Rm uncommented

* Add failing test

* Add path to keystore

* Assert encoded contains "path"

* Fix lint

Ran `bazel run //:gazelle -- fix`

Co-authored-by: james-prysm <90280386+james-prysm@users.noreply.github.com>

WORKSPACE

@@ -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,
 )

beacon-chain/blockchain/BUILD.bazel

@@ -12,7 +12,9 @@ go_library(
         "log.go",
         "metrics.go",
         "new_slot.go",
+        "optimistic_sync.go",
         "options.go",
+        "pow_block.go",
         "process_attestation.go",
         "process_attestation_helpers.go",
         "process_block.go",
@@ -37,6 +39,7 @@ 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",
@@ -53,6 +56,7 @@ go_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",
@@ -62,6 +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",
@@ -70,6 +75,8 @@ go_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_holiman_uint256//: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",
@@ -101,6 +108,8 @@ go_test(
         "log_test.go",
         "metrics_test.go",
         "mock_test.go",
+        "optimistic_sync_test.go",
+        "pow_block_test.go",
         "process_attestation_test.go",
         "process_block_test.go",
         "receive_attestation_test.go",

beacon-chain/blockchain/chain_info.go

@@ -36,7 +36,7 @@ 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
@@ -48,12 +48,14 @@ 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, slot types.Slot) (bool, error)
 	HeadSyncCommitteeFetcher
 	HeadDomainFetcher
 }
@@ -212,8 +214,8 @@ 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()
 
@@ -221,7 +223,7 @@ func (s *Service) HeadGenesisValidatorRoot() [32]byte {
 		return [32]byte{}
 	}
 
-	return s.headGenesisValidatorRoot()
+	return s.headGenesisValidatorsRoot()
 }
 
 // HeadETH1Data returns the eth1data of the current head state.
@@ -245,16 +247,16 @@ 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.
@@ -328,6 +330,19 @@ func (s *Service) HeadValidatorIndexToPublicKey(_ context.Context, index types.V
 	return v.PublicKey(), nil
 }
 
+// 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)
+}
+
+// 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, slot types.Slot) (bool, error) {
+	return s.cfg.ForkChoiceStore.Optimistic(ctx, root, slot)
+}
+
 // SetGenesisTime sets the genesis time of beacon chain.
 func (s *Service) SetGenesisTime(t time.Time) {
 	s.genesisTime = t

beacon-chain/blockchain/chain_info_test.go

@@ -185,15 +185,15 @@ 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) {
@@ -265,17 +265,17 @@ 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) {
@@ -355,3 +355,25 @@ func TestService_HeadValidatorIndexToPublicKeyNil(t *testing.T) {
 	require.NoError(t, err)
 	require.Equal(t, [fieldparams.BLSPubkeyLength]byte{}, p)
 }
+
+func TestService_IsOptimistic(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{}, [32]byte{}, 0, 0))
+	require.NoError(t, c.cfg.ForkChoiceStore.ProcessBlock(ctx, 101, [32]byte{'b'}, [32]byte{'a'}, [32]byte{}, 0, 0))
+
+	opt, err := c.IsOptimistic(ctx)
+	require.NoError(t, err)
+	require.Equal(t, true, opt)
+}
+
+func TestService_IsOptimisticForRoot(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{}, [32]byte{}, 0, 0))
+	require.NoError(t, c.cfg.ForkChoiceStore.ProcessBlock(ctx, 101, [32]byte{'b'}, [32]byte{'a'}, [32]byte{}, 0, 0))
+
+	opt, err := c.IsOptimisticForRoot(ctx, [32]byte{'a'}, 100)
+	require.NoError(t, err)
+	require.Equal(t, true, opt)
+}

beacon-chain/blockchain/head.go

@@ -265,10 +265,10 @@ 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/log.go

@@ -51,11 +51,11 @@ func logBlockSyncStatus(block block.BeaconBlock, blockRoot [32]byte, finalized *
 	log.WithFields(logrus.Fields{
 		"slot":           block.Slot(),
 		"slotInEpoch":    block.Slot() % params.BeaconConfig().SlotsPerEpoch,
-		"block":          fmt.Sprintf("0x%s...", hex.EncodeToString(blockRoot[:])[:8]),
+		"blockRoot":      fmt.Sprintf("0x%s...", hex.EncodeToString(blockRoot[:])[:8]),
+		"parentRoot":     fmt.Sprintf("0x%s...", hex.EncodeToString(blockRoot[:])[:8]),
 		"epoch":          slots.ToEpoch(block.Slot()),
 		"finalizedEpoch": finalized.Epoch,
 		"finalizedRoot":  fmt.Sprintf("0x%s...", hex.EncodeToString(finalized.Root)[:8]),
-		"parentRoot":     fmt.Sprintf("0x%s...", hex.EncodeToString(block.ParentRoot())[:8]),
 		"version":        version.String(block.Version()),
 	}).Info("Synced new block")
 	log.WithFields(logrus.Fields{

beacon-chain/blockchain/optimistic_sync.go

@@ -0,0 +1,53 @@
+package blockchain
+
+import (
+	"context"
+
+	"github.com/pkg/errors"
+	types "github.com/prysmaticlabs/eth2-types"
+	"github.com/prysmaticlabs/prysm/beacon-chain/core/blocks"
+	"github.com/prysmaticlabs/prysm/config/params"
+	"github.com/prysmaticlabs/prysm/encoding/bytesutil"
+	"github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1/block"
+)
+
+// 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())
+}
+
+// loadSyncedTips loads a previously saved synced Tips from DB
+// if no synced tips are saved, then it creates one from the given
+// root and slot number.
+func (s *Service) loadSyncedTips(root [32]byte, slot types.Slot) error {
+	// Initialize synced tips
+	tips, err := s.cfg.BeaconDB.ValidatedTips(s.ctx)
+	if err != nil || len(tips) == 0 {
+		tips[root] = slot
+		if err != nil {
+			log.WithError(err).Warn("Could not read synced tips from DB, using finalized checkpoint as synced tip")
+		}
+	}
+	if err := s.cfg.ForkChoiceStore.SetSyncedTips(tips); err != nil {
+		return errors.Wrap(err, "could not set synced tips")
+	}
+	return nil
+}

beacon-chain/blockchain/optimistic_sync_test.go

@@ -0,0 +1,141 @@
+package blockchain
+
+import (
+	"context"
+	"testing"
+	"time"
+
+	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"
+	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/require"
+	"github.com/prysmaticlabs/prysm/testing/util"
+	"github.com/prysmaticlabs/prysm/time/slots"
+)
+
+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.Random = 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"
+	v1 "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 v1.EngineCaller) 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

@@ -0,0 +1,29 @@
+package blockchain
+
+import (
+	"math/big"
+
+	"github.com/holiman/uint256"
+	"github.com/pkg/errors"
+	"github.com/prysmaticlabs/prysm/config/params"
+)
+
+// 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, 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, nil
+}

beacon-chain/blockchain/pow_block_test.go

@@ -0,0 +1,93 @@
+package blockchain
+
+import (
+	"fmt"
+	"math/big"
+	"testing"
+
+	"github.com/holiman/uint256"
+	"github.com/prysmaticlabs/prysm/config/params"
+	"github.com/prysmaticlabs/prysm/testing/require"
+)
+
+func Test_validTerminalPowBlock(t *testing.T) {
+	tests := []struct {
+		name              string
+		currentDifficulty *uint256.Int
+		parentDifficulty  *uint256.Int
+		ttd               uint64
+		want              bool
+	}{
+		{
+			name:              "current > ttd, parent > ttd",
+			currentDifficulty: uint256.NewInt(2),
+			parentDifficulty:  uint256.NewInt(2),
+			ttd:               1,
+			want:              false,
+		},
+		{
+			name:              "current < ttd, parent < ttd",
+			currentDifficulty: uint256.NewInt(2),
+			parentDifficulty:  uint256.NewInt(2),
+			ttd:               3,
+			want:              false,
+		},
+		{
+			name:              "current == ttd, parent == ttd",
+			currentDifficulty: uint256.NewInt(2),
+			parentDifficulty:  uint256.NewInt(2),
+			ttd:               2,
+			want:              false,
+		},
+		{
+			name:              "current > ttd, parent == ttd",
+			currentDifficulty: uint256.NewInt(2),
+			parentDifficulty:  uint256.NewInt(1),
+			ttd:               1,
+			want:              false,
+		},
+		{
+			name:              "current == ttd, parent < ttd",
+			currentDifficulty: uint256.NewInt(2),
+			parentDifficulty:  uint256.NewInt(1),
+			ttd:               2,
+			want:              true,
+		},
+		{
+			name:              "current > ttd, parent < ttd",
+			currentDifficulty: uint256.NewInt(3),
+			parentDifficulty:  uint256.NewInt(1),
+			ttd:               2,
+			want:              true,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			cfg := params.BeaconConfig()
+			cfg.TerminalTotalDifficulty = fmt.Sprint(tt.ttd)
+			params.OverrideBeaconConfig(cfg)
+			got, err := validTerminalPowBlock(tt.currentDifficulty, tt.parentDifficulty)
+			require.NoError(t, err)
+			if got != tt.want {
+				t.Errorf("validTerminalPowBlock() = %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 := validTerminalPowBlock(current, parent)
+	require.NoError(t, err)
+	require.Equal(t, true, got)
+}

beacon-chain/blockchain/process_block.go

@@ -1,11 +1,15 @@
 package blockchain
 
 import (
+	"bytes"
 	"context"
 	"fmt"
 	"time"
 
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/holiman/uint256"
 	"github.com/pkg/errors"
+	"github.com/prysmaticlabs/prysm/beacon-chain/core/blocks"
 	"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"
@@ -17,11 +21,14 @@ import (
 	"github.com/prysmaticlabs/prysm/crypto/bls"
 	"github.com/prysmaticlabs/prysm/encoding/bytesutil"
 	"github.com/prysmaticlabs/prysm/monitoring/tracing"
+	enginev1 "github.com/prysmaticlabs/prysm/proto/engine/v1"
 	ethpbv1 "github.com/prysmaticlabs/prysm/proto/eth/v1"
 	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"
+	"github.com/sirupsen/logrus"
 	"go.opencensus.io/trace"
 )
 
@@ -97,12 +104,70 @@ func (s *Service) onBlock(ctx context.Context, signed block.SignedBeaconBlock, b
 	if err != nil {
 		return err
 	}
+	// TODO_MERGE: Optimize this copy.
+	copiedPreState := preState.Copy()
 
+	body := signed.Block().Body()
+	// TODO_MERGE: Break `ExecuteStateTransition` into per_slot and block processing so we can call `ExecutePayload` in the middle.
 	postState, err := transition.ExecuteStateTransition(ctx, preState, signed)
 	if err != nil {
+		// TODO_MERGE: Notify execution client in the event of invalid conensus block
 		return err
 	}
 
+	fullyValidated := false
+	if copiedPreState.Version() == version.Bellatrix || postState.Version() == version.Bellatrix {
+		executionEnabled, err := blocks.ExecutionEnabled(postState, body)
+		if err != nil {
+			return errors.Wrap(err, "could not check if execution is enabled")
+		}
+		if executionEnabled {
+			payload, err := body.ExecutionPayload()
+			if err != nil {
+				return errors.Wrap(err, "could not get body execution payload")
+			}
+			// This is not the earliest we can call `ExecutePayload`, see above to do as the soonest we can call is after per_slot processing.
+			status, err := s.cfg.ExecutionEngineCaller.NewPayload(ctx, payload)
+			if err != nil {
+				return err
+			}
+			switch status.Status {
+			case enginev1.PayloadStatus_INVALID, enginev1.PayloadStatus_INVALID_BLOCK_HASH, enginev1.PayloadStatus_INVALID_TERMINAL_BLOCK:
+				// TODO_MERGE walk up the parent chain removing
+				return fmt.Errorf("could not prcess execution payload with status : %v", status.Status)
+			case enginev1.PayloadStatus_SYNCING, enginev1.PayloadStatus_ACCEPTED:
+				candidate, err := s.optimisticCandidateBlock(ctx, b)
+				if err != nil {
+					return errors.Wrap(err, "could not check if block is optimistic candidate")
+				}
+				if !candidate {
+					return errors.New("could not optimistically sync block")
+				}
+				log.WithFields(logrus.Fields{
+					"slot":        b.Slot(),
+					"root":        fmt.Sprintf("%#x", bytesutil.Trunc(blockRoot[:])),
+					"payloadHash": fmt.Sprintf("%#x", bytesutil.Trunc(payload.BlockHash)),
+				}).Info("Block is optimistic candidate")
+				break
+			case enginev1.PayloadStatus_VALID:
+				fullyValidated = true
+			default:
+				return errors.New("unknown payload status")
+			}
+			if copiedPreState.Version() == version.Bellatrix && fullyValidated {
+				mergeBlock, err := blocks.MergeTransitionBlock(copiedPreState, body)
+				if err != nil {
+					return errors.Wrap(err, "could not check if merge block is terminal")
+				}
+				if mergeBlock {
+					if err := s.validateTerminalBlock(ctx, signed); err != nil {
+						return err
+					}
+				}
+			}
+		}
+	}
+
 	// 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.
 	if err := s.cfg.ForkChoiceStore.BoostProposerRoot(
@@ -115,6 +180,20 @@ func (s *Service) onBlock(ctx context.Context, signed block.SignedBeaconBlock, b
 		return err
 	}
 
+	// update forkchoice synced tips if the block is not optimistic
+	if fullyValidated {
+		root, err := b.HashTreeRoot()
+		if err != nil {
+			return err
+		}
+		if err := s.cfg.ForkChoiceStore.UpdateSyncedTipsWithValidRoot(ctx, root); err != nil {
+			return err
+		}
+		if err := s.saveSyncedTipsDB(ctx); err != nil {
+			return err
+		}
+	}
+
 	// If slasher is configured, forward the attestations in the block via
 	// an event feed for processing.
 	if features.Get().EnableSlasher {
@@ -175,6 +254,59 @@ func (s *Service) onBlock(ctx context.Context, signed block.SignedBeaconBlock, b
 		log.WithError(err).Warn("Could not update head")
 	}
 
+	// Notify execution layer with fork choice head update if this is post merge block.
+	if postState.Version() == version.Bellatrix {
+		executionEnabled, err := blocks.ExecutionEnabled(postState, body)
+		if err != nil {
+			return errors.Wrap(err, "could not check if execution is enabled")
+		}
+		if executionEnabled {
+			headPayload, err := s.headBlock().Block().Body().ExecutionPayload()
+			if err != nil {
+				return err
+			}
+			// TODO_MERGE: Loading the finalized block from DB on per block is not ideal. Finalized block should be cached here
+			finalizedBlock, err := s.cfg.BeaconDB.Block(ctx, bytesutil.ToBytes32(finalized.Root))
+			if err != nil {
+				return err
+			}
+			finalizedBlockHash := params.BeaconConfig().ZeroHash[:]
+			if finalizedBlock != nil && finalizedBlock.Version() == version.Bellatrix {
+				finalizedPayload, err := finalizedBlock.Block().Body().ExecutionPayload()
+				if err != nil {
+					return err
+				}
+				finalizedBlockHash = finalizedPayload.BlockHash
+			}
+
+			fcs := &enginev1.ForkchoiceState{
+				HeadBlockHash:      headPayload.BlockHash,
+				SafeBlockHash:      headPayload.BlockHash,
+				FinalizedBlockHash: finalizedBlockHash,
+			}
+			resp, err := s.cfg.ExecutionEngineCaller.ForkchoiceUpdated(ctx, fcs, nil /* attribute */)
+			if err != nil {
+				return err
+			}
+			switch resp.Status.Status {
+			case enginev1.PayloadStatus_INVALID, enginev1.PayloadStatus_INVALID_BLOCK_HASH, enginev1.PayloadStatus_INVALID_TERMINAL_BLOCK:
+				return fmt.Errorf("could not prcess execution payload with status : %v", resp.Status.Status)
+			case enginev1.PayloadStatus_SYNCING, enginev1.PayloadStatus_ACCEPTED:
+				candidate, err := s.optimisticCandidateBlock(ctx, b)
+				if err != nil {
+					return errors.Wrap(err, "could not check if block is optimistic candidate")
+				}
+				if !candidate {
+					return errors.Wrap(err, "could not optimistically sync block")
+				}
+				break
+			case enginev1.PayloadStatus_VALID:
+			default:
+				return errors.Wrap(err, "could not execute payload")
+			}
+		}
+	}
+
 	if err := s.pruneCanonicalAttsFromPool(ctx, blockRoot, signed); err != nil {
 		return err
 	}
@@ -247,32 +379,33 @@ func (s *Service) onBlock(ctx context.Context, signed block.SignedBeaconBlock, b
 }
 
 func (s *Service) onBlockBatch(ctx context.Context, blks []block.SignedBeaconBlock,
-	blockRoots [][32]byte) ([]*ethpb.Checkpoint, []*ethpb.Checkpoint, error) {
+	blockRoots [][32]byte) ([]*ethpb.Checkpoint, []*ethpb.Checkpoint, []bool, error) {
 	ctx, span := trace.StartSpan(ctx, "blockChain.onBlockBatch")
 	defer span.End()
 
 	if len(blks) == 0 || len(blockRoots) == 0 {
-		return nil, nil, errors.New("no blocks provided")
+		return nil, nil, nil, errors.New("no blocks provided")
 	}
 	if err := helpers.BeaconBlockIsNil(blks[0]); err != nil {
-		return nil, nil, err
+		return nil, nil, nil, err
 	}
 	b := blks[0].Block()
 
