WIP refactoring blockchain service startup

* manual proto changes

* generated files

* missed comment

beacon-chain/blockchain/BUILD.bazel

@@ -4,6 +4,7 @@ go_library(
     name = "go_default_library",
     srcs = [
         "chain_info.go",
+        "clock.go",
         "error.go",
         "execution_engine.go",
         "head.go",
@@ -52,6 +53,7 @@ go_library(
         "//beacon-chain/forkchoice/doubly-linked-tree:go_default_library",
         "//beacon-chain/forkchoice/protoarray:go_default_library",
         "//beacon-chain/forkchoice/types:go_default_library",
+        "//beacon-chain/geninit:go_default_library",
         "//beacon-chain/operations/attestations:go_default_library",
         "//beacon-chain/operations/slashings:go_default_library",
         "//beacon-chain/operations/voluntaryexits:go_default_library",
@@ -59,7 +61,6 @@ go_library(
         "//beacon-chain/powchain:go_default_library",
         "//beacon-chain/state:go_default_library",
         "//beacon-chain/state/stategen:go_default_library",
-        "//cmd/beacon-chain/flags:go_default_library",
         "//config/features:go_default_library",
         "//config/fieldparams:go_default_library",
         "//config/params:go_default_library",

beacon-chain/blockchain/chain_info.go

@@ -27,8 +27,8 @@ type ChainInfoFetcher interface {
 	GenesisFetcher
 	CanonicalFetcher
 	ForkFetcher
-	TimeFetcher
 	HeadDomainFetcher
+	ClockProvider
 }
 
 // HeadUpdater defines a common interface for methods in blockchain service
@@ -37,9 +37,7 @@ type HeadUpdater interface {
 	UpdateHead(context.Context) error
 }
 
-// TimeFetcher retrieves the Ethereum consensus data that's related to time.
-type TimeFetcher interface {
-	GenesisTime() time.Time
+type CurrentSlotter interface {
 	CurrentSlot() types.Slot
 }
 
@@ -220,11 +218,6 @@ func (s *Service) HeadETH1Data() *ethpb.Eth1Data {
 	return s.head.state.Eth1Data()
 }
 
-// GenesisTime returns the genesis time of beacon chain.
-func (s *Service) GenesisTime() time.Time {
-	return s.genesisTime
-}
-
 // GenesisValidatorsRoot returns the genesis validators
 // root of the chain.
 func (s *Service) GenesisValidatorsRoot() [32]byte {
@@ -370,10 +363,44 @@ func (s *Service) IsOptimisticForRoot(ctx context.Context, root [32]byte) (bool,
 
 // SetGenesisTime sets the genesis time of beacon chain.
 func (s *Service) SetGenesisTime(t time.Time) {
-	s.genesisTime = t
+	s.clock = NewClock(t)
+	close(s.clockReady)
+}
+
+func (s *Service) setClock(c Clock) {
+	s.clock = c
+	close(s.clockReady)
+}
+
+func (s *Service) genesisTime() time.Time {
+	c, err := s.WaitForClock(context.TODO())
+	if err != nil {
+		panic(err)
+	}
+	return c.GenesisTime()
 }
 
 // ForkChoiceStore returns the fork choice store in the service.
 func (s *Service) ForkChoiceStore() forkchoice.ForkChoicer {
 	return s.cfg.ForkChoiceStore
 }
+
+// ClockProvider implements WaitForClock, yielding a clock type that can be used to get
+// the genesis time, slot values derived from genesis, or a possibly synthetic time.Now value
+type ClockProvider interface {
+	WaitForClock(context.Context) (Clock, error)
+}
+
+// WaitForClock will block until the Clock is ready. This provides a syncronization mechanism for services that
+// need the clock to be available before they can start running.
+func (s *Service) WaitForClock(ctx context.Context) (Clock, error) {
+	if s.clockReady != nil {
+		select {
+		case <-s.clockReady:
+			return s.clock, nil
+		case <-ctx.Done():
+			return nil, ctx.Err()
+		}
+	}
+	return s.clock, nil
+}

beacon-chain/blockchain/chain_info_test.go

@@ -28,7 +28,6 @@ import (
 
 // Ensure Service implements chain info interface.
 var _ ChainInfoFetcher = (*Service)(nil)
-var _ TimeFetcher = (*Service)(nil)
 var _ ForkFetcher = (*Service)(nil)
 
 // prepareForkchoiceState prepares a beacon state with the given data to mock
@@ -202,9 +201,9 @@ func TestHeadState_CanRetrieve(t *testing.T) {
 }
 
 func TestGenesisTime_CanRetrieve(t *testing.T) {
-	c := &Service{genesisTime: time.Unix(999, 0)}
+	c := &Service{clock: NewClock(time.Unix(999, 0))}
 	wanted := time.Unix(999, 0)
-	assert.Equal(t, wanted, c.GenesisTime(), "Did not get wanted genesis time")
+	assert.Equal(t, wanted, c.genesisTime(), "Did not get wanted genesis time")
 }
 
 func TestCurrentFork_CanRetrieve(t *testing.T) {
@@ -304,6 +303,7 @@ func TestService_HeadGenesisValidatorsRoot(t *testing.T) {
 	root = c.HeadGenesisValidatorsRoot()
 	require.DeepEqual(t, root[:], s.GenesisValidatorsRoot())
 }
+
 func TestService_ChainHeads_ProtoArray(t *testing.T) {
 	ctx := context.Background()
 	c := &Service{cfg: &config{ForkChoiceStore: protoarray.New()}}
@@ -474,7 +474,7 @@ func TestService_IsOptimistic_DoublyLinkedTree(t *testing.T) {
 
 func TestService_IsOptimisticBeforeBellatrix(t *testing.T) {
 	ctx := context.Background()
-	c := &Service{genesisTime: time.Now()}
+	c := &Service{clock: NewClock(time.Now())}
 	opt, err := c.IsOptimistic(ctx)
 	require.NoError(t, err)
 	require.Equal(t, false, opt)

beacon-chain/blockchain/clock.go

@@ -0,0 +1,69 @@
+package blockchain
+
+import (
+	types "github.com/prysmaticlabs/prysm/consensus-types/primitives"
+	"github.com/prysmaticlabs/prysm/time/slots"
+	"time"
+)
+
+// Clock abstracts important time-related concerns in the beacon chain:
+// - genesis time
+// - provides a time.Now() construct that can be overriden in tests
+// - syncronization point for code that needs to know the genesis time
+// - CurrentSlot: convenience conversion for current time -> slot
+//   - support backwards compatibility with the TimeFetcher interface
+type Clock interface {
+	GenesisTime() time.Time
+	CurrentSlot() types.Slot
+	Now() time.Time
+}
+
+// clock is a type that fulfills the TimeFetcher interface. This can be used in a number of places where
+// blockchain.ChainInfoFetcher has historically been used.
+type clock struct {
+	time.Time
+	now Now
+}
+var _ Clock = &clock{}
+
+// clock provides an accessor to the embedded time, also fulfilling the blockchain.TimeFetcher interface.
+func (gt clock) GenesisTime() time.Time {
+	return gt.Time
+}
+
+// CurrentSlot returns the current slot relative to the time.Time value clock embeds.
+func (gt clock) CurrentSlot() types.Slot {
+	return slots.Duration(gt.Time, gt.now())
+}
+
+// Now provides a value for time.Now() that can be overriden in tests.
+func (gt clock) Now() time.Time {
+	return gt.now()
+}
+
+// ClockOpt is a functional option to change the behavior of a clock value made by NewClock.
+// It is primarily intended as a way to inject an alternate time.Now() callback (WithNow) for testing.
+type ClockOpt func(*clock)
+
+// WithNow allows tests in particular to inject an alternate implementation of time.Now (vs using system time)
+func WithNow(n Now) ClockOpt {
+	return func(gt *clock) {
+		gt.now = n
+	}
+}
+
+// NewClock constructs a clock value using the given time value. Optional ClockOpt can be provided.
+// If an implementation of the Now function type is not provided (via WithNow), time.Now (system time) will be used by default.
+func NewClock(t time.Time, opts ...ClockOpt) clock {
+	gt := clock{Time: t}
+	for _, o :=  range opts {
+		o(&gt)
+	}
+	if gt.now == nil {
+		gt.now = time.Now
+	}
+	return gt
+}
+
+// Now is a function that can return the current time. This will be time.Now by default, but can be overridden for tests.
+type Now func() time.Time

beacon-chain/blockchain/clock_test.go

@@ -0,0 +1,31 @@
+package blockchain
+
+import (
+	"github.com/prysmaticlabs/prysm/config/params"
+	types "github.com/prysmaticlabs/prysm/consensus-types/primitives"
+	"github.com/prysmaticlabs/prysm/testing/require"
+	"testing"
+	"time"
+)
+
+func TestClock_GenesisTime(t *testing.T) {
+	n := time.Now()
+	gt := NewClock(n)
+	gtt := gt.GenesisTime()
+	require.Equal(t, gt.Time, gtt)
+	require.Equal(t, n, gtt)
+}
+
+func TestWithNow(t *testing.T) {
+	genUnix := time.Unix(0, 0)
+	var expectedSlots uint64 = 7200 // a day worth of slots
+	now := genUnix.Add(time.Second * time.Duration(params.BeaconConfig().SecondsPerSlot * expectedSlots))
+	fn := func() time.Time {
+		return now
+	}
+
+	gt := NewClock(genUnix, WithNow(fn))
+	// in this scenario, "genesis" is exactly 24 hours before "now"
+	// so "now" should be 7200 slots after "genesis"
+	require.Equal(t, types.Slot(expectedSlots), gt.CurrentSlot())
+}

beacon-chain/blockchain/execution_engine.go

@@ -315,7 +315,7 @@ func (s *Service) getPayloadAttribute(ctx context.Context, st state.BeaconState,
 	}
 
 	// Get timestamp.
-	t, err := slots.ToTime(uint64(s.genesisTime.Unix()), slot)
+	t, err := slots.ToTime(uint64(s.genesisTime().Unix()), slot)
 	if err != nil {
 		return false, nil, 0, err
 	}

beacon-chain/blockchain/execution_engine_test.go

@@ -535,7 +535,7 @@ func Test_NotifyNewPayload(t *testing.T) {
 	service, err := NewService(ctx, opts...)
 	require.NoError(t, err)
 	st := params.BeaconConfig().SlotsPerEpoch.Mul(uint64(epochsSinceFinalitySaveHotStateDB))
-	service.genesisTime = time.Now().Add(time.Duration(-1*int64(st)*int64(params.BeaconConfig().SecondsPerSlot)) * time.Second)
+	service.SetGenesisTime(time.Now().Add(time.Duration(-1*int64(st)*int64(params.BeaconConfig().SecondsPerSlot)) * time.Second))
 	r, err := bellatrixBlk.Block().HashTreeRoot()
 	require.NoError(t, err)
 	ojc := &ethpb.Checkpoint{Root: params.BeaconConfig().ZeroHash[:]}
@@ -800,7 +800,7 @@ func Test_IsOptimisticCandidateBlock(t *testing.T) {
 	require.NoError(t, err)
 
 	params.BeaconConfig().SafeSlotsToImportOptimistically = 128
-	service.genesisTime = time.Now().Add(-time.Second * 12 * 2 * 128)
+	service.SetGenesisTime(time.Now().Add(-time.Second * 12 * 2 * 128))
 
 	parentBlk := util.NewBeaconBlockBellatrix()
 	wrappedParentBlock, err := wrapper.WrappedSignedBeaconBlock(parentBlk)
@@ -903,7 +903,7 @@ func Test_IsOptimisticShallowExecutionParent(t *testing.T) {
 	require.NoError(t, err)
 
 	params.BeaconConfig().SafeSlotsToImportOptimistically = 128
-	service.genesisTime = time.Now().Add(-time.Second * 12 * 2 * 128)
+	service.SetGenesisTime(time.Now().Add(-time.Second * 12 * 2 * 128))
 	payload := &v1.ExecutionPayload{
 		ParentHash:    make([]byte, 32),
 		FeeRecipient:  make([]byte, 20),

beacon-chain/blockchain/head_test.go

@@ -219,7 +219,7 @@ func TestSaveOrphanedAtts_NoCommonAncestor(t *testing.T) {
 	ctx := context.Background()
 	beaconDB := testDB.SetupDB(t)
 	service := setupBeaconChain(t, beaconDB)
-	service.genesisTime = time.Now().Add(time.Duration(-10*int64(1)*int64(params.BeaconConfig().SecondsPerSlot)) * time.Second)
+	service.SetGenesisTime(time.Now().Add(time.Duration(-10*int64(1)*int64(params.BeaconConfig().SecondsPerSlot)) * time.Second))
 
 	// Chain setup
 	// 0 -- 1 -- 2 -- 3
@@ -273,7 +273,7 @@ func TestSaveOrphanedAtts(t *testing.T) {
 	ctx := context.Background()
 	beaconDB := testDB.SetupDB(t)
 	service := setupBeaconChain(t, beaconDB)
-	service.genesisTime = time.Now().Add(time.Duration(-10*int64(1)*int64(params.BeaconConfig().SecondsPerSlot)) * time.Second)
+	service.SetGenesisTime(time.Now().Add(time.Duration(-10*int64(1)*int64(params.BeaconConfig().SecondsPerSlot)) * time.Second))
 
 	// Chain setup
 	// 0 -- 1 -- 2 -- 3
@@ -339,7 +339,7 @@ func TestSaveOrphanedAtts_CanFilter(t *testing.T) {
 	ctx := context.Background()
 	beaconDB := testDB.SetupDB(t)
 	service := setupBeaconChain(t, beaconDB)
-	service.genesisTime = time.Now().Add(time.Duration(-1*int64(params.BeaconConfig().SlotsPerEpoch+2)*int64(params.BeaconConfig().SecondsPerSlot)) * time.Second)
+	service.SetGenesisTime(time.Now().Add(time.Duration(-1*int64(params.BeaconConfig().SlotsPerEpoch+2)*int64(params.BeaconConfig().SecondsPerSlot)) * time.Second))
 
 	// Chain setup
 	// 0 -- 1 -- 2
@@ -393,7 +393,7 @@ func TestSaveOrphanedAtts_NoCommonAncestor_DoublyLinkedTrie(t *testing.T) {
 	ctx := context.Background()
 	beaconDB := testDB.SetupDB(t)
 	service := setupBeaconChain(t, beaconDB)
-	service.genesisTime = time.Now().Add(time.Duration(-10*int64(1)*int64(params.BeaconConfig().SecondsPerSlot)) * time.Second)
+	service.SetGenesisTime(time.Now().Add(time.Duration(-10*int64(1)*int64(params.BeaconConfig().SecondsPerSlot)) * time.Second))
 
 	// Chain setup
 	// 0 -- 1 -- 2 -- 3
@@ -452,7 +452,7 @@ func TestSaveOrphanedAtts_DoublyLinkedTrie(t *testing.T) {
 	ctx := context.Background()
 	beaconDB := testDB.SetupDB(t)
 	service := setupBeaconChain(t, beaconDB)
-	service.genesisTime = time.Now().Add(time.Duration(-10*int64(1)*int64(params.BeaconConfig().SecondsPerSlot)) * time.Second)
+	service.SetGenesisTime(time.Now().Add(time.Duration(-10*int64(1)*int64(params.BeaconConfig().SecondsPerSlot)) * time.Second))
 
 	// Chain setup
 	// 0 -- 1 -- 2 -- 3
@@ -522,7 +522,7 @@ func TestSaveOrphanedAtts_CanFilter_DoublyLinkedTrie(t *testing.T) {
 	ctx := context.Background()
 	beaconDB := testDB.SetupDB(t)
 	service := setupBeaconChain(t, beaconDB)
-	service.genesisTime = time.Now().Add(time.Duration(-1*int64(params.BeaconConfig().SlotsPerEpoch+2)*int64(params.BeaconConfig().SecondsPerSlot)) * time.Second)
+	service.SetGenesisTime(time.Now().Add(time.Duration(-1*int64(params.BeaconConfig().SlotsPerEpoch+2)*int64(params.BeaconConfig().SecondsPerSlot)) * time.Second))
 
