Implement ListForkChoiceHeads in the debug API (#8675)

* initial implementation

* use ChainHeads to get heads

* API unit tests

* remove unnecessary identifier

* fix formatting

* gzl

* Update chainheads to fork choice scope

* use HeadFetcher

* fix test

* gzl

* remove junk

* remove ChainHeads from forkchoice

Co-authored-by: terence tsao <terence@prysmaticlabs.com>
Co-authored-by: Victor Farazdagi <simple.square@gmail.com>

beacon-chain/blockchain/testing/BUILD.bazel

@@ -21,6 +21,7 @@ go_library(
         "//beacon-chain/state/interface:go_default_library",
         "//beacon-chain/state/stateV0:go_default_library",
         "//proto/beacon/p2p/v1:go_default_library",
+        "//shared/bytesutil:go_default_library",
         "//shared/event:go_default_library",
         "//shared/params:go_default_library",
         "@com_github_pkg_errors//:go_default_library",

beacon-chain/blockchain/testing/mock.go

@@ -22,6 +22,7 @@ import (
 	iface "github.com/prysmaticlabs/prysm/beacon-chain/state/interface"
 	"github.com/prysmaticlabs/prysm/beacon-chain/state/stateV0"
 	pb "github.com/prysmaticlabs/prysm/proto/beacon/p2p/v1"
+	"github.com/prysmaticlabs/prysm/shared/bytesutil"
 	"github.com/prysmaticlabs/prysm/shared/event"
 	"github.com/prysmaticlabs/prysm/shared/params"
 	"github.com/sirupsen/logrus"
@@ -385,5 +386,9 @@ func (s *ChainService) VerifyFinalizedConsistency(_ context.Context, r []byte) e
 
 // ChainHeads mocks ChainHeads and always return nil.
 func (s *ChainService) ChainHeads() ([][32]byte, []types.Slot) {
-	return [][32]byte{}, []types.Slot{}
+	return [][32]byte{
+			bytesutil.ToBytes32(bytesutil.PadTo([]byte("foo"), 32)),
+			bytesutil.ToBytes32(bytesutil.PadTo([]byte("bar"), 32)),
+		},
+		[]types.Slot{0, 1}
 }

beacon-chain/rpc/debugv1/BUILD.bazel

@@ -10,11 +10,12 @@ go_library(
     importpath = "github.com/prysmaticlabs/prysm/beacon-chain/rpc/debugv1",
     visibility = ["//beacon-chain:__subpackages__"],
     deps = [
+        "//beacon-chain/blockchain:go_default_library",
         "//beacon-chain/db:go_default_library",
         "//beacon-chain/rpc/statefetcher:go_default_library",
         "@com_github_gogo_protobuf//types:go_default_library",
-        "@com_github_pkg_errors//:go_default_library",
         "@com_github_prysmaticlabs_ethereumapis//eth/v1:go_default_library",
+        "@io_opencensus_go//trace:go_default_library",
         "@org_golang_google_grpc//codes:go_default_library",
         "@org_golang_google_grpc//status:go_default_library",
     ],
@@ -25,10 +26,14 @@ go_test(
     srcs = ["debug_test.go"],
     embed = [":go_default_library"],
     deps = [
+        "//beacon-chain/blockchain/testing:go_default_library",
         "//beacon-chain/rpc/testutil:go_default_library",
+        "//shared/bytesutil:go_default_library",
         "//shared/testutil:go_default_library",
         "//shared/testutil/assert:go_default_library",
         "//shared/testutil/require:go_default_library",
+        "@com_github_gogo_protobuf//types:go_default_library",
+        "@com_github_prysmaticlabs_eth2_types//:go_default_library",
         "@com_github_prysmaticlabs_ethereumapis//eth/v1:go_default_library",
     ],
 )

beacon-chain/rpc/debugv1/debug.go

@@ -4,8 +4,8 @@ import (
 	"context"
 
 	ptypes "github.com/gogo/protobuf/types"
-	"github.com/pkg/errors"
 	ethpb "github.com/prysmaticlabs/ethereumapis/eth/v1"
+	"go.opencensus.io/trace"
 	"google.golang.org/grpc/codes"
 	"google.golang.org/grpc/status"
 )
@@ -29,5 +29,19 @@ func (ds *Server) GetBeaconState(ctx context.Context, req *ethpb.StateRequest) (
 