 	// Retrieve incoming block's pre state.
 	if err := s.verifyBlkPreState(ctx, b); err != nil {
-		return nil, nil, err
+		return nil, nil, nil, err
 	}
 	preState, err := s.cfg.StateGen.StateByRootInitialSync(ctx, bytesutil.ToBytes32(b.ParentRoot()))
 	if err != nil {
-		return nil, nil, err
+		return nil, nil, nil, err
 	}
 	if preState == nil || preState.IsNil() {
-		return nil, nil, fmt.Errorf("nil pre state for slot %d", b.Slot())
+		return nil, nil, nil, fmt.Errorf("nil pre state for slot %d", b.Slot())
 	}
 
 	jCheckpoints := make([]*ethpb.Checkpoint, len(blks))
 	fCheckpoints := make([]*ethpb.Checkpoint, len(blks))
+	optimistic := make([]bool, len(blks))
 	sigSet := &bls.SignatureBatch{
 		Signatures: [][]byte{},
 		PublicKeys: []bls.PublicKey{},
@@ -281,43 +414,140 @@ func (s *Service) onBlockBatch(ctx context.Context, blks []block.SignedBeaconBlo
 	var set *bls.SignatureBatch
 	boundaries := make(map[[32]byte]state.BeaconState)
 	for i, b := range blks {
+		preStateCopied := preState.Copy() // TODO_MERGE: Optimize this copy.
 		set, preState, err = transition.ExecuteStateTransitionNoVerifyAnySig(ctx, preState, b)
 		if err != nil {
-			return nil, nil, err
+			return nil, nil, nil, err
 		}
+
+		// Non merge blocks are never optimistic
+		optimistic[i] = false
+		if preState.Version() == version.Bellatrix {
+			executionEnabled, err := blocks.ExecutionEnabled(preState, b.Block().Body())
+			if err != nil {
+				return nil, nil, nil, errors.Wrap(err, "could not check if execution is enabled")
+			}
+			if executionEnabled {
+				payload, err := b.Block().Body().ExecutionPayload()
+				if err != nil {
+					return nil, nil, nil, errors.Wrap(err, "could not get body execution payload")
+				}
+				status, err := s.cfg.ExecutionEngineCaller.NewPayload(ctx, payload)
+				if err != nil {
+					return nil, nil, nil, err
+				}
+				switch status.Status {
+				case enginev1.PayloadStatus_INVALID, enginev1.PayloadStatus_INVALID_BLOCK_HASH, enginev1.PayloadStatus_INVALID_TERMINAL_BLOCK:
+					// TODO_MERGE walk up the parent chain removing
+					return nil, nil, nil, fmt.Errorf("could not prcess execution payload with status : %v", status.Status)
+				case enginev1.PayloadStatus_SYNCING, enginev1.PayloadStatus_ACCEPTED:
+					candidate, err := s.optimisticCandidateBlock(ctx, b.Block())
+					if err != nil {
+						return nil, nil, nil, errors.Wrap(err, "could not check if block is optimistic candidate")
+					}
+					if !candidate {
+						return nil, nil, nil, errors.New("could not optimistically sync block")
+					}
+					log.WithFields(logrus.Fields{
+						"slot":        b.Block().Slot(),
+						"root":        fmt.Sprintf("%#x", bytesutil.Trunc(blockRoots[i][:])),
+						"payloadHash": fmt.Sprintf("%#x", bytesutil.Trunc(payload.BlockHash)),
+					}).Info("Block is optimistic candidate")
+					optimistic[i] = true
+					break
+				case enginev1.PayloadStatus_VALID:
+				default:
+					return nil, nil, nil, errors.New("unknown payload status")
+				}
+				if !optimistic[i] {
+					mergeBlock, err := blocks.MergeTransitionBlock(preStateCopied, b.Block().Body())
+					if err != nil {
+						return nil, nil, nil, errors.Wrap(err, "could not check if merge block is terminal")
+					}
+					if mergeBlock {
+						if err := s.validateTerminalBlock(ctx, b); err != nil {
+							return nil, nil, nil, err
+						}
+					}
+				}
+
+				headPayload, err := b.Block().Body().ExecutionPayload()
+				if err != nil {
+					return nil, nil, nil, err
+
+				}
+				// TODO_MERGE: Loading the finalized block from DB on per block is not ideal. Finalized block should be cached here
+				finalizedBlock, err := s.cfg.BeaconDB.Block(ctx, bytesutil.ToBytes32(preState.FinalizedCheckpoint().Root))
+				if err != nil {
+					return nil, nil, nil, err
+
+				}
+				finalizedBlockHash := params.BeaconConfig().ZeroHash[:]
+				if finalizedBlock != nil && finalizedBlock.Version() == version.Bellatrix {
+					finalizedPayload, err := finalizedBlock.Block().Body().ExecutionPayload()
+					if err != nil {
+						return nil, nil, nil, err
+
+					}
+					finalizedBlockHash = finalizedPayload.BlockHash
+				}
+
+				fcs := &enginev1.ForkchoiceState{
+					HeadBlockHash:      headPayload.BlockHash,
+					SafeBlockHash:      headPayload.BlockHash,
+					FinalizedBlockHash: finalizedBlockHash,
+				}
+
+				resp, err := s.cfg.ExecutionEngineCaller.ForkchoiceUpdated(ctx, fcs, nil /* attribute */)
+				if err != nil {
+					return nil, nil, nil, err
+				}
+				switch resp.Status.Status {
+				case enginev1.PayloadStatus_INVALID, enginev1.PayloadStatus_INVALID_BLOCK_HASH, enginev1.PayloadStatus_INVALID_TERMINAL_BLOCK:
+					return nil, nil, nil, fmt.Errorf("could not prcess execution payload with status : %v", resp.Status.Status)
+				case enginev1.PayloadStatus_SYNCING, enginev1.PayloadStatus_ACCEPTED:
+					break
+				case enginev1.PayloadStatus_VALID:
+				default:
+					return nil, nil, nil, errors.Wrap(err, "could not execute payload")
+				}
+			}
+		}
+
 		// Save potential boundary states.
 		if slots.IsEpochStart(preState.Slot()) {
 			boundaries[blockRoots[i]] = preState.Copy()
 			if err := s.handleEpochBoundary(ctx, preState); err != nil {
-				return nil, nil, errors.Wrap(err, "could not handle epoch boundary state")
+				return nil, nil, nil, errors.Wrap(err, "could not handle epoch boundary state")
 			}
 		}
 		jCheckpoints[i] = preState.CurrentJustifiedCheckpoint()
 		fCheckpoints[i] = preState.FinalizedCheckpoint()
+
 		sigSet.Join(set)
 	}
 	verify, err := sigSet.Verify()
 	if err != nil {
-		return nil, nil, err
+		return nil, nil, nil, err
 	}
 	if !verify {
-		return nil, nil, errors.New("batch block signature verification failed")
+		return nil, nil, nil, errors.New("batch block signature verification failed")
 	}
 	for r, st := range boundaries {
 		if err := s.cfg.StateGen.SaveState(ctx, r, st); err != nil {
-			return nil, nil, err
+			return nil, nil, nil, err
 		}
 	}
 	// Also saves the last post state which to be used as pre state for the next batch.
 	lastB := blks[len(blks)-1]
 	lastBR := blockRoots[len(blockRoots)-1]
 	if err := s.cfg.StateGen.SaveState(ctx, lastBR, preState); err != nil {
-		return nil, nil, err
+		return nil, nil, nil, err
 	}
 	if err := s.saveHeadNoDB(ctx, lastB, lastBR, preState); err != nil {
-		return nil, nil, err
+		return nil, nil, nil, err
 	}
-	return fCheckpoints, jCheckpoints, nil
+	return fCheckpoints, jCheckpoints, optimistic, nil
 }
 
 // handles a block after the block's batch has been verified, where we can save blocks
@@ -501,3 +731,84 @@ func (s *Service) pruneCanonicalAttsFromPool(ctx context.Context, r [32]byte, b
 	}
 	return nil
 }
+
+// validates terminal block hash in the event of manual overrides before checking for total difficulty.
+//
+// def validate_merge_block(block: BeaconBlock) -> None:
+//    """
+//    Check the parent PoW block of execution payload is a valid terminal PoW block.
+//
+//    Note: Unavailable PoW block(s) may later become available,
+//    and a client software MAY delay a call to ``validate_merge_block``
+//    until the PoW block(s) become available.
+//    """
+//    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
+//        return block.block_hash == TERMINAL_BLOCK_HASH
+//
+//    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) validateTerminalBlock(ctx context.Context, b block.SignedBeaconBlock) error {
+	payload, err := b.Block().Body().ExecutionPayload()
+	if err != nil {
+		return err
+	}
+	if bytesutil.ToBytes32(params.BeaconConfig().TerminalBlockHash.Bytes()) != [32]byte{} {
+		// `TERMINAL_BLOCK_HASH` is used as an override, the activation epoch must be reached.
+		if params.BeaconConfig().TerminalBlockHashActivationEpoch > slots.ToEpoch(b.Block().Slot()) {
+			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
+	}
+	transitionBlk, err := s.cfg.ExecutionEngineCaller.ExecutionBlockByHash(ctx, common.BytesToHash(payload.ParentHash))
+	if err != nil {
+		return errors.Wrap(err, "could not get transition block")
+	}
+	parentTransitionBlk, err := s.cfg.ExecutionEngineCaller.ExecutionBlockByHash(ctx, common.BytesToHash(transitionBlk.ParentHash))
+	if err != nil {
+		return errors.Wrap(err, "could not get transition parent block")
+	}
+	transitionBlkTTD := new(uint256.Int)
+	transitionBlkTTD.SetBytes(bytesutil.ReverseByteOrder(transitionBlk.TotalDifficulty))
+
+	parentTransitionBlkTTD := new(uint256.Int)
+	parentTransitionBlkTTD.SetBytes(bytesutil.ReverseByteOrder(parentTransitionBlk.TotalDifficulty))
+
+	validated, err := validTerminalPowBlock(transitionBlkTTD, parentTransitionBlkTTD)
+	if err != nil {
+		return err
+	}
+	if !validated {
+		return errors.New("invalid difficulty for terminal block")
+	}
+
+	log.WithFields(logrus.Fields{
+		"slot":                                 b.Block().Slot(),
+		"transitionBlockHash":                  common.BytesToHash(payload.ParentHash).String(),
+		"transitionBlockParentHash":            common.BytesToHash(transitionBlk.ParentHash).String(),
+		"terminalTotalDifficulty":              params.BeaconConfig().TerminalTotalDifficulty,
+		"transitionBlockTotalDifficulty":       transitionBlkTTD,
+		"transitionBlockParentTotalDifficulty": parentTransitionBlkTTD,
+	}).Info("Verified terminal block")
+
+	return nil
+}
+
+// Saves synced and validated tips to DB.
+func (s *Service) saveSyncedTipsDB(ctx context.Context) error {
+	tips := s.cfg.ForkChoiceStore.SyncedTips()
+	if len(tips) == 0 {
+		return nil
+	}
+	return s.cfg.BeaconDB.UpdateValidatedTips(ctx, tips)
+}

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)

beacon-chain/blockchain/process_block_test.go

@@ -100,7 +100,7 @@ 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",
@@ -178,7 +178,7 @@ func TestStore_OnBlockBatch(t *testing.T) {
 	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:])
+	_, _, _, err = service.onBlockBatch(ctx, blks[1:], blkRoots[1:])
 	require.NoError(t, err)
 }
 
@@ -789,7 +789,7 @@ 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",
@@ -996,3 +996,49 @@ 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 TestService_saveSyncedTipsDB(t *testing.T) {
+	ctx := context.Background()
+	beaconDB := testDB.SetupDB(t)
+	service := setupBeaconChain(t, beaconDB)
+
+	b1 := util.NewBeaconBlock()
+	b1.Block.Slot = 1
+	b1.Block.ParentRoot = bytesutil.PadTo([]byte{'a'}, 32)
+	r1, err := b1.Block.HashTreeRoot()
+	require.NoError(t, err)
+	b100 := util.NewBeaconBlock()
+	b100.Block.Slot = 100
+	b100.Block.ParentRoot = r1[:]
+	r100, err := b100.Block.HashTreeRoot()
+	require.NoError(t, err)
+	b200 := util.NewBeaconBlock()
+	b200.Block.Slot = 200
+	b200.Block.ParentRoot = r1[:]
+	r200, err := b200.Block.HashTreeRoot()
+	require.NoError(t, err)
+	for _, b := range []*ethpb.SignedBeaconBlock{b1, b100, b200} {
+		beaconBlock := util.NewBeaconBlock()
+		beaconBlock.Block.Slot = b.Block.Slot
+		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))
+	}
+
+	require.NoError(t, service.cfg.ForkChoiceStore.UpdateSyncedTipsWithValidRoot(ctx, r100))
+	require.NoError(t, service.saveSyncedTipsDB(ctx))
+	savedTips, err := service.cfg.BeaconDB.ValidatedTips(ctx)
+	require.NoError(t, err)
+	require.Equal(t, 2, len(savedTips))
+	require.Equal(t, types.Slot(1), savedTips[r1])
+	require.Equal(t, types.Slot(100), savedTips[r100])
+
+	// Delete invalid root
+	require.NoError(t, service.cfg.ForkChoiceStore.UpdateSyncedTipsWithInvalidRoot(ctx, r200))
+	require.NoError(t, service.saveSyncedTipsDB(ctx))
+	savedTips, err = service.cfg.BeaconDB.ValidatedTips(ctx)
+	require.NoError(t, err)
+	require.Equal(t, 1, len(savedTips))
+	require.Equal(t, types.Slot(100), savedTips[r100])
+}

beacon-chain/blockchain/receive_block.go

@@ -77,7 +77,7 @@ func (s *Service) ReceiveBlockBatch(ctx context.Context, blocks []block.SignedBe
 	defer span.End()
 
 	// Apply state transition on the incoming newly received blockCopy without verifying its BLS contents.
-	fCheckpoints, jCheckpoints, err := s.onBlockBatch(ctx, blocks, blkRoots)
+	fCheckpoints, jCheckpoints, optimistic, err := s.onBlockBatch(ctx, blocks, blkRoots)
 	if err != nil {
 		err := errors.Wrap(err, "could not process block in batch")
 		tracing.AnnotateError(span, err)
@@ -90,6 +90,19 @@ func (s *Service) ReceiveBlockBatch(ctx context.Context, blocks []block.SignedBe
 			tracing.AnnotateError(span, err)
 			return err
 		}
+		if !optimistic[i] {
+			root, err := b.Block().HashTreeRoot()
+			if err != nil {
+				return err
+			}
+			if err := s.cfg.ForkChoiceStore.UpdateSyncedTipsWithValidRoot(ctx, root); err != nil {
+				return err
+			}
+			if err := s.saveSyncedTipsDB(ctx); err != nil {
+				return errors.Wrap(err, "could not save synced tips")
+			}
+		}
+
 		// Send notification of the processed block to the state feed.
 		s.cfg.StateNotifier.StateFeed().Send(&feed.Event{
 			Type: statefeed.BlockProcessed,

beacon-chain/blockchain/service.go

@@ -27,6 +27,7 @@ import (
 	"github.com/prysmaticlabs/prysm/beacon-chain/operations/voluntaryexits"
 	"github.com/prysmaticlabs/prysm/beacon-chain/p2p"
 	"github.com/prysmaticlabs/prysm/beacon-chain/powchain"
+	v1 "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"
@@ -82,6 +83,8 @@ type config struct {
 	StateGen                *stategen.State
 	SlasherAttestationsFeed *event.Feed
 	WeakSubjectivityCheckpt *ethpb.Checkpoint
+	BlockFetcher            powchain.POWBlockFetcher
+	ExecutionEngineCaller   v1.EngineCaller
 	FinalizedStateAtStartUp state.BeaconState
 }
 
@@ -187,6 +190,10 @@ func (s *Service) startFromSavedState(saved state.BeaconState) error {
 	store := protoarray.New(justified.Epoch, finalized.Epoch, bytesutil.ToBytes32(finalized.Root))
 	s.cfg.ForkChoiceStore = store
 
+	if err := s.loadSyncedTips(originRoot, saved.Slot()); err != nil {
+		return err
+	}
+
 	ss, err := slots.EpochStart(finalized.Epoch)
 	if err != nil {
 		return errors.Wrap(err, "could not get start slot of finalized epoch")
@@ -213,7 +220,7 @@ func (s *Service) startFromSavedState(saved state.BeaconState) error {
 		Type: statefeed.Initialized,
 		Data: &statefeed.InitializedData{
 			StartTime:             s.genesisTime,
-			GenesisValidatorsRoot: saved.GenesisValidatorRoot(),
+			GenesisValidatorsRoot: saved.GenesisValidatorsRoot(),
 		},
 	})
 
@@ -375,7 +382,7 @@ func (s *Service) onPowchainStart(ctx context.Context, genesisTime time.Time) {
 		Type: statefeed.Initialized,
 		Data: &statefeed.InitializedData{
 			StartTime:             genesisTime,
-			GenesisValidatorsRoot: initializedState.GenesisValidatorRoot(),
+			GenesisValidatorsRoot: initializedState.GenesisValidatorsRoot(),
 		},
 	})
 }

beacon-chain/blockchain/service_test.go

@@ -8,6 +8,7 @@ import (
 	"time"
 
 	"github.com/ethereum/go-ethereum/common"
+	types "github.com/prysmaticlabs/eth2-types"
 	"github.com/prysmaticlabs/prysm/async/event"
 	"github.com/prysmaticlabs/prysm/beacon-chain/blockchain/store"
 	mock "github.com/prysmaticlabs/prysm/beacon-chain/blockchain/testing"
@@ -163,6 +164,74 @@ func TestChainStartStop_Initialized(t *testing.T) {
 	require.LogsContain(t, hook, "data already exists")
 }
 
+func TestChainStart_SyncedTipsInDB(t *testing.T) {
+	ctx := context.Background()
+	beaconDB := testDB.SetupDB(t)
+
+	chainService := setupBeaconChain(t, beaconDB)
+
+	genesisBlk := util.NewBeaconBlock()
+	blkRoot, err := genesisBlk.Block.HashTreeRoot()
+	require.NoError(t, err)
+	require.NoError(t, beaconDB.SaveBlock(ctx, wrapper.WrappedPhase0SignedBeaconBlock(genesisBlk)))
+	s, err := util.NewBeaconState()
+	require.NoError(t, err)
+	require.NoError(t, s.SetSlot(1))
+	require.NoError(t, beaconDB.SaveState(ctx, s, blkRoot))
+	require.NoError(t, beaconDB.SaveHeadBlockRoot(ctx, blkRoot))
+	require.NoError(t, beaconDB.SaveGenesisBlockRoot(ctx, blkRoot))
+	require.NoError(t, beaconDB.SaveJustifiedCheckpoint(ctx, &ethpb.Checkpoint{Root: blkRoot[:]}))
+	require.NoError(t, beaconDB.SaveFinalizedCheckpoint(ctx, &ethpb.Checkpoint{Root: blkRoot[:]}))
+	chainService.cfg.FinalizedStateAtStartUp = s
+
+	tips := make(map[[32]byte]types.Slot)
+	tips[bytesutil.ToBytes32([]byte{'a'})] = 1
+	tips[bytesutil.ToBytes32([]byte{'b'})] = 2
+	require.NoError(t, beaconDB.UpdateValidatedTips(ctx, tips))
+
+	// Test the start function.
+	chainService.Start()
+
+	// Test synced Tips in DB
+	tips2 := chainService.cfg.ForkChoiceStore.SyncedTips()
+	require.Equal(t, len(tips2), len(tips))
+	for k, v := range tips {
+		v2, ok := tips2[k]
+		require.Equal(t, true, ok)
+		require.Equal(t, v, v2)
+	}
+}
+
+func TestChainStart_SyncedTipsNotInDB(t *testing.T) {
+	ctx := context.Background()
+	beaconDB := testDB.SetupDB(t)
+
+	chainService := setupBeaconChain(t, beaconDB)
+
+	genesisBlk := util.NewBeaconBlock()
+	blkRoot, err := genesisBlk.Block.HashTreeRoot()
+	require.NoError(t, err)
+	require.NoError(t, beaconDB.SaveBlock(ctx, wrapper.WrappedPhase0SignedBeaconBlock(genesisBlk)))
+	s, err := util.NewBeaconState()
+	require.NoError(t, err)
+	require.NoError(t, s.SetSlot(1))
+	require.NoError(t, beaconDB.SaveState(ctx, s, blkRoot))
+	require.NoError(t, beaconDB.SaveHeadBlockRoot(ctx, blkRoot))
+	require.NoError(t, beaconDB.SaveGenesisBlockRoot(ctx, blkRoot))
+	require.NoError(t, beaconDB.SaveJustifiedCheckpoint(ctx, &ethpb.Checkpoint{Root: blkRoot[:]}))
+	require.NoError(t, beaconDB.SaveFinalizedCheckpoint(ctx, &ethpb.Checkpoint{Root: blkRoot[:]}))
+	chainService.cfg.FinalizedStateAtStartUp = s
+	// Test the start function.
+	chainService.Start()
+
+	// Test synced Tips in DB
+	tips := chainService.cfg.ForkChoiceStore.SyncedTips()
+	require.Equal(t, 1, len(tips))
+	slot, ok := tips[blkRoot]
+	require.Equal(t, true, ok)
+	require.Equal(t, types.Slot(1), slot)
+}
+
 func TestChainStartStop_GenesisZeroHashes(t *testing.T) {
 	hook := logTest.NewGlobal()
 	ctx := context.Background()
@@ -278,7 +347,7 @@ 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 +391,7 @@ 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 +447,7 @@ 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))

beacon-chain/blockchain/testing/BUILD.bazel

@@ -20,7 +20,6 @@ go_library(
         "//beacon-chain/db:go_default_library",
         "//beacon-chain/forkchoice/protoarray: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