 	// Chain setup
 	// 0 -- 1 -- 2

beacon-chain/blockchain/init_sync_process_block_test.go

@@ -29,7 +29,7 @@ func TestService_getBlock(t *testing.T) {
 	// block in cache
 	b, err := wrapper.WrappedSignedBeaconBlock(b1)
 	require.NoError(t, err)
-	s.saveInitSyncBlock(ctx, r1, b)
+	require.NoError(t, s.saveInitSyncBlock(ctx, r1, b))
 	got, err := s.getBlock(ctx, r1)
 	require.NoError(t, err)
 	require.DeepEqual(t, b, got)
@@ -59,7 +59,7 @@ func TestService_hasBlockInInitSyncOrDB(t *testing.T) {
 	// block in cache
 	b, err := wrapper.WrappedSignedBeaconBlock(b1)
 	require.NoError(t, err)
-	s.saveInitSyncBlock(ctx, r1, b)
+	require.NoError(t, s.saveInitSyncBlock(ctx, r1, b))
 	require.Equal(t, true, s.hasBlockInInitSyncOrDB(ctx, r1))
 
 	// block in db

beacon-chain/blockchain/process_attestation.go

@@ -59,7 +59,7 @@ func (s *Service) OnAttestation(ctx context.Context, a *ethpb.Attestation) error
 		return err
 	}
 
-	genesisTime := uint64(s.genesisTime.Unix())
+	genesisTime := uint64(s.genesisTime().Unix())
 
 	// Verify attestation target is from current epoch or previous epoch.
 	if err := verifyAttTargetEpoch(ctx, genesisTime, uint64(time.Now().Unix()), tgt); err != nil {

beacon-chain/blockchain/process_block.go

@@ -132,8 +132,12 @@ func (s *Service) onBlock(ctx context.Context, signed interfaces.SignedBeaconBlo
 			return err
 		}
 	}
-	if err := s.savePostStateInfo(ctx, blockRoot, signed, postState); err != nil {
-		return err
+
+	if err := s.cfg.BeaconDB.SaveBlock(ctx, signed); err != nil {
+		return errors.Wrapf(err, "could not save block from slot %d", signed.Block().Slot())
+	}
+	if err := s.cfg.StateGen.SaveState(ctx, blockRoot, postState); err != nil {
+		return errors.Wrap(err, "could not save state")
 	}
 
 	if err := s.insertBlockAndAttestationsToForkChoiceStore(ctx, signed.Block(), blockRoot, postState); err != nil {
@@ -538,20 +542,6 @@ func (s *Service) InsertSlashingsToForkChoiceStore(ctx context.Context, slashing
 	}
 }
 
-// This saves post state info to DB or cache. This also saves post state info to fork choice store.
-// Post state info consists of processed block and state. Do not call this method unless the block and state are verified.
-func (s *Service) savePostStateInfo(ctx context.Context, r [32]byte, b interfaces.SignedBeaconBlock, st state.BeaconState) error {
-	ctx, span := trace.StartSpan(ctx, "blockChain.savePostStateInfo")
-	defer span.End()
-	if err := s.cfg.BeaconDB.SaveBlock(ctx, b); err != nil {
-		return errors.Wrapf(err, "could not save block from slot %d", b.Block().Slot())
-	}
-	if err := s.cfg.StateGen.SaveState(ctx, r, st); err != nil {
-		return errors.Wrap(err, "could not save state")
-	}
-	return nil
-}
-
 // This removes the attestations from the mem pool. It will only remove the attestations if input root `r` is canonical,
 // meaning the block `b` is part of the canonical chain.
 func (s *Service) pruneCanonicalAttsFromPool(ctx context.Context, r [32]byte, b interfaces.SignedBeaconBlock) error {

beacon-chain/blockchain/process_block_helpers.go

@@ -24,7 +24,11 @@ import (
 
 // CurrentSlot returns the current slot based on time.
 func (s *Service) CurrentSlot() types.Slot {
-	return slots.CurrentSlot(uint64(s.genesisTime.Unix()))
+	c, err := s.WaitForClock(context.TODO())
+	if err != nil {
+		panic(err)
+	}
+	return c.CurrentSlot()
 }
 
 // getBlockPreState returns the pre state of an incoming block. It uses the parent root of the block
@@ -48,7 +52,7 @@ func (s *Service) getBlockPreState(ctx context.Context, b interfaces.BeaconBlock
 	}
 
 	// Verify block slot time is not from the future.
-	if err := slots.VerifyTime(uint64(s.genesisTime.Unix()), b.Slot(), params.BeaconNetworkConfig().MaximumGossipClockDisparity); err != nil {
+	if err := slots.VerifyTime(uint64(s.genesisTime().Unix()), b.Slot(), params.BeaconNetworkConfig().MaximumGossipClockDisparity); err != nil {
 		return nil, err
 	}
 

beacon-chain/blockchain/process_block_test.go

@@ -873,7 +873,7 @@ func blockTree1(t *testing.T, beaconDB db.Database, genesisRoot []byte) ([][]byt
 }
 
 func TestCurrentSlot_HandlesOverflow(t *testing.T) {
-	svc := Service{genesisTime: prysmTime.Now().Add(1 * time.Hour)}
+	svc := Service{clock: NewClock(prysmTime.Now().Add(1 * time.Hour))}
 
 	slot := svc.CurrentSlot()
 	require.Equal(t, types.Slot(0), slot, "Unexpected slot")

beacon-chain/blockchain/receive_attestation.go

@@ -4,8 +4,6 @@ import (
 	"bytes"
 	"context"
 	"fmt"
-	"time"
-
 	"github.com/pkg/errors"
 	"github.com/prysmaticlabs/prysm/async/event"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/feed"
@@ -38,7 +36,7 @@ func (s *Service) AttestationTargetState(ctx context.Context, target *ethpb.Chec
 	if err != nil {
 		return nil, err
 	}
-	if err := slots.ValidateClock(ss, uint64(s.genesisTime.Unix())); err != nil {
+	if err := slots.ValidateClock(ss, uint64(s.genesisTime().Unix())); err != nil {
 		return nil, err
 	}
 	return s.getAttPreState(ctx, target)
@@ -102,19 +100,14 @@ func (s *Service) spawnProcessAttestationsRoutine(stateFeed *event.Feed) {
 			break
 		}
 
-		if s.genesisTime.IsZero() {
-			log.Warn("ProcessAttestations routine waiting for genesis time")
-			for s.genesisTime.IsZero() {
-				if err := s.ctx.Err(); err != nil {
-					log.WithError(err).Error("Giving up waiting for genesis time")
-					return
-				}
-				time.Sleep(1 * time.Second)
-			}
-			log.Warn("Genesis time received, now available to process attestations")
+		log.Warn("ProcessAttestations routine waiting for genesis time")
+		c, err := s.WaitForClock(s.ctx)
+		if err != nil {
+			log.WithError(err).Error("timeout waiting for genesis time in spawnProcessAttestationsRoutine")
 		}
+		log.Warn("Genesis time received, now available to process attestations")
 
-		st := slots.NewSlotTicker(s.genesisTime, params.BeaconConfig().SecondsPerSlot)
+		st := slots.NewSlotTicker(c.GenesisTime(), params.BeaconConfig().SecondsPerSlot)
 		for {
 			select {
 			case <-s.ctx.Done():
@@ -219,7 +212,7 @@ func (s *Service) processAttestations(ctx context.Context) {
 		// This delays consideration in the fork choice until their slot is in the past.
 		// https://github.com/ethereum/consensus-specs/blob/dev/specs/phase0/fork-choice.md#validate_on_attestation
 		nextSlot := a.Data.Slot + 1
-		if err := slots.VerifyTime(uint64(s.genesisTime.Unix()), nextSlot, params.BeaconNetworkConfig().MaximumGossipClockDisparity); err != nil {
+		if err := slots.VerifyTime(uint64(s.genesisTime().Unix()), nextSlot, params.BeaconNetworkConfig().MaximumGossipClockDisparity); err != nil {
 			continue
 		}
 
@@ -233,7 +226,7 @@ func (s *Service) processAttestations(ctx context.Context) {
 			log.WithError(err).Error("Could not delete fork choice attestation in pool")
 		}
 
-		if !helpers.VerifyCheckpointEpoch(a.Data.Target, s.genesisTime) {
+		if !helpers.VerifyCheckpointEpoch(a.Data.Target, s.genesisTime()) {
 			continue
 		}
 

beacon-chain/blockchain/receive_attestation_test.go

@@ -33,7 +33,7 @@ func TestAttestationCheckPtState_FarFutureSlot(t *testing.T) {
 	beaconDB := testDB.SetupDB(t)
 
 	chainService := setupBeaconChain(t, beaconDB)
-	chainService.genesisTime = time.Now()
+	chainService.SetGenesisTime(time.Now())
 
 	e := types.Epoch(slots.MaxSlotBuffer/uint64(params.BeaconConfig().SlotsPerEpoch) + 1)
 	_, err := chainService.AttestationTargetState(context.Background(), &ethpb.Checkpoint{Epoch: e})
@@ -102,7 +102,7 @@ func TestProcessAttestations_Ok(t *testing.T) {
 
 	service, err := NewService(ctx, opts...)
 	require.NoError(t, err)
-	service.genesisTime = prysmTime.Now().Add(-1 * time.Duration(params.BeaconConfig().SecondsPerSlot) * time.Second)
+	service.SetGenesisTime(prysmTime.Now().Add(-1 * time.Duration(params.BeaconConfig().SecondsPerSlot) * time.Second))
 	genesisState, pks := util.DeterministicGenesisState(t, 64)
 	require.NoError(t, genesisState.SetGenesisTime(uint64(prysmTime.Now().Unix())-params.BeaconConfig().SecondsPerSlot))
 	require.NoError(t, service.saveGenesisData(ctx, genesisState))
@@ -209,7 +209,7 @@ func TestService_ProcessAttestationsAndUpdateHead(t *testing.T) {
 
 	service, err := NewService(ctx, opts...)
 	require.NoError(t, err)
-	service.genesisTime = prysmTime.Now().Add(-2 * time.Duration(params.BeaconConfig().SecondsPerSlot) * time.Second)
+	service.SetGenesisTime(prysmTime.Now().Add(-2 * time.Duration(params.BeaconConfig().SecondsPerSlot) * time.Second))
 	genesisState, pks := util.DeterministicGenesisState(t, 64)
 	require.NoError(t, service.saveGenesisData(ctx, genesisState))
 	copied := genesisState.Copy()

beacon-chain/blockchain/receive_block.go

@@ -7,17 +7,12 @@ import (
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/feed"
 	statefeed "github.com/prysmaticlabs/prysm/beacon-chain/core/feed/state"
 	"github.com/prysmaticlabs/prysm/consensus-types/interfaces"
-	types "github.com/prysmaticlabs/prysm/consensus-types/primitives"
 	"github.com/prysmaticlabs/prysm/monitoring/tracing"
 	ethpb "github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1"
 	"github.com/prysmaticlabs/prysm/time"
-	"github.com/prysmaticlabs/prysm/time/slots"
 	"go.opencensus.io/trace"
 )
 
-// This defines how many epochs since finality the run time will begin to save hot state on to the DB.
-var epochsSinceFinalitySaveHotStateDB = types.Epoch(100)
-
 // BlockReceiver interface defines the methods of chain service for receiving and processing new blocks.
 type BlockReceiver interface {
 	ReceiveBlock(ctx context.Context, block interfaces.SignedBeaconBlock, blockRoot [32]byte) error
@@ -53,18 +48,13 @@ func (s *Service) ReceiveBlock(ctx context.Context, block interfaces.SignedBeaco
 		return err
 	}
 
-	// Have we been finalizing? Should we start saving hot states to db?
-	if err := s.checkSaveHotStateDB(ctx); err != nil {
-		return err
-	}
-
 	// Reports on block and fork choice metrics.
 	finalized := s.FinalizedCheckpt()
 	reportSlotMetrics(blockCopy.Block().Slot(), s.HeadSlot(), s.CurrentSlot(), finalized)
 
 	// Log block sync status.
 	justified := s.CurrentJustifiedCheckpt()
-	if err := logBlockSyncStatus(blockCopy.Block(), blockRoot, justified, finalized, receivedTime, uint64(s.genesisTime.Unix())); err != nil {
+	if err := logBlockSyncStatus(blockCopy.Block(), blockRoot, justified, finalized, receivedTime, uint64(s.genesisTime().Unix())); err != nil {
 		log.WithError(err).Error("Unable to log block sync status")
 	}
 	// Log payload data
@@ -160,25 +150,3 @@ func (s *Service) handlePostBlockOperations(b interfaces.BeaconBlock) error {
 	}
 	return nil
 }
-
-// This checks whether it's time to start saving hot state to DB.
-// It's time when there's `epochsSinceFinalitySaveHotStateDB` epochs of non-finality.
-func (s *Service) checkSaveHotStateDB(ctx context.Context) error {
-	currentEpoch := slots.ToEpoch(s.CurrentSlot())
-	// Prevent `sinceFinality` going underflow.
-	var sinceFinality types.Epoch
-	finalized := s.FinalizedCheckpt()
-	if finalized == nil {
-		return errNilFinalizedInStore
-	}
-	if currentEpoch > finalized.Epoch {
-		sinceFinality = currentEpoch - finalized.Epoch
-	}
-
-	if sinceFinality >= epochsSinceFinalitySaveHotStateDB {
-		s.cfg.StateGen.EnableSaveHotStateToDB(ctx)
-		return nil
-	}
-
-	return s.cfg.StateGen.DisableSaveHotStateToDB(ctx)
-}

beacon-chain/blockchain/receive_block_test.go

@@ -2,10 +2,6 @@ package blockchain
 
 import (
 	"context"
-	"sync"
-	"testing"
-	"time"
-
 	blockchainTesting "github.com/prysmaticlabs/prysm/beacon-chain/blockchain/testing"
 	testDB "github.com/prysmaticlabs/prysm/beacon-chain/db/testing"
 	"github.com/prysmaticlabs/prysm/beacon-chain/forkchoice/protoarray"
@@ -21,7 +17,8 @@ import (
 	"github.com/prysmaticlabs/prysm/testing/assert"
 	"github.com/prysmaticlabs/prysm/testing/require"
 	"github.com/prysmaticlabs/prysm/testing/util"
-	logTest "github.com/sirupsen/logrus/hooks/test"
+	"sync"
+	"testing"
 )
 
 func TestService_ReceiveBlock(t *testing.T) {
@@ -284,40 +281,3 @@ func TestService_HasBlock(t *testing.T) {
 	require.NoError(t, err)
 	require.Equal(t, true, s.HasBlock(context.Background(), r))
 }
-
-func TestCheckSaveHotStateDB_Enabling(t *testing.T) {
-	opts := testServiceOptsWithDB(t)
-	hook := logTest.NewGlobal()
-	s, err := NewService(context.Background(), opts...)
-	require.NoError(t, err)
-	st := params.BeaconConfig().SlotsPerEpoch.Mul(uint64(epochsSinceFinalitySaveHotStateDB))
-	s.genesisTime = time.Now().Add(time.Duration(-1*int64(st)*int64(params.BeaconConfig().SecondsPerSlot)) * time.Second)
-
-	require.NoError(t, s.checkSaveHotStateDB(context.Background()))
-	assert.LogsContain(t, hook, "Entering mode to save hot states in DB")
-}
-
-func TestCheckSaveHotStateDB_Disabling(t *testing.T) {
-	hook := logTest.NewGlobal()
-	opts := testServiceOptsWithDB(t)
-	s, err := NewService(context.Background(), opts...)
-	require.NoError(t, err)
-	st := params.BeaconConfig().SlotsPerEpoch.Mul(uint64(epochsSinceFinalitySaveHotStateDB))
-	s.genesisTime = time.Now().Add(time.Duration(-1*int64(st)*int64(params.BeaconConfig().SecondsPerSlot)) * time.Second)
-	require.NoError(t, s.checkSaveHotStateDB(context.Background()))
-	s.genesisTime = time.Now()
-
-	require.NoError(t, s.checkSaveHotStateDB(context.Background()))
-	assert.LogsContain(t, hook, "Exiting mode to save hot states in DB")
-}
-
-func TestCheckSaveHotStateDB_Overflow(t *testing.T) {
-	hook := logTest.NewGlobal()
-	opts := testServiceOptsWithDB(t)
-	s, err := NewService(context.Background(), opts...)
-	require.NoError(t, err)
-	s.genesisTime = time.Now()
-
-	require.NoError(t, s.checkSaveHotStateDB(context.Background()))
-	assert.LogsDoNotContain(t, hook, "Entering mode to save hot states in DB")
-}

