlock(ctx, 2, indexToHash(2), indexToHash(1), 0, 0, false)
+	require.ErrorContains(t, "context canceled", err)
+}
+
+func TestStore_Insert(t *testing.T) {
+	// The new node does not have a parent.
+	treeRootNode := &Node{slot: 0, root: indexToHash(0)}
+	nodeByRoot := map[[32]byte]*Node{indexToHash(0): treeRootNode}
+	s := &Store{nodeByRoot: nodeByRoot, treeRootNode: treeRootNode}
+	require.NoError(t, s.insert(context.Background(), 100, indexToHash(100), indexToHash(0), 1, 1, false))
+	assert.Equal(t, 2, len(s.nodeByRoot), "Did not insert block")
+	assert.Equal(t, (*Node)(nil), treeRootNode.parent, "Incorrect parent")
+	assert.Equal(t, 1, len(treeRootNode.children), "Incorrect children number")
+	child := treeRootNode.children[0]
+	assert.Equal(t, types.Epoch(1), child.justifiedEpoch, "Incorrect justification")
+	assert.Equal(t, types.Epoch(1), child.finalizedEpoch, "Incorrect finalization")
+	assert.Equal(t, indexToHash(100), child.root, "Incorrect root")
+}
+
+func TestStore_updateCheckpoints(t *testing.T) {
+	f := setup(0, 0)
+	s := f.store
+
+	s.updateCheckpoints(1, 1)
+	assert.Equal(t, types.Epoch(1), s.justifiedEpoch, "Did not update justified epoch")
+	assert.Equal(t, types.Epoch(1), s.finalizedEpoch, "Did not update finalized epoch")
+}
+
+func TestStore_Prune_LessThanThreshold(t *testing.T) {
+	// Define 100 nodes in store.
+	numOfNodes := uint64(100)
+	f := setup(0, 0)
+	ctx := context.Background()
+	require.NoError(t, f.ProcessBlock(ctx, 1, indexToHash(1), params.BeaconConfig().ZeroHash, 0, 0, false))
+	for i := uint64(2); i < numOfNodes; i++ {
+		require.NoError(t, f.ProcessBlock(ctx, types.Slot(i), indexToHash(i), indexToHash(i-1), 0, 0, false))
+	}
+
+	s := f.store
+	s.pruneThreshold = 100
+
+	// Finalized root has depth 99 so everything before it should be pruned,
+	// but PruneThreshold is at 100 so nothing will be pruned.
+	require.NoError(t, s.prune(context.Background(), indexToHash(99)))
+	assert.Equal(t, 100, len(s.nodeByRoot), "Incorrect nodes count")
+}
+
+func TestStore_Prune_MoreThanThreshold(t *testing.T) {
+	// Define 100 nodes in store.
+	numOfNodes := uint64(100)
+	f := setup(0, 0)
+	ctx := context.Background()
+	require.NoError(t, f.ProcessBlock(ctx, 1, indexToHash(1), params.BeaconConfig().ZeroHash, 0, 0, false))
+	for i := uint64(2); i < numOfNodes; i++ {
+		require.NoError(t, f.ProcessBlock(ctx, types.Slot(i), indexToHash(i), indexToHash(i-1), 0, 0, false))
+	}
+
+	s := f.store
+	s.pruneThreshold = 0
+
+	// Finalized root is at index 99 so everything before 99 should be pruned.
+	require.NoError(t, s.prune(context.Background(), indexToHash(99)))
+	assert.Equal(t, 1, len(s.nodeByRoot), "Incorrect nodes count")
+}
+
+func TestStore_Prune_MoreThanOnce(t *testing.T) {
+	// Define 100 nodes in store.
+	numOfNodes := uint64(100)
+	f := setup(0, 0)
+	ctx := context.Background()
+	require.NoError(t, f.ProcessBlock(ctx, 1, indexToHash(1), params.BeaconConfig().ZeroHash, 0, 0, false))
+	for i := uint64(2); i < numOfNodes; i++ {
+		require.NoError(t, f.ProcessBlock(ctx, types.Slot(i), indexToHash(i), indexToHash(i-1), 0, 0, false))
+	}
+
+	s := f.store
+	s.pruneThreshold = 0
+
+	// Finalized root is at index 11 so everything before 11 should be pruned.