@@ -20,7 +20,6 @@ import (
 	"github.com/prysmaticlabs/prysm/beacon-chain/db"
 	"github.com/prysmaticlabs/prysm/beacon-chain/forkchoice/protoarray"
 	"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"
@@ -29,6 +28,8 @@ import (
 	"github.com/sirupsen/logrus"
 )
 
+var ErrNilState = errors.New("nil state")
+
 // ChainService defines the mock interface for testing
 type ChainService struct {
 	State                       state.BeaconState
@@ -159,7 +160,7 @@ 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 +187,7 @@ 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 +216,7 @@ 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())
@@ -328,8 +329,8 @@ 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 +370,8 @@ 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{}
 }
 
@@ -438,3 +439,13 @@ func (s *ChainService) HeadSyncSelectionProofDomain(_ context.Context, _ types.S
 func (s *ChainService) HeadSyncContributionProofDomain(_ context.Context, _ types.Slot) ([]byte, error) {
 	return s.SyncContributionProofDomain, nil
 }
+
+// IsOptimistic mocks the same method in the chain service.
+func (s *ChainService) IsOptimistic(_ context.Context) (bool, error) {
+	return false, nil
+}
+
+// IsOptimisticForRoot mocks the same method in the chain service.
+func (s *ChainService) IsOptimisticForRoot(_ context.Context, _ [32]byte, _ types.Slot) (bool, error) {
+	return false, 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 +17,13 @@ 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) {
+func MergeTransitionComplete(st state.BeaconState) (bool, error) {
 	h, err := st.LatestExecutionPayloadHeader()
 	if err != nil {
 		return false, err
@@ -31,15 +32,15 @@ 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 +48,20 @@ func IsMergeBlock(st state.BeaconState, blk block.BeaconBlockBody) (bool, error)
 		return false, err
 	}
 
-	payload, err := blk.ExecutionPayload()
+	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 +73,15 @@ 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 +92,7 @@ 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
 	}
@@ -291,3 +304,16 @@ func isEmptyHeader(h *ethpb.ExecutionPayloadHeader) bool {
 	}
 	return true
 }
+
+func EmptyPayload() *enginev1.ExecutionPayload {
+	return &enginev1.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),
+		Random:        make([]byte, fieldparams.RootLength),
+		BaseFeePerGas: make([]byte, fieldparams.RootLength),
+		BlockHash:     make([]byte, fieldparams.RootLength),
+	}
+}

beacon-chain/core/blocks/payload_test.go

@@ -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)
@@ -341,15 +341,49 @@ 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_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
@@ -617,7 +651,7 @@ 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)
 	}
 }

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,

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())

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/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_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/iface/interface.go

@@ -30,6 +30,7 @@ type ReadOnlyDatabase interface {
 	IsFinalizedBlock(ctx context.Context, blockRoot [32]byte) bool
 	FinalizedChildBlock(ctx context.Context, blockRoot [32]byte) (block.SignedBeaconBlock, error)
 	HighestSlotBlocksBelow(ctx context.Context, slot types.Slot) ([]block.SignedBeaconBlock, error)
+	ValidatedTips(ctx context.Context) (map[[32]byte]types.Slot, error)
 	// State related methods.
 	State(ctx context.Context, blockRoot [32]byte) (state.BeaconState, error)
 	GenesisState(ctx context.Context) (state.BeaconState, error)
@@ -58,9 +59,11 @@ 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
+	UpdateValidatedTips(ctx context.Context, newVals map[[32]byte]types.Slot) error
 	// State related methods.
 	SaveState(ctx context.Context, state state.ReadOnlyBeaconState, blockRoot [32]byte) error
 	SaveStates(ctx context.Context, states []state.ReadOnlyBeaconState, blockRoots [][32]byte) error

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

@@ -2,6 +2,9 @@ package kv
 
 import "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")

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/deterministic-genesis/service.go

@@ -132,7 +132,11 @@ 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/interfaces.go

@@ -8,7 +8,7 @@ import (
 	"github.com/prysmaticlabs/prysm/beacon-chain/forkchoice/protoarray"
 )
 
-// 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.
@@ -16,11 +16,13 @@ type ForkChoicer interface {
 	Pruner               // to clean old data for fork choice.
 	Getter               // to retrieve fork choice information.
 	ProposerBooster      // ability to boost timely-proposed block roots.
+	SyncTipper           // to update and retrieve validated sync tips.
 }
 
-// HeadRetriever retrieves head root of the current chain.
+// 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)
 }
 
 // BlockProcessor processes the block that's used for accounting fork choice.
@@ -54,3 +56,11 @@ type Getter interface {
 	AncestorRoot(ctx context.Context, root [32]byte, slot types.Slot) ([]byte, error)
 	IsCanonical(root [32]byte) bool
 }
+
+// SyncTipper returns sync tips related information.
+type SyncTipper interface {
+	SyncedTips() map[[32]byte]types.Slot
+	SetSyncedTips(tips map[[32]byte]types.Slot) error
+	UpdateSyncedTipsWithValidRoot(ctx context.Context, root [32]byte) error
+	UpdateSyncedTipsWithInvalidRoot(ctx context.Context, root [32]byte) error
+}

beacon-chain/forkchoice/protoarray/doc.go

@@ -1,7 +1,7 @@
 /*
 Package protoarray implements proto array fork choice as outlined:
 https://github.com/protolambda/lmd-ghost#array-based-stateful-dag-proto_array
-This was motivated by the the original implementation by Sigma Prime here:
+This was motivated by the original implementation by Sigma Prime here:
 https://github.com/sigp/lighthouse/pull/804
 */
 package protoarray

beacon-chain/forkchoice/protoarray/errors.go

@@ -11,3 +11,4 @@ var errInvalidBestDescendantIndex = errors.New("best descendant index is invalid
 var errInvalidParentDelta = errors.New("parent delta is invalid")
 var errInvalidNodeDelta = errors.New("node delta is invalid")
 var errInvalidDeltaLength = errors.New("delta length is invalid")
+var errInvalidSyncedTips = errors.New("invalid synced tips")

beacon-chain/forkchoice/protoarray/helpers.go

@@ -24,7 +24,7 @@ func computeDeltas(
 		oldBalance := uint64(0)
 		newBalance := uint64(0)
 
-		// Skip if validator has never voted for current root and next root (ie. if the
+		// 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

beacon-chain/forkchoice/protoarray/metrics.go

@@ -48,4 +48,16 @@ var (
 			Help: "The number of times pruning happened.",
 		},
 	)
+	lastSyncedTipSlot = promauto.NewGauge(
+		prometheus.GaugeOpts{
+			Name: "proto_array_last_synced_tip_slot",
+			Help: "The slot of the last fully validated block added to the proto array.",
+		},
+	)
+	syncedTipsCount = promauto.NewGauge(
+		prometheus.GaugeOpts{
+			Name: "proto_array_synced_tips_count",
+			Help: "The number of elements in the syncedTips structure.",
+		},
+	)
 )

beacon-chain/forkchoice/protoarray/optimistic_sync.go

@@ -89,17 +89,37 @@ func (f *ForkChoice) Optimistic(ctx context.Context, root [32]byte, slot types.S
 	return f.Optimistic(ctx, root, slot)
 }
 
-// UpdateSyncedTips updates the synced_tips map when the block with the given root becomes VALID
-func (f *ForkChoice) UpdateSyncedTips(ctx context.Context, root [32]byte) error {
+// This function returns the index of sync tip node that's ancestor to the input node.
+// In the event of none, `NonExistentNode` is returned.
+// This internal method assumes the caller holds a lock on syncedTips and s.nodesLock
+func (s *Store) findSyncedTip(ctx context.Context, node *Node, syncedTips *optimisticStore) (uint64, error) {
+	for {
+		if ctx.Err() != nil {
+			return 0, ctx.Err()
+		}
+		if _, ok := syncedTips.validatedTips[node.root]; ok {
+			return s.nodesIndices[node.root], nil
+		}
+		if node.parent == NonExistentNode {
+			return NonExistentNode, nil
+		}
+		node = s.nodes[node.parent]
+	}
+}
+
+// UpdateSyncedTipsWithValidRoot is called with the root of a block that was returned as
+// VALID by the EL. This routine recomputes and updates the synced_tips map to
+// account for this new tip.
+func (f *ForkChoice) UpdateSyncedTipsWithValidRoot(ctx context.Context, root [32]byte) error {
 	f.store.nodesLock.RLock()
 	defer f.store.nodesLock.RUnlock()
-	// We can only update if given root is in fork choice
+	// We can only update if given root is in Fork Choice
 	index, ok := f.store.nodesIndices[root]
 	if !ok {
 		return errInvalidNodeIndex
 	}
 
-	// We can only update if root is a leaf in fork choice
+	// We can only update if root is a leaf in Fork Choice
 	node := f.store.nodes[index]
 	if node.bestChild != NonExistentNode {
 		return errInvalidBestChildIndex
@@ -114,7 +134,9 @@ func (f *ForkChoice) UpdateSyncedTips(ctx context.Context, root [32]byte) error
 	}
 
 	// Cache root and slot to validated tips
-	f.syncedTips.validatedTips[root] = node.slot
+	newTips := make(map[[32]byte]types.Slot)
+	newValidSlot := node.slot
+	newTips[root] = newValidSlot
 
 	// Compute the full valid path from the given node to its previous synced tip
 	// This path will now consist of fully validated blocks. Notice that
@@ -122,6 +144,7 @@ func (f *ForkChoice) UpdateSyncedTips(ctx context.Context, root [32]byte) error
 	// In this case, only one block can be in syncedTips as the whole
 	// Fork Choice would be a descendant of this block.
 	validPath := make(map[uint64]bool)
+	validPath[index] = true
 	for {
 		if ctx.Err() != nil {
 			return ctx.Err()
@@ -144,27 +167,19 @@ func (f *ForkChoice) UpdateSyncedTips(ctx context.Context, root [32]byte) error
 
 	// Retrieve the list of leaves in the Fork Choice
 	// These are all the nodes that have NonExistentNode as best child.
-	var leaves []uint64
-	for i := uint64(0); i < uint64(len(f.store.nodes)); i++ {
-		if ctx.Err() != nil {
-			return ctx.Err()
-		}
-		node = f.store.nodes[i]
-		if node.bestChild == NonExistentNode {
-			leaves = append(leaves, i)
-		}
+	leaves, err := f.store.leaves()
+	if err != nil {
+		return err
 	}
 
 	// For each leaf, recompute the new tip.
-	newTips := make(map[[32]byte]types.Slot)
 	for _, i := range leaves {
-		if ctx.Err() != nil {
-			return ctx.Err()
-		}
-
 		node = f.store.nodes[i]
 		j := i
 		for {
+			if ctx.Err() != nil {
+				return ctx.Err()
+			}
 			// Stop if we reached the previous tip
 			_, ok = f.syncedTips.validatedTips[node.root]
 			if ok {
@@ -191,5 +206,117 @@ func (f *ForkChoice) UpdateSyncedTips(ctx context.Context, root [32]byte) error
 	}
 
 	f.syncedTips.validatedTips = newTips
+	lastSyncedTipSlot.Set(float64(newValidSlot))
+	syncedTipsCount.Set(float64(len(newTips)))
+	return nil
+}
+
+// UpdateSyncedTipsWithInvalidRoot updates the synced_tips map when the block with the given root becomes INVALID.
+func (f *ForkChoice) UpdateSyncedTipsWithInvalidRoot(ctx context.Context, root [32]byte) error {
+	f.store.nodesLock.Lock()
+	defer f.store.nodesLock.Unlock()
+	idx, ok := f.store.nodesIndices[root]
+	if !ok {
+		return errInvalidNodeIndex
+	}
+	node := f.store.nodes[idx]
+	// We only support changing status for the tips in Fork Choice store.
+	if node.bestChild != NonExistentNode {
+		return errInvalidNodeIndex
+	}
+
+	parentIndex := node.parent
+	// This should not happen
+	if parentIndex == NonExistentNode {
+		return errInvalidNodeIndex
+	}
+	// Update the weights of the nodes subtracting the INVALID node's weight
+	weight := node.weight
+	node = f.store.nodes[parentIndex]
+	for {
+		if ctx.Err() != nil {
+			return ctx.Err()
+		}
+		node.weight -= weight
+		if node.parent == NonExistentNode {
+			break
+		}
+		node = f.store.nodes[node.parent]
+	}
+	parent := copyNode(f.store.nodes[parentIndex])
+
+	// delete the invalid node, order is important
+	f.store.nodes = append(f.store.nodes[:idx], f.store.nodes[idx+1:]...)
+	delete(f.store.nodesIndices, root)
+	// Fix parent and best child for each node
+	for _, node := range f.store.nodes {
+		if node.parent == NonExistentNode {
+			node.parent = NonExistentNode
+		} else if node.parent > idx {
+			node.parent -= 1
+		}
+		if node.bestChild == NonExistentNode || node.bestChild == idx {
+			node.bestChild = NonExistentNode
+		} else if node.bestChild > idx {
+			node.bestChild -= 1
+		}
+		if node.bestDescendant == NonExistentNode || node.bestDescendant == idx {
+			node.bestDescendant = NonExistentNode
+		} else if node.bestDescendant > idx {
+			node.bestDescendant -= 1
+		}
+	}
+
+	// Update the parent's best child and best descendant if necessary.
+	if parent.bestChild == idx || parent.bestDescendant == idx {
+		for childIndex, child := range f.store.nodes {
+			if child.parent == parentIndex {
+				err := f.store.updateBestChildAndDescendant(
+					parentIndex, uint64(childIndex))
+				if err != nil {
+					return err
+				}
+				break
+			}
+		}
+	}
+
+	// Return early if the parent is not a synced_tip.
+	f.syncedTips.Lock()
+	defer f.syncedTips.Unlock()
+	parentRoot := parent.root
+	_, ok = f.syncedTips.validatedTips[parentRoot]
+	if !ok {
+		return nil
+	}
+
+	leaves, err := f.store.leaves()
+	if err != nil {
+		return err
+	}
+
+	for _, i := range leaves {
+		node = f.store.nodes[i]
+		for {
+			if ctx.Err() != nil {
+				return ctx.Err()
+			}
+
+			// Return early if the parent is still a synced tip
+			if node.root == parentRoot {
+				return nil
+			}
+			_, ok = f.syncedTips.validatedTips[node.root]
+			if ok {
+				break
+			}
+			if node.parent == NonExistentNode {
+				break
+			}
+			node = f.store.nodes[node.parent]
+		}
+	}
+	delete(f.syncedTips.validatedTips, parentRoot)
+	syncedTipsCount.Set(float64(len(f.syncedTips.validatedTips)))
 	return nil
 }

beacon-chain/forkchoice/protoarray/optimistic_sync_test.go

@@ -216,7 +216,7 @@ func TestOptimistic(t *testing.T) {
 // And every block in the Fork choice is optimistic. Synced_Tips contains a
 // single block that is outside of Fork choice
 //
-func TestUpdateSyncedTips(t *testing.T) {
+func TestUpdateSyncTipsWithValidRoots(t *testing.T) {
 	ctx := context.Background()
 	f := setup(1, 1)
 