beacon-chain/blockchain/service.go

@@ -6,6 +6,7 @@ import (
 	"bytes"
 	"context"
 	"fmt"
+	"github.com/prysmaticlabs/prysm/beacon-chain/geninit"
 	"runtime"
 	"sync"
 	"time"
@@ -17,7 +18,6 @@ import (
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/feed"
 	statefeed "github.com/prysmaticlabs/prysm/beacon-chain/core/feed/state"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
-	"github.com/prysmaticlabs/prysm/beacon-chain/core/transition"
 	"github.com/prysmaticlabs/prysm/beacon-chain/db"
 	f "github.com/prysmaticlabs/prysm/beacon-chain/forkchoice"
 	doublylinkedtree "github.com/prysmaticlabs/prysm/beacon-chain/forkchoice/doubly-linked-tree"
@@ -30,7 +30,6 @@ import (
 	"github.com/prysmaticlabs/prysm/beacon-chain/powchain"
 	"github.com/prysmaticlabs/prysm/beacon-chain/state"
 	"github.com/prysmaticlabs/prysm/beacon-chain/state/stategen"
-	"github.com/prysmaticlabs/prysm/cmd/beacon-chain/flags"
 	"github.com/prysmaticlabs/prysm/config/features"
 	"github.com/prysmaticlabs/prysm/config/params"
 	"github.com/prysmaticlabs/prysm/consensus-types/interfaces"
@@ -53,7 +52,6 @@ type Service struct {
 	cfg                     *config
 	ctx                     context.Context
 	cancel                  context.CancelFunc
-	genesisTime             time.Time
 	head                    *head
 	headLock                sync.RWMutex
 	originBlockRoot         [32]byte // genesis root, or weak subjectivity checkpoint root, depending on how the node is initialized
@@ -65,6 +63,9 @@ type Service struct {
 	justifiedBalances       *stateBalanceCache
 	wsVerifier              *WeakSubjectivityVerifier
 	processAttestationsLock sync.Mutex
+	clock Clock
+	clockReady chan struct{}
+	clockWaiter             geninit.ClockWaiter
 }
 
 // config options for the service.
@@ -138,6 +139,70 @@ func (s *Service) Start() {
 	s.fillMissingPayloadIDRoutine(s.ctx, s.cfg.StateNotifier.StateFeed())
 }
 
+func (s *Service) CombinedStart(genesis state.BeaconState) error {
+	// TODO: we only do this on the genesis code path, not from disk - why?
+	/*
+		// Update committee shuffled indices for genesis epoch.
+		if err := helpers.UpdateCommitteeCache(ctx, genesisState, 0); err != nil {
+			return nil, err
+		}
+		if err := helpers.UpdateProposerIndicesInCache(ctx, genesisState); err != nil {
+			return nil, err
+		}
+	 */
+	gt := time.Unix(int64(genesis.GenesisTime()), 0)
+	s.SetGenesisTime(gt)
+	s.cfg.AttService.SetGenesisTime(genesis.GenesisTime())
+
+	if features.Get().EnableForkChoiceDoublyLinkedTree {
+		s.cfg.ForkChoiceStore = doublylinkedtree.New()
+	} else {
+		s.cfg.ForkChoiceStore = protoarray.New()
+	}
+	// TODO: move head to use fork choice - we currently do not call initializeHeadFromDB!!
+
+	gb, err := s.cfg.BeaconDB.GenesisBlock(s.ctx)
+	if err != nil {
+		return errors.Wrap(err, "could not get genesis block from db")
+	}
+	if err := wrapper.BeaconBlockIsNil(gb); err != nil {
+		return errors.Wrap(err, "nil value from database block query")
+	}
+	gbr, err := gb.Block().HashTreeRoot()
+	if err != nil {
+		return errors.Wrap(err, "could not compute hash_tree_root of genesis block")
+	}
+	if err := s.cfg.ForkChoiceStore.InsertNode(s.ctx, genesis, gbr); err != nil {
+		log.Fatalf("Could not process genesis block for fork choice: %v", err)
+	}
+	s.cfg.ForkChoiceStore.SetGenesisTime(genesis.GenesisTime())
+
+	obr, err := s.cfg.BeaconDB.OriginCheckpointBlockRoot(s.ctx)
+	if err == nil {
+		// this means checkpoint sync was used, use the database origin root value
+		s.originBlockRoot = obr
+	} else {
+		if !errors.Is(err, db.ErrNotFound) {
+			return errors.Wrap(err, "could not retrieve checkpoint sync chain origin data from db")
+		}
+		// this means we got ErrNotFound, meaning checkpoint sync wasn't used, so the node should
+		// be synced from genesis. In this case, use the genesis block root as origin.
+		s.originBlockRoot = gbr
+	}
+	// TODO: should we set origin root when its the genesis block root, or is this method only for checkpoint sync?
+	s.cfg.ForkChoiceStore.SetOriginRoot(s.originBlockRoot)
+
+	spawnCountdownIfPreGenesis(s.ctx, gt, genesis)
+	s.cfg.StateNotifier.StateFeed().Send(&feed.Event{
+		Type: statefeed.Initialized,
+		Data: &statefeed.InitializedData{
+			StartTime:             gt,
+			GenesisValidatorsRoot: genesis.GenesisValidatorsRoot(),
+		},
+	})
+	return nil
+}
+
 // Stop the blockchain service's main event loop and associated goroutines.
 func (s *Service) Stop() error {
 	defer s.cancel()
@@ -173,7 +238,7 @@ func (s *Service) Status() error {
 // StartFromSavedState initializes the blockchain using a previously saved finalized checkpoint.
 func (s *Service) StartFromSavedState(saved state.BeaconState) error {
 	log.Info("Blockchain data already exists in DB, initializing...")
-	s.genesisTime = time.Unix(int64(saved.GenesisTime()), 0) // lint:ignore uintcast -- Genesis time will not exceed int64 in your lifetime.
+	s.SetGenesisTime(time.Unix(int64(saved.GenesisTime()), 0)) // lint:ignore uintcast -- Genesis time will not exceed int64 in your lifetime.
 	s.cfg.AttService.SetGenesisTime(saved.GenesisTime())
 
 	originRoot, err := s.originRootFromSavedState(s.ctx)
@@ -185,7 +250,12 @@ func (s *Service) StartFromSavedState(saved state.BeaconState) error {
 	if err := s.initializeHeadFromDB(s.ctx); err != nil {
 		return errors.Wrap(err, "could not set up chain info")
 	}
-	spawnCountdownIfPreGenesis(s.ctx, s.genesisTime, s.cfg.BeaconDB)
+	gs, err := s.cfg.BeaconDB.GenesisState(s.ctx)
+	if err != nil {
+		return err
+	}
+	gt := time.Unix(int64(gs.GenesisTime()), 0)
+	spawnCountdownIfPreGenesis(s.ctx, gt, gs)
 
 	justified, err := s.cfg.BeaconDB.JustifiedCheckpoint(s.ctx)
 	if err != nil {
@@ -218,7 +288,7 @@ func (s *Service) StartFromSavedState(saved state.BeaconState) error {
 		Root: bytesutil.ToBytes32(finalized.Root)}); err != nil {
 		return errors.Wrap(err, "could not update forkchoice's finalized checkpoint")
 	}
-	forkChoicer.SetGenesisTime(uint64(s.genesisTime.Unix()))
+	forkChoicer.SetGenesisTime(uint64(s.genesisTime().Unix()))
 
 	st, err := s.cfg.StateGen.StateByRoot(s.ctx, fRoot)
 	if err != nil {
@@ -247,7 +317,7 @@ func (s *Service) StartFromSavedState(saved state.BeaconState) error {
 	s.cfg.StateNotifier.StateFeed().Send(&feed.Event{
 		Type: statefeed.Initialized,
 		Data: &statefeed.InitializedData{
-			StartTime:             s.genesisTime,
+			StartTime:             s.genesisTime(),
 			GenesisValidatorsRoot: saved.GenesisValidatorsRoot(),
 		},
 	})
@@ -295,48 +365,11 @@ func (s *Service) initializeHeadFromDB(ctx context.Context) error {
 		return errors.New("no finalized epoch in the database")
 	}
 	finalizedRoot := s.ensureRootNotZeros(bytesutil.ToBytes32(finalized.Root))
-	var finalizedState state.BeaconState
-
-	finalizedState, err = s.cfg.StateGen.Resume(ctx, s.cfg.FinalizedStateAtStartUp)
+	finalizedState, err := s.cfg.StateGen.Resume(ctx, s.cfg.FinalizedStateAtStartUp)
 	if err != nil {
 		return errors.Wrap(err, "could not get finalized state from db")
 	}
 
-	if flags.Get().HeadSync {
-		headBlock, err := s.cfg.BeaconDB.HeadBlock(ctx)
-		if err != nil {
-			return errors.Wrap(err, "could not retrieve head block")
-		}
-		headEpoch := slots.ToEpoch(headBlock.Block().Slot())
-		var epochsSinceFinality types.Epoch
-		if headEpoch > finalized.Epoch {
-			epochsSinceFinality = headEpoch - finalized.Epoch
-		}
-		// Head sync when node is far enough beyond known finalized epoch,
-		// this becomes really useful during long period of non-finality.
-		if epochsSinceFinality >= headSyncMinEpochsAfterCheckpoint {
-			headRoot, err := headBlock.Block().HashTreeRoot()
-			if err != nil {
-				return errors.Wrap(err, "could not hash head block")
-			}
-			finalizedState, err := s.cfg.StateGen.Resume(ctx, s.cfg.FinalizedStateAtStartUp)
-			if err != nil {
-				return errors.Wrap(err, "could not get finalized state from db")
-			}
-			log.Infof("Regenerating state from the last checkpoint at slot %d to current head slot of %d."+
-				"This process may take a while, please wait.", finalizedState.Slot(), headBlock.Block().Slot())
-			headState, err := s.cfg.StateGen.StateByRoot(ctx, headRoot)
-			if err != nil {
-				return errors.Wrap(err, "could not retrieve head state")
-			}
-			s.setHead(headRoot, headBlock, headState)
-			return nil
-		} else {
-			log.Warnf("Finalized checkpoint at slot %d is too close to the current head slot, "+
-				"resetting head from the checkpoint ('--%s' flag is ignored).",
-				finalizedState.Slot(), flags.HeadSync.Name)
-		}
-	}
 	if finalizedState == nil || finalizedState.IsNil() {
 		return errors.New("finalized state can't be nil")
 	}
@@ -352,34 +385,15 @@ func (s *Service) initializeHeadFromDB(ctx context.Context) error {
 
 func (s *Service) startFromPOWChain() error {
 	log.Info("Waiting to reach the validator deposit threshold to start the beacon chain...")
-	if s.cfg.ChainStartFetcher == nil {
-		return errors.New("not configured web3Service for POW chain")
-	}
 	go func() {
-		stateChannel := make(chan *feed.Event, 1)
-		stateSub := s.cfg.StateNotifier.StateFeed().Subscribe(stateChannel)
-		defer stateSub.Unsubscribe()
-		for {
-			select {
-			case e := <-stateChannel:
-				if e.Type == statefeed.ChainStarted {
-					data, ok := e.Data.(*statefeed.ChainStartedData)
-					if !ok {
-						log.Error("event data is not type *statefeed.ChainStartedData")
-						return
-					}
-					log.WithField("starttime", data.StartTime).Debug("Received chain start event")
-					s.onPowchainStart(s.ctx, data.StartTime)
-					return
-				}
-			case <-s.ctx.Done():
-				log.Debug("Context closed, exiting goroutine")
-				return
-			case err := <-stateSub.Err():
-				log.WithError(err).Error("Subscription to state notifier failed")
-				return
-			}
+		c, err := s.clockWaiter.WaitForClock(s.ctx)
+		if err != nil {
+			log.WithError(err).Error("timeout while waiting for genesis during blockchain service startup")
+			return
 		}
+		log.WithField("starttime", c.GenesisTime()).Debug("Received chain start event")
+		s.onPowchainStart(s.ctx, c.GenesisTime())
+		s.setClock(c)
 	}()
 
 	return nil
@@ -388,8 +402,7 @@ func (s *Service) startFromPOWChain() error {
 // onPowchainStart initializes a series of deposits from the ChainStart deposits in the eth1
 // deposit contract, initializes the beacon chain's state, and kicks off the beacon chain.
 func (s *Service) onPowchainStart(ctx context.Context, genesisTime time.Time) {
-	preGenesisState := s.cfg.ChainStartFetcher.PreGenesisState()
-	initializedState, err := s.initializeBeaconChain(ctx, genesisTime, preGenesisState, s.cfg.ChainStartFetcher.ChainStartEth1Data())
+	initializedState, err := s.initializeBeaconChain(ctx, genesisTime, preGenesisState)
 	if err != nil {
 		log.Fatalf("Could not initialize beacon chain: %v", err)
 	}
@@ -414,29 +427,10 @@ func (s *Service) onPowchainStart(ctx context.Context, genesisTime time.Time) {
 // initializes the state and genesis block of the beacon chain to persistent storage
 // based on a genesis timestamp value obtained from the ChainStart event emitted
 // by the ETH1.0 Deposit Contract and the POWChain service of the node.
-func (s *Service) initializeBeaconChain(
-	ctx context.Context,
-	genesisTime time.Time,
-	preGenesisState state.BeaconState,
-	eth1data *ethpb.Eth1Data) (state.BeaconState, error) {
+func (s *Service) initializeBeaconChain(ctx context.Context, genesisTime time.Time) (state.BeaconState, error) {
 	ctx, span := trace.StartSpan(ctx, "beacon-chain.Service.initializeBeaconChain")
 	defer span.End()
-	s.genesisTime = genesisTime
-	unixTime := uint64(genesisTime.Unix())
-
-	genesisState, err := transition.OptimizedGenesisBeaconState(unixTime, preGenesisState, eth1data)
-	if err != nil {
-		return nil, errors.Wrap(err, "could not initialize genesis state")
-	}
-
-	if err := s.saveGenesisData(ctx, genesisState); err != nil {
-		return nil, errors.Wrap(err, "could not save genesis data")
-	}
-
-	log.Info("Initialized beacon chain genesis state")
-
-	// Clear out all pre-genesis data now that the state is initialized.
-	s.cfg.ChainStartFetcher.ClearPreGenesisData()
+	s.SetGenesisTime(genesisTime)
 
 	// Update committee shuffled indices for genesis epoch.
 	if err := helpers.UpdateCommitteeCache(ctx, genesisState, 0); err != nil {
@@ -447,15 +441,11 @@ func (s *Service) initializeBeaconChain(
 	}
 
 	s.cfg.AttService.SetGenesisTime(genesisState.GenesisTime())
-
 	return genesisState, nil
 }
 