+	require.NoError(t, s.prune(context.Background(), indexToHash(10)))
+	assert.Equal(t, 90, len(s.nodeByRoot), "Incorrect nodes count")
+
+	// One more time.
+	require.NoError(t, s.prune(context.Background(), indexToHash(20)))
+	assert.Equal(t, 80, len(s.nodeByRoot), "Incorrect nodes count")
+}
+
+// This unit tests starts with a simple branch like this
+//
+//       - 1
+//     /
+// -- 0 -- 2
+//
+// And we finalize 1. As a result only 1 should survive
+func TestStore_Prune_NoDanglingBranch(t *testing.T) {
+	f := setup(0, 0)
+	ctx := context.Background()
+	require.NoError(t, f.ProcessBlock(ctx, 1, indexToHash(1), params.BeaconConfig().ZeroHash, 0, 0, false))
+	require.NoError(t, f.ProcessBlock(ctx, 2, indexToHash(2), params.BeaconConfig().ZeroHash, 0, 0, false))
+	f.store.pruneThreshold = 0
+
+	s := f.store
+	require.NoError(t, s.prune(context.Background(), indexToHash(1)))
+	require.Equal(t, len(s.nodeByRoot), 1)
+}
+
+// This test starts with the following branching diagram
+/// We start with the following diagram
+//
+//                E -- F
+//               /
+//         C -- D
+//        /      \
+//  A -- B        G -- H -- I
+//        \        \
+//         J        -- K -- L
+//
+//
+func TestStore_tips(t *testing.T) {
+	ctx := context.Background()
+	f := setup(1, 1)
+
+	require.NoError(t, f.ProcessBlock(ctx, 100, [32]byte{'a'}, params.BeaconConfig().ZeroHash, 1, 1, true))
+	require.NoError(t, f.ProcessBlock(ctx, 101, [32]byte{'b'}, [32]byte{'a'}, 1, 1, true))
+	require.NoError(t, f.ProcessBlock(ctx, 102, [32]byte{'c'}, [32]byte{'b'}, 1, 1, true))
+	require.NoError(t, f.ProcessBlock(ctx, 102, [32]byte{'j'}, [32]byte{'b'}, 1, 1, true))
+	require.NoError(t, f.ProcessBlock(ctx, 103, [32]byte{'d'}, [32]byte{'c'}, 1, 1, true))
+	require.NoError(t, f.ProcessBlock(ctx, 104, [32]byte{'e'}, [32]byte{'d'}, 1, 1, true))
+	require.NoError(t, f.ProcessBlock(ctx, 104, [32]byte{'g'}, [32]byte{'d'}, 1, 1, true))
+	require.NoError(t, f.ProcessBlock(ctx, 105, [32]byte{'f'}, [32]byte{'e'}, 1, 1, true))
+	require.NoError(t, f.ProcessBlock(ctx, 105, [32]byte{'h'}, [32]byte{'g'}, 1, 1, true))
+	require.NoError(t, f.ProcessBlock(ctx, 105, [32]byte{'k'}, [32]byte{'g'}, 1, 1, true))
+	require.NoError(t, f.ProcessBlock(ctx, 106, [32]byte{'i'}, [32]byte{'h'}, 1, 1, true))
+	require.NoError(t, f.ProcessBlock(ctx, 106, [32]byte{'l'}, [32]byte{'k'}, 1, 1, true))
+	expectedMap := map[[32]byte]types.Slot{
+		[32]byte{'f'}: 105,
+		[32]byte{'i'}: 106,
+		[32]byte{'l'}: 106,
+		[32]byte{'j'}: 102,
+	}
+	roots, slots := f.store.tips()
+	for i, r := range roots {
+		expectedSlot, ok := expectedMap[r]
+		require.Equal(t, true, ok)
+		require.Equal(t, slots[i], expectedSlot)
+	}
+}
+
+func TestStore_PruneMapsNodes(t *testing.T) {
+	f := setup(0, 0)
+	ctx := context.Background()
+	require.NoError(t, f.ProcessBlock(ctx, 1, indexToHash(1), params.BeaconConfig().ZeroHash, 0, 0, false))
+	require.NoError(t, f.ProcessBlock(ctx, 2, indexToHash(2), params.BeaconConfig().ZeroHash, 0, 0, false))
+
+	s := f.store
+	s.pruneThreshold = 0
+	require.NoError(t, s.prune(context.Background(), indexToHash(uint64(1))))
+	require.Equal(t, len(s.nodeByRoot), 1)
+
+}
+