@@ -235,7 +235,7 @@ func TestUpdateSyncedTips(t *testing.T) {
 	tests := []struct {
 		root      [32]byte                // the root of the new VALID block
 		tips      map[[32]byte]types.Slot // the old synced tips
-		newtips   map[[32]byte]types.Slot // the updated synced tips
+		newTips   map[[32]byte]types.Slot // the updated synced tips
 		wantedErr error
 	}{
 		{
@@ -321,14 +321,230 @@ func TestUpdateSyncedTips(t *testing.T) {
 		f.syncedTips.Lock()
 		f.syncedTips.validatedTips = tc.tips
 		f.syncedTips.Unlock()
-		err := f.UpdateSyncedTips(context.Background(), tc.root)
+		err := f.UpdateSyncedTipsWithValidRoot(context.Background(), tc.root)
 		if tc.wantedErr != nil {
 			require.ErrorIs(t, err, tc.wantedErr)
 		} else {
 			require.NoError(t, err)
 			f.syncedTips.RLock()
-			require.DeepEqual(t, f.syncedTips.validatedTips, tc.newtips)
+			require.DeepEqual(t, f.syncedTips.validatedTips, tc.newTips)
 			f.syncedTips.RUnlock()
 		}
 	}
 }
+
+// We test the algorithm to update a node from SYNCING to INVALID
+// We start with the same diagram as above:
+//
+//                         E(2) -- F(1)
+//                        /
+//             C(7) -- D(6)
+//            /           \
+//  A(10) -- B(9)          G(3) -- H(1) -- I(0)
+//            \               \
+//             J(1)             -- K(1) -- L(0)
+//
+// And every block in the Fork choice is optimistic. Synced_Tips contains a
+// single block that is outside of Fork choice. The numbers in parentheses are
+// the weights of the nodes before removal
+//
+func TestUpdateSyncTipsWithInvalidRoot(t *testing.T) {
+	tests := []struct {
+		root              [32]byte                // the root of the new INVALID block
+		tips              map[[32]byte]types.Slot // the old synced tips
+		wantedParentTip   bool
+		newBestChild      uint64
+		newBestDescendant uint64
+		newParentWeight   uint64
+	}{
+		{
+			[32]byte{'j'},
+			map[[32]byte]types.Slot{
+				[32]byte{'b'}: 101,
+				[32]byte{'d'}: 103,
+				[32]byte{'g'}: 104,
+			},
+			false,
+			3,
+			4,
+			8,
+		},
+		{
+			[32]byte{'j'},
+			map[[32]byte]types.Slot{
+				[32]byte{'b'}: 101,
+			},
+			true,
+			3,
+			4,
+			8,
+		},
+		{
+			[32]byte{'i'},
+			map[[32]byte]types.Slot{
+				[32]byte{'b'}: 101,
+				[32]byte{'d'}: 103,
+				[32]byte{'g'}: 104,
+				[32]byte{'h'}: 105,
+			},
+			true,
+			NonExistentNode,
+			NonExistentNode,
+			1,
+		},
+		{
+			[32]byte{'i'},
+			map[[32]byte]types.Slot{
+				[32]byte{'b'}: 101,
+				[32]byte{'d'}: 103,
+				[32]byte{'g'}: 104,
+			},
+			false,
+			NonExistentNode,
+			NonExistentNode,
+			1,
+		},
+	}
+	for _, tc := range tests {
+		ctx := context.Background()
+		f := setup(1, 1)
+
+		require.NoError(t, f.ProcessBlock(ctx, 100, [32]byte{'a'}, params.BeaconConfig().ZeroHash, [32]byte{}, 1, 1))
+		require.NoError(t, f.ProcessBlock(ctx, 101, [32]byte{'b'}, [32]byte{'a'}, [32]byte{}, 1, 1))
+		require.NoError(t, f.ProcessBlock(ctx, 102, [32]byte{'c'}, [32]byte{'b'}, [32]byte{}, 1, 1))
+		require.NoError(t, f.ProcessBlock(ctx, 102, [32]byte{'j'}, [32]byte{'b'}, [32]byte{}, 1, 1))
+		require.NoError(t, f.ProcessBlock(ctx, 103, [32]byte{'d'}, [32]byte{'c'}, [32]byte{}, 1, 1))
+		require.NoError(t, f.ProcessBlock(ctx, 104, [32]byte{'e'}, [32]byte{'d'}, [32]byte{}, 1, 1))
+		require.NoError(t, f.ProcessBlock(ctx, 104, [32]byte{'g'}, [32]byte{'d'}, [32]byte{}, 1, 1))
+		require.NoError(t, f.ProcessBlock(ctx, 105, [32]byte{'f'}, [32]byte{'e'}, [32]byte{}, 1, 1))
+		require.NoError(t, f.ProcessBlock(ctx, 105, [32]byte{'h'}, [32]byte{'g'}, [32]byte{}, 1, 1))
+		require.NoError(t, f.ProcessBlock(ctx, 105, [32]byte{'k'}, [32]byte{'g'}, [32]byte{}, 1, 1))
+		require.NoError(t, f.ProcessBlock(ctx, 106, [32]byte{'i'}, [32]byte{'h'}, [32]byte{}, 1, 1))
+		require.NoError(t, f.ProcessBlock(ctx, 106, [32]byte{'l'}, [32]byte{'k'}, [32]byte{}, 1, 1))
+		weights := []uint64{10, 10, 9, 7, 1, 6, 2, 3, 1, 1, 1, 0, 0}
+		f.syncedTips.Lock()
+		f.syncedTips.validatedTips = tc.tips
+		f.syncedTips.Unlock()
+		f.store.nodesLock.Lock()
+		for i, node := range f.store.nodes {
+			node.weight = weights[i]
+		}
+		// Make j be the best child and descendant of b
+		nodeB := f.store.nodes[2]
+		nodeB.bestChild = 4
+		nodeB.bestDescendant = 4
+		idx := f.store.nodesIndices[tc.root]
+		node := f.store.nodes[idx]
+		parentIndex := node.parent
+		require.NotEqual(t, NonExistentNode, parentIndex)
+		parent := f.store.nodes[parentIndex]
+		f.store.nodesLock.Unlock()
+		err := f.UpdateSyncedTipsWithInvalidRoot(context.Background(), tc.root)
+		require.NoError(t, err)
+		f.syncedTips.RLock()
+		_, parentSyncedTip := f.syncedTips.validatedTips[parent.root]
+		f.syncedTips.RUnlock()
+		require.Equal(t, tc.wantedParentTip, parentSyncedTip)
+		require.Equal(t, tc.newBestChild, parent.bestChild)
+		require.Equal(t, tc.newBestDescendant, parent.bestDescendant)
+		require.Equal(t, tc.newParentWeight, parent.weight)
+	}
+}
+
+// This tests the algorithm to find the tip of a given node
+// We start with the following diagram
+//
+//                E -- F
+//               /
+//         C -- D
+//        /      \
+//  A -- B        G -- H -- I
+//        \        \
+//         J        -- K -- L
+//
+//
+func TestFindSyncedTip(t *testing.T) {
+	ctx := context.Background()
+	f := setup(1, 1)
+
+	require.NoError(t, f.ProcessBlock(ctx, 100, [32]byte{'a'}, params.BeaconConfig().ZeroHash, [32]byte{}, 1, 1))
+	require.NoError(t, f.ProcessBlock(ctx, 101, [32]byte{'b'}, [32]byte{'a'}, [32]byte{}, 1, 1))
+	require.NoError(t, f.ProcessBlock(ctx, 102, [32]byte{'c'}, [32]byte{'b'}, [32]byte{}, 1, 1))
+	require.NoError(t, f.ProcessBlock(ctx, 102, [32]byte{'j'}, [32]byte{'b'}, [32]byte{}, 1, 1))
+	require.NoError(t, f.ProcessBlock(ctx, 103, [32]byte{'d'}, [32]byte{'c'}, [32]byte{}, 1, 1))
+	require.NoError(t, f.ProcessBlock(ctx, 104, [32]byte{'e'}, [32]byte{'d'}, [32]byte{}, 1, 1))
+	require.NoError(t, f.ProcessBlock(ctx, 104, [32]byte{'g'}, [32]byte{'d'}, [32]byte{}, 1, 1))
+	require.NoError(t, f.ProcessBlock(ctx, 105, [32]byte{'f'}, [32]byte{'e'}, [32]byte{}, 1, 1))
+	require.NoError(t, f.ProcessBlock(ctx, 105, [32]byte{'h'}, [32]byte{'g'}, [32]byte{}, 1, 1))
+	require.NoError(t, f.ProcessBlock(ctx, 105, [32]byte{'k'}, [32]byte{'g'}, [32]byte{}, 1, 1))
+	require.NoError(t, f.ProcessBlock(ctx, 106, [32]byte{'i'}, [32]byte{'h'}, [32]byte{}, 1, 1))
+	require.NoError(t, f.ProcessBlock(ctx, 106, [32]byte{'l'}, [32]byte{'k'}, [32]byte{}, 1, 1))
+	tests := []struct {
+		root   [32]byte                // the root of the block
+		tips   map[[32]byte]types.Slot // the synced tips
+		wanted [32]byte                // the root of expected tip
+	}{
+		{
+			[32]byte{'i'},
+			map[[32]byte]types.Slot{
+				[32]byte{'b'}: 101,
+				[32]byte{'d'}: 103,
+				[32]byte{'g'}: 104,
+			},
+			[32]byte{'g'},
+		},
+		{
+			[32]byte{'g'},
+			map[[32]byte]types.Slot{
+				[32]byte{'b'}: 101,
+				[32]byte{'d'}: 103,
+				[32]byte{'h'}: 104,
+				[32]byte{'k'}: 106,
+			},
+			[32]byte{'d'},
+		},
+		{
+			[32]byte{'e'},
+			map[[32]byte]types.Slot{
+				[32]byte{'b'}: 101,
+				[32]byte{'d'}: 103,
+				[32]byte{'g'}: 103,
+			},
+			[32]byte{'d'},
+		},
+		{
+			[32]byte{'j'},
+			map[[32]byte]types.Slot{
+				[32]byte{'b'}: 101,
+				[32]byte{'f'}: 105,
+				[32]byte{'g'}: 104,
+				[32]byte{'i'}: 106,
+			},
+			[32]byte{'b'},
+		},
+		{
+			[32]byte{'g'},
+			map[[32]byte]types.Slot{
+				[32]byte{'b'}: 101,
+				[32]byte{'f'}: 105,
+				[32]byte{'g'}: 104,
+				[32]byte{'i'}: 106,
+			},
+			[32]byte{'g'},
+		},
+	}
+	for _, tc := range tests {
+		f.store.nodesLock.RLock()
+		node := f.store.nodes[f.store.nodesIndices[tc.root]]
+		syncedTips := &optimisticStore{
+			validatedTips: tc.tips,
+		}
+		syncedTips.RLock()
+		idx, err := f.store.findSyncedTip(ctx, node, syncedTips)
+		require.NoError(t, err)
+		require.Equal(t, tc.wanted, f.store.nodes[idx].root)
+
+		f.store.nodesLock.RUnlock()
+		syncedTips.RUnlock()
+	}
+}

beacon-chain/forkchoice/protoarray/proposer_boost_test.go

@@ -143,7 +143,7 @@ func TestForkChoice_BoostProposerRoot_PreventsExAnteAttack(t *testing.T) {
 		// Ancestors have the added weights of their children. Genesis is a special exception at 0 weight,
 		require.Equal(t, f.store.nodes[0].weight, uint64(0))
 
-		// Otherwise assuming a block, A, that is not-genesis:
+		// Otherwise, assuming a block, A, that is not-genesis:
 		//
 		// A -> B -> C
 		//
@@ -160,7 +160,7 @@ func TestForkChoice_BoostProposerRoot_PreventsExAnteAttack(t *testing.T) {
 		// (A: 54) -> (B: 44) -> (C: 24)
 		//				    \_->(D: 10)
 		//
-		// So B has its own weight, 10, and the sum of of both C and D thats why we see weight 54 in the
+		// 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).
 		require.Equal(t, f.store.nodes[1].weight, uint64(54))
 		require.Equal(t, f.store.nodes[2].weight, uint64(44))

beacon-chain/forkchoice/protoarray/store.go

@@ -40,6 +40,33 @@ func New(justifiedEpoch, finalizedEpoch types.Epoch, finalizedRoot [32]byte) *Fo
 	return &ForkChoice{store: s, balances: b, votes: v, syncedTips: st}
 }
 
+// SetSyncedTips sets the synced and validated tips from the passed map
+func (f *ForkChoice) SetSyncedTips(tips map[[32]byte]types.Slot) error {
+	if len(tips) == 0 {
+		return errInvalidSyncedTips
+	}
+	newTips := make(map[[32]byte]types.Slot, len(tips))
+	for k, v := range tips {
+		newTips[k] = v
+	}
+	f.syncedTips.Lock()
+	defer f.syncedTips.Unlock()
+	f.syncedTips.validatedTips = newTips
+	return nil
+}
+
+// SyncedTips returns the synced and validated tips from the fork choice store.
+func (f *ForkChoice) SyncedTips() map[[32]byte]types.Slot {
+	f.syncedTips.RLock()
+	defer f.syncedTips.RUnlock()
+
+	m := make(map[[32]byte]types.Slot)
+	for k, v := range f.syncedTips.validatedTips {
+		m[k] = v
+	}
+	return m
+}
+
 // 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(
@@ -119,7 +146,7 @@ func (f *ForkChoice) ProcessBlock(
 // 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)
+	return f.store.prune(ctx, finalizedRoot, f.syncedTips)
 }
 
 // Nodes returns the copied list of block nodes in the fork choice store.
@@ -268,7 +295,7 @@ func (s *Store) head(ctx context.Context, justifiedRoot [32]byte) ([32]byte, err
 
 	justifiedNode := s.nodes[justifiedIndex]
 	bestDescendantIndex := justifiedNode.bestDescendant
-	// If the justified node doesn't have a best descendent,
+	// If the justified node doesn't have a best descendant,
 	// the best node is itself.
 	if bestDescendantIndex == NonExistentNode {
 		bestDescendantIndex = justifiedIndex
@@ -351,7 +378,7 @@ func (s *Store) insert(ctx context.Context,
 
 	index := uint64(len(s.nodes))
 	parentIndex, ok := s.nodesIndices[parent]
-	// Mark genesis block's parent as non existent.
+	// Mark genesis block's parent as non-existent.
 	if !ok {
 		parentIndex = NonExistentNode
 	}
@@ -371,7 +398,7 @@ func (s *Store) insert(ctx context.Context,
 	s.nodesIndices[root] = index
 	s.nodes = append(s.nodes, n)
 
-	// Update parent with the best child and descendent only if it's available.
+	// Update parent with the best child and descendant only if it's available.
 	if n.parent != NonExistentNode {
 		if err := s.updateBestChildAndDescendant(parentIndex, index); err != nil {
 			return err
@@ -387,8 +414,8 @@ func (s *Store) insert(ctx context.Context,
 
 // applyWeightChanges iterates backwards through the nodes in store. It checks all nodes parent
 // and its best child. For each node, it updates the weight with input delta and
-// back propagate the nodes delta to its parents delta. After scoring changes,
-// the best child is then updated along with best descendant.
+// back propagate the nodes' delta to its parents' delta. After scoring changes,
+// the best child is then updated along with the best descendant.
 func (s *Store) applyWeightChanges(
 	ctx context.Context, justifiedEpoch, finalizedEpoch types.Epoch, newBalances []uint64, delta []int,
 ) error {
@@ -439,33 +466,25 @@ func (s *Store) applyWeightChanges(
 		}
 		s.proposerBoostLock.Unlock()
 
+		// A node's weight can not be negative but the delta can be negative.
 		if nodeDelta < 0 {
-			// A node's weight can not be negative but the delta can be negative.
-			if int(n.weight)+nodeDelta < 0 {
+			d := uint64(-nodeDelta)
+			if n.weight < d {
 				n.weight = 0
 			} else {
-				// Absolute value of node delta.
-				d := nodeDelta
-				if nodeDelta < 0 {
-					d *= -1
-				}
-				// Subtract node's weight.
-				n.weight -= uint64(d)
+				n.weight -= d
 			}
 		} else {
-			// Add node's weight.
 			n.weight += uint64(nodeDelta)
 		}
 
-		s.nodes[i] = n
-
-		// Update parent's best child and descendent if the node has a known parent.
+		// Update parent's best child and descendant if the node has a known parent.
 		if n.parent != NonExistentNode {
 			// Protection against node parent index out of bound. This should not happen.
 			if int(n.parent) >= len(delta) {
 				return errInvalidParentDelta
 			}
-			// Back propagate the nodes delta to its parent.
+			// Back propagate the nodes' delta to its parent.
 			delta[n.parent] += nodeDelta
 		}
 	}
@@ -491,14 +510,14 @@ func (s *Store) applyWeightChanges(
 	return nil
 }
 
-// updateBestChildAndDescendant updates parent node's best child and descendent.
+// updateBestChildAndDescendant updates parent node's best child and descendant.
 // It looks at input parent node and input child node and potentially modifies parent's best
-// child and best descendent indices.
+// child and best descendant indices.
 // There are four outcomes:
-// 1.)  The child is already the best child but it's now invalid due to a FFG change and should be removed.
+// 1.)  The child is already the best child, but it's now invalid due to a FFG change and should be removed.
 // 2.)  The child is already the best child and the parent is updated with the new best descendant.
 // 3.)  The child is not the best child but becomes the best child.
-// 4.)  The child is not the best child and does not become best child.
+// 4.)  The child is not the best child and does not become the best child.
 func (s *Store) updateBestChildAndDescendant(parentIndex, childIndex uint64) error {
 
 	// Protection against parent index out of bound, this should not happen.
@@ -533,12 +552,12 @@ func (s *Store) updateBestChildAndDescendant(parentIndex, childIndex uint64) err
 
 	if parent.bestChild != NonExistentNode {
 		if parent.bestChild == childIndex && !childLeadsToViableHead {
-			// If the child is already the best child of the parent but it's not viable for head,
+			// If the child is already the best child of the parent, but it's not viable for head,
 			// we should remove it. (Outcome 1)
 			newParentChild = changeToNone
 		} else if parent.bestChild == childIndex {
-			// If the child is already the best child of the parent, set it again to ensure best
-			// descendent of the parent is updated. (Outcome 2)
+			// If the child is already the best child of the parent, set it again to ensure the best
+			// descendant of the parent is updated. (Outcome 2)
 			newParentChild = changeToChild
 		} else {
 			// Protection against parent's best child going out of bound.
@@ -553,7 +572,7 @@ func (s *Store) updateBestChildAndDescendant(parentIndex, childIndex uint64) err
 			}
 
 			if childLeadsToViableHead && !bestChildLeadsToViableHead {
-				// The child leads to a viable head, but the current parent's best child doesnt.
+				// The child leads to a viable head, but the current parent's best child doesn't.
 				newParentChild = changeToChild
 			} else if !childLeadsToViableHead && bestChildLeadsToViableHead {
 				// The child doesn't lead to a viable head, the current parent's best child does.
@@ -596,7 +615,7 @@ func (s *Store) updateBestChildAndDescendant(parentIndex, childIndex uint64) err
 // prune prunes the store with the new finalized root. The tree is only
 // pruned if the input finalized root are different than the one in stored and
 // the number of the nodes in store has met prune threshold.
-func (s *Store) prune(ctx context.Context, finalizedRoot [32]byte) error {
+func (s *Store) prune(ctx context.Context, finalizedRoot [32]byte, syncedTips *optimisticStore) error {
 	_, span := trace.StartSpan(ctx, "protoArrayForkChoice.prune")
 	defer span.End()
 
@@ -618,12 +637,20 @@ func (s *Store) prune(ctx context.Context, finalizedRoot [32]byte) error {
 
 	// Traverse through the node list starting from the finalized node at index 0.
 	// Nodes that are not branching off from the finalized node will be removed.
+	syncedTips.Lock()
+	defer syncedTips.Unlock()
+
 	canonicalNodesMap := make(map[uint64]uint64, uint64(len(s.nodes))-finalizedIndex)
 	canonicalNodes := make([]*Node, 1, uint64(len(s.nodes))-finalizedIndex)
 	finalizedNode := s.nodes[finalizedIndex]
+	finalizedTipIndex, err := s.findSyncedTip(ctx, finalizedNode, syncedTips)
+	if err != nil {
+		return err
+	}
 	finalizedNode.parent = NonExistentNode
 	canonicalNodes[0] = finalizedNode
 	canonicalNodesMap[finalizedIndex] = uint64(0)
+
 	for idx := uint64(0); idx < uint64(len(s.nodes)); idx++ {
 		node := copyNode(s.nodes[idx])
 		parentIdx, ok := canonicalNodesMap[node.parent]
@@ -633,13 +660,17 @@ func (s *Store) prune(ctx context.Context, finalizedRoot [32]byte) error {
 			node.parent = parentIdx
 			canonicalNodes = append(canonicalNodes, node)
 		} else {
-			// Remove node that is not part of finalized branch.
+			// Remove node and synced tip that is not part of finalized branch.
 			delete(s.nodesIndices, node.root)
+			_, ok := syncedTips.validatedTips[node.root]
+			if ok && idx != finalizedTipIndex {
+				delete(syncedTips.validatedTips, node.root)
+			}
 		}
 	}
 	s.nodesIndices[finalizedRoot] = uint64(0)
 
-	// Recompute best child and descendant for each canonical nodes.
+	// Recompute the best child and descendant for each canonical nodes.
 	for _, node := range canonicalNodes {
 		if node.bestChild != NonExistentNode {
 			node.bestChild = canonicalNodesMap[node.bestChild]
@@ -651,31 +682,31 @@ func (s *Store) prune(ctx context.Context, finalizedRoot [32]byte) error {
 
 	s.nodes = canonicalNodes
 	prunedCount.Inc()
-
+	syncedTipsCount.Set(float64(len(syncedTips.validatedTips)))
 	return nil
 }
 
-// leadsToViableHead returns true if the node or the best descendent of the node is viable for head.
+// leadsToViableHead returns true if the node or the best descendant of the node is viable for head.
 // Any node with diff finalized or justified epoch than the ones in fork choice store
 // should not be viable to head.
 func (s *Store) leadsToViableHead(node *Node) (bool, error) {
-	var bestDescendentViable bool
-	bestDescendentIndex := node.bestDescendant
+	var bestDescendantViable bool
+	bestDescendantIndex := node.bestDescendant
 
 	// If the best descendant is not part of the leaves.
-	if bestDescendentIndex != NonExistentNode {
-		// Protection against out of bound, best descendent index can not be
+	if bestDescendantIndex != NonExistentNode {
+		// Protection against out of bound, the best descendant index can not be
 		// exceeds length of nodes list.
-		if bestDescendentIndex >= uint64(len(s.nodes)) {
+		if bestDescendantIndex >= uint64(len(s.nodes)) {
 			return false, errInvalidBestDescendantIndex
 		}
 
-		bestDescendentNode := s.nodes[bestDescendentIndex]
-		bestDescendentViable = s.viableForHead(bestDescendentNode)
+		bestDescendantNode := s.nodes[bestDescendantIndex]
+		bestDescendantViable = s.viableForHead(bestDescendantNode)
 	}
 
-	// The node is viable as long as the best descendent is viable.
-	return bestDescendentViable || s.viableForHead(node), nil
+	// The node is viable as long as the best descendant is viable.
+	return bestDescendantViable || s.viableForHead(node), nil
 }
 