 // This gets called when beacon chain is first initialized to save genesis data (state, block, and more) in db.
 func (s *Service) saveGenesisData(ctx context.Context, genesisState state.BeaconState) error {
-	if err := s.cfg.BeaconDB.SaveGenesisData(ctx, genesisState); err != nil {
-		return errors.Wrap(err, "could not save genesis data")
-	}
 	genesisBlk, err := s.cfg.BeaconDB.GenesisBlock(ctx)
 	if err != nil || genesisBlk == nil || genesisBlk.IsNil() {
 		return fmt.Errorf("could not load genesis block: %v", err)
@@ -476,7 +466,7 @@ func (s *Service) saveGenesisData(ctx context.Context, genesisState state.Beacon
 	if err := s.cfg.ForkChoiceStore.SetOptimisticToValid(ctx, genesisBlkRoot); err != nil {
 		return errors.Wrap(err, "Could not set optimistic status of genesis block to false")
 	}
-	s.cfg.ForkChoiceStore.SetGenesisTime(uint64(s.genesisTime.Unix()))
+	s.cfg.ForkChoiceStore.SetGenesisTime(uint64(s.genesisTime().Unix()))
 
 	s.setHead(genesisBlkRoot, genesisBlk, genesisState)
 	return nil
@@ -494,19 +484,14 @@ func (s *Service) hasBlock(ctx context.Context, root [32]byte) bool {
 	return s.cfg.BeaconDB.HasBlock(ctx, root)
 }
 
-func spawnCountdownIfPreGenesis(ctx context.Context, genesisTime time.Time, db db.HeadAccessDatabase) {
-	currentTime := prysmTime.Now()
-	if currentTime.After(genesisTime) {
+func spawnCountdownIfPreGenesis(ctx context.Context, gt time.Time, gs state.BeaconState) {
+	// only proceed if this function runs before genesis time
+	if prysmTime.Now().After(gt) {
 		return
 	}
-
-	gState, err := db.GenesisState(ctx)
+	gr, err := gs.HashTreeRoot(ctx)
 	if err != nil {
-		log.Fatalf("Could not retrieve genesis state: %v", err)
+		log.WithError(err).Fatal("Could not compute hash_tree_root of genesis state")
 	}
-	gRoot, err := gState.HashTreeRoot(ctx)
-	if err != nil {
-		log.Fatalf("Could not hash tree root genesis state: %v", err)
-	}
-	go slots.CountdownToGenesis(ctx, genesisTime, uint64(gState.NumValidators()), gRoot)
+	go slots.CountdownToGenesis(ctx, gt, uint64(gs.NumValidators()), gr)
 }

beacon-chain/blockchain/service_test.go

@@ -136,7 +136,7 @@ func setupBeaconChain(t *testing.T, beaconDB db.Database) *Service {
 
 	chainService, err := NewService(ctx, opts...)
 	require.NoError(t, err, "Unable to setup chain service")
-	chainService.genesisTime = time.Unix(1, 0) // non-zero time
+	chainService.SetGenesisTime(time.Unix(1, 0)) // non-zero time
 
 	return chainService
 }

beacon-chain/blockchain/testing/BUILD.bazel

@@ -11,6 +11,7 @@ go_library(
     ],
     deps = [
         "//async/event:go_default_library",
+        "//beacon-chain/blockchain:go_default_library",
         "//beacon-chain/core/epoch/precompute:go_default_library",
         "//beacon-chain/core/feed:go_default_library",
         "//beacon-chain/core/feed/block:go_default_library",

beacon-chain/blockchain/testing/mock.go

@@ -5,6 +5,7 @@ package testing
 import (
 	"bytes"
 	"context"
+	"github.com/prysmaticlabs/prysm/beacon-chain/blockchain"
 	"sync"
 	"time"
 
@@ -64,6 +65,7 @@ type ChainService struct {
 	ReceiveBlockMockErr         error
 	OptimisticCheckRootReceived [32]byte
 	FinalizedRoots              map[[32]byte]bool
+	Clock blockchain.Clock
 }
 
 // ForkChoicer mocks the same method in the chain service
@@ -326,6 +328,13 @@ func (s *ChainService) GenesisTime() time.Time {
 	return s.Genesis
 }
 
+func (s *ChainService) WaitForClock(ctx context.Context) (blockchain.Clock, error) {
+	if s.Clock == nil {
+		return blockchain.NewClock(time.Now()), nil
+	}
+	return s.Clock, nil
+}
+
 // GenesisValidatorsRoot mocks the same method in the chain service.
 func (s *ChainService) GenesisValidatorsRoot() [32]byte {
 	return s.ValidatorsRoot
@@ -336,7 +345,7 @@ func (s *ChainService) CurrentSlot() types.Slot {
 	if s.Slot != nil {
 		return *s.Slot
 	}
-	return types.Slot(uint64(time.Now().Unix()-s.Genesis.Unix()) / params.BeaconConfig().SecondsPerSlot)
+	return s.Clock.CurrentSlot()
 }
 
 // Participation mocks the same method in the chain service.
@@ -464,3 +473,11 @@ func (s *ChainService) ReceiveAttesterSlashing(context.Context, *ethpb.AttesterS
 func (s *ChainService) IsFinalized(_ context.Context, blockRoot [32]byte) bool {
 	return s.FinalizedRoots[blockRoot]
 }
+
+func NewMockClock(now time.Time, slotsAfterGenesis types.Slot) blockchain.Clock {
+	offset := uint64(slotsAfterGenesis) * params.BeaconConfig().SecondsPerSlot
+	genesis := now.Add(-1 * time.Second * time.Duration(offset))
+	return blockchain.NewClock(genesis, blockchain.WithNow(func() time.Time {
+		return genesis
+	}))
+}

beacon-chain/geninit/clock.go

@@ -0,0 +1,69 @@
+package geninit
+
+import (
+	types "github.com/prysmaticlabs/prysm/consensus-types/primitives"
+	"github.com/prysmaticlabs/prysm/time/slots"
+	"time"
+)
+
+// Clock abstracts important time-related concerns in the beacon chain:
+// - genesis time
+// - provides a time.Now() construct that can be overriden in tests
+// - syncronization point for code that needs to know the genesis time
+// - CurrentSlot: convenience conversion for current time -> slot
+//   - support backwards compatibility with the TimeFetcher interface
+type Clock interface {
+	GenesisTime() time.Time
+	CurrentSlot() types.Slot
+	Now() time.Time
+}
+
+// clock is a type that fulfills the TimeFetcher interface. This can be used in a number of places where
+// blockchain.ChainInfoFetcher has historically been used.
+type clock struct {
+	genesis time.Time
+	now Now
+}
+var _ Clock = &clock{}
+
+// clock provides an accessor to the embedded time, also fulfilling the blockchain.TimeFetcher interface.
+func (gt clock) GenesisTime() time.Time {
+	return gt.genesis
+}
+
+// CurrentSlot returns the current slot relative to the time.Time value clock embeds.
+func (gt clock) CurrentSlot() types.Slot {
+	return slots.Duration(gt.genesis, gt.now())
+}
+
+// Now provides a value for time.Now() that can be overriden in tests.
+func (gt clock) Now() time.Time {
+	return gt.now()
+}
+
+// ClockOpt is a functional option to change the behavior of a clock value made by NewClock.
+// It is primarily intended as a way to inject an alternate time.Now() callback (WithNow) for testing.
+type ClockOpt func(*clock)
+
+// WithNow allows tests in particular to inject an alternate implementation of time.Now (vs using system time)
+func WithNow(n Now) ClockOpt {
+	return func(gt *clock) {
+		gt.now = n
+	}
+}
+
+// NewClock constructs a clock value using the given time value. Optional ClockOpt can be provided.
+// If an implementation of the Now function type is not provided (via WithNow), time.Now (system time) will be used by default.
+func NewClock(t time.Time, opts ...ClockOpt) clock {
+	gt := clock{genesis: t}
+	for _, o :=  range opts {
+		o(&gt)
+	}
+	if gt.now == nil {
+		gt.now = time.Now
+	}
+	return gt
+}
+
+// Now is a function that can return the current time. This will be time.Now by default, but can be overridden for tests.
+type Now func() time.Time

beacon-chain/geninit/service.go

@@ -0,0 +1,84 @@
+package geninit
+
+import (
+	"context"
+	"github.com/pkg/errors"
+	"github.com/prysmaticlabs/prysm/beacon-chain/core/transition"
+	"github.com/prysmaticlabs/prysm/beacon-chain/db"
+	"github.com/prysmaticlabs/prysm/beacon-chain/powchain"
+	"go.opencensus.io/trace"
+	"time"
+
+	"github.com/prysmaticlabs/prysm/runtime"
+	log "github.com/sirupsen/logrus"
+)
+
+type Service struct {
+	ctx context.Context
+	powWaiter ClockWaiter
+	genesisSetter ClockSetter
+	powFetcher powchain.ChainStartFetcher
+	d db.HeadAccessDatabase
+}
+var _ runtime.Service = &Service{}
+
+type ServiceOption func(*Service)
+
+func New(ctx context.Context, pw ClockWaiter, gs ClockSetter, f powchain.ChainStartFetcher, d db.HeadAccessDatabase, opts ...ServiceOption) (*Service, error) {
+	s := &Service{
+		ctx: ctx,
+		powWaiter: pw,
+		genesisSetter: gs,
+		powFetcher: f,
+		d: d,
+	}
+	for _, o := range opts {
+		o(s)
+	}
+	return s, nil
+}
+
+func (s *Service) Start() {
+	go s.run()
+}
+
+func (s *Service) run() {
+	c, err := s.powWaiter.WaitForClock(s.ctx)
+	if err != nil {
+		log.WithError(err).Error("timeout waiting for genesis timestamp")
+	}
+	if err = s.saveGenesis(c); err != nil {
+		log.Fatalf("Could not initialize beacon chain, %s", err.Error())
+	}
+	s.genesisSetter.SetGenesisClock(c)
+}
+
+func (s *Service) saveGenesis(c Clock) error {
+	ctx, span := trace.StartSpan(s.ctx, "beacon-chain.geninit.Service.saveGenesis")
+	defer span.End()
+	eth1 := s.powFetcher.ChainStartEth1Data()
+	pst := s.powFetcher.PreGenesisState()
+	st, err := transition.OptimizedGenesisBeaconState(uint64(c.GenesisTime().Unix()), pst, eth1)
+	if err != nil {
+		return err
+	}
+	if err := s.d.SaveGenesisData(ctx, st); err != nil {
+		return errors.Wrap(err, "db error, could not save genesis data")
+	}
+	log.Info("Initialized beacon chain genesis state")
+	// Clear out all pre-genesis data now that the state is initialized.
+	s.powFetcher.ClearPreGenesisData()
+	return nil
+}
+
+func (s *Service) Stop() error {
+	return nil
+}
+
+func (s *Service) Status() error {
+	return nil
+}
+
+type GenesisReady struct {
+	time time.Time
+}

beacon-chain/geninit/waiter.go

@@ -0,0 +1,50 @@
+package geninit
+
+import (
+	"context"
+	"time"
+)
+
+type ClockWaiter interface {
+	WaitForClock(context.Context) (Clock, error)
+}
+
+type ClockSetter interface {
+	SetGenesisTime(time.Time)
+	SetGenesisClock(Clock)
+}
+
+type ClockSync struct {
+	ready chan struct{}
+	c Clock
+}
+
+func (w *ClockSync) SetGenesisTime(g time.Time) {
+	w.c = NewClock(g)
+	close(w.ready)
+	w.ready = nil
+}
+
+func (w *ClockSync) SetGenesisClock(c Clock) {
+	w.c = c
+	close(w.ready)
+	w.ready = nil
+}
+
+func (w *ClockSync) WaitForClock(ctx context.Context) (Clock, error) {
+	if w.ready == nil {
+		return w.c, nil
+	}
+	select {
+	case <-w.ready:
+		return w.c, nil
+	case <-ctx.Done():
+		return nil, ctx.Err()
+	}
+}
+
+func NewClockSync() *ClockSync {
+	return &ClockSync{
+		ready: make(chan struct{}),
+	}
+}

beacon-chain/node/BUILD.bazel

@@ -29,6 +29,7 @@ go_library(
         "//beacon-chain/forkchoice/doubly-linked-tree:go_default_library",
         "//beacon-chain/forkchoice/protoarray:go_default_library",
         "//beacon-chain/gateway:go_default_library",
+        "//beacon-chain/geninit:go_default_library",
         "//beacon-chain/monitor:go_default_library",
         "//beacon-chain/node/registration:go_default_library",
         "//beacon-chain/operations/attestations:go_default_library",

beacon-chain/node/node.go

@@ -31,6 +31,7 @@ import (
 	doublylinkedtree "github.com/prysmaticlabs/prysm/beacon-chain/forkchoice/doubly-linked-tree"
 	"github.com/prysmaticlabs/prysm/beacon-chain/forkchoice/protoarray"
 	"github.com/prysmaticlabs/prysm/beacon-chain/gateway"
+	"github.com/prysmaticlabs/prysm/beacon-chain/geninit"
 	"github.com/prysmaticlabs/prysm/beacon-chain/monitor"
 	"github.com/prysmaticlabs/prysm/beacon-chain/node/registration"
 	"github.com/prysmaticlabs/prysm/beacon-chain/operations/attestations"
@@ -211,8 +212,17 @@ func New(cliCtx *cli.Context, opts ...Option) (*BeaconNode, error) {
 		return nil, err
 	}
 
+	powSync := geninit.NewClockSync()
+	genSync := geninit.NewClockSync()
+
 	log.Debugln("Registering POW Chain Service")
-	if err := beacon.registerPOWChainService(); err != nil {
+	powService, err := beacon.registerPOWChainService(powSync)
+	if err != nil {
+		return nil, err
+	}
+
+	log.Debugln("Registering Genesis Init Service")
+	if err := beacon.registerGenesisInitService(powSync, genSync, powService, beacon.db); err != nil {
 		return nil, err
 	}
 
@@ -629,17 +639,17 @@ func (b *BeaconNode) registerBlockchainService() error {
 	return b.services.RegisterService(blockchainService)
 }
 
-func (b *BeaconNode) registerPOWChainService() error {
+func (b *BeaconNode) registerPOWChainService(gcs geninit.ClockSetter) (*powchain.Service, error) {
 	if b.cliCtx.Bool(testSkipPowFlag) {
-		return b.services.RegisterService(&powchain.Service{})
+		return nil, b.services.RegisterService(&powchain.Service{})
 	}
 	bs, err := powchain.NewPowchainCollector(b.ctx)
 	if err != nil {
-		return err
+		return nil, err
 	}
 	depositContractAddr, err := powchain.DepositContractAddress()
 	if err != nil {
-		return err
+		return nil, err
 	}
 
 	// skipcq: CRT-D0001
@@ -652,13 +662,23 @@ func (b *BeaconNode) registerPOWChainService() error {
 		powchain.WithStateGen(b.stateGen),
 		powchain.WithBeaconNodeStatsUpdater(bs),
 		powchain.WithFinalizedStateAtStartup(b.finalizedStateAtStartUp),
+		powchain.WithGenesisClockSetter(gcs),
 	)
-	web3Service, err := powchain.NewService(b.ctx, opts...)
+	srv, err := powchain.NewService(b.ctx, opts...)
 	if err != nil {
-		return errors.Wrap(err, "could not register proof-of-work chain web3Service")
+		return nil, errors.Wrap(err, "could not register proof-of-work chain web3Service")
 	}
 