+func TestStore_HasParent(t *testing.T) {
+	f := setup(1, 1)
+	ctx := context.Background()
+	require.NoError(t, f.ProcessBlock(ctx, 1, indexToHash(1), params.BeaconConfig().ZeroHash, 1, 1, false))
+	require.NoError(t, f.ProcessBlock(ctx, 2, indexToHash(2), indexToHash(1), 1, 1, false))
+	require.NoError(t, f.ProcessBlock(ctx, 3, indexToHash(3), indexToHash(2), 1, 1, false))
+	require.Equal(t, false, f.HasParent(params.BeaconConfig().ZeroHash))
+	require.Equal(t, true, f.HasParent(indexToHash(1)))
+	require.Equal(t, true, f.HasParent(indexToHash(2)))
+	require.Equal(t, true, f.HasParent(indexToHash(3)))
+	require.Equal(t, false, f.HasParent(indexToHash(4)))
+}

beacon-chain/forkchoice/doubly-linked-tree/types.go

@@ -0,0 +1,53 @@
+package doublylinkedtree
+
+import (
+	"sync"
+
+	types "github.com/prysmaticlabs/eth2-types"
+	fieldparams "github.com/prysmaticlabs/prysm/config/fieldparams"
+)
+
+// ForkChoice defines the overall fork choice store which includes all block nodes, validator's latest votes and balances.
+type ForkChoice struct {
+	store     *Store
+	votes     []Vote // tracks individual validator's last vote.
+	votesLock sync.RWMutex
+	balances  []uint64 // tracks individual validator's last justified balances.
+}
+
+// Store defines the fork choice store which includes block nodes and the last view of checkpoint information.
+type Store struct {
+	justifiedEpoch             types.Epoch                            // latest justified epoch in store.
+	finalizedEpoch             types.Epoch                            // latest finalized epoch in store.
+	pruneThreshold             uint64                                 // do not prune tree unless threshold is reached.
+	proposerBoostRoot          [fieldparams.RootLength]byte           // latest block root that was boosted after being received in a timely manner.
+	previousProposerBoostRoot  [fieldparams.RootLength]byte           // previous block root that was boosted after being received in a timely manner.
+	previousProposerBoostScore uint64                                 // previous proposer boosted root score.
+	treeRootNode               *Node                                  // the root node of the store tree.
+	headNode                   *Node                                  // last head Node
+	nodeByRoot                 map[[fieldparams.RootLength]byte]*Node // nodes indexed by roots.
+	nodesLock                  sync.RWMutex
+	proposerBoostLock          sync.RWMutex
+}
+
+// Node defines the individual block which includes its block parent, ancestor and how much weight accounted for it.
+// This is used as an array based stateful DAG for efficient fork choice look up.
+type Node struct {
+	slot           types.Slot                   // slot of the block converted to the node.
+	root           [fieldparams.RootLength]byte // root of the block converted to the node.
+	parent         *Node                        // parent index of this node.
+	children       []*Node                      // the list of direct children of this Node
+	justifiedEpoch types.Epoch                  // justifiedEpoch of this node.
+	finalizedEpoch types.Epoch                  // finalizedEpoch of this node.