 // viableForHead returns true if the node is viable to head.
@@ -689,3 +720,17 @@ func (s *Store) viableForHead(node *Node) bool {
 
 	return justified && finalized
 }
+
+// Returns the list of leaves in the Fork Choice store.
+// These are all the nodes that have NonExistentNode as best child.
+// This internal method assumes that the caller holds a lock in s.nodesLock.
+func (s *Store) leaves() ([]uint64, error) {
+	var leaves []uint64
+	for i := uint64(0); i < uint64(len(s.nodes)); i++ {
+		node := s.nodes[i]
+		if node.bestChild == NonExistentNode {
+			leaves = append(leaves, i)
+		}
+	}
+	return leaves, nil
+}

beacon-chain/forkchoice/protoarray/store_test.go

@@ -5,6 +5,7 @@ import (
 	"testing"
 
 	types "github.com/prysmaticlabs/eth2-types"
+	"github.com/prysmaticlabs/prysm/config/params"
 	"github.com/prysmaticlabs/prysm/encoding/bytesutil"
 	"github.com/prysmaticlabs/prysm/testing/assert"
 	"github.com/prysmaticlabs/prysm/testing/require"
@@ -133,7 +134,7 @@ func TestStore_Head_BestDescendant(t *testing.T) {
 	indices := make(map[[32]byte]uint64)
 	indices[r] = 0
 
-	// Since the justified node's best descendent is at index 1 and it's root is `best`,
+	// Since the justified node's best descendant is at index 1, and its root is `best`,
 	// the head should be `best`.
 	s := &Store{nodesIndices: indices, nodes: []*Node{{root: r, bestDescendant: 1}, {root: best}}, canonicalNodes: make(map[[32]byte]bool)}
 	h, err := s.head(context.Background(), r)
@@ -264,7 +265,7 @@ func TestStore_UpdateBestChildAndDescendant_UpdateDescendant(t *testing.T) {
 
 func TestStore_UpdateBestChildAndDescendant_ChangeChildByViability(t *testing.T) {
 	// Make parent's best child not equal to child index, child leads to viable index and
-	// parents best child doesnt lead to viable index.
+	// parent's best child doesn't lead to viable index.
 	s := &Store{
 		justifiedEpoch: 1,
 		finalizedEpoch: 1,
@@ -361,16 +362,39 @@ func TestStore_Prune_LessThanThreshold(t *testing.T) {
 	numOfNodes := 100
 	indices := make(map[[32]byte]uint64)
 	nodes := make([]*Node, 0)
-	for i := 0; i < numOfNodes; i++ {
+	indices[indexToHash(uint64(0))] = uint64(0)
+	nodes = append(nodes, &Node{
+		slot:           types.Slot(0),
+		root:           indexToHash(uint64(0)),
+		bestDescendant: uint64(numOfNodes - 1),
+		bestChild:      uint64(1),
+		parent:         NonExistentNode,
+	})
+	for i := 1; i < numOfNodes-1; i++ {
 		indices[indexToHash(uint64(i))] = uint64(i)
-		nodes = append(nodes, &Node{slot: types.Slot(i)})
+		nodes = append(nodes, &Node{
+			slot:           types.Slot(i),
+			root:           indexToHash(uint64(i)),
+			bestDescendant: uint64(numOfNodes - 1),
+			bestChild:      uint64(i + 1),
+			parent:         uint64(i) - 1,
+		})
 	}
+	indices[indexToHash(uint64(numOfNodes-1))] = uint64(numOfNodes - 1)
+	nodes = append(nodes, &Node{
+		slot:           types.Slot(numOfNodes - 1),
+		root:           indexToHash(uint64(numOfNodes - 1)),
+		bestDescendant: NonExistentNode,
+		bestChild:      NonExistentNode,
+		parent:         uint64(numOfNodes - 2),
+	})
 
 	s := &Store{nodes: nodes, nodesIndices: indices, pruneThreshold: 100}
+	syncedTips := &optimisticStore{}
 
 	// Finalized root is at index 99 so everything before 99 should be pruned,
 	// but PruneThreshold is at 100 so nothing will be pruned.
-	require.NoError(t, s.prune(context.Background(), indexToHash(99)))
+	require.NoError(t, s.prune(context.Background(), indexToHash(99), syncedTips))
 	assert.Equal(t, 100, len(s.nodes), "Incorrect nodes count")
 	assert.Equal(t, 100, len(s.nodesIndices), "Incorrect node indices count")
 }
@@ -380,16 +404,37 @@ func TestStore_Prune_MoreThanThreshold(t *testing.T) {
 	numOfNodes := 100
 	indices := make(map[[32]byte]uint64)
 	nodes := make([]*Node, 0)
-	for i := 0; i < numOfNodes; i++ {
+	indices[indexToHash(uint64(0))] = uint64(0)
+	nodes = append(nodes, &Node{
+		slot:           types.Slot(0),
+		root:           indexToHash(uint64(0)),
+		bestDescendant: uint64(numOfNodes - 1),
+		bestChild:      uint64(1),
+		parent:         NonExistentNode,
+	})
+	for i := 1; i < numOfNodes-1; i++ {
 		indices[indexToHash(uint64(i))] = uint64(i)
-		nodes = append(nodes, &Node{slot: types.Slot(i), root: indexToHash(uint64(i)),
-			bestDescendant: NonExistentNode, bestChild: NonExistentNode})
+		nodes = append(nodes, &Node{
+			slot:           types.Slot(i),
+			root:           indexToHash(uint64(i)),
+			bestDescendant: uint64(numOfNodes - 1),
+			bestChild:      uint64(i + 1),
+			parent:         uint64(i) - 1,
+		})
 	}
-
+	nodes = append(nodes, &Node{
+		slot:           types.Slot(numOfNodes - 1),
+		root:           indexToHash(uint64(numOfNodes - 1)),
+		bestDescendant: NonExistentNode,
+		bestChild:      NonExistentNode,
+		parent:         uint64(numOfNodes - 2),
+	})
+	indices[indexToHash(uint64(numOfNodes-1))] = uint64(numOfNodes - 1)
 	s := &Store{nodes: nodes, nodesIndices: indices}
+	syncedTips := &optimisticStore{}
 
 	// Finalized root is at index 99 so everything before 99 should be pruned.
-	require.NoError(t, s.prune(context.Background(), indexToHash(99)))
+	require.NoError(t, s.prune(context.Background(), indexToHash(99), syncedTips))
 	assert.Equal(t, 1, len(s.nodes), "Incorrect nodes count")
 	assert.Equal(t, 1, len(s.nodesIndices), "Incorrect node indices count")
 }
@@ -425,14 +470,15 @@ func TestStore_Prune_MoreThanOnce(t *testing.T) {
 	})
 
 	s := &Store{nodes: nodes, nodesIndices: indices}
+	syncedTips := &optimisticStore{}
 
 	// Finalized root is at index 11 so everything before 11 should be pruned.
-	require.NoError(t, s.prune(context.Background(), indexToHash(10)))
+	require.NoError(t, s.prune(context.Background(), indexToHash(10), syncedTips))
 	assert.Equal(t, 90, len(s.nodes), "Incorrect nodes count")
 	assert.Equal(t, 90, len(s.nodesIndices), "Incorrect node indices count")
 
 	// One more time.
-	require.NoError(t, s.prune(context.Background(), indexToHash(20)))
+	require.NoError(t, s.prune(context.Background(), indexToHash(20), syncedTips))
 	assert.Equal(t, 80, len(s.nodes), "Incorrect nodes count")
 	assert.Equal(t, 80, len(s.nodesIndices), "Incorrect node indices count")
 }
@@ -468,6 +514,7 @@ func TestStore_Prune_NoDanglingBranch(t *testing.T) {
 			bestDescendant: NonExistentNode,
 		},
 	}
+	syncedTips := &optimisticStore{}
 	s := &Store{
 		pruneThreshold: 0,
 		nodes:          nodes,
@@ -477,10 +524,56 @@ func TestStore_Prune_NoDanglingBranch(t *testing.T) {
 			indexToHash(uint64(2)): 2,
 		},
 	}
-	require.NoError(t, s.prune(context.Background(), indexToHash(uint64(1))))
+	require.NoError(t, s.prune(context.Background(), indexToHash(uint64(1)), syncedTips))
 	require.Equal(t, len(s.nodes), 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
+//
+//
+// Synced tips are B, D and E. And we finalize F. All that is left in fork
+// choice is F, and the only synced tip left is E which is now away from Fork
+// Choice.
+func TestStore_PruneSyncedTips(t *testing.T) {
+	ctx := context.Background()
+	f := setup(1, 1)
+
+	require.NoError(t, f.ProcessBlock(ctx, 100, [32]byte{'a'}, params.BeaconConfig().ZeroHash, [32]byte{}, 1, 1))
+	require.NoError(t, f.ProcessBlock(ctx, 101, [32]byte{'b'}, [32]byte{'a'}, [32]byte{}, 1, 1))
+	require.NoError(t, f.ProcessBlock(ctx, 102, [32]byte{'c'}, [32]byte{'b'}, [32]byte{}, 1, 1))
+	require.NoError(t, f.ProcessBlock(ctx, 102, [32]byte{'j'}, [32]byte{'b'}, [32]byte{}, 1, 1))
+	require.NoError(t, f.ProcessBlock(ctx, 103, [32]byte{'d'}, [32]byte{'c'}, [32]byte{}, 1, 1))
+	require.NoError(t, f.ProcessBlock(ctx, 104, [32]byte{'e'}, [32]byte{'d'}, [32]byte{}, 1, 1))
+	require.NoError(t, f.ProcessBlock(ctx, 104, [32]byte{'g'}, [32]byte{'d'}, [32]byte{}, 1, 1))
+	require.NoError(t, f.ProcessBlock(ctx, 105, [32]byte{'f'}, [32]byte{'e'}, [32]byte{}, 1, 1))
+	require.NoError(t, f.ProcessBlock(ctx, 105, [32]byte{'h'}, [32]byte{'g'}, [32]byte{}, 1, 1))
+	require.NoError(t, f.ProcessBlock(ctx, 105, [32]byte{'k'}, [32]byte{'g'}, [32]byte{}, 1, 1))
+	require.NoError(t, f.ProcessBlock(ctx, 106, [32]byte{'i'}, [32]byte{'h'}, [32]byte{}, 1, 1))
+	require.NoError(t, f.ProcessBlock(ctx, 106, [32]byte{'l'}, [32]byte{'k'}, [32]byte{}, 1, 1))
+	syncedTips := &optimisticStore{
+		validatedTips: map[[32]byte]types.Slot{
+			[32]byte{'b'}: 101,
+			[32]byte{'d'}: 103,
+			[32]byte{'e'}: 104,
+		},
+	}
+	f.syncedTips = syncedTips
+	f.store.pruneThreshold = 0
+	require.NoError(t, f.Prune(ctx, [32]byte{'f'}))
+	require.Equal(t, 1, len(f.syncedTips.validatedTips))
+	_, ok := f.syncedTips.validatedTips[[32]byte{'e'}]
+	require.Equal(t, true, ok)
+}
+
 func TestStore_LeadsToViableHead(t *testing.T) {
 	tests := []struct {
 		n              *Node
@@ -507,6 +600,20 @@ func TestStore_LeadsToViableHead(t *testing.T) {
 	}
 }
 
+func TestStore_SetSyncedTips(t *testing.T) {
+	f := setup(1, 1)
+	tips := make(map[[32]byte]types.Slot)
+	require.ErrorIs(t, errInvalidSyncedTips, f.SetSyncedTips(tips))
+	tips[bytesutil.ToBytes32([]byte{'a'})] = 1
+	require.NoError(t, f.SetSyncedTips(tips))
+	f.syncedTips.RLock()
+	defer f.syncedTips.RUnlock()
+	require.Equal(t, 1, len(f.syncedTips.validatedTips))
+	slot, ok := f.syncedTips.validatedTips[bytesutil.ToBytes32([]byte{'a'})]
+	require.Equal(t, true, ok)
+	require.Equal(t, types.Slot(1), slot)
+}
+
 func TestStore_ViableForHead(t *testing.T) {
 	tests := []struct {
 		n              *Node

beacon-chain/forkchoice/protoarray/vote_test.go

@@ -12,6 +12,7 @@ import (
 func TestVotes_CanFindHead(t *testing.T) {
 	balances := []uint64{1, 1}
 	f := setup(1, 1)
+	syncedTips := &optimisticStore{}
 
 	// The head should always start at the finalized block.
 	r, err := f.Head(context.Background(), 1, params.BeaconConfig().ZeroHash, balances, 1)
@@ -248,7 +249,7 @@ func TestVotes_CanFindHead(t *testing.T) {
 
 	// Verify pruning below the prune threshold does not affect head.
 	f.store.pruneThreshold = 1000
-	require.NoError(t, f.store.prune(context.Background(), indexToHash(5)))
+	require.NoError(t, f.store.prune(context.Background(), indexToHash(5), syncedTips))
 	assert.Equal(t, 11, len(f.store.nodes), "Incorrect nodes length after prune")
 
 	r, err = f.Head(context.Background(), 2, indexToHash(5), balances, 2)
@@ -272,7 +273,7 @@ func TestVotes_CanFindHead(t *testing.T) {
 	//         / \
 	//        9  10
 	f.store.pruneThreshold = 1
-	require.NoError(t, f.store.prune(context.Background(), indexToHash(5)))
+	require.NoError(t, f.store.prune(context.Background(), indexToHash(5), syncedTips))
 	assert.Equal(t, 5, len(f.store.nodes), "Incorrect nodes length after prune")
 
 	r, err = f.Head(context.Background(), 2, indexToHash(5), balances, 2)

beacon-chain/node/config.go

@@ -45,6 +45,14 @@ func configureHistoricalSlasher(cliCtx *cli.Context) {
 	}
 }
 
+func configureSafeSlotsToImportOptimistically(cliCtx *cli.Context) {
+	if cliCtx.IsSet(flags.SafeSlotsToImportOptimistically.Name) {
+		c := params.BeaconConfig()
+		c.SafeSlotsToImportOptimistically = types.Slot(cliCtx.Int(flags.SafeSlotsToImportOptimistically.Name))
+		params.OverrideBeaconConfig(c)
+	}
+}
+
 func configureSlotsPerArchivedPoint(cliCtx *cli.Context) {
 	if cliCtx.IsSet(flags.SlotsPerArchivedPoint.Name) {
 		c := params.BeaconConfig()

beacon-chain/node/config_test.go

@@ -37,6 +37,20 @@ func TestConfigureHistoricalSlasher(t *testing.T) {
 	)
 }
 
+func TestConfigureSafeSlotsToImportOptimistically(t *testing.T) {
+	params.SetupTestConfigCleanup(t)
+
+	app := cli.App{}
+	set := flag.NewFlagSet("test", 0)
+	set.Int(flags.SafeSlotsToImportOptimistically.Name, 0, "")
+	require.NoError(t, set.Set(flags.SafeSlotsToImportOptimistically.Name, strconv.Itoa(128)))
+	cliCtx := cli.NewContext(&app, set, nil)
+
+	configureSafeSlotsToImportOptimistically(cliCtx)
+
+	assert.Equal(t, types.Slot(128), params.BeaconConfig().SafeSlotsToImportOptimistically)
+}
+
 func TestConfigureSlotsPerArchivedPoint(t *testing.T) {
 	params.SetupTestConfigCleanup(t)
 

beacon-chain/node/node.go

@@ -114,10 +114,12 @@ func New(cliCtx *cli.Context, opts ...Option) (*BeaconNode, error) {
 	flags.ConfigureGlobalFlags(cliCtx)
 	configureChainConfig(cliCtx)
 	configureHistoricalSlasher(cliCtx)
+	configureSafeSlotsToImportOptimistically(cliCtx)
 	configureSlotsPerArchivedPoint(cliCtx)
 	configureEth1Config(cliCtx)
 	configureNetwork(cliCtx)
 	configureInteropConfig(cliCtx)
+	configureExecutionSetting(cliCtx)
 
 	// Initializes any forks here.
 	params.BeaconConfig().InitializeForkSchedule()
@@ -153,65 +155,80 @@ func New(cliCtx *cli.Context, opts ...Option) (*BeaconNode, error) {
 	if err != nil {
 		return nil, err
 	}
+	log.Debugln("Starting DB")
 	if err := beacon.startDB(cliCtx, depositAddress); err != nil {
 		return nil, err
 	}
-
+	log.Debugln("Starting Slashing DB")
 	if err := beacon.startSlasherDB(cliCtx); err != nil {
 		return nil, err
 	}
 
+	log.Debugln("Starting State Gen")
 	if err := beacon.startStateGen(); err != nil {
 		return nil, err
 	}
 
+	log.Debugln("Registering P2P Service")
 	if err := beacon.registerP2P(cliCtx); err != nil {
 		return nil, err
 	}
 
+	log.Debugln("Registering POW Chain Service")
 	if err := beacon.registerPOWChainService(); err != nil {
 		return nil, err
 	}
 
+	log.Debugln("Registering Attestation Pool Service")
 	if err := beacon.registerAttestationPool(); err != nil {
 		return nil, err
 	}
 
+	log.Debugln("Registering Determinstic Genesis Service")
 	if err := beacon.registerDeterminsticGenesisService(); err != nil {
 		return nil, err
 	}
 
+	log.Debugln("Starting Fork Choice")
 	beacon.startForkChoice()
 
+	log.Debugln("Registering Blockchain Service")
 	if err := beacon.registerBlockchainService(); err != nil {
 		return nil, err
 	}
 
+	log.Debugln("Registering Intial Sync Service")
 	if err := beacon.registerInitialSyncService(); err != nil {
 		return nil, err
 	}
 
+	log.Debugln("Registering Sync Service")
 	if err := beacon.registerSyncService(); err != nil {
 		return nil, err
 	}
 
+	log.Debugln("Registering Slasher Service")
 	if err := beacon.registerSlasherService(); err != nil {
 		return nil, err
 	}
 
+	log.Debugln("Registering RPC Service")
 	if err := beacon.registerRPCService(); err != nil {
 		return nil, err
 	}
 
+	log.Debugln("Registering GRPC Gateway Service")
 	if err := beacon.registerGRPCGateway(); err != nil {
 		return nil, err
 	}
 
+	log.Debugln("Registering Validator Monitoring Service")
 	if err := beacon.registerValidatorMonitorService(); err != nil {
 		return nil, err
 	}
 
 	if !cliCtx.Bool(cmd.DisableMonitoringFlag.Name) {
+		log.Debugln("Registering Prometheus Service")
 		if err := beacon.registerPrometheusService(cliCtx); err != nil {
 			return nil, err
 		}
@@ -538,6 +555,7 @@ func (b *BeaconNode) registerBlockchainService() error {
 		blockchain.WithDatabase(b.db),
 		blockchain.WithDepositCache(b.depositCache),
 		blockchain.WithChainStartFetcher(web3Service),
+		blockchain.WithExecutionEngineCaller(web3Service.EngineAPIClient()),
 		blockchain.WithAttestationPool(b.attestationPool),
 		blockchain.WithExitPool(b.exitPool),
 		blockchain.WithSlashingPool(b.slashingsPool),
@@ -764,6 +782,7 @@ func (b *BeaconNode) registerRPCService() error {
 		StateGen:                b.stateGen,
 		EnableDebugRPCEndpoints: enableDebugRPCEndpoints,
 		MaxMsgSize:              maxMsgSize,
+		ExecutionEngineCaller:   web3Service.EngineAPIClient(),
 	})
 
 	return b.services.RegisterService(rpcService)

beacon-chain/p2p/pubsub.go

@@ -98,7 +98,7 @@ func (s *Service) PublishToTopic(ctx context.Context, topic string, data []byte,
 