-	return b.services.RegisterService(web3Service)
+	err = b.services.RegisterService(srv)
+	return srv, err
+}
+
+func (b *BeaconNode) registerGenesisInitService(w geninit.ClockWaiter, s geninit.ClockSetter, f powchain.ChainStartFetcher, d db.HeadAccessDatabase) error {
+	g, err := geninit.New(b.ctx, w, s, f, d)
+	if err != nil {
+		return err
+	}
+	return b.services.RegisterService(g)
 }
 
 func (b *BeaconNode) registerSyncService() error {
@@ -821,7 +841,6 @@ func (b *BeaconNode) registerRPCService() error {
 		FinalizationFetcher:           chainService,
 		BlockReceiver:                 chainService,
 		AttestationReceiver:           chainService,
-		GenesisTimeFetcher:            chainService,
 		GenesisFetcher:                chainService,
 		OptimisticModeFetcher:         chainService,
 		AttestationsPool:              b.attestationPool,
@@ -844,6 +863,7 @@ func (b *BeaconNode) registerRPCService() error {
 		MaxMsgSize:                    maxMsgSize,
 		ProposerIdsCache:              b.proposerIdsCache,
 		BlockBuilder:                  b.fetchBuilderService(),
+		ClockProvider:                 chainService,
 	})
 
 	return b.services.RegisterService(rpcService)

beacon-chain/powchain/BUILD.bazel

@@ -32,6 +32,7 @@ go_library(
         "//beacon-chain/core/helpers:go_default_library",
         "//beacon-chain/core/transition:go_default_library",
         "//beacon-chain/db:go_default_library",
+        "//beacon-chain/geninit:go_default_library",
         "//beacon-chain/powchain/types:go_default_library",
         "//beacon-chain/state:go_default_library",
         "//beacon-chain/state/state-native:go_default_library",

beacon-chain/powchain/log_processing.go

@@ -255,6 +255,7 @@ func (s *Service) ProcessChainStart(genesisTime uint64, eth1BlockHash [32]byte,
 	log.WithFields(logrus.Fields{
 		"ChainStartTime": chainStartTime,
 	}).Info("Minimum number of validators reached for beacon-chain to start")
+	s.genSync.SetGenesisTime(chainStartTime)
 	s.cfg.stateNotifier.StateFeed().Send(&feed.Event{
 		Type: statefeed.ChainStarted,
 		Data: &statefeed.ChainStartedData{

beacon-chain/powchain/options.go

@@ -5,6 +5,7 @@ import (
 	"github.com/prysmaticlabs/prysm/beacon-chain/cache/depositcache"
 	statefeed "github.com/prysmaticlabs/prysm/beacon-chain/core/feed/state"
 	"github.com/prysmaticlabs/prysm/beacon-chain/db"
+	"github.com/prysmaticlabs/prysm/beacon-chain/geninit"
 	"github.com/prysmaticlabs/prysm/beacon-chain/state"
 	"github.com/prysmaticlabs/prysm/beacon-chain/state/stategen"
 	"github.com/prysmaticlabs/prysm/network"
@@ -123,3 +124,10 @@ func WithFinalizedStateAtStartup(st state.BeaconState) Option {
 		return nil
 	}
 }
+
+func WithGenesisClockSetter(cs geninit.ClockSetter) Option {
+	return func(s *Service) error {
+		s.genSync = cs
+		return nil
+	}
+}

beacon-chain/powchain/service.go

@@ -27,6 +27,7 @@ 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"
+	"github.com/prysmaticlabs/prysm/beacon-chain/geninit"
 	"github.com/prysmaticlabs/prysm/beacon-chain/powchain/types"
 	"github.com/prysmaticlabs/prysm/beacon-chain/state"
 	native "github.com/prysmaticlabs/prysm/beacon-chain/state/state-native"
@@ -161,6 +162,7 @@ type Service struct {
 	lastReceivedMerkleIndex int64 // Keeps track of the last received index to prevent log spam.
 	runError                error
 	preGenesisState         state.BeaconState
+	genSync                 geninit.ClockSetter
 }
 
 // NewService sets up a new instance with an ethclient when given a web3 endpoint as a string in the config.
@@ -580,7 +582,10 @@ func (s *Service) initPOWService() {
 
 			if err := s.processPastLogs(ctx); err != nil {
 				s.retryExecutionClientConnection(ctx, err)
-				errorLogger(err, "Unable to process past deposit contract logs")
+				errorLogger(
+					err,
+					"Unable to process past deposit contract logs, perhaps your execution client is not fully synced",
+				)
 				continue
 			}
 			// Cache eth1 headers from our voting period.

beacon-chain/rpc/BUILD.bazel

@@ -46,6 +46,7 @@ go_library(
         "@com_github_grpc_ecosystem_go_grpc_middleware//recovery:go_default_library",
         "@com_github_grpc_ecosystem_go_grpc_middleware//tracing/opentracing:go_default_library",
         "@com_github_grpc_ecosystem_go_grpc_prometheus//:go_default_library",
+        "@com_github_pkg_errors//:go_default_library",
         "@com_github_sirupsen_logrus//:go_default_library",
         "@io_opencensus_go//plugin/ocgrpc:go_default_library",
         "@org_golang_google_grpc//:go_default_library",
@@ -61,6 +62,7 @@ go_test(
     srcs = ["service_test.go"],
     embed = [":go_default_library"],
     deps = [
+        "//beacon-chain/blockchain:go_default_library",
         "//beacon-chain/blockchain/testing:go_default_library",
         "//beacon-chain/powchain/testing:go_default_library",
         "//beacon-chain/sync/initial-sync/testing:go_default_library",

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

@@ -80,6 +80,7 @@ go_test(
     embed = [":go_default_library"],
     deps = [
         "//api/grpc:go_default_library",
+        "//beacon-chain/blockchain:go_default_library",
         "//beacon-chain/blockchain/testing:go_default_library",
         "//beacon-chain/core/signing:go_default_library",
         "//beacon-chain/db:go_default_library",

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

@@ -53,7 +53,11 @@ func (e *blockIdParseError) Error() string {
 // GetWeakSubjectivity computes the starting epoch of the current weak subjectivity period, and then also
 // determines the best block root and state root to use for a Checkpoint Sync starting from that point.
 func (bs *Server) GetWeakSubjectivity(ctx context.Context, _ *empty.Empty) (*ethpbv1.WeakSubjectivityResponse, error) {
-	if err := rpchelpers.ValidateSync(ctx, bs.SyncChecker, bs.HeadFetcher, bs.GenesisTimeFetcher, bs.OptimisticModeFetcher); err != nil {
+	c, err := bs.ClockProvider.WaitForClock(ctx)
+	if err != nil {
+		return nil, status.Errorf(codes.Internal, "timeout while waiting for genesis timestamp, %s", err)
+	}
+	if err := rpchelpers.ValidateSync(ctx, bs.SyncChecker, bs.HeadFetcher, c, bs.OptimisticModeFetcher); err != nil {
 		// This is already a grpc error, so we can't wrap it any further
 		return nil, err
 	}
@@ -70,7 +74,11 @@ func (bs *Server) GetWeakSubjectivity(ctx context.Context, _ *empty.Empty) (*eth
 	if err != nil {
 		return nil, status.Errorf(codes.Internal, "could not get weak subjectivity slot: %v", err)
 	}
-	cbr, err := bs.CanonicalHistory.BlockRootForSlot(ctx, wsSlot)
+	h, err := bs.CanonicalHistoryWaiter.WaitForCanonicalHistory(ctx)
+	if err != nil {
+		return nil, status.Error(codes.Internal, err.Error())
+	}
+	cbr, err := h.BlockRootForSlot(ctx, wsSlot)
 	if err != nil {
 		return nil, status.Errorf(codes.Internal, fmt.Sprintf("could not find highest block below slot %d", wsSlot))
 	}

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

@@ -24,7 +24,6 @@ import (
 type Server struct {
 	BeaconDB                      db.ReadOnlyDatabase
 	ChainInfoFetcher              blockchain.ChainInfoFetcher
-	GenesisTimeFetcher            blockchain.TimeFetcher
 	BlockReceiver                 blockchain.BlockReceiver
 	BlockNotifier                 blockfeed.Notifier
 	OperationNotifier             operation.Notifier
@@ -37,8 +36,9 @@ type Server struct {
 	HeadFetcher                   blockchain.HeadFetcher
 	OptimisticModeFetcher         blockchain.OptimisticModeFetcher
 	V1Alpha1ValidatorServer       *v1alpha1validator.Server
-	SyncChecker                   sync.Checker
-	CanonicalHistory              *stategen.CanonicalHistory
-	HeadUpdater                   blockchain.HeadUpdater
+	SyncChecker            sync.Checker
+	CanonicalHistoryWaiter stategen.CanonicalHistoryWaiter
+	HeadUpdater            blockchain.HeadUpdater
 	ExecutionPayloadReconstructor powchain.ExecutionPayloadReconstructor
+	ClockProvider                 blockchain.ClockProvider
 }

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

@@ -30,10 +30,11 @@ func (bs *Server) GetGenesis(ctx context.Context, _ *emptypb.Empty) (*ethpb.Gene
 	ctx, span := trace.StartSpan(ctx, "beacon.GetGenesis")
 	defer span.End()
 
-	genesisTime := bs.GenesisTimeFetcher.GenesisTime()
-	if genesisTime.IsZero() {
-		return nil, status.Errorf(codes.NotFound, "Chain genesis info is not yet known")
+	c, err := bs.ClockProvider.WaitForClock(ctx)
+	if err != nil {
+		return nil, status.Errorf(codes.Internal, "timeout waiting for genesis timestamp, %s", err)
 	}
+	genesisTime := c.GenesisTime()
 	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

@@ -2,6 +2,7 @@ package beacon
 
 import (
 	"context"
+	"github.com/prysmaticlabs/prysm/beacon-chain/blockchain"
 	"testing"
 	"time"
 
@@ -29,11 +30,11 @@ func TestGetGenesis(t *testing.T) {
 
 	t.Run("OK", func(t *testing.T) {
 		chainService := &chainMock.ChainService{
-			Genesis:        genesis,
+			Clock:        blockchain.NewClock(genesis),
 			ValidatorsRoot: validatorsRoot,
 		}
 		s := Server{
-			GenesisTimeFetcher: chainService,
+			ClockProvider: chainService,
 			ChainInfoFetcher:   chainService,
 		}
 		resp, err := s.GetGenesis(ctx, &emptypb.Empty{})
@@ -46,11 +47,11 @@ func TestGetGenesis(t *testing.T) {
 
 	t.Run("No genesis time", func(t *testing.T) {
 		chainService := &chainMock.ChainService{
-			Genesis:        time.Time{},
+			Clock:        blockchain.NewClock(time.Time{}),
 			ValidatorsRoot: validatorsRoot,
 		}
 		s := Server{
-			GenesisTimeFetcher: chainService,
+			ClockProvider: chainService,
 			ChainInfoFetcher:   chainService,
 		}
 		_, err := s.GetGenesis(ctx, &emptypb.Empty{})
@@ -59,11 +60,11 @@ func TestGetGenesis(t *testing.T) {
 
 	t.Run("No genesis validators root", func(t *testing.T) {
 		chainService := &chainMock.ChainService{
-			Genesis:        genesis,
+			Clock:        blockchain.NewClock(genesis),
 			ValidatorsRoot: [32]byte{},
 		}
 		s := Server{
-			GenesisTimeFetcher: chainService,
+			ClockProvider: chainService,
 			ChainInfoFetcher:   chainService,
 		}
 		_, err := s.GetGenesis(ctx, &emptypb.Empty{})

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

@@ -27,7 +27,11 @@ func (bs *Server) ListSyncCommittees(ctx context.Context, req *ethpbv2.StateSync
 	ctx, span := trace.StartSpan(ctx, "beacon.ListSyncCommittees")
 	defer span.End()
 
-	currentSlot := bs.GenesisTimeFetcher.CurrentSlot()
+	c, err := bs.ClockProvider.WaitForClock(ctx)
+	if err != nil {
+		return nil, status.Errorf(codes.Internal, "timeout waiting for genesis timestamp, %s", err)
+	}
+	currentSlot := c.CurrentSlot()
 	currentEpoch := slots.ToEpoch(currentSlot)
 	currentPeriodStartEpoch, err := slots.SyncCommitteePeriodStartEpoch(currentEpoch)
 	if err != nil {

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

@@ -3,6 +3,7 @@ package beacon
 import (
 	"bytes"
 	"context"
+	"github.com/prysmaticlabs/prysm/beacon-chain/blockchain"
 	"strconv"
 	"strings"
 	"testing"
@@ -161,11 +162,9 @@ func TestListSyncCommittees(t *testing.T) {
 	require.NoError(t, err)
 	db := dbTest.SetupDB(t)
 
-	chainService := &mock.ChainService{}
+	chainService := &mock.ChainService{Clock: blockchain.NewClock(time.Now())}
 	s := &Server{
-		GenesisTimeFetcher: &testutil.MockGenesisTimeFetcher{
-			Genesis: time.Now(),
-		},
+		ClockProvider: chainService,
 		StateFetcher: &testutil.MockFetcher{
 			BeaconState: st,
 		},
@@ -204,11 +203,9 @@ func TestListSyncCommittees(t *testing.T) {
 		util.SaveBlock(t, ctx, db, blk)
 		require.NoError(t, db.SaveGenesisBlockRoot(ctx, root))
 
-		chainService := &mock.ChainService{Optimistic: true}
+		chainService := &mock.ChainService{Optimistic: true, Clock: blockchain.NewClock(time.Now())}
 		s := &Server{
-			GenesisTimeFetcher: &testutil.MockGenesisTimeFetcher{
-				Genesis: time.Now(),
-			},
+			ClockProvider: chainService,
 			StateFetcher: &testutil.MockFetcher{
 				BeaconState: st,
 			},
@@ -262,11 +259,9 @@ func TestListSyncCommitteesFuture(t *testing.T) {
 	}))
 	db := dbTest.SetupDB(t)
 
-	chainService := &mock.ChainService{}
+	chainService := &mock.ChainService{Clock: blockchain.NewClock(time.Now())}
 	s := &Server{
-		GenesisTimeFetcher: &testutil.MockGenesisTimeFetcher{
-			Genesis: time.Now(),
-		},
+		ClockProvider: chainService,
 		StateFetcher: &futureSyncMockFetcher{
 			BeaconState: st,
 		},

beacon-chain/rpc/eth/helpers/sync.go

@@ -21,7 +21,7 @@ func ValidateSync(
 	ctx context.Context,
 	syncChecker sync.Checker,
 	headFetcher blockchain.HeadFetcher,
-	timeFetcher blockchain.TimeFetcher,
+	clock blockchain.Clock,
 	optimisticModeFetcher blockchain.OptimisticModeFetcher,
 ) error {
 	if !syncChecker.Syncing() {
@@ -36,7 +36,7 @@ func ValidateSync(
 	syncDetailsContainer := &syncDetailsContainer{
 		SyncDetails: &SyncDetailsJson{
 			HeadSlot:     strconv.FormatUint(uint64(headSlot), 10),
-			SyncDistance: strconv.FormatUint(uint64(timeFetcher.CurrentSlot()-headSlot), 10),
+			SyncDistance: strconv.FormatUint(uint64(clock.CurrentSlot()-headSlot), 10),
 			IsSyncing:    true,
 			IsOptimistic: isOptimistic,
 		},

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

@@ -270,11 +270,19 @@ func (ns *Server) GetSyncStatus(ctx context.Context, _ *emptypb.Empty) (*ethpb.S
 		return nil, status.Errorf(codes.Internal, "Could not check optimistic status: %v", err)
 	}
 
+	c, err := ns.ClockProvider.WaitForClock(ctx)
+	if err != nil {
+		return nil, status.Errorf(codes.Internal, "timeout while waiting for genesis timestamp, %s", err)
+	}
 	headSlot := ns.HeadFetcher.HeadSlot()
+	sd, err := c.CurrentSlot().SafeSubSlot(headSlot)
+	if err != nil {
+		return nil, status.Errorf(codes.Internal, "error computing sync_distance, head > current slot, %s", err)
+	}
 	return &ethpb.SyncingResponse{
 		Data: &ethpb.SyncInfo{
 			HeadSlot:     headSlot,
-			SyncDistance: ns.GenesisTimeFetcher.CurrentSlot() - headSlot,
+			SyncDistance: sd,
 			IsSyncing:    ns.SyncChecker.Syncing(),
 			IsOptimistic: isOptimistic,
 		},

beacon-chain/rpc/eth/node/node_test.go

@@ -173,7 +173,7 @@ func TestSyncStatus(t *testing.T) {
 
 	s := &Server{
 		HeadFetcher:           chainService,
-		GenesisTimeFetcher:    chainService,
+		ClockProvider:         chainService,
 		OptimisticModeFetcher: chainService,
 		SyncChecker:           syncChecker,
 	}

beacon-chain/rpc/eth/node/server.go

@@ -22,6 +22,6 @@ type Server struct {
 	PeersFetcher          p2p.PeersProvider
 	PeerManager           p2p.PeerManager
 	MetadataProvider      p2p.MetadataProvider
-	GenesisTimeFetcher    blockchain.TimeFetcher
 	HeadFetcher           blockchain.HeadFetcher
+	ClockProvider         blockchain.ClockProvider
 }