+	balance        uint64                       // the balance that voted for this node directly
+	weight         uint64                       // weight of this node: the total balance including children
+	bestDescendant *Node                        // bestDescendant node of this node.
+	optimistic     bool                         // whether the block has been fully validated or not
+}
+
+// Vote defines an individual validator's vote.
+type Vote struct {
+	currentRoot [fieldparams.RootLength]byte // current voting root.
+	nextRoot    [fieldparams.RootLength]byte // next voting root.
+	nextEpoch   types.Epoch                  // epoch of next voting period.
+}

beacon-chain/forkchoice/doubly-linked-tree/vote_test.go

@@ -0,0 +1,297 @@
+package doublylinkedtree
+
+import (
+	"context"
+	"testing"
+
+	"github.com/prysmaticlabs/prysm/config/params"
+	"github.com/prysmaticlabs/prysm/testing/assert"
+	"github.com/prysmaticlabs/prysm/testing/require"
+)
+
+func TestVotes_CanFindHead(t *testing.T) {
+	balances := []uint64{1, 1}
+	f := setup(1, 1)
+
+	// The head should always start at the finalized block.
+	r, err := f.Head(context.Background(), 1, params.BeaconConfig().ZeroHash, balances, 1)
+	require.NoError(t, err)
+	assert.Equal(t, params.BeaconConfig().ZeroHash, r, "Incorrect head with genesis")
+
+	// Insert block 2 into the tree and verify head is at 2:
+	//         0
+	//        /
+	//       2 <- head
+	require.NoError(t, f.ProcessBlock(context.Background(), 0, indexToHash(2), params.BeaconConfig().ZeroHash, 1, 1, true))
+
+	r, err = f.Head(context.Background(), 1, params.BeaconConfig().ZeroHash, balances, 1)
+	require.NoError(t, err)
+	assert.Equal(t, indexToHash(2), r, "Incorrect head for with justified epoch at 1")
+
+	// Insert block 1 into the tree and verify head is still at 2:
+	//            0
+	//           / \
+	//  head -> 2  1
+	require.NoError(t, f.ProcessBlock(context.Background(), 0, indexToHash(1), params.BeaconConfig().ZeroHash, 1, 1, true))
+
+	r, err = f.Head(context.Background(), 1, params.BeaconConfig().ZeroHash, balances, 1)
+	require.NoError(t, err)
+	assert.Equal(t, indexToHash(2), r, "Incorrect head for with justified epoch at 1")
+
+	// Add a vote to block 1 of the tree and verify head is switched to 1:
+	//            0
+	//           / \
+	//          2  1 <- +vote, new head
+	f.ProcessAttestation(context.Background(), []uint64{0}, indexToHash(1), 2)
+	r, err = f.Head(context.Background(), 1, params.BeaconConfig().ZeroHash, balances, 1)
+	require.NoError(t, err)
+	assert.Equal(t, indexToHash(1), r, "Incorrect head for with justified epoch at 1")
+
+	// Add a vote to block 2 of the tree and verify head is switched to 2:
+	//                     0
+	//                    / \
+	// vote, new head -> 2  1
+	f.ProcessAttestation(context.Background(), []uint64{1}, indexToHash(2), 2)
+	r, err = f.Head(context.Background(), 1, params.BeaconConfig().ZeroHash, balances, 1)
+	require.NoError(t, err)
+	assert.Equal(t, indexToHash(2), r, "Incorrect head for with justified epoch at 1")
+
+	// Insert block 3 into the tree and verify head is still at 2:
+	//            0
+	//           / \
+	//  head -> 2  1
+	//             |
+	//             3
+	require.NoError(t, f.ProcessBlock(context.Background(), 0, indexToHash(3), indexToHash(1), 1, 1, true))
+
+	r, err = f.Head(context.Background(), 1, params.BeaconConfig().ZeroHash, balances, 1)
+	require.NoError(t, err)
+	assert.Equal(t, indexToHash(2), r, "Incorrect head for with justified epoch at 1")
+
+	// Move validator 0's vote from 1 to 3 and verify head is still at 2:
+	//            0
+	//           / \