 // SubscribeToTopic joins (if necessary) and subscribes to PubSub topic.
 func (s *Service) SubscribeToTopic(topic string, opts ...pubsub.SubOpt) (*pubsub.Subscription, error) {
-	s.awaitStateInitialized() // Genesis time and genesis validator root are required to subscribe.
+	s.awaitStateInitialized() // Genesis time and genesis validators root are required to subscribe.
 
 	topicHandle, err := s.JoinTopic(topic)
 	if err != nil {

beacon-chain/p2p/service.go

@@ -490,7 +490,7 @@ func (s *Service) connectToBootnodes() error {
 	return nil
 }
 
-// Returns true if the service is aware of the genesis time and genesis validator root. This is
+// Returns true if the service is aware of the genesis time and genesis validators root. This is
 // required for discovery and pubsub validation.
 func (s *Service) isInitialized() bool {
 	return !s.genesisTime.IsZero() && len(s.genesisValidatorsRoot) == 32

beacon-chain/p2p/service_test.go

@@ -306,7 +306,7 @@ func TestService_JoinLeaveTopic(t *testing.T) {
 // digest associated with that genesis event.
 func initializeStateWithForkDigest(ctx context.Context, t *testing.T, ef *event.Feed) [4]byte {
 	gt := prysmTime.Now()
-	gvr := bytesutil.PadTo([]byte("genesis validator root"), 32)
+	gvr := bytesutil.PadTo([]byte("genesis validators root"), 32)
 	for n := 0; n == 0; {
 		if ctx.Err() != nil {
 			t.Fatal(ctx.Err())

beacon-chain/powchain/BUILD.bazel

@@ -27,10 +27,13 @@ go_library(
         "//beacon-chain/core/helpers:go_default_library",
         "//beacon-chain/core/transition:go_default_library",
         "//beacon-chain/db:go_default_library",
+        "//beacon-chain/powchain/engine-api-client/v1:go_default_library",
         "//beacon-chain/powchain/types:go_default_library",
         "//beacon-chain/state:go_default_library",
+        "//beacon-chain/state/state-native/v1:go_default_library",
         "//beacon-chain/state/stategen:go_default_library",
         "//beacon-chain/state/v1:go_default_library",
+        "//config/features:go_default_library",
         "//config/params:go_default_library",
         "//container/trie:go_default_library",
         "//contracts/deposit:go_default_library",

beacon-chain/powchain/engine-api-client/v1/BUILD.bazel

@@ -0,0 +1,33 @@
+load("@prysm//tools/go:def.bzl", "go_library", "go_test")
+
+go_library(
+    name = "go_default_library",
+    srcs = [
+        "client.go",
+        "errors.go",
+        "options.go",
+    ],
+    importpath = "github.com/prysmaticlabs/prysm/beacon-chain/powchain/engine-api-client/v1",
+    visibility = ["//beacon-chain:__subpackages__"],
+    deps = [
+        "//proto/engine/v1:go_default_library",
+        "@com_github_ethereum_go_ethereum//common:go_default_library",
+        "@com_github_ethereum_go_ethereum//rpc:go_default_library",
+        "@com_github_pkg_errors//:go_default_library",
+    ],
+)
+
+go_test(
+    name = "go_default_test",
+    srcs = ["client_test.go"],
+    embed = [":go_default_library"],
+    deps = [
+        "//config/fieldparams:go_default_library",
+        "//encoding/bytesutil:go_default_library",
+        "//proto/engine/v1:go_default_library",
+        "//testing/require:go_default_library",
+        "@com_github_ethereum_go_ethereum//common:go_default_library",
+        "@com_github_ethereum_go_ethereum//rpc:go_default_library",
+        "@com_github_pkg_errors//:go_default_library",
+    ],
+)

beacon-chain/powchain/engine-api-client/v1/client.go

@@ -0,0 +1,164 @@
+// Package v1 defines an API client for the engine API defined in https://github.com/ethereum/execution-apis.
+// This client is used for the Prysm consensus node to connect to execution node as part of
+// the Ethereum proof-of-stake machinery.
+package v1
+
+import (
+	"context"
+	"net/url"
+	"time"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/rpc"
+	"github.com/pkg/errors"
+	pb "github.com/prysmaticlabs/prysm/proto/engine/v1"
+)
+
+const (
+	// NewPayloadMethod v1 request string for JSON-RPC.
+	NewPayloadMethod = "engine_newPayloadV1"
+	// ForkchoiceUpdatedMethod v1 request string for JSON-RPC.
+	ForkchoiceUpdatedMethod = "engine_forkchoiceUpdatedV1"
+	// GetPayloadMethod v1 request string for JSON-RPC.
+	GetPayloadMethod = "engine_getPayloadV1"
+	// ExecutionBlockByHashMethod request string for JSON-RPC.
+	ExecutionBlockByHashMethod = "eth_getBlockByHash"
+	// ExecutionBlockByNumberMethod request string for JSON-RPC.
+	ExecutionBlockByNumberMethod = "eth_getBlockByNumber"
+	// DefaultTimeout for HTTP.
+	DefaultTimeout = time.Second * 5
+)
+
+// ForkchoiceUpdatedResponse is the response kind received by the
+// engine_forkchoiceUpdatedV1 endpoint.
+type ForkchoiceUpdatedResponse struct {
+	Status    *pb.PayloadStatus  `json:"payloadStatus"`
+	PayloadId *pb.PayloadIDBytes `json:"payloadId"`
+}
+
+// EngineCaller defines a client that can interact with an Ethereum
+// execution node's engine service via JSON-RPC.
+type EngineCaller interface {
+	NewPayload(ctx context.Context, payload *pb.ExecutionPayload) (*pb.PayloadStatus, error)
+	ForkchoiceUpdated(
+		ctx context.Context, state *pb.ForkchoiceState, attrs *pb.PayloadAttributes,
+	) (*ForkchoiceUpdatedResponse, error)
+	GetPayload(ctx context.Context, payloadId [8]byte) (*pb.ExecutionPayload, error)
+	LatestExecutionBlock(ctx context.Context) (*pb.ExecutionBlock, error)
+	ExecutionBlockByHash(ctx context.Context, hash common.Hash) (*pb.ExecutionBlock, error)
+}
+
+// Client defines a new engine API client for the Prysm consensus node
+// to interact with an Ethereum execution node.
+type Client struct {
+	cfg *config
+	rpc *rpc.Client
+}
+
+// New returns a ready, engine API client from an endpoint and configuration options.
+// Only http(s) and ipc (inter-process communication) URL schemes are supported.
+func New(ctx context.Context, endpoint string, opts ...Option) (*Client, error) {
+	u, err := url.Parse(endpoint)
+	if err != nil {
+		return nil, err
+	}
+	c := &Client{
+		cfg: defaultConfig(),
+	}
+	switch u.Scheme {
+	case "http", "https":
+		c.rpc, err = rpc.DialHTTPWithClient(endpoint, c.cfg.httpClient)
+	case "":
+		c.rpc, err = rpc.DialIPC(ctx, endpoint)
+	default:
+		return nil, errors.Wrapf(ErrUnsupportedScheme, "%q", u.Scheme)
+	}
+	if err != nil {
+		return nil, err
+	}
+	for _, opt := range opts {
+		if err := opt(c); err != nil {
+			return nil, err
+		}
+	}
+	return c, nil
+}
+
+// NewPayload calls the engine_newPayloadV1 method via JSON-RPC.
+func (c *Client) NewPayload(ctx context.Context, payload *pb.ExecutionPayload) (*pb.PayloadStatus, error) {
+	result := &pb.PayloadStatus{}
+	err := c.rpc.CallContext(ctx, result, NewPayloadMethod, payload)
+	return result, handleRPCError(err)
+}
+
+// ForkchoiceUpdated calls the engine_forkchoiceUpdatedV1 method via JSON-RPC.
+func (c *Client) ForkchoiceUpdated(
+	ctx context.Context, state *pb.ForkchoiceState, attrs *pb.PayloadAttributes,
+) (*ForkchoiceUpdatedResponse, error) {
+	result := &ForkchoiceUpdatedResponse{}
+	err := c.rpc.CallContext(ctx, result, ForkchoiceUpdatedMethod, state, attrs)
+	return result, handleRPCError(err)
+}
+
+// GetPayload calls the engine_getPayloadV1 method via JSON-RPC.
+func (c *Client) GetPayload(ctx context.Context, payloadId [8]byte) (*pb.ExecutionPayload, error) {
+	result := &pb.ExecutionPayload{}
+	err := c.rpc.CallContext(ctx, result, GetPayloadMethod, pb.PayloadIDBytes(payloadId))
+	return result, handleRPCError(err)
+}
+
+// LatestExecutionBlock fetches the latest execution engine block by calling
+// eth_blockByNumber via JSON-RPC.
+func (c *Client) LatestExecutionBlock(ctx context.Context) (*pb.ExecutionBlock, error) {
+	result := &pb.ExecutionBlock{}
+	err := c.rpc.CallContext(
+		ctx,
+		result,
+		ExecutionBlockByNumberMethod,
+		"latest",
+		false, /* no full transaction objects */
+	)
+	return result, handleRPCError(err)
+}
+
+// ExecutionBlockByHash fetches an execution engine block by hash by calling
+// eth_blockByHash via JSON-RPC.
+func (c *Client) ExecutionBlockByHash(ctx context.Context, hash common.Hash) (*pb.ExecutionBlock, error) {
+	result := &pb.ExecutionBlock{}
+	err := c.rpc.CallContext(ctx, result, ExecutionBlockByHashMethod, hash, false /* no full transaction objects */)
+	return result, handleRPCError(err)
+}
+
+// Handles errors received from the RPC server according to the specification.
+func handleRPCError(err error) error {
+	if err == nil {
+		return nil
+	}
+	e, ok := err.(rpc.Error)
+	if !ok {
+		return errors.Wrap(err, "got an unexpected error")
+	}
+	switch e.ErrorCode() {
+	case -32700:
+		return ErrParse
+	case -32600:
+		return ErrInvalidRequest
+	case -32601:
+		return ErrMethodNotFound
+	case -32602:
+		return ErrInvalidParams
+	case -32603:
+		return ErrInternal
+	case -32001:
+		return ErrUnknownPayload
+	case -32000:
+		// Only -32000 status codes are data errors in the RPC specification.
+		errWithData, ok := err.(rpc.DataError)
+		if !ok {
+			return errors.Wrap(err, "got an unexpected error")
+		}
+		return errors.Wrapf(ErrServer, "%v", errWithData.ErrorData())
+	default:
+		return err
+	}
+}