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

@@ -48,6 +48,7 @@ go_test(
     srcs = ["validator_test.go"],
     embed = [":go_default_library"],
     deps = [
+        "//beacon-chain/blockchain:go_default_library",
         "//beacon-chain/blockchain/testing:go_default_library",
         "//beacon-chain/cache:go_default_library",
         "//beacon-chain/core/altair:go_default_library",

beacon-chain/rpc/eth/validator/server.go

@@ -15,7 +15,6 @@ import (
 type Server struct {
 	HeadFetcher           blockchain.HeadFetcher
 	HeadUpdater           blockchain.HeadUpdater
-	TimeFetcher           blockchain.TimeFetcher
 	SyncChecker           sync.Checker
 	AttestationsPool      attestations.Pool
 	PeerManager           p2p.PeerManager
@@ -24,4 +23,5 @@ type Server struct {
 	OptimisticModeFetcher blockchain.OptimisticModeFetcher
 	SyncCommitteePool     synccommittee.Pool
 	V1Alpha1Server        *v1alpha1validator.Server
+	ClockProvider         blockchain.ClockProvider
 }

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

@@ -42,12 +42,16 @@ func (vs *Server) GetAttesterDuties(ctx context.Context, req *ethpbv1.AttesterDu
 	ctx, span := trace.StartSpan(ctx, "validator.GetAttesterDuties")
 	defer span.End()
 
-	if err := rpchelpers.ValidateSync(ctx, vs.SyncChecker, vs.HeadFetcher, vs.TimeFetcher, vs.OptimisticModeFetcher); err != nil {
+	c, err := vs.ClockProvider.WaitForClock(ctx)
+	if err != nil {
+		return nil, status.Errorf(codes.Internal, "timeout while waiting for genesis timestamp, %s", err)
+	}
+	if err := rpchelpers.ValidateSync(ctx, vs.SyncChecker, vs.HeadFetcher, c, vs.OptimisticModeFetcher); err != nil {
 		// We simply return the error because it's already a gRPC error.
 		return nil, err
 	}
 
-	cs := vs.TimeFetcher.CurrentSlot()
+	cs := c.CurrentSlot()
 	currentEpoch := slots.ToEpoch(cs)
 	if req.Epoch > currentEpoch+1 {
 		return nil, status.Errorf(codes.InvalidArgument, "Request epoch %d can not be greater than next epoch %d", req.Epoch, currentEpoch+1)
@@ -125,12 +129,16 @@ func (vs *Server) GetProposerDuties(ctx context.Context, req *ethpbv1.ProposerDu
 	ctx, span := trace.StartSpan(ctx, "validator.GetProposerDuties")
 	defer span.End()
 
-	if err := rpchelpers.ValidateSync(ctx, vs.SyncChecker, vs.HeadFetcher, vs.TimeFetcher, vs.OptimisticModeFetcher); err != nil {
+	c, err := vs.ClockProvider.WaitForClock(ctx)
+	if err != nil {
+		return nil, status.Errorf(codes.Internal, "timeout while waiting for genesis timestamp, %s", err)
+	}
+	if err := rpchelpers.ValidateSync(ctx, vs.SyncChecker, vs.HeadFetcher, c, vs.OptimisticModeFetcher); err != nil {
 		// We simply return the error because it's already a gRPC error.
 		return nil, err
 	}
 
-	cs := vs.TimeFetcher.CurrentSlot()
+	cs := c.CurrentSlot()
 	currentEpoch := slots.ToEpoch(cs)
 	if req.Epoch > currentEpoch+1 {
 		return nil, status.Errorf(codes.InvalidArgument, "Request epoch %d can not be greater than next epoch %d", req.Epoch, currentEpoch+1)
@@ -202,12 +210,16 @@ func (vs *Server) GetSyncCommitteeDuties(ctx context.Context, req *ethpbv2.SyncC
 	ctx, span := trace.StartSpan(ctx, "validator.GetSyncCommitteeDuties")
 	defer span.End()
 
-	if err := rpchelpers.ValidateSync(ctx, vs.SyncChecker, vs.HeadFetcher, vs.TimeFetcher, vs.OptimisticModeFetcher); err != nil {
+	c, err := vs.ClockProvider.WaitForClock(ctx)
+	if err != nil {
+		return nil, status.Errorf(codes.Internal, "timeout while waiting for genesis timestamp, %s", err)
+	}
+	if err := rpchelpers.ValidateSync(ctx, vs.SyncChecker, vs.HeadFetcher, c, vs.OptimisticModeFetcher); err != nil {
 		// We simply return the error because it's already a gRPC error.
 		return nil, err
 	}
 
-	currentEpoch := slots.ToEpoch(vs.TimeFetcher.CurrentSlot())
+	currentEpoch := slots.ToEpoch(c.CurrentSlot())
 	lastValidEpoch := syncCommitteeDutiesLastValidEpoch(currentEpoch)
 	if req.Epoch > lastValidEpoch {
 		return nil, status.Errorf(codes.InvalidArgument, "Epoch is too far in the future. Maximum valid epoch is %v.", lastValidEpoch)
@@ -272,7 +284,11 @@ func (vs *Server) ProduceBlock(ctx context.Context, req *ethpbv1.ProduceBlockReq
 	ctx, span := trace.StartSpan(ctx, "validator.ProduceBlock")
 	defer span.End()
 
-	if err := rpchelpers.ValidateSync(ctx, vs.SyncChecker, vs.HeadFetcher, vs.TimeFetcher, vs.OptimisticModeFetcher); err != nil {
+	c, err := vs.ClockProvider.WaitForClock(ctx)
+	if err != nil {
+		return nil, status.Errorf(codes.Internal, "timeout while waiting for genesis timestamp, %s", err)
+	}
+	if err := rpchelpers.ValidateSync(ctx, vs.SyncChecker, vs.HeadFetcher, c, vs.OptimisticModeFetcher); err != nil {
 		// We simply return the error because it's already a gRPC error.
 		return nil, err
 	}
@@ -289,7 +305,11 @@ func (vs *Server) ProduceBlockV2(ctx context.Context, req *ethpbv1.ProduceBlockR
 	ctx, span := trace.StartSpan(ctx, "validator.ProduceBlockV2")
 	defer span.End()
 
-	if err := rpchelpers.ValidateSync(ctx, vs.SyncChecker, vs.HeadFetcher, vs.TimeFetcher, vs.OptimisticModeFetcher); err != nil {
+	c, err := vs.ClockProvider.WaitForClock(ctx)
+	if err != nil {
+		return nil, status.Errorf(codes.Internal, "timeout while waiting for genesis timestamp, %s", err)
+	}
+	if err := rpchelpers.ValidateSync(ctx, vs.SyncChecker, vs.HeadFetcher, c, vs.OptimisticModeFetcher); err != nil {
 		// We simply return the error because it's already a gRPC error.
 		return nil, err
 	}
@@ -353,7 +373,11 @@ func (vs *Server) ProduceBlockV2SSZ(ctx context.Context, req *ethpbv1.ProduceBlo
 	ctx, span := trace.StartSpan(ctx, "validator.ProduceBlockV2SSZ")
 	defer span.End()
 
-	if err := rpchelpers.ValidateSync(ctx, vs.SyncChecker, vs.HeadFetcher, vs.TimeFetcher, vs.OptimisticModeFetcher); err != nil {
+	c, err := vs.ClockProvider.WaitForClock(ctx)
+	if err != nil {
+		return nil, status.Errorf(codes.Internal, "timeout while waiting for genesis timestamp, %s", err)
+	}
+	if err := rpchelpers.ValidateSync(ctx, vs.SyncChecker, vs.HeadFetcher, c, vs.OptimisticModeFetcher); err != nil {
 		// We simply return the error because it's already a gRPC error.
 		return nil, err
 	}
@@ -424,7 +448,11 @@ func (vs *Server) ProduceBlindedBlock(ctx context.Context, req *ethpbv1.ProduceB
 	ctx, span := trace.StartSpan(ctx, "validator.ProduceBlindedBlock")
 	defer span.End()
 
-	if err := rpchelpers.ValidateSync(ctx, vs.SyncChecker, vs.HeadFetcher, vs.TimeFetcher, vs.OptimisticModeFetcher); err != nil {
+	c, err := vs.ClockProvider.WaitForClock(ctx)
+	if err != nil {
+		return nil, status.Errorf(codes.Internal, "timeout while waiting for genesis timestamp, %s", err)
+	}
+	if err := rpchelpers.ValidateSync(ctx, vs.SyncChecker, vs.HeadFetcher, c, vs.OptimisticModeFetcher); err != nil {
 		// We simply return the error because it's already a gRPC error.
 		return nil, err
 	}
@@ -491,7 +519,11 @@ func (vs *Server) ProduceBlindedBlockSSZ(ctx context.Context, req *ethpbv1.Produ
 	ctx, span := trace.StartSpan(ctx, "validator.ProduceBlindedBlockSSZ")
 	defer span.End()
 
-	if err := rpchelpers.ValidateSync(ctx, vs.SyncChecker, vs.HeadFetcher, vs.TimeFetcher, vs.OptimisticModeFetcher); err != nil {
+	c, err := vs.ClockProvider.WaitForClock(ctx)
+	if err != nil {
+		return nil, status.Errorf(codes.Internal, "timeout while waiting for genesis timestamp, %s", err)
+	}
+	if err := rpchelpers.ValidateSync(ctx, vs.SyncChecker, vs.HeadFetcher, c, vs.OptimisticModeFetcher); err != nil {
 		// We simply return the error because it's already a gRPC error.
 		return nil, err
 	}
@@ -633,6 +665,10 @@ func (vs *Server) SubmitAggregateAndProofs(ctx context.Context, req *ethpbv1.Sub
 	ctx, span := trace.StartSpan(ctx, "validator.SubmitAggregateAndProofs")
 	defer span.End()
 
+	c, err := vs.ClockProvider.WaitForClock(ctx)
+	if err != nil {
+		return nil, status.Errorf(codes.Internal, "timeout waiting for genesis timestamp, %s", err)
+	}
 	for _, agg := range req.Data {
 		if agg == nil || agg.Message == nil || agg.Message.Aggregate == nil || agg.Message.Aggregate.Data == nil {
 			return nil, status.Error(codes.InvalidArgument, "Signed aggregate request can't be nil")
@@ -648,7 +684,7 @@ func (vs *Server) SubmitAggregateAndProofs(ctx context.Context, req *ethpbv1.Sub
 
 		// As a preventive measure, a beacon node shouldn't broadcast an attestation whose slot is out of range.
 		if err := helpers.ValidateAttestationTime(agg.Message.Aggregate.Data.Slot,
-			vs.TimeFetcher.GenesisTime(), params.BeaconNetworkConfig().MaximumGossipClockDisparity); err != nil {
+			c.GenesisTime(), params.BeaconNetworkConfig().MaximumGossipClockDisparity); err != nil {
 			return nil, status.Error(codes.InvalidArgument, "Attestation slot is no longer valid from current time")
 		}
 	}
@@ -683,7 +719,11 @@ func (vs *Server) SubmitBeaconCommitteeSubscription(ctx context.Context, req *et
 	ctx, span := trace.StartSpan(ctx, "validator.SubmitBeaconCommitteeSubscription")
 	defer span.End()
 
-	if err := rpchelpers.ValidateSync(ctx, vs.SyncChecker, vs.HeadFetcher, vs.TimeFetcher, vs.OptimisticModeFetcher); err != nil {
+	c, err := vs.ClockProvider.WaitForClock(ctx)
+	if err != nil {
+		return nil, status.Errorf(codes.Internal, "timeout while waiting for genesis timestamp, %s", err)
+	}
+	if err := rpchelpers.ValidateSync(ctx, vs.SyncChecker, vs.HeadFetcher, c, vs.OptimisticModeFetcher); err != nil {
 		// We simply return the error because it's already a gRPC error.
 		return nil, err
 	}
@@ -760,7 +800,11 @@ func (vs *Server) SubmitSyncCommitteeSubscription(ctx context.Context, req *ethp
 	ctx, span := trace.StartSpan(ctx, "validator.SubmitSyncCommitteeSubscription")
 	defer span.End()
 
-	if err := rpchelpers.ValidateSync(ctx, vs.SyncChecker, vs.HeadFetcher, vs.TimeFetcher, vs.OptimisticModeFetcher); err != nil {
+	c, err := vs.ClockProvider.WaitForClock(ctx)
+	if err != nil {
+		return nil, status.Errorf(codes.Internal, "timeout while waiting for genesis timestamp, %s", err)
+	}
+	if err := rpchelpers.ValidateSync(ctx, vs.SyncChecker, vs.HeadFetcher, c, vs.OptimisticModeFetcher); err != nil {
 		// We simply return the error because it's already a gRPC error.
 		return nil, err
 	}

beacon-chain/rpc/eth/validator/validator_test.go

@@ -3,6 +3,7 @@ package validator
 import (
 	"context"
 	"fmt"
+	"github.com/prysmaticlabs/prysm/beacon-chain/blockchain"
 	"strconv"
 	"testing"
 	"time"
@@ -75,13 +76,12 @@ func TestGetAttesterDuties(t *testing.T) {
 		pubKeys[i] = deposits[i].Data.PublicKey
 	}
 
-	chainSlot := types.Slot(0)
 	chain := &mockChain.ChainService{
-		State: bs, Root: genesisRoot[:], Slot: &chainSlot,
+		State: bs, Root: genesisRoot[:],
 	}
 	vs := &Server{
 		HeadFetcher:           chain,
-		TimeFetcher:           chain,
+		ClockProvider:         chain,
 		SyncChecker:           &mockSync.Sync{IsSyncing: false},
 		OptimisticModeFetcher: chain,
 	}
@@ -155,12 +155,13 @@ func TestGetAttesterDuties(t *testing.T) {
 			indices[i] = uint64(i)
 		}
 		chainSlot := params.BeaconConfig().SlotsPerEpoch.Mul(2)
+		clock := mockChain.NewMockClock(time.Now(), chainSlot)
 		chain := &mockChain.ChainService{
-			State: bs, Root: genesisRoot[:], Slot: &chainSlot,
+			State: bs, Root: genesisRoot[:], Clock: clock,
 		}
 		vs := &Server{
 			HeadFetcher:           chain,
-			TimeFetcher:           chain,
+			ClockProvider:           chain,
 			OptimisticModeFetcher: chain,
 			SyncChecker:           &mockSync.Sync{IsSyncing: false},
 		}
@@ -224,13 +225,12 @@ func TestGetAttesterDuties(t *testing.T) {
 		util.SaveBlock(t, ctx, db, blk)
 		require.NoError(t, db.SaveGenesisBlockRoot(ctx, root))
 
-		chainSlot := types.Slot(0)
 		chain := &mockChain.ChainService{
-			State: bs, Root: genesisRoot[:], Slot: &chainSlot, Optimistic: true,
+			State: bs, Root: genesisRoot[:], Optimistic: true,
 		}
 		vs := &Server{
 			HeadFetcher:           chain,
-			TimeFetcher:           chain,
+			ClockProvider:           chain,
 			OptimisticModeFetcher: chain,
 			SyncChecker:           &mockSync.Sync{IsSyncing: false},
 		}
@@ -251,7 +251,7 @@ func TestGetAttesterDuties_SyncNotReady(t *testing.T) {
 	vs := &Server{
 		SyncChecker:           &mockSync.Sync{IsSyncing: true},
 		HeadFetcher:           chainService,
-		TimeFetcher:           chainService,
+		ClockProvider:         chainService,
 		OptimisticModeFetcher: chainService,
 	}
 	_, err = vs.GetAttesterDuties(context.Background(), &ethpbv1.AttesterDutiesRequest{})
@@ -282,13 +282,12 @@ func TestGetProposerDuties(t *testing.T) {
 		pubKeys[i] = deposits[i].Data.PublicKey
 	}
 