+	//  head -> 2  1 <- old vote
+	//             |
+	//             3 <- new vote
+	f.ProcessAttestation(context.Background(), []uint64{0}, indexToHash(3), 3)
+	r, err = f.Head(context.Background(), 1, params.BeaconConfig().ZeroHash, balances, 1)
+	require.NoError(t, err)
+	assert.Equal(t, indexToHash(2), r, "Incorrect head for with justified epoch at 1")
+
+	// Move validator 1's vote from 2 to 1 and verify head is switched to 3:
+	//               0
+	//              / \
+	// old vote -> 2  1 <- new vote
+	//                |
+	//                3 <- head
+	f.ProcessAttestation(context.Background(), []uint64{1}, indexToHash(1), 3)
+	r, err = f.Head(context.Background(), 1, params.BeaconConfig().ZeroHash, balances, 1)
+	require.NoError(t, err)
+	assert.Equal(t, indexToHash(3), r, "Incorrect head for with justified epoch at 1")
+
+	// Insert block 4 into the tree and verify head is at 4:
+	//            0
+	//           / \
+	//          2  1
+	//             |
+	//             3
+	//             |
+	//             4 <- head
+	require.NoError(t, f.ProcessBlock(context.Background(), 0, indexToHash(4), indexToHash(3), 1, 1, true))
+
+	r, err = f.Head(context.Background(), 1, params.BeaconConfig().ZeroHash, balances, 1)
+	require.NoError(t, err)
+	assert.Equal(t, indexToHash(4), r, "Incorrect head for with justified epoch at 1")
+
+	// Insert block 5 with justified epoch 2, it should be filtered out:
+	//            0
+	//           / \
+	//          2  1
+	//             |
+	//             3
+	//             |
+	//             4 <- head
+	//            /
+	//           5 <- justified epoch = 2
+	require.NoError(t, f.ProcessBlock(context.Background(), 0, indexToHash(5), indexToHash(4), 2, 2, true))
+
+	r, err = f.Head(context.Background(), 1, params.BeaconConfig().ZeroHash, balances, 1)
+	require.NoError(t, err)
+	assert.Equal(t, indexToHash(4), r, "Incorrect head for with justified epoch at 1")
+
+	// Insert block 6 with justified epoch 0:
+	//            0
+	//           / \
+	//          2  1
+	//             |
+	//             3
+	//             |
+	//             4 <- head
+	//            / \
+	//           5  6 <- justified epoch = 0
+	require.NoError(t, f.ProcessBlock(context.Background(), 0, indexToHash(6), indexToHash(4), 1, 1, true))
+
+	// Moved 2 votes to block 5:
+	//            0
+	//           / \
+	//          2  1
+	//             |
+	//             3
+	//             |
+	//             4
+	//            / \
+	// 2 votes-> 5  6
+	require.NoError(t, f.ProcessBlock(context.Background(), 0, indexToHash(6), indexToHash(4), 1, 1, true))
+
+	f.ProcessAttestation(context.Background(), []uint64{0, 1}, indexToHash(5), 4)
+
+	// Inset blocks 7, 8 and 9:
+	// 6 should still be the head, even though 5 has all the votes.
+	//            0
+	//           / \
+	//          2  1
+	//             |
+	//             3
+	//             |
+	//             4
+	//            / \
+	//           5  6 <- head
+	//           |
+	//           7
+	//           |
+	//           8
+	//           |
+	//           9
+	require.NoError(t, f.ProcessBlock(context.Background(), 0, indexToHash(7), indexToHash(5), 2, 2, true))
+	require.NoError(t, f.ProcessBlock(context.Background(), 0, indexToHash(8), indexToHash(7), 2, 2, true))
+	require.NoError(t, f.ProcessBlock(context.Background(), 0, indexToHash(9), indexToHash(8), 2, 2, true))
+
+	r, err = f.Head(context.Background(), 1, params.BeaconConfig().ZeroHash, balances, 1)
+	require.NoError(t, err)
+	assert.Equal(t, indexToHash(6), r, "Incorrect head for with justified epoch at 1")
+
+	// Update fork choice justified epoch to 1 and start block to 5.