beacon-chain/powchain/engine-api-client/v1/client_test.go

@@ -0,0 +1,522 @@
+package v1
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"math/big"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/rpc"
+	"github.com/pkg/errors"
+	fieldparams "github.com/prysmaticlabs/prysm/config/fieldparams"
+	"github.com/prysmaticlabs/prysm/encoding/bytesutil"
+	pb "github.com/prysmaticlabs/prysm/proto/engine/v1"
+	"github.com/prysmaticlabs/prysm/testing/require"
+)
+
+var _ = EngineCaller(&Client{})
+
+func TestClient_IPC(t *testing.T) {
+	server := newTestIPCServer(t)
+	defer server.Stop()
+	rpcClient := rpc.DialInProc(server)
+	defer rpcClient.Close()
+	client := &Client{}
+	client.rpc = rpcClient
+	ctx := context.Background()
+	fix := fixtures()
+
+	t.Run(GetPayloadMethod, func(t *testing.T) {
+		want, ok := fix["ExecutionPayload"].(*pb.ExecutionPayload)
+		require.Equal(t, true, ok)
+		payloadId := [8]byte{1}
+		resp, err := client.GetPayload(ctx, payloadId)
+		require.NoError(t, err)
+		require.DeepEqual(t, want, resp)
+	})
+	t.Run(ForkchoiceUpdatedMethod, func(t *testing.T) {
+		want, ok := fix["ForkchoiceUpdatedResponse"].(*ForkchoiceUpdatedResponse)
+		require.Equal(t, true, ok)
+		resp, err := client.ForkchoiceUpdated(ctx, &pb.ForkchoiceState{}, &pb.PayloadAttributes{})
+		require.NoError(t, err)
+		require.DeepEqual(t, want.Status, resp.Status)
+		require.DeepEqual(t, want.PayloadId, resp.PayloadId)
+	})
+	t.Run(NewPayloadMethod, func(t *testing.T) {
+		want, ok := fix["PayloadStatus"].(*pb.PayloadStatus)
+		require.Equal(t, true, ok)
+		req, ok := fix["ExecutionPayload"].(*pb.ExecutionPayload)
+		require.Equal(t, true, ok)
+		resp, err := client.NewPayload(ctx, req)
+		require.NoError(t, err)
+		require.DeepEqual(t, want, resp)
+	})
+	t.Run(ExecutionBlockByNumberMethod, func(t *testing.T) {
+		want, ok := fix["ExecutionBlock"].(*pb.ExecutionBlock)
+		require.Equal(t, true, ok)
+		resp, err := client.LatestExecutionBlock(ctx)
+		require.NoError(t, err)
+		require.DeepEqual(t, want, resp)
+	})
+	t.Run(ExecutionBlockByHashMethod, func(t *testing.T) {
+		want, ok := fix["ExecutionBlock"].(*pb.ExecutionBlock)
+		require.Equal(t, true, ok)
+		arg := common.BytesToHash([]byte("foo"))
+		resp, err := client.ExecutionBlockByHash(ctx, arg)
+		require.NoError(t, err)
+		require.DeepEqual(t, want, resp)
+	})
+}
+
+func TestClient_HTTP(t *testing.T) {
+	ctx := context.Background()
+	fix := fixtures()
+
+	t.Run(GetPayloadMethod, func(t *testing.T) {
+		payloadId := [8]byte{1}
+		want, ok := fix["ExecutionPayload"].(*pb.ExecutionPayload)
+		require.Equal(t, true, ok)
+		srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			w.Header().Set("Content-Type", "application/json")
+			defer func() {
+				require.NoError(t, r.Body.Close())
+			}()
+			enc, err := ioutil.ReadAll(r.Body)
+			require.NoError(t, err)
+			jsonRequestString := string(enc)
+
+			reqArg, err := json.Marshal(pb.PayloadIDBytes(payloadId))
+			require.NoError(t, err)
+
+			// We expect the JSON string RPC request contains the right arguments.
+			require.Equal(t, true, strings.Contains(
+				jsonRequestString, string(reqArg),
+			))
+			resp := map[string]interface{}{
+				"jsonrpc": "2.0",
+				"id":      1,
+				"result":  want,
+			}
+			err = json.NewEncoder(w).Encode(resp)
+			require.NoError(t, err)
+		}))
+		defer srv.Close()
+
+		rpcClient, err := rpc.DialHTTP(srv.URL)
+		require.NoError(t, err)
+		defer rpcClient.Close()
+
+		client := &Client{}
+		client.rpc = rpcClient
+
+		// We call the RPC method via HTTP and expect a proper result.
+		resp, err := client.GetPayload(ctx, payloadId)
+		require.NoError(t, err)
+		require.DeepEqual(t, want, resp)
+	})
+	t.Run(ForkchoiceUpdatedMethod, func(t *testing.T) {
+		forkChoiceState := &pb.ForkchoiceState{
+			HeadBlockHash:      []byte("head"),
+			SafeBlockHash:      []byte("safe"),
+			FinalizedBlockHash: []byte("finalized"),
+		}
+		payloadAttributes := &pb.PayloadAttributes{
+			Timestamp:             1,
+			Random:                []byte("random"),
+			SuggestedFeeRecipient: []byte("suggestedFeeRecipient"),
+		}
+		want, ok := fix["ForkchoiceUpdatedResponse"].(*ForkchoiceUpdatedResponse)
+		require.Equal(t, true, ok)
+
+		srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			w.Header().Set("Content-Type", "application/json")
+			defer func() {
+				require.NoError(t, r.Body.Close())
+			}()
+			enc, err := ioutil.ReadAll(r.Body)
+			require.NoError(t, err)
+			jsonRequestString := string(enc)
+
+			forkChoiceStateReq, err := json.Marshal(forkChoiceState)
+			require.NoError(t, err)
+			payloadAttrsReq, err := json.Marshal(payloadAttributes)
+			require.NoError(t, err)
+
+			// We expect the JSON string RPC request contains the right arguments.
+			require.Equal(t, true, strings.Contains(
+				jsonRequestString, string(forkChoiceStateReq),
+			))
+			require.Equal(t, true, strings.Contains(
+				jsonRequestString, string(payloadAttrsReq),
+			))
+			resp := map[string]interface{}{
+				"jsonrpc": "2.0",
+				"id":      1,
+				"result":  want,
+			}
+			err = json.NewEncoder(w).Encode(resp)
+			require.NoError(t, err)
+		}))
+		defer srv.Close()
+
+		rpcClient, err := rpc.DialHTTP(srv.URL)
+		require.NoError(t, err)
+		defer rpcClient.Close()
+
+		client := &Client{}
+		client.rpc = rpcClient
+
+		// We call the RPC method via HTTP and expect a proper result.
+		resp, err := client.ForkchoiceUpdated(ctx, forkChoiceState, payloadAttributes)
+		require.NoError(t, err)
+		require.DeepEqual(t, want.Status, resp.Status)
+		require.DeepEqual(t, want.PayloadId, resp.PayloadId)
+	})
+	t.Run(NewPayloadMethod, func(t *testing.T) {
+		execPayload, ok := fix["ExecutionPayload"].(*pb.ExecutionPayload)
+		require.Equal(t, true, ok)
+		want, ok := fix["PayloadStatus"].(*pb.PayloadStatus)
+		require.Equal(t, true, ok)
+		srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			w.Header().Set("Content-Type", "application/json")
+			defer func() {
+				require.NoError(t, r.Body.Close())
+			}()
+			enc, err := ioutil.ReadAll(r.Body)
+			require.NoError(t, err)
+			jsonRequestString := string(enc)
+
+			reqArg, err := json.Marshal(execPayload)
+			require.NoError(t, err)
+
+			// We expect the JSON string RPC request contains the right arguments.
+			require.Equal(t, true, strings.Contains(
+				jsonRequestString, string(reqArg),
+			))
+			resp := map[string]interface{}{
+				"jsonrpc": "2.0",
+				"id":      1,
+				"result":  want,
+			}
+			err = json.NewEncoder(w).Encode(resp)
+			require.NoError(t, err)
+		}))
+		defer srv.Close()
+
+		rpcClient, err := rpc.DialHTTP(srv.URL)
+		require.NoError(t, err)
+		defer rpcClient.Close()
+
+		client := &Client{}
+		client.rpc = rpcClient
+
+		// We call the RPC method via HTTP and expect a proper result.
+		resp, err := client.NewPayload(ctx, execPayload)
+		require.NoError(t, err)
+		require.DeepEqual(t, want, resp)
+	})
+	t.Run(ExecutionBlockByNumberMethod, func(t *testing.T) {
+		want, ok := fix["ExecutionBlock"].(*pb.ExecutionBlock)
+		require.Equal(t, true, ok)
+		srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			w.Header().Set("Content-Type", "application/json")
+			defer func() {
+				require.NoError(t, r.Body.Close())
+			}()
+			resp := map[string]interface{}{
+				"jsonrpc": "2.0",
+				"id":      1,
+				"result":  want,
+			}
+			err := json.NewEncoder(w).Encode(resp)
+			require.NoError(t, err)
+		}))
+		defer srv.Close()
+
+		rpcClient, err := rpc.DialHTTP(srv.URL)
+		require.NoError(t, err)
+		defer rpcClient.Close()
+
+		client := &Client{}
+		client.rpc = rpcClient
+
+		// We call the RPC method via HTTP and expect a proper result.
+		resp, err := client.LatestExecutionBlock(ctx)
+		require.NoError(t, err)
+		require.DeepEqual(t, want, resp)
+	})
+	t.Run(ExecutionBlockByHashMethod, func(t *testing.T) {
+		arg := common.BytesToHash([]byte("foo"))
+		want, ok := fix["ExecutionBlock"].(*pb.ExecutionBlock)
+		require.Equal(t, true, ok)
+		srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			w.Header().Set("Content-Type", "application/json")
+			defer func() {
+				require.NoError(t, r.Body.Close())
+			}()
+			enc, err := ioutil.ReadAll(r.Body)
+			require.NoError(t, err)
+			jsonRequestString := string(enc)
+			// We expect the JSON string RPC request contains the right arguments.
+			require.Equal(t, true, strings.Contains(
+				jsonRequestString, fmt.Sprintf("%#x", arg),
+			))
+			resp := map[string]interface{}{
+				"jsonrpc": "2.0",
+				"id":      1,
+				"result":  want,
+			}
+			err = json.NewEncoder(w).Encode(resp)
+			require.NoError(t, err)
+		}))
+		defer srv.Close()
+
+		rpcClient, err := rpc.DialHTTP(srv.URL)
+		require.NoError(t, err)
+		defer rpcClient.Close()
+
+		client := &Client{}
+		client.rpc = rpcClient
+
+		// We call the RPC method via HTTP and expect a proper result.
+		resp, err := client.ExecutionBlockByHash(ctx, arg)
+		require.NoError(t, err)
+		require.DeepEqual(t, want, resp)
+	})
+}
+
+type customError struct {
+	code int
+}
+
+func (c *customError) ErrorCode() int {
+	return c.code
+}
+
+func (*customError) Error() string {
+	return "something went wrong"
+}
+
+type dataError struct {
+	code int
+	data interface{}
+}
+
+func (c *dataError) ErrorCode() int {
+	return c.code
+}
+
+func (*dataError) Error() string {
+	return "something went wrong"
+}
+
+func (c *dataError) ErrorData() interface{} {
+	return c.data
+}
+
+func Test_handleRPCError(t *testing.T) {
+	got := handleRPCError(nil)
+	require.Equal(t, true, got == nil)
+
+	var tests = []struct {
+		name             string
+		expected         error
+		expectedContains string
+		given            error
+	}{
+		{
+			name:             "not an rpc error",
+			expectedContains: "got an unexpected error",
+			given:            errors.New("foo"),
+		},
+		{
+			name:             "ErrParse",
+			expectedContains: ErrParse.Error(),
+			given:            &customError{code: -32700},
+		},
+		{
+			name:             "ErrInvalidRequest",
+			expectedContains: ErrInvalidRequest.Error(),
+			given:            &customError{code: -32600},
+		},
+		{
+			name:             "ErrMethodNotFound",
+			expectedContains: ErrMethodNotFound.Error(),
+			given:            &customError{code: -32601},
+		},
+		{
+			name:             "ErrInvalidParams",
+			expectedContains: ErrInvalidParams.Error(),
+			given:            &customError{code: -32602},
+		},
+		{
+			name:             "ErrInternal",
+			expectedContains: ErrInternal.Error(),
+			given:            &customError{code: -32603},
+		},
+		{
+			name:             "ErrUnknownPayload",
+			expectedContains: ErrUnknownPayload.Error(),
+			given:            &customError{code: -32001},
+		},
+		{
+			name:             "ErrServer unexpected no data",
+			expectedContains: "got an unexpected error",
+			given:            &customError{code: -32000},
+		},
+		{
+			name:             "ErrServer with data",
+			expectedContains: ErrServer.Error(),
+			given:            &dataError{code: -32000, data: 5},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := handleRPCError(tt.given)
+			require.ErrorContains(t, tt.expectedContains, got)
+		})
+	}
+}
+
+func newTestIPCServer(t *testing.T) *rpc.Server {
+	server := rpc.NewServer()
+	err := server.RegisterName("engine", new(testEngineService))
+	require.NoError(t, err)
+	err = server.RegisterName("eth", new(testEngineService))
+	require.NoError(t, err)
+	return server
+}
+
+func fixtures() map[string]interface{} {
+	foo := bytesutil.ToBytes32([]byte("foo"))
+	bar := bytesutil.PadTo([]byte("bar"), 20)
+	baz := bytesutil.PadTo([]byte("baz"), 256)
+	baseFeePerGas := big.NewInt(6)
+	executionPayloadFixture := &pb.ExecutionPayload{
+		ParentHash:    foo[:],
+		FeeRecipient:  bar,
+		StateRoot:     foo[:],
+		ReceiptsRoot:  foo[:],
+		LogsBloom:     baz,
+		Random:        foo[:],
+		BlockNumber:   1,
+		GasLimit:      1,
+		GasUsed:       1,
+		Timestamp:     1,
+		ExtraData:     foo[:],
+		BaseFeePerGas: bytesutil.PadTo(baseFeePerGas.Bytes(), fieldparams.RootLength),
+		BlockHash:     foo[:],
+		Transactions:  [][]byte{foo[:]},
+	}
+	number := bytesutil.PadTo([]byte("100"), fieldparams.RootLength)
+	hash := bytesutil.PadTo([]byte("hash"), fieldparams.RootLength)
+	parent := bytesutil.PadTo([]byte("parentHash"), fieldparams.RootLength)
+	sha3Uncles := bytesutil.PadTo([]byte("sha3Uncles"), fieldparams.RootLength)
+	miner := bytesutil.PadTo([]byte("miner"), fieldparams.FeeRecipientLength)
+	stateRoot := bytesutil.PadTo([]byte("stateRoot"), fieldparams.RootLength)
+	transactionsRoot := bytesutil.PadTo([]byte("transactionsRoot"), fieldparams.RootLength)
+	receiptsRoot := bytesutil.PadTo([]byte("receiptsRoot"), fieldparams.RootLength)
+	logsBloom := bytesutil.PadTo([]byte("logs"), fieldparams.LogsBloomLength)
+	executionBlock := &pb.ExecutionBlock{
+		Number:           number,
+		Hash:             hash,
+		ParentHash:       parent,
+		Sha3Uncles:       sha3Uncles,
+		Miner:            miner,
+		StateRoot:        stateRoot,
+		TransactionsRoot: transactionsRoot,
+		ReceiptsRoot:     receiptsRoot,
+		LogsBloom:        logsBloom,
+		Difficulty:       bytesutil.PadTo([]byte("1"), fieldparams.RootLength),
+		TotalDifficulty:  bytesutil.PadTo([]byte("2"), fieldparams.RootLength),
+		GasLimit:         3,
+		GasUsed:          4,
+		Timestamp:        5,
+		Size:             bytesutil.PadTo([]byte("6"), fieldparams.RootLength),
+		ExtraData:        bytesutil.PadTo([]byte("extraData"), fieldparams.RootLength),
+		BaseFeePerGas:    bytesutil.PadTo([]byte("baseFeePerGas"), fieldparams.RootLength),
+		Transactions:     [][]byte{foo[:]},
+		Uncles:           [][]byte{foo[:]},
+	}
+	status := &pb.PayloadStatus{
+		Status:          pb.PayloadStatus_ACCEPTED,
+		LatestValidHash: foo[:],
+		ValidationError: "",
+	}
+	id := pb.PayloadIDBytes([8]byte{1, 0, 0, 0, 0, 0, 0, 0})
+	forkChoiceResp := &ForkchoiceUpdatedResponse{
+		Status:    status,
+		PayloadId: &id,
+	}
+	return map[string]interface{}{
+		"ExecutionBlock":            executionBlock,
+		"ExecutionPayload":          executionPayloadFixture,
+		"PayloadStatus":             status,
+		"ForkchoiceUpdatedResponse": forkChoiceResp,
+	}
+}
+
+type testEngineService struct{}
+
+func (*testEngineService) NoArgsRets() {}
+
+func (*testEngineService) GetBlockByHash(
+	_ context.Context, _ common.Hash, _ bool,
+) *pb.ExecutionBlock {
+	fix := fixtures()
+	item, ok := fix["ExecutionBlock"].(*pb.ExecutionBlock)
+	if !ok {
+		panic("not found")
+	}
+	return item
+}
+
+func (*testEngineService) GetBlockByNumber(
+	_ context.Context, _ string, _ bool,
+) *pb.ExecutionBlock {
+	fix := fixtures()
+	item, ok := fix["ExecutionBlock"].(*pb.ExecutionBlock)
+	if !ok {
+		panic("not found")
+	}
+	return item
+}
+
+func (*testEngineService) GetPayloadV1(
+	_ context.Context, _ pb.PayloadIDBytes,
+) *pb.ExecutionPayload {
+	fix := fixtures()
+	item, ok := fix["ExecutionPayload"].(*pb.ExecutionPayload)
+	if !ok {
+		panic("not found")
+	}
+	return item
+}
+
+func (*testEngineService) ForkchoiceUpdatedV1(
+	_ context.Context, _ *pb.ForkchoiceState, _ *pb.PayloadAttributes,
+) *ForkchoiceUpdatedResponse {
+	fix := fixtures()
+	item, ok := fix["ForkchoiceUpdatedResponse"].(*ForkchoiceUpdatedResponse)
+	if !ok {
+		panic("not found")
+	}
+	return item
+}
+
+func (*testEngineService) NewPayloadV1(
+	_ context.Context, _ *pb.ExecutionPayload,
+) *pb.PayloadStatus {
+	fix := fixtures()
+	item, ok := fix["PayloadStatus"].(*pb.PayloadStatus)
+	if !ok {
+		panic("not found")
+	}
+	return item
+}

beacon-chain/powchain/engine-api-client/v1/errors.go

@@ -0,0 +1,22 @@
+package v1
+
+import "github.com/pkg/errors"
+
+var (
+	// ErrParse corresponds to JSON-RPC code -32700.
+	ErrParse = errors.New("invalid JSON was received by the server")
+	// ErrInvalidRequest corresponds to JSON-RPC code -32600.
+	ErrInvalidRequest = errors.New("JSON sent is not valid request object")
+	// ErrMethodNotFound corresponds to JSON-RPC code -32601.
+	ErrMethodNotFound = errors.New("method not found")
+	// ErrInvalidParams corresponds to JSON-RPC code -32602.
+	ErrInvalidParams = errors.New("invalid method parameter(s)")
+	// ErrInternal corresponds to JSON-RPC code -32603.
+	ErrInternal = errors.New("internal JSON-RPC error")
+	// ErrServer corresponds to JSON-RPC code -32000.
+	ErrServer = errors.New("client error while processing request")
+	// ErrUnknownPayload corresponds to JSON-RPC code -32001.
+	ErrUnknownPayload = errors.New("payload does not exist or is not available")
+	// ErrUnsupportedScheme for unsupported URL schemes.
+	ErrUnsupportedScheme = errors.New("unsupported url scheme, only http(s) and ipc are supported")
+)

beacon-chain/powchain/engine-api-client/v1/options.go

@@ -0,0 +1,29 @@
+package v1
+
+import (
+	"net/http"
+)
+
+// Option for configuring the engine API client.
+type Option func(c *Client) error
+
+type config struct {
+	httpClient *http.Client
+}
+
+func defaultConfig() *config {
+	return &config{
+		httpClient: &http.Client{
+			Timeout: DefaultTimeout,
+		},
+	}
+}
+
+// WithHTTPClient allows setting a custom HTTP client
+// for the API connection.
+func WithHTTPClient(httpClient *http.Client) Option {
+	return func(c *Client) error {
+		c.cfg.httpClient = httpClient
+		return nil
+	}
+}

beacon-chain/powchain/options.go

@@ -32,6 +32,14 @@ func WithHttpEndpoints(endpointStrings []string) Option {
 	}
 }
 
+// WithExecutionEndpoint for the execution node JSON-RPC endpoint.
+func WithExecutionEndpoint(endpoint string) Option {
+	return func(s *Service) error {
+		s.cfg.executionEndpoint = endpoint
+		return nil
+	}
+}
+
 // WithDepositContractAddress for the deposit contract.
 func WithDepositContractAddress(addr common.Address) Option {
 	return func(s *Service) error {

beacon-chain/powchain/service.go

@@ -27,10 +27,13 @@ import (
 	statefeed "github.com/prysmaticlabs/prysm/beacon-chain/core/feed/state"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/transition"
 	"github.com/prysmaticlabs/prysm/beacon-chain/db"
+	engine "github.com/prysmaticlabs/prysm/beacon-chain/powchain/engine-api-client/v1"
 	"github.com/prysmaticlabs/prysm/beacon-chain/powchain/types"
 	"github.com/prysmaticlabs/prysm/beacon-chain/state"
+	nativev1 "github.com/prysmaticlabs/prysm/beacon-chain/state/state-native/v1"
 	"github.com/prysmaticlabs/prysm/beacon-chain/state/stategen"
 	v1 "github.com/prysmaticlabs/prysm/beacon-chain/state/v1"
+	"github.com/prysmaticlabs/prysm/config/features"
 	"github.com/prysmaticlabs/prysm/config/params"
 	"github.com/prysmaticlabs/prysm/container/trie"
 	contracts "github.com/prysmaticlabs/prysm/contracts/deposit"
@@ -133,6 +136,7 @@ type config struct {
 	eth1HeaderReqLimit      uint64
 	beaconNodeStatsUpdater  BeaconNodeStatsUpdater
 	httpEndpoints           []network.Endpoint
+	executionEndpoint       string
 	currHttpEndpoint        network.Endpoint
 	finalizedStateAtStartup state.BeaconState
 }
@@ -153,6 +157,7 @@ type Service struct {
 	headTicker              *time.Ticker
 	httpLogger              bind.ContractFilterer
 	eth1DataFetcher         RPCDataFetcher
+	engineAPIClient         *engine.Client
 	rpcClient               RPCClient
 	headerCache             *headerCache // cache to store block hash/block height.
 	latestEth1Data          *ethpb.LatestETH1Data
@@ -208,6 +213,10 @@ func NewService(ctx context.Context, opts ...Option) (*Service, error) {
 		}
 	}
 
+	if err := s.initializeEngineAPIClient(ctx); err != nil {
+		return nil, errors.Wrap(err, "unable to initialize engine API client")
+	}
+
 	if err := s.ensureValidPowchainData(ctx); err != nil {
 		return nil, errors.Wrap(err, "unable to validate powchain data")
 	}
@@ -271,7 +280,11 @@ func (s *Service) ChainStartDeposits() []*ethpb.Deposit {
 // ClearPreGenesisData clears out the stored chainstart deposits and beacon state.
 func (s *Service) ClearPreGenesisData() {
 	s.chainStartData.ChainstartDeposits = []*ethpb.Deposit{}
-	s.preGenesisState = &v1.BeaconState{}
+	if features.Get().EnableNativeState {
+		s.preGenesisState = &nativev1.BeaconState{}
+	} else {
+		s.preGenesisState = &v1.BeaconState{}
+	}
 }
 
 // ChainStartEth1Data returns the eth1 data at chainstart.
@@ -298,6 +311,12 @@ func (s *Service) Status() error {
 	return nil
 }
 
+// EngineAPIClient returns the associated engine API client to interact
+// with an execution node via JSON-RPC.
+func (s *Service) EngineAPIClient() *engine.Client {
+	return s.engineAPIClient
+}
+
 func (s *Service) updateBeaconNodeStats() {
 	bs := clientstats.BeaconNodeStats{}
 	if len(s.cfg.httpEndpoints) > 1 {
@@ -783,12 +802,14 @@ func (s *Service) initPOWService() {
 			s.latestEth1Data.BlockHeight = header.Number.Uint64()
 			s.latestEth1Data.BlockHash = header.Hash().Bytes()
 			s.latestEth1Data.BlockTime = header.Time
-
-			if err := s.processPastLogs(ctx); err != nil {
-				log.Errorf("Unable to process past logs %v", err)
-				s.retryETH1Node(err)
-				continue
+			if !features.Get().KilnTestnet {
+				if err := s.processPastLogs(ctx); err != nil {
+					log.Errorf("Unable to process past logs %v", err)
+					s.retryETH1Node(err)
+					continue
+				}
 			}
+
 			// Cache eth1 headers from our voting period.
 			if err := s.cacheHeadersForEth1DataVote(ctx); err != nil {
 				log.Errorf("Unable to process past headers %v", err)
@@ -797,14 +818,21 @@ func (s *Service) initPOWService() {
 			}
 			// Handle edge case with embedded genesis state by fetching genesis header to determine
 			// its height.
-			if s.chainStartData.Chainstarted && s.chainStartData.GenesisBlock == 0 {
-				genHeader, err := s.eth1DataFetcher.HeaderByHash(ctx, common.BytesToHash(s.chainStartData.Eth1Data.BlockHash))
-				if err != nil {
-					log.Errorf("Unable to retrieve genesis ETH1.0 chain header: %v", err)
-					s.retryETH1Node(err)
-					continue
+			if s.chainStartData.Chainstarted && s.chainStartData.GenesisBlock == 0 && !features.Get().KilnTestnet {
+				genHash := common.BytesToHash(s.chainStartData.Eth1Data.BlockHash)
+				genBlock := s.chainStartData.GenesisBlock
+				// In the event our provided chainstart data references a non-existent blockhash
+				// we assume the genesis block to be 0.
+				if genHash != [32]byte{} {
+					genHeader, err := s.eth1DataFetcher.HeaderByHash(ctx, genHash)
+					if err != nil {
+						log.Errorf("Unable to retrieve genesis ETH1.0 chain header: %v", err)
+						s.retryETH1Node(err)
+						continue
+					}
+					genBlock = genHeader.Number.Uint64()
 				}
-				s.chainStartData.GenesisBlock = genHeader.Number.Uint64()
+				s.chainStartData.GenesisBlock = genBlock
 				if err := s.savePowchainData(ctx); err != nil {
 					log.Errorf("Unable to save powchain data: %v", err)
 				}
@@ -1073,6 +1101,19 @@ func (s *Service) ensureValidPowchainData(ctx context.Context) error {
 	return nil
 }
 
+// Initializes a connection to the engine API if an execution provider endpoint is set.
+func (s *Service) initializeEngineAPIClient(ctx context.Context) error {
+	if s.cfg.executionEndpoint == "" {
+		return nil
+	}
+	client, err := engine.New(ctx, s.cfg.executionEndpoint)
+	if err != nil {
+		return err
+	}
+	s.engineAPIClient = client
+	return nil
+}
+
 func dedupEndpoints(endpoints []string) []string {
 	selectionMap := make(map[string]bool)
 	newEndpoints := make([]string, 0, len(endpoints))

beacon-chain/powchain/testing/BUILD.bazel

@@ -24,5 +24,6 @@ go_library(
         "@com_github_ethereum_go_ethereum//common/hexutil:go_default_library",
         "@com_github_ethereum_go_ethereum//core/types:go_default_library",
         "@com_github_ethereum_go_ethereum//rpc:go_default_library",
+        "@com_github_pkg_errors//:go_default_library",
     ],
 )

beacon-chain/powchain/testing/mock_faulty_powchain.go

@@ -2,10 +2,10 @@ package testing
 
 import (
 	"context"
-	"errors"
 	"math/big"
 
 	"github.com/ethereum/go-ethereum/common"
+	"github.com/pkg/errors"
 	"github.com/prysmaticlabs/prysm/async/event"
 	"github.com/prysmaticlabs/prysm/beacon-chain/powchain/types"
 	"github.com/prysmaticlabs/prysm/beacon-chain/state"
@@ -76,7 +76,11 @@ func (_ *FaultyMockPOWChain) ChainStartEth1Data() *ethpb.Eth1Data {
 
 // PreGenesisState --
 func (_ *FaultyMockPOWChain) PreGenesisState() state.BeaconState {
-	return &v1.BeaconState{}
+	s, err := v1.InitializeFromProtoUnsafe(&ethpb.BeaconState{})
+	if err != nil {
+		panic("could not initialize state")
+	}
+	return s
 }
 
 // ClearPreGenesisData --

beacon-chain/rpc/BUILD.bazel

@@ -22,6 +22,7 @@ go_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/rpc/eth/beacon:go_default_library",
         "//beacon-chain/rpc/eth/debug:go_default_library",
         "//beacon-chain/rpc/eth/events:go_default_library",

beacon-chain/rpc/eth/beacon/config_test.go

@@ -31,6 +31,7 @@ func TestGetSpec(t *testing.T) {
 	config.HysteresisQuotient = 9
 	config.HysteresisDownwardMultiplier = 10
 	config.HysteresisUpwardMultiplier = 11
+	config.SafeSlotsToImportOptimistically = 128
 	config.SafeSlotsToUpdateJustified = 12
 	config.Eth1FollowDistance = 13
 	config.TargetAggregatorsPerCommittee = 14
@@ -51,7 +52,6 @@ func TestGetSpec(t *testing.T) {
 	config.BellatrixForkEpoch = 101
 	config.ShardingForkVersion = []byte("ShardingForkVersion")
 	config.ShardingForkEpoch = 102
-	config.MinAnchorPowBlockDifficulty = 1000
 	config.BLSWithdrawalPrefixByte = byte('b')
 	config.GenesisDelay = 24
 	config.SecondsPerSlot = 25
@@ -99,7 +99,7 @@ func TestGetSpec(t *testing.T) {
 	config.MinSyncCommitteeParticipants = 71
 	config.TerminalBlockHash = common.HexToHash("TerminalBlockHash")
 	config.TerminalBlockHashActivationEpoch = 72
-	config.TerminalTotalDifficulty = 73
+	config.TerminalTotalDifficulty = "73"
 	config.FeeRecipient = common.HexToAddress("FeeRecipient")
 
 	var dbp [4]byte
@@ -130,7 +130,7 @@ func TestGetSpec(t *testing.T) {
 	resp, err := server.GetSpec(context.Background(), &emptypb.Empty{})
 	require.NoError(t, err)
 
-	assert.Equal(t, 99, len(resp.Data))
+	assert.Equal(t, 98, len(resp.Data))
 	for k, v := range resp.Data {
 		switch k {
 		case "CONFIG_NAME":
@@ -341,6 +341,8 @@ func TestGetSpec(t *testing.T) {
 			assert.Equal(t, "70", v)
 		case "INTERVALS_PER_SLOT":
 			assert.Equal(t, "3", v)
+		case "SAFE_SLOTS_TO_IMPORT_OPTIMISTICALLY":
+			assert.Equal(t, "128", v)
 		default:
 			t.Errorf("Incorrect key: %s", k)
 		}

beacon-chain/rpc/eth/beacon/pool.go

@@ -275,7 +275,7 @@ func (bs *Server) SubmitVoluntaryExit(ctx context.Context, req *ethpbv1.SignedVo
 		return nil, status.Errorf(codes.Internal, "Could not get exiting validator: %v", err)
 	}
 	alphaExit := migration.V1ExitToV1Alpha1(req)
-	err = blocks.VerifyExitAndSignature(validator, headState.Slot(), headState.Fork(), alphaExit, headState.GenesisValidatorRoot())
+	err = blocks.VerifyExitAndSignature(validator, headState.Slot(), headState.Fork(), alphaExit, headState.GenesisValidatorsRoot())
 	if err != nil {
 		return nil, status.Errorf(codes.InvalidArgument, "Invalid voluntary exit: %v", err)
 	}

beacon-chain/rpc/eth/beacon/state.go

@@ -34,7 +34,7 @@ func (bs *Server) GetGenesis(ctx context.Context, _ *emptypb.Empty) (*ethpb.Gene
 	if genesisTime.IsZero() {
 		return nil, status.Errorf(codes.NotFound, "Chain genesis info is not yet known")
 	}
-	validatorRoot := bs.ChainInfoFetcher.GenesisValidatorRoot()
+	validatorRoot := bs.ChainInfoFetcher.GenesisValidatorsRoot()
 	if bytes.Equal(validatorRoot[:], params.BeaconConfig().ZeroHash[:]) {
 		return nil, status.Errorf(codes.NotFound, "Chain genesis info is not yet known")
 	}

beacon-chain/rpc/eth/beacon/state_test.go

@@ -56,7 +56,7 @@ func TestGetGenesis(t *testing.T) {
 		assert.ErrorContains(t, "Chain genesis info is not yet known", err)
 	})
 
-	t.Run("No genesis validator root", func(t *testing.T) {
+	t.Run("No genesis validators root", func(t *testing.T) {
 		chainService := &chainMock.ChainService{
 			Genesis:        genesis,
 			ValidatorsRoot: [32]byte{},

beacon-chain/rpc/eth/debug/BUILD.bazel

@@ -13,8 +13,7 @@ go_library(
         "//beacon-chain/db:go_default_library",
         "//beacon-chain/rpc/eth/helpers:go_default_library",
         "//beacon-chain/rpc/statefetcher:go_default_library",
-        "//beacon-chain/state/v1:go_default_library",
-        "//beacon-chain/state/v2:go_default_library",
+        "//beacon-chain/state:go_default_library",
         "//proto/eth/v1:go_default_library",
         "//proto/eth/v2:go_default_library",
         "//proto/migration:go_default_library",

beacon-chain/rpc/eth/debug/debug.go

@@ -4,8 +4,7 @@ import (
 	"context"
 
 	"github.com/prysmaticlabs/prysm/beacon-chain/rpc/eth/helpers"
-	statev1 "github.com/prysmaticlabs/prysm/beacon-chain/state/v1"
-	statev2 "github.com/prysmaticlabs/prysm/beacon-chain/state/v2"
+	"github.com/prysmaticlabs/prysm/beacon-chain/state"
 	ethpbv1 "github.com/prysmaticlabs/prysm/proto/eth/v1"
 	ethpbv2 "github.com/prysmaticlabs/prysm/proto/eth/v2"
 	"github.com/prysmaticlabs/prysm/proto/migration"
@@ -26,11 +25,10 @@ func (ds *Server) GetBeaconState(ctx context.Context, req *ethpbv1.StateRequest)
 		return nil, helpers.PrepareStateFetchGRPCError(err)
 	}
 
-	st, ok := beaconSt.(*statev1.BeaconState)
-	if !ok {
-		return nil, status.Error(codes.Internal, "State type assertion failed")
+	if beaconSt.Version() != version.Phase0 {
+		return nil, status.Error(codes.Internal, "State has incorrect type")
 	}
-	protoSt, err := migration.BeaconStateToV1(st)
+	protoSt, err := migration.BeaconStateToV1(beaconSt)
 	if err != nil {
 		return nil, status.Errorf(codes.Internal, "Could not convert state to proto: %v", err)
 	}
@@ -69,11 +67,7 @@ func (ds *Server) GetBeaconStateV2(ctx context.Context, req *ethpbv2.StateReques
 	}
 	switch beaconSt.Version() {
 	case version.Phase0:
-		st, ok := beaconSt.(*statev1.BeaconState)
-		if !ok {
-			return nil, status.Error(codes.Internal, "State type assertion failed")
-		}
-		protoSt, err := migration.BeaconStateToV1(st)
+		protoSt, err := migration.BeaconStateToV1(beaconSt)
 		if err != nil {
 			return nil, status.Errorf(codes.Internal, "Could not convert state to proto: %v", err)
 		}
@@ -84,7 +78,7 @@ func (ds *Server) GetBeaconStateV2(ctx context.Context, req *ethpbv2.StateReques
 			},
 		}, nil
 	case version.Altair:
-		altairState, ok := beaconSt.(*statev2.BeaconState)
+		altairState, ok := beaconSt.(state.BeaconStateAltair)
 		if !ok {
 			return nil, status.Error(codes.Internal, "Altair state type assertion failed")
 		}

beacon-chain/rpc/prysm/v1alpha1/beacon/attestations_test.go

@@ -910,7 +910,7 @@ func TestServer_StreamIndexedAttestations_OK(t *testing.T) {
 					},
 				},
 			}
-			domain, err := signing.Domain(headState.Fork(), 0, params.BeaconConfig().DomainBeaconAttester, headState.GenesisValidatorRoot())
+			domain, err := signing.Domain(headState.Fork(), 0, params.BeaconConfig().DomainBeaconAttester, headState.GenesisValidatorsRoot())
 			require.NoError(t, err)
 			encoded, err := signing.ComputeSigningRoot(attExample.Data, domain)
 			require.NoError(t, err)

beacon-chain/rpc/prysm/v1alpha1/node/server.go

@@ -68,7 +68,7 @@ func (ns *Server) GetGenesis(ctx context.Context, _ *empty.Empty) (*ethpb.Genesi
 		gt = timestamppb.New(genesisTime)
 	}
 
-	genValRoot := ns.GenesisFetcher.GenesisValidatorRoot()
+	genValRoot := ns.GenesisFetcher.GenesisValidatorsRoot()
 	return &ethpb.Genesis{
 		GenesisTime:            gt,
 		DepositContractAddress: contractAddr,
@@ -227,7 +227,11 @@ func (ns *Server) GetETH1ConnectionStatus(ctx context.Context, _ *empty.Empty) (
 	errs := ns.POWChainInfoFetcher.ETH1ConnectionErrors()
 	// Extract string version of the errors.
 	for _, err := range errs {
-		errStrs = append(errStrs, err.Error())
+		if err == nil {
+			errStrs = append(errStrs, "")
+		} else {
+			errStrs = append(errStrs, err.Error())
+		}
 	}
 	return &ethpb.ETH1ConnectionStatus{
 		CurrentAddress:         ns.POWChainInfoFetcher.CurrentETH1Endpoint(),

beacon-chain/rpc/prysm/v1alpha1/node/server_test.go

@@ -153,8 +153,8 @@ func TestNodeServer_ListPeers(t *testing.T) {
 func TestNodeServer_GetETH1ConnectionStatus(t *testing.T) {
 	server := grpc.NewServer()
 	eps := []string{"foo", "bar"}
-	errs := []error{fmt.Errorf("error 1"), fmt.Errorf("error 2")}
-	errStrs := []string{"error 1", "error 2"}
+	errs := []error{fmt.Errorf("error 1"), fmt.Errorf("error 2"), nil}
+	errStrs := []string{"error 1", "error 2", ""}
 	mockFetcher := &testutil.MockPOWChainInfoFetcher{
 		CurrEndpoint: eps[0],
 		CurrError:    errs[0],

beacon-chain/rpc/prysm/v1alpha1/validator/BUILD.bazel

@@ -12,8 +12,10 @@ go_library(
         "proposer.go",
         "proposer_altair.go",
         "proposer_attestations.go",
+        "proposer_bellatrix.go",
         "proposer_deposits.go",
         "proposer_eth1data.go",
+        "proposer_execution_payload.go",
         "proposer_phase0.go",
         "proposer_sync_aggregate.go",
         "server.go",
@@ -39,12 +41,14 @@ go_library(
         "//beacon-chain/core/transition:go_default_library",
         "//beacon-chain/core/transition/interop:go_default_library",
         "//beacon-chain/core/validators:go_default_library",
+        "//beacon-chain/db:go_default_library",
         "//beacon-chain/operations/attestations:go_default_library",
         "//beacon-chain/operations/slashings:go_default_library",
         "//beacon-chain/operations/synccommittee: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",
         "//beacon-chain/sync:go_default_library",
@@ -59,6 +63,7 @@ go_library(
         "//encoding/bytesutil:go_default_library",
         "//monitoring/tracing:go_default_library",
         "//network/forks: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/aggregation:go_default_library",
@@ -69,7 +74,9 @@ go_library(
         "//runtime/version:go_default_library",
         "//time:go_default_library",
         "//time/slots:go_default_library",
+        "@com_github_ethereum_go_ethereum//common:go_default_library",
         "@com_github_ferranbt_fastssz//:go_default_library",
+        "@com_github_holiman_uint256//:go_default_library",
         "@com_github_pkg_errors//:go_default_library",
         "@com_github_prysmaticlabs_eth2_types//:go_default_library",
         "@com_github_prysmaticlabs_go_bitfield//:go_default_library",
@@ -134,6 +141,7 @@ go_test(
         "//container/trie:go_default_library",
         "//crypto/bls:go_default_library",
         "//encoding/bytesutil: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",

beacon-chain/rpc/prysm/v1alpha1/validator/aggregator_test.go

@@ -30,7 +30,8 @@ import (
 func TestSubmitAggregateAndProof_Syncing(t *testing.T) {
 	ctx := context.Background()
 
-	s := &v1.BeaconState{}
+	s, err := v1.InitializeFromProtoUnsafe(&ethpb.BeaconState{})
+	require.NoError(t, err)
 
 	aggregatorServer := &Server{
 		HeadFetcher: &mock.ChainService{State: s},
@@ -39,7 +40,7 @@ func TestSubmitAggregateAndProof_Syncing(t *testing.T) {
 
 	req := &ethpb.AggregateSelectionRequest{CommitteeIndex: 1}
 	wanted := "Syncing to latest head, not ready to respond"
-	_, err := aggregatorServer.SubmitAggregateSelectionProof(ctx, req)
+	_, err = aggregatorServer.SubmitAggregateSelectionProof(ctx, req)
 	assert.ErrorContains(t, wanted, err)
 }
 

beacon-chain/rpc/prysm/v1alpha1/validator/exit.go

@@ -34,7 +34,7 @@ func (vs *Server) ProposeExit(ctx context.Context, req *ethpb.SignedVoluntaryExi
 		return nil, status.Error(codes.InvalidArgument, "validator index exceeds validator set length")
 	}
 
-	if err := blocks.VerifyExitAndSignature(val, s.Slot(), s.Fork(), req, s.GenesisValidatorRoot()); err != nil {
+	if err := blocks.VerifyExitAndSignature(val, s.Slot(), s.Fork(), req, s.GenesisValidatorsRoot()); err != nil {
 		return nil, status.Error(codes.InvalidArgument, err.Error())
 	}
 

beacon-chain/rpc/prysm/v1alpha1/validator/proposer.go

@@ -40,12 +40,20 @@ func (vs *Server) GetBeaconBlock(ctx context.Context, req *ethpb.BlockRequest) (
 			return nil, status.Errorf(codes.Internal, "Could not fetch phase0 beacon block: %v", err)
 		}
 		return &ethpb.GenericBeaconBlock{Block: &ethpb.GenericBeaconBlock_Phase0{Phase0: blk}}, nil
+	} else if slots.ToEpoch(req.Slot) < params.BeaconConfig().BellatrixForkEpoch {
+		blk, err := vs.getAltairBeaconBlock(ctx, req)
+		if err != nil {
+			return nil, status.Errorf(codes.Internal, "Could not fetch Altair beacon block: %v", err)
+		}
+		return &ethpb.GenericBeaconBlock{Block: &ethpb.GenericBeaconBlock_Altair{Altair: blk}}, nil
 	}
-	blk, err := vs.getAltairBeaconBlock(ctx, req)
+
+	blk, err := vs.getBellatrixBeaconBlock(ctx, req)
 	if err != nil {
-		return nil, status.Errorf(codes.Internal, "Could not fetch Altair beacon block: %v", err)
+		return nil, status.Errorf(codes.Internal, "Could not fetch Bellatrix beacon block: %v", err)
 	}
-	return &ethpb.GenericBeaconBlock{Block: &ethpb.GenericBeaconBlock_Altair{Altair: blk}}, nil
+
+	return &ethpb.GenericBeaconBlock{Block: &ethpb.GenericBeaconBlock_Bellatrix{Bellatrix: blk}}, nil
 }
 
 // GetBlock is called by a proposer during its assigned slot to request a block to sign
@@ -75,6 +83,11 @@ func (vs *Server) ProposeBeaconBlock(ctx context.Context, req *ethpb.GenericSign
 		if err != nil {
 			return nil, status.Error(codes.Internal, "could not wrap altair beacon block")
 		}
+	case *ethpb.GenericSignedBeaconBlock_Bellatrix:
+		blk, err = wrapper.WrappedBellatrixSignedBeaconBlock(b.Bellatrix)
+		if err != nil {
+			return nil, status.Error(codes.Internal, "could not wrap Bellatrix beacon block")
+		}
 	default:
 		return nil, status.Error(codes.Internal, "block version not supported")
 	}

beacon-chain/rpc/prysm/v1alpha1/validator/proposer_altair.go

@@ -15,8 +15,8 @@ import (
 	"go.opencensus.io/trace"
 )
 
-func (vs *Server) getAltairBeaconBlock(ctx context.Context, req *ethpb.BlockRequest) (*ethpb.BeaconBlockAltair, error) {
-	ctx, span := trace.StartSpan(ctx, "ProposerServer.getAltairBeaconBlock")
+func (vs *Server) buildAltairBeaconBlock(ctx context.Context, req *ethpb.BlockRequest) (*ethpb.BeaconBlockAltair, error) {
+	ctx, span := trace.StartSpan(ctx, "ProposerServer.buildAltairBeaconBlock")
 	defer span.End()
 	blkData, err := vs.buildPhase0BlockData(ctx, req)
 	if err != nil {
@@ -33,7 +33,7 @@ func (vs *Server) getAltairBeaconBlock(ctx context.Context, req *ethpb.BlockRequ
 		return nil, err
 	}
 
-	blk := &ethpb.BeaconBlockAltair{
+	return &ethpb.BeaconBlockAltair{
 		Slot:          req.Slot,
 		ParentRoot:    blkData.ParentRoot,
 		StateRoot:     stateRoot,
@@ -49,6 +49,15 @@ func (vs *Server) getAltairBeaconBlock(ctx context.Context, req *ethpb.BlockRequ
 			Graffiti:          blkData.Graffiti[:],
 			SyncAggregate:     syncAggregate,
 		},
+	}, nil
+}
+
+func (vs *Server) getAltairBeaconBlock(ctx context.Context, req *ethpb.BlockRequest) (*ethpb.BeaconBlockAltair, error) {
+	ctx, span := trace.StartSpan(ctx, "ProposerServer.getAltairBeaconBlock")
+	defer span.End()
+	blk, err := vs.buildAltairBeaconBlock(ctx, req)
+	if err != nil {
+		return nil, fmt.Errorf("could not build block data: %v", err)
 	}
 	// Compute state root with the newly constructed block.
 	wsb, err := wrapper.WrappedAltairSignedBeaconBlock(
@@ -57,7 +66,7 @@ func (vs *Server) getAltairBeaconBlock(ctx context.Context, req *ethpb.BlockRequ
 	if err != nil {
 		return nil, err
 	}
-	stateRoot, err = vs.computeStateRoot(ctx, wsb)
+	stateRoot, err := vs.computeStateRoot(ctx, wsb)
 	if err != nil {
 		interop.WriteBlockToDisk(wsb, true /*failed*/)
 		return nil, fmt.Errorf("could not compute state root: %v", err)