-	chainSlot := types.Slot(0)
 	chain := &mockChain.ChainService{
-		State: bs, Root: genesisRoot[:], Slot: &chainSlot,
+		State: bs, Root: genesisRoot[:],
 	}
 	vs := &Server{
 		HeadFetcher:           chain,
-		TimeFetcher:           chain,
+		ClockProvider:         chain,
 		OptimisticModeFetcher: chain,
 		SyncChecker:           &mockSync.Sync{IsSyncing: false},
 	}
@@ -334,12 +333,15 @@ func TestGetProposerDuties(t *testing.T) {
 			indices[i] = uint64(i)
 		}
 		chainSlot := params.BeaconConfig().SlotsPerEpoch.Mul(2)
+		clock := mockChain.NewMockClock(time.Now(), chainSlot)
 		chain := &mockChain.ChainService{
-			State: bs, Root: genesisRoot[:], Slot: &chainSlot,
+			State: bs,
+			Root: genesisRoot[:],
+			Clock: clock,
 		}
 		vs := &Server{
 			HeadFetcher:           chain,
-			TimeFetcher:           chain,
+			ClockProvider:           chain,
 			OptimisticModeFetcher: chain,
 			SyncChecker:           &mockSync.Sync{IsSyncing: false},
 		}
@@ -383,13 +385,12 @@ func TestGetProposerDuties(t *testing.T) {
 		util.SaveBlock(t, ctx, db, blk)
 		require.NoError(t, db.SaveGenesisBlockRoot(ctx, root))
 
-		chainSlot := types.Slot(0)
 		chain := &mockChain.ChainService{
-			State: bs, Root: genesisRoot[:], Slot: &chainSlot, Optimistic: true,
+			State: bs, Root: genesisRoot[:], Optimistic: true,
 		}
 		vs := &Server{
 			HeadFetcher:           chain,
-			TimeFetcher:           chain,
+			ClockProvider:         chain,
 			OptimisticModeFetcher: chain,
 			SyncChecker:           &mockSync.Sync{IsSyncing: false},
 		}
@@ -409,7 +410,7 @@ func TestGetProposerDuties_SyncNotReady(t *testing.T) {
 	vs := &Server{
 		SyncChecker:           &mockSync.Sync{IsSyncing: true},
 		HeadFetcher:           chainService,
-		TimeFetcher:           chainService,
+		ClockProvider:         chainService,
 		OptimisticModeFetcher: chainService,
 	}
 	_, err = vs.GetProposerDuties(context.Background(), &ethpbv1.ProposerDutiesRequest{})
@@ -437,11 +438,11 @@ func TestGetSyncCommitteeDuties(t *testing.T) {
 	require.NoError(t, st.SetNextSyncCommittee(nextCommittee))
 	db := dbutil.SetupDB(t)
 
-	mockChainService := &mockChain.ChainService{Genesis: genesisTime}
+	mockChainService := &mockChain.ChainService{Clock: blockchain.NewClock(genesisTime)}
 	vs := &Server{
 		StateFetcher:          &testutil.MockFetcher{BeaconState: st},
 		SyncChecker:           &mockSync.Sync{IsSyncing: false},
-		TimeFetcher:           mockChainService,
+		ClockProvider:           mockChainService,
 		HeadFetcher:           mockChainService,
 		OptimisticModeFetcher: mockChainService,
 	}
@@ -576,11 +577,14 @@ func TestGetSyncCommitteeDuties(t *testing.T) {
 				return newSyncPeriodSt
 			}
 		}
-		mockChainService := &mockChain.ChainService{Genesis: genesisTime, Slot: &newSyncPeriodStartSlot}
+		clock := mockChain.NewMockClock(time.Now(), newSyncPeriodStartSlot)
+		mockChainService := &mockChain.ChainService{
+			Clock: clock,
+		}
 		vs := &Server{
 			StateFetcher:          &testutil.MockFetcher{BeaconState: stateFetchFn(newSyncPeriodStartSlot)},
 			SyncChecker:           &mockSync.Sync{IsSyncing: false},
-			TimeFetcher:           mockChainService,
+			ClockProvider:         mockChainService,
 			HeadFetcher:           mockChainService,
 			OptimisticModeFetcher: mockChainService,
 		}
@@ -610,11 +614,14 @@ func TestGetSyncCommitteeDuties(t *testing.T) {
 		util.SaveBlock(t, ctx, db, blk)
 		require.NoError(t, db.SaveGenesisBlockRoot(ctx, root))
 
-		mockChainService := &mockChain.ChainService{Genesis: genesisTime, Optimistic: true}
+		mockChainService := &mockChain.ChainService{
+			Clock:      blockchain.NewClock(genesisTime),
+			Optimistic: true,
+		}
 		vs := &Server{
 			StateFetcher:          &testutil.MockFetcher{BeaconState: st},
 			SyncChecker:           &mockSync.Sync{IsSyncing: false},
-			TimeFetcher:           mockChainService,
+			ClockProvider:         mockChainService,
 			HeadFetcher:           mockChainService,
 			OptimisticModeFetcher: mockChainService,
 		}
@@ -635,7 +642,7 @@ func TestGetSyncCommitteeDuties_SyncNotReady(t *testing.T) {
 	vs := &Server{
 		SyncChecker:           &mockSync.Sync{IsSyncing: true},
 		HeadFetcher:           chainService,
-		TimeFetcher:           chainService,
+		ClockProvider:           chainService,
 		OptimisticModeFetcher: chainService,
 	}
 	_, err = vs.GetSyncCommitteeDuties(context.Background(), &ethpbv2.SyncCommitteeDutiesRequest{})
@@ -745,7 +752,7 @@ func TestProduceBlock_SyncNotReady(t *testing.T) {
 	vs := &Server{
 		SyncChecker:           &mockSync.Sync{IsSyncing: true},
 		HeadFetcher:           chainService,
-		TimeFetcher:           chainService,
+		ClockProvider:           chainService,
 		OptimisticModeFetcher: chainService,
 	}
 	_, err = vs.ProduceBlock(context.Background(), &ethpbv1.ProduceBlockRequest{})
@@ -1011,7 +1018,7 @@ func TestProduceBlockV2(t *testing.T) {
 					TotalDifficulty: "0x1",
 				},
 			},
-			TimeFetcher:            &mockChain.ChainService{},
+			ClockProvider:          &mockChain.ChainService{},
 			HeadFetcher:            &mockChain.ChainService{State: beaconState, Root: parentRoot[:]},
 			OptimisticModeFetcher:  &mockChain.ChainService{},
 			SyncChecker:            &mockSync.Sync{IsSyncing: false},
@@ -1500,7 +1507,7 @@ func TestProduceBlockV2SSZ(t *testing.T) {
 					TotalDifficulty: "0x1",
 				},
 			},
-			TimeFetcher:            &mockChain.ChainService{},
+			ClockProvider:          &mockChain.ChainService{},
 			HeadFetcher:            &mockChain.ChainService{State: bs, Root: parentRoot[:]},
 			OptimisticModeFetcher:  &mockChain.ChainService{},
 			SyncChecker:            &mockSync.Sync{IsSyncing: false},
@@ -1691,7 +1698,7 @@ func TestProduceBlockV2_SyncNotReady(t *testing.T) {
 	vs := &Server{
 		SyncChecker:           &mockSync.Sync{IsSyncing: true},
 		HeadFetcher:           chainService,
-		TimeFetcher:           chainService,
+		ClockProvider:           chainService,
 		OptimisticModeFetcher: chainService,
 	}
 	_, err = vs.ProduceBlockV2(context.Background(), &ethpbv1.ProduceBlockRequest{})
@@ -1705,7 +1712,7 @@ func TestProduceBlockV2SSZ_SyncNotReady(t *testing.T) {
 	vs := &Server{
 		SyncChecker:           &mockSync.Sync{IsSyncing: true},
 		HeadFetcher:           chainService,
-		TimeFetcher:           chainService,
+		ClockProvider:           chainService,
 		OptimisticModeFetcher: chainService,
 	}
 	_, err = vs.ProduceBlockV2SSZ(context.Background(), &ethpbv1.ProduceBlockRequest{})
@@ -1971,7 +1978,7 @@ func TestProduceBlindedBlock(t *testing.T) {
 					TotalDifficulty: "0x1",
 				},
 			},
-			TimeFetcher:            &mockChain.ChainService{},
+			ClockProvider:          &mockChain.ChainService{},
 			HeadFetcher:            &mockChain.ChainService{State: beaconState, Root: parentRoot[:]},
 			OptimisticModeFetcher:  &mockChain.ChainService{},
 			SyncChecker:            &mockSync.Sync{IsSyncing: false},
@@ -2460,7 +2467,7 @@ func TestProduceBlindedBlockSSZ(t *testing.T) {
 					TotalDifficulty: "0x1",
 				},
 			},
-			TimeFetcher:            &mockChain.ChainService{},
+			ClockProvider:            &mockChain.ChainService{},
 			HeadFetcher:            &mockChain.ChainService{State: bs, Root: parentRoot[:]},
 			OptimisticModeFetcher:  &mockChain.ChainService{},
 			SyncChecker:            &mockSync.Sync{IsSyncing: false},
@@ -2651,7 +2658,7 @@ func TestProduceBlindedBlock_SyncNotReady(t *testing.T) {
 	vs := &Server{
 		SyncChecker:           &mockSync.Sync{IsSyncing: true},
 		HeadFetcher:           chainService,
-		TimeFetcher:           chainService,
+		ClockProvider:           chainService,
 		OptimisticModeFetcher: chainService,
 	}
 	_, err = vs.ProduceBlindedBlock(context.Background(), &ethpbv1.ProduceBlockRequest{})
@@ -2665,7 +2672,7 @@ func TestProduceBlindedBlockSSZ_SyncNotReady(t *testing.T) {
 	vs := &Server{
 		SyncChecker:           &mockSync.Sync{IsSyncing: true},
 		HeadFetcher:           chainService,
-		TimeFetcher:           chainService,
+		ClockProvider:           chainService,
 		OptimisticModeFetcher: chainService,
 	}
 	_, err = vs.ProduceBlindedBlockSSZ(context.Background(), &ethpbv1.ProduceBlockRequest{})
@@ -2704,6 +2711,7 @@ func TestProduceAttestationData(t *testing.T) {
 		Genesis: time.Now(),
 	}
 	offset := int64(slot.Mul(params.BeaconConfig().SecondsPerSlot))
+	gent := time.Now().Add(time.Duration(-1*offset) * time.Second)
 	v1Alpha1Server := &v1alpha1validator.Server{
 		P2P:              &p2pmock.MockBroadcaster{},
 		SyncChecker:      &mockSync.Sync{IsSyncing: false},
@@ -2714,8 +2722,8 @@ func TestProduceAttestationData(t *testing.T) {
 		FinalizationFetcher: &mockChain.ChainService{
 			CurrentJustifiedCheckPoint: beaconState.CurrentJustifiedCheckpoint(),
 		},
-		TimeFetcher: &mockChain.ChainService{
-			Genesis: time.Now().Add(time.Duration(-1*offset) * time.Second),
+		ClockProvider: &mockChain.ChainService{
+			Clock: blockchain.NewClock(gent),
 		},
 		StateNotifier: chainService.StateNotifier(),
 	}
@@ -2925,11 +2933,11 @@ func TestSubmitBeaconCommitteeSubscription(t *testing.T) {
 
 	chainSlot := types.Slot(0)
 	chain := &mockChain.ChainService{
-		State: bs, Root: genesisRoot[:], Slot: &chainSlot,
+		State: bs, Root:genesisRoot[:], Slot: &chainSlot,
 	}
 	vs := &Server{
 		HeadFetcher:    chain,
-		TimeFetcher:    chain,
+		ClockProvider:    chain,
 		SyncChecker:    &mockSync.Sync{IsSyncing: false},
 		V1Alpha1Server: &v1alpha1validator.Server{},
 	}
@@ -3040,7 +3048,7 @@ func TestSubmitBeaconCommitteeSubscription_SyncNotReady(t *testing.T) {
 	vs := &Server{
 		SyncChecker:           &mockSync.Sync{IsSyncing: true},
 		HeadFetcher:           chainService,
-		TimeFetcher:           chainService,
+		ClockProvider:         chainService,
 		OptimisticModeFetcher: chainService,
 	}
 	_, err = vs.SubmitBeaconCommitteeSubscription(context.Background(), &ethpbv1.SubmitBeaconCommitteeSubscriptionsRequest{})
@@ -3069,11 +3077,12 @@ func TestSubmitSyncCommitteeSubscription(t *testing.T) {
 
 	chainSlot := types.Slot(0)
 	chain := &mockChain.ChainService{
-		State: bs, Root: genesisRoot[:], Slot: &chainSlot,
+		State: bs,
+		Root: genesisRoot[:],
 	}
 	vs := &Server{
 		HeadFetcher:    chain,
-		TimeFetcher:    chain,
+		ClockProvider:  chain,
 		SyncChecker:    &mockSync.Sync{IsSyncing: false},
 		V1Alpha1Server: &v1alpha1validator.Server{},
 	}
@@ -3199,7 +3208,7 @@ func TestSubmitSyncCommitteeSubscription_SyncNotReady(t *testing.T) {
 	vs := &Server{
 		SyncChecker:           &mockSync.Sync{IsSyncing: true},
 		HeadFetcher:           chainService,
-		TimeFetcher:           chainService,
+		ClockProvider:           chainService,
 		OptimisticModeFetcher: chainService,
 	}
 	_, err = vs.SubmitSyncCommitteeSubscription(context.Background(), &ethpbv2.SubmitSyncCommitteeSubscriptionsRequest{})
@@ -3236,11 +3245,12 @@ func TestSubmitAggregateAndProofs(t *testing.T) {
 	t.Run("OK", func(t *testing.T) {
 		chainSlot := types.Slot(0)
 		chain := &mockChain.ChainService{
-			Genesis: time.Now(), Slot: &chainSlot,
+			Clock: blockchain.NewClock(time.Now()),
+			Slot: &chainSlot,
 		}
 		broadcaster := &p2pmock.MockBroadcaster{}
 		vs := Server{
-			TimeFetcher: chain,
+			ClockProvider: chain,
 			Broadcaster: broadcaster,
 		}
 
@@ -3458,11 +3468,11 @@ func TestSubmitAggregateAndProofs(t *testing.T) {
 	t.Run("invalid attestation time", func(t *testing.T) {
 		chainSlot := types.Slot(0)
 		chain := &mockChain.ChainService{
-			Genesis: time.Now().Add(time.Hour * 2), Slot: &chainSlot,
+			Clock: blockchain.NewClock(time.Now().Add(time.Hour * 2)), Slot: &chainSlot,
 		}
 		broadcaster := &p2pmock.MockBroadcaster{}
 		vs := Server{
-			TimeFetcher: chain,
+			ClockProvider: chain,
 			Broadcaster: broadcaster,
 		}
 

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

@@ -83,6 +83,7 @@ go_test(
     embed = [":go_default_library"],
     shard_count = 4,
     deps = [
+        "//beacon-chain/blockchain:go_default_library",
         "//beacon-chain/blockchain/testing:go_default_library",
         "//beacon-chain/core/altair:go_default_library",
         "//beacon-chain/core/epoch/precompute:go_default_library",

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

@@ -32,6 +32,10 @@ func (bs *Server) ListValidatorAssignments(
 		)
 	}
 
+	c, err := bs.ClockProvider.WaitForClock(ctx)
+	if err != nil {
+		return nil, status.Errorf(codes.Internal, "timeout waiting for genesis timestamp, %s", err)
+	}
 	var res []*ethpb.ValidatorAssignments_CommitteeAssignment
 	filtered := map[types.ValidatorIndex]bool{} // track filtered validators to prevent duplication in the response.
 	filteredIndices := make([]types.ValidatorIndex, 0)
@@ -45,7 +49,7 @@ func (bs *Server) ListValidatorAssignments(
 		requestedEpoch = q.Epoch
 	}
 