+	// Verify 9 is the head:
+	//            0
+	//           / \
+	//          2  1
+	//             |
+	//             3
+	//             |
+	//             4
+	//            / \
+	//           5  6
+	//           |
+	//           7
+	//           |
+	//           8
+	//           |
+	//           9 <- head
+	r, err = f.Head(context.Background(), 2, indexToHash(5), balances, 2)
+	require.NoError(t, err)
+	assert.Equal(t, indexToHash(9), r, "Incorrect head for with justified epoch at 2")
+
+	// Insert block 10 and 2 validators updated their vote to 9.
+	// Verify 9 is the head:
+	//             0
+	//            / \
+	//           2  1
+	//              |
+	//              3
+	//              |
+	//              4
+	//             / \
+	//            5  6
+	//            |
+	//            7
+	//            |
+	//            8
+	//           / \
+	// 2 votes->9  10
+	f.ProcessAttestation(context.Background(), []uint64{0, 1}, indexToHash(9), 5)
+	require.NoError(t, f.ProcessBlock(context.Background(), 0, indexToHash(10), indexToHash(8), 2, 2, true))
+
+	r, err = f.Head(context.Background(), 2, indexToHash(5), balances, 2)
+	require.NoError(t, err)
+	assert.Equal(t, indexToHash(9), r, "Incorrect head for with justified epoch at 2")
+
+	// Add 3 more validators to the system.
+	balances = []uint64{1, 1, 1, 1, 1}
+	// The new validators voted for 10.
+	f.ProcessAttestation(context.Background(), []uint64{2, 3, 4}, indexToHash(10), 5)
+	// The new head should be 10.
+	r, err = f.Head(context.Background(), 2, indexToHash(5), balances, 2)
+	require.NoError(t, err)
+	assert.Equal(t, indexToHash(10), r, "Incorrect head for with justified epoch at 2")
+
+	// Set the balances of the last 2 validators to 0.
+	balances = []uint64{1, 1, 1, 0, 0}
+	// The head should be back to 9.
+	r, err = f.Head(context.Background(), 2, indexToHash(5), balances, 2)
+	require.NoError(t, err)
+	assert.Equal(t, indexToHash(9), r, "Incorrect head for with justified epoch at 1")
+
+	// Set the balances back to normal.
+	balances = []uint64{1, 1, 1, 1, 1}
+	// The head should be back to 10.
+	r, err = f.Head(context.Background(), 2, indexToHash(5), balances, 2)
+	require.NoError(t, err)
+	assert.Equal(t, indexToHash(10), r, "Incorrect head for with justified epoch at 2")
+
+	// Remove the last 2 validators.
+	balances = []uint64{1, 1, 1}
+	// The head should be back to 9.
+	r, err = f.Head(context.Background(), 2, indexToHash(5), balances, 2)
+	require.NoError(t, err)
+	assert.Equal(t, indexToHash(9), r, "Incorrect head for with justified epoch at 1")
+
+	// Verify pruning below the prune threshold does not affect head.
+	f.store.pruneThreshold = 1000
+	require.NoError(t, f.store.prune(context.Background(), indexToHash(5)))
+	assert.Equal(t, 11, len(f.store.nodeByRoot), "Incorrect nodes length after prune")
+
+	r, err = f.Head(context.Background(), 2, indexToHash(5), balances, 2)
+	require.NoError(t, err)
+	assert.Equal(t, indexToHash(9), r, "Incorrect head for with justified epoch at 2")
+
+	// Verify pruning above the prune threshold does prune:
+	//          0
+	//         / \
+	//        2   1
+	//            |
+	//            3
+	//            |
+	//            4
+	// -------pruned here ------
+	//          5   6
+	//          |
+	//          7
+	//          |
+	//          8
+	//         / \
+	//        9  10
+	f.store.pruneThreshold = 1
+	require.NoError(t, f.store.prune(context.Background(), indexToHash(5)))
+	assert.Equal(t, 5, len(f.store.nodeByRoot), "Incorrect nodes length after prune")
+
+	r, err = f.Head(context.Background(), 2, indexToHash(5), balances, 2)
+	require.NoError(t, err)
+	assert.Equal(t, indexToHash(9), r, "Incorrect head for with justified epoch at 2")
+
+	// Insert new block 11 and verify head is at 11.