 // ListForkChoiceHeads retrieves the fork choice leaves for the current head.
 func (ds *Server) ListForkChoiceHeads(ctx context.Context, _ *ptypes.Empty) (*ethpb.ForkChoiceHeadsResponse, error) {
-	return nil, errors.New("unimplemented")
+	ctx, span := trace.StartSpan(ctx, "debugv1.ListForkChoiceHeads")
+	defer span.End()
+
+	headRoots, headSlots := ds.HeadFetcher.ChainHeads()
+	resp := &ethpb.ForkChoiceHeadsResponse{
+		Data: make([]*ethpb.ForkChoiceHead, len(headRoots)),
+	}
+	for i := range headRoots {
+		resp.Data[i] = &ethpb.ForkChoiceHead{
+			Root: headRoots[i][:],
+			Slot: headSlots[i],
+		}
+	}
+
+	return resp, nil
 }

beacon-chain/rpc/debugv1/debug_test.go

@@ -4,8 +4,12 @@ import (
 	"context"
 	"testing"
 
+	protoTypes "github.com/gogo/protobuf/types"
+	types "github.com/prysmaticlabs/eth2-types"
 	ethpb "github.com/prysmaticlabs/ethereumapis/eth/v1"
+	blockchainmock "github.com/prysmaticlabs/prysm/beacon-chain/blockchain/testing"
 	"github.com/prysmaticlabs/prysm/beacon-chain/rpc/testutil"
+	"github.com/prysmaticlabs/prysm/shared/bytesutil"
 	sharedtestutil "github.com/prysmaticlabs/prysm/shared/testutil"
 	"github.com/prysmaticlabs/prysm/shared/testutil/assert"
 	"github.com/prysmaticlabs/prysm/shared/testutil/require"
@@ -25,3 +29,35 @@ func TestGetBeaconState(t *testing.T) {
 	require.NoError(t, err)
 	assert.NotNil(t, resp)
 }
+
+func TestListForkChoiceHeads(t *testing.T) {
+	ctx := context.Background()
+
+	expectedSlotsAndRoots := []struct {
+		Slot types.Slot
+		Root [32]byte
+	}{{
+		Slot: 0,
+		Root: bytesutil.ToBytes32(bytesutil.PadTo([]byte("foo"), 32)),
+	}, {
+		Slot: 1,
+		Root: bytesutil.ToBytes32(bytesutil.PadTo([]byte("bar"), 32)),
+	}}
+
+	server := &Server{
+		HeadFetcher: &blockchainmock.ChainService{},
+	}
+	resp, err := server.ListForkChoiceHeads(ctx, &protoTypes.Empty{})
+	require.NoError(t, err)
+	assert.Equal(t, 2, len(resp.Data))
+	for _, sr := range expectedSlotsAndRoots {
+		found := false
+		for _, h := range resp.Data {
+			if h.Slot == sr.Slot {
+				found = true
+				assert.DeepEqual(t, sr.Root[:], h.Root)
+			}
+		}
+		assert.Equal(t, true, found, "Expected head not found")
+	}
+}

beacon-chain/rpc/debugv1/server.go

@@ -6,6 +6,7 @@ package debugv1
 import (
 	"context"
 
+	"github.com/prysmaticlabs/prysm/beacon-chain/blockchain"
 	"github.com/prysmaticlabs/prysm/beacon-chain/db"
 	"github.com/prysmaticlabs/prysm/beacon-chain/rpc/statefetcher"
 )
@@ -16,5 +17,6 @@ import (
 type Server struct {
 	Ctx          context.Context
 	BeaconDB     db.ReadOnlyDatabase
+	HeadFetcher  blockchain.HeadFetcher
 	StateFetcher statefetcher.Fetcher
 }

beacon-chain/rpc/service.go

@@ -278,8 +278,9 @@ func (s *Service) Start() {
 			PeersFetcher:       s.cfg.PeersFetcher,
 		}
 		debugServerV1 := &debugv1.Server{
-			Ctx:      s.ctx,
-			BeaconDB: s.cfg.BeaconDB,
+			Ctx:         s.ctx,
+			BeaconDB:    s.cfg.BeaconDB,
+			HeadFetcher: s.cfg.HeadFetcher,
 			StateFetcher: &statefetcher.StateProvider{
 				BeaconDB:           s.cfg.BeaconDB,
 				ChainInfoFetcher:   s.cfg.ChainInfoFetcher,