-	currentEpoch := slots.ToEpoch(bs.GenesisTimeFetcher.CurrentSlot())
+	currentEpoch := slots.ToEpoch(c.CurrentSlot())
 	if requestedEpoch > currentEpoch {
 		return nil, status.Errorf(
 			codes.InvalidArgument,
@@ -59,7 +63,11 @@ func (bs *Server) ListValidatorAssignments(
 	if err != nil {
 		return nil, err
 	}
-	requestedState, err := bs.ReplayerBuilder.ReplayerForSlot(startSlot).ReplayBlocks(ctx)
+	b, err := bs.CanonicalHistoryWaiter.WaitForCanonicalHistory(ctx)
+	if err != nil {
+		return nil, status.Error(codes.Internal, err.Error())
+	}
+	requestedState, err := b.ReplayerForSlot(startSlot).ReplayBlocks(ctx)
 	if err != nil {
 		msg := fmt.Sprintf("could not replay all blocks from the closest stored state (at slot %d) "+
 			"to the requested epoch (%d) - %v", startSlot, requestedEpoch, err)

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

@@ -28,16 +28,18 @@ func TestServer_ListAssignments_CannotRequestFutureEpoch(t *testing.T) {
 	ctx := context.Background()
 	bs := &Server{
 		BeaconDB:           db,
-		GenesisTimeFetcher: &mock.ChainService{},
+		ClockProvider: &mock.ChainService{},
 	}
 	addDefaultReplayerBuilder(bs, db)
 
+	c, err := bs.ClockProvider.WaitForClock(ctx)
+	require.NoError(t, err)
 	wanted := errNoEpochInfoError
-	_, err := bs.ListValidatorAssignments(
+	_, err = bs.ListValidatorAssignments(
 		ctx,
 		&ethpb.ListValidatorAssignmentsRequest{
 			QueryFilter: &ethpb.ListValidatorAssignmentsRequest_Epoch{
-				Epoch: slots.ToEpoch(bs.GenesisTimeFetcher.CurrentSlot()) + 1,
+				Epoch: slots.ToEpoch(c.CurrentSlot()) + 1,
 			},
 		},
 	)
@@ -59,7 +61,7 @@ func TestServer_ListAssignments_NoResults(t *testing.T) {
 
 	bs := &Server{
 		BeaconDB:           db,
-		GenesisTimeFetcher: &mock.ChainService{},
+		ClockProvider: &mock.ChainService{},
 		StateGen:           stategen.New(db),
 		ReplayerBuilder:    mockstategen.NewMockReplayerBuilder(mockstategen.WithMockState(st)),
 	}
@@ -121,7 +123,7 @@ func TestServer_ListAssignments_Pagination_InputOutOfRange(t *testing.T) {
 				Epoch: 0,
 			},
 		},
-		GenesisTimeFetcher: &mock.ChainService{},
+		ClockProvider: &mock.ChainService{},
 		StateGen:           stategen.New(db),
 		ReplayerBuilder:    mockstategen.NewMockReplayerBuilder(mockstategen.WithMockState(s)),
 	}
@@ -197,7 +199,7 @@ func TestServer_ListAssignments_Pagination_DefaultPageSize_NoArchive(t *testing.
 				Epoch: 0,
 			},
 		},
-		GenesisTimeFetcher: &mock.ChainService{},
+		ClockProvider: &mock.ChainService{},
 		StateGen:           stategen.New(db),
 		ReplayerBuilder:    mockstategen.NewMockReplayerBuilder(mockstategen.WithMockState(s)),
 	}
@@ -264,7 +266,7 @@ func TestServer_ListAssignments_FilterPubkeysIndices_NoPagination(t *testing.T)
 				Epoch: 0,
 			},
 		},
-		GenesisTimeFetcher: &mock.ChainService{},
+		ClockProvider: &mock.ChainService{},
 		StateGen:           stategen.New(db),
 		ReplayerBuilder:    mockstategen.NewMockReplayerBuilder(mockstategen.WithMockState(s)),
 	}
@@ -335,7 +337,7 @@ func TestServer_ListAssignments_CanFilterPubkeysIndices_WithPagination(t *testin
 				Epoch: 0,
 			},
 		},
-		GenesisTimeFetcher: &mock.ChainService{},
+		ClockProvider: &mock.ChainService{},
 		StateGen:           stategen.New(db),
 	}
 

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

@@ -340,7 +340,12 @@ func (bs *Server) StreamIndexedAttestations(
 func (bs *Server) collectReceivedAttestations(ctx context.Context) {
 	attsByRoot := make(map[[32]byte][]*ethpb.Attestation)
 	twoThirdsASlot := 2 * slots.DivideSlotBy(3) /* 2/3 slot duration */
-	ticker := slots.NewSlotTickerWithOffset(bs.GenesisTimeFetcher.GenesisTime(), twoThirdsASlot, params.BeaconConfig().SecondsPerSlot)
+	c, err := bs.ClockProvider.WaitForClock(ctx)
+	if err != nil {
+		log.WithError(err).Error("timeout while waiting for genesis timestamp in collectReceivedAttestations")
+		return
+	}
+	ticker := slots.NewSlotTickerWithOffset(c.GenesisTime(), twoThirdsASlot, params.BeaconConfig().SecondsPerSlot)
 	for {
 		select {
 		case <-ticker.C():

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

@@ -3,11 +3,6 @@ package beacon
 import (
 	"context"
 	"fmt"
-	"sort"
-	"strconv"
-	"testing"
-	"time"
-
 	"github.com/golang/mock/gomock"
 	"github.com/prysmaticlabs/go-bitfield"
 	chainMock "github.com/prysmaticlabs/prysm/beacon-chain/blockchain/testing"
@@ -36,6 +31,9 @@ import (
 	"github.com/prysmaticlabs/prysm/time/slots"
 	"google.golang.org/protobuf/proto"
 	"google.golang.org/protobuf/types/known/emptypb"
+	"sort"
+	"strconv"
+	"testing"
 )
 
 func TestServer_ListAttestations_NoResults(t *testing.T) {
@@ -567,7 +565,7 @@ func TestServer_ListIndexedAttestations_GenesisEpoch(t *testing.T) {
 
 	bs := &Server{
 		BeaconDB:           db,
-		GenesisTimeFetcher: &chainMock.ChainService{State: state},
+		ClockProvider:      &chainMock.ChainService{State: state},
 		HeadFetcher:        &chainMock.ChainService{State: state},
 		StateGen:           stategen.New(db),
 	}
@@ -666,9 +664,7 @@ func TestServer_ListIndexedAttestations_OldEpoch(t *testing.T) {
 
 	bs := &Server{
 		BeaconDB: db,
-		GenesisTimeFetcher: &chainMock.ChainService{
-			Genesis: time.Now(),
-		},
+		ClockProvider: &chainMock.ChainService{},
 		StateGen: stategen.New(db),
 	}
 	err = db.SaveStateSummary(ctx, &ethpb.StateSummary{
@@ -831,9 +827,7 @@ func TestServer_StreamIndexedAttestations_ContextCanceled(t *testing.T) {
 	server := &Server{
 		Ctx:                 ctx,
 		AttestationNotifier: chainService.OperationNotifier(),
-		GenesisTimeFetcher: &chainMock.ChainService{
-			Genesis: time.Now(),
-		},
+		ClockProvider: &chainMock.ChainService{},
 	}
 
 	exitRoutine := make(chan bool)
@@ -935,9 +929,7 @@ func TestServer_StreamIndexedAttestations_OK(t *testing.T) {
 		HeadFetcher: &chainMock.ChainService{
 			State: headState,
 		},
-		GenesisTimeFetcher: &chainMock.ChainService{
-			Genesis: time.Now(),
-		},
+		ClockProvider: &chainMock.ChainService{},
 		AttestationNotifier:         chainService.OperationNotifier(),
 		CollectedAttestationsBuffer: make(chan []*ethpb.Attestation, 1),
 		StateGen:                    stategen.New(db),

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

@@ -23,7 +23,11 @@ func (bs *Server) ListBeaconCommittees(
 	ctx context.Context,
 	req *ethpb.ListCommitteesRequest,
 ) (*ethpb.BeaconCommittees, error) {
-	currentSlot := bs.GenesisTimeFetcher.CurrentSlot()
+	c, err := bs.ClockProvider.WaitForClock(ctx)
+	if err != nil {
+		return nil, status.Errorf(codes.Internal, "timeout waiting for genesis timestamp, %s", err)
+	}
+	currentSlot := c.CurrentSlot()
 	var requestedSlot types.Slot
 	switch q := req.QueryFilter.(type) {
 	case *ethpb.ListCommitteesRequest_Epoch:
@@ -74,7 +78,11 @@ func (bs *Server) retrieveCommitteesForEpoch(
 	if err != nil {
 		return nil, nil, err
 	}
-	requestedState, err := bs.ReplayerBuilder.ReplayerForSlot(startSlot).ReplayBlocks(ctx)
+	b, err := bs.CanonicalHistoryWaiter.WaitForCanonicalHistory(ctx)
+	if err != nil {
+		return nil, nil, status.Error(codes.Internal, err.Error())
+	}
+	requestedState, err := b.ReplayerForSlot(startSlot).ReplayBlocks(ctx)
 	if err != nil {
 		return nil, nil, status.Errorf(codes.Internal, "error replaying blocks for state at slot %d: %v", startSlot, err)
 	}

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

@@ -3,6 +3,7 @@ package beacon
 import (
 	"context"
 	"encoding/binary"
+	"github.com/prysmaticlabs/prysm/beacon-chain/blockchain"
 	"math"
 	"testing"
 	"time"
@@ -35,12 +36,13 @@ func TestServer_ListBeaconCommittees_CurrentEpoch(t *testing.T) {
 	headState := setupActiveValidators(t, numValidators)
 
 	offset := int64(headState.Slot().Mul(params.BeaconConfig().SecondsPerSlot))
+	gent := prysmTime.Now().Add(time.Duration(-1*offset) * time.Second)
 	m := &mock.ChainService{
-		Genesis: prysmTime.Now().Add(time.Duration(-1*offset) * time.Second),
+		Clock: blockchain.NewClock(gent),
 	}
 	bs := &Server{
 		HeadFetcher:        m,
-		GenesisTimeFetcher: m,
+		ClockProvider: m,
 		StateGen:           stategen.New(db),
 	}
 	b := util.NewBeaconBlock()
@@ -106,13 +108,14 @@ func TestServer_ListBeaconCommittees_PreviousEpoch(t *testing.T) {
 	require.NoError(t, db.SaveState(ctx, headState, gRoot))
 
 	offset := int64(headState.Slot().Mul(params.BeaconConfig().SecondsPerSlot))
+	gent := prysmTime.Now().Add(time.Duration(-1*offset) * time.Second)
 	m := &mock.ChainService{
 		State:   headState,
-		Genesis: prysmTime.Now().Add(time.Duration(-1*offset) * time.Second),
+		Clock: blockchain.NewClock(gent),
 	}
 	bs := &Server{
 		HeadFetcher:        m,
-		GenesisTimeFetcher: m,
+		ClockProvider: m,
 		StateGen:           stategen.New(db),
 	}
 	addDefaultReplayerBuilder(bs, db)
@@ -162,12 +165,13 @@ func TestRetrieveCommitteesForRoot(t *testing.T) {
 	headState := setupActiveValidators(t, numValidators)
 
 	offset := int64(headState.Slot().Mul(params.BeaconConfig().SecondsPerSlot))
+	gent := prysmTime.Now().Add(time.Duration(-1*offset) * time.Second)
 	m := &mock.ChainService{
-		Genesis: prysmTime.Now().Add(time.Duration(-1*offset) * time.Second),
+		Clock: blockchain.NewClock(gent),
 	}
 	bs := &Server{
 		HeadFetcher:        m,
-		GenesisTimeFetcher: m,
+		ClockProvider: m,
 		StateGen:           stategen.New(db),
 	}
 	b := util.NewBeaconBlock()

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

@@ -33,7 +33,6 @@ type Server struct {
 	FinalizationFetcher         blockchain.FinalizationFetcher
 	DepositFetcher              depositcache.DepositFetcher
 	BlockFetcher                powchain.POWBlockFetcher
-	GenesisTimeFetcher          blockchain.TimeFetcher
 	StateNotifier               statefeed.Notifier
 	BlockNotifier               blockfeed.Notifier
 	AttestationNotifier         operation.Notifier
@@ -44,8 +43,9 @@ type Server struct {
 	ReceivedAttestationsBuffer  chan *ethpb.Attestation
 	CollectedAttestationsBuffer chan []*ethpb.Attestation
 	StateGen                    stategen.StateManager
-	SyncChecker                 sync.Checker
-	ReplayerBuilder             stategen.ReplayerBuilder
-	HeadUpdater                 blockchain.HeadUpdater
+	SyncChecker            sync.Checker
+	CanonicalHistoryWaiter stategen.CanonicalHistoryWaiter
+	HeadUpdater            blockchain.HeadUpdater
 	OptimisticModeFetcher       blockchain.OptimisticModeFetcher
+	ClockProvider               blockchain.ClockProvider
 }

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

@@ -38,10 +38,11 @@ func (bs *Server) ListValidatorBalances(
 			req.PageSize, cmd.Get().MaxRPCPageSize)
 	}
 
-	if bs.GenesisTimeFetcher == nil {
-		return nil, status.Errorf(codes.Internal, "Nil genesis time fetcher")
+	c, err := bs.ClockProvider.WaitForClock(ctx)
+	if err != nil {
+		return nil, status.Errorf(codes.Internal, "timeout waiting for genesis timestamp, %s", err)
 	}
-	currentEpoch := slots.ToEpoch(bs.GenesisTimeFetcher.CurrentSlot())
+	currentEpoch := slots.ToEpoch(c.CurrentSlot())
 	requestedEpoch := currentEpoch
 	switch q := req.QueryFilter.(type) {
 	case *ethpb.ListValidatorBalancesRequest_Epoch:
@@ -65,7 +66,11 @@ func (bs *Server) ListValidatorBalances(
 	if err != nil {
 		return nil, err
 	}
-	requestedState, err := bs.ReplayerBuilder.ReplayerForSlot(startSlot).ReplayBlocks(ctx)
+	b, err := bs.CanonicalHistoryWaiter.WaitForCanonicalHistory(ctx)
+	if err != nil {
+		return nil, status.Error(codes.Internal, err.Error())
+	}
+	requestedState, err := b.ReplayerForSlot(startSlot).ReplayBlocks(ctx)
 	if err != nil {
 		return nil, status.Error(codes.Internal, fmt.Sprintf("error replaying blocks for state at slot %d: %v", startSlot, err))
 	}
@@ -193,7 +198,11 @@ func (bs *Server) ListValidators(
 			req.PageSize, cmd.Get().MaxRPCPageSize)
 	}
 
-	currentEpoch := slots.ToEpoch(bs.GenesisTimeFetcher.CurrentSlot())
+	c, err := bs.ClockProvider.WaitForClock(ctx)
+	if err != nil {
+		return nil, status.Errorf(codes.Internal, "timeout waiting for genesis timestamp, %s", err)
+	}
+	currentEpoch := slots.ToEpoch(c.CurrentSlot())
 	requestedEpoch := currentEpoch
 
 	switch q := req.QueryFilter.(type) {
@@ -213,14 +222,17 @@ func (bs *Server) ListValidators(
 		requestedEpoch = q.Epoch
 	}
 	var reqState state.BeaconState
-	var err error
 	if requestedEpoch != currentEpoch {
 		var s types.Slot
 		s, err = slots.EpochStart(requestedEpoch)
 		if err != nil {
 			return nil, err
 		}
-		reqState, err = bs.ReplayerBuilder.ReplayerForSlot(s).ReplayBlocks(ctx)
+		b, err := bs.CanonicalHistoryWaiter.WaitForCanonicalHistory(ctx)
+		if err != nil {
+			return nil, status.Error(codes.Internal, err.Error())
+		}
+		reqState, err = b.ReplayerForSlot(