+	//          5   6
+	//          |
+	//          7
+	//          |
+	//          8
+	//         / \
+	//        9  10
+	//        |
+	// head-> 11
+	require.NoError(t, f.ProcessBlock(context.Background(), 0, indexToHash(11), indexToHash(9), 2, 2, true))
+
+	r, err = f.Head(context.Background(), 2, indexToHash(5), balances, 2)
+	require.NoError(t, err)
+	assert.Equal(t, indexToHash(11), r, "Incorrect head for with justified epoch at 2")
+}

beacon-chain/forkchoice/interfaces.go

@@ -5,28 +5,37 @@ import (
 	"time"
 
 	types "github.com/prysmaticlabs/eth2-types"
-	"github.com/prysmaticlabs/prysm/beacon-chain/forkchoice/protoarray"
+	fieldparams "github.com/prysmaticlabs/prysm/config/fieldparams"
+	pbrpc "github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1"
 )
 
-// ForkChoicer represents the full fork choice interface composed of all of the sub-interfaces.
+// ForkChoicer represents the full fork choice interface composed of all the sub-interfaces.
 type ForkChoicer interface {
 	HeadRetriever        // to compute head.
 	BlockProcessor       // to track new block for fork choice.
 	AttestationProcessor // to track new attestation for fork choice.
 	Pruner               // to clean old data for fork choice.
 	Getter               // to retrieve fork choice information.
+	Setter               // to set fork choice information.
 	ProposerBooster      // ability to boost timely-proposed block roots.
 }
 
 // HeadRetriever retrieves head root and optimistic info of the current chain.
 type HeadRetriever interface {
 	Head(context.Context, types.Epoch, [32]byte, []uint64, types.Epoch) ([32]byte, error)
-	Optimistic(ctx context.Context, root [32]byte, slot types.Slot) (bool, error)
+	Tips() ([][32]byte, []types.Slot)
+	IsOptimistic(ctx context.Context, root [32]byte) (bool, error)
 }
 
 // BlockProcessor processes the block that's used for accounting fork choice.
 type BlockProcessor interface {
-	ProcessBlock(context.Context, types.Slot, [32]byte, [32]byte, [32]byte, types.Epoch, types.Epoch) error
+	ProcessBlock(ctx context.Context,
+		slot types.Slot,
+		root [32]byte,
+		parentRoot [32]byte,
+		justifiedEpoch types.Epoch,
+		finalizedEpoch types.Epoch,
+		optimisticStatus bool) error
 }
 
 // AttestationProcessor processes the attestation that's used for accounting fork choice.
@@ -47,11 +56,19 @@ type ProposerBooster interface {
 
 // Getter returns fork choice related information.
 type Getter interface {
-	Nodes() []*protoarray.Node
-	Node([32]byte) *protoarray.Node
 	HasNode([32]byte) bool
-	Store() *protoarray.Store
+	ProposerBoost() [fieldparams.RootLength]byte
 	HasParent(root [32]byte) bool
 	AncestorRoot(ctx context.Context, root [32]byte, slot types.Slot) ([]byte, error)
 	IsCanonical(root [32]byte) bool
+	FinalizedEpoch() types.Epoch
+	JustifiedEpoch() types.Epoch
+	ForkChoiceNodes() []*pbrpc.ForkChoiceNode
+	NodeCount() int
+}
+
+// Setter allows to set forkchoice information
+type Setter interface {
+	SetOptimisticToValid(context.Context, [fieldparams.RootLength]byte) error
+	SetOptimisticToInvalid(context.Context, [fieldparams.RootLength]byte) error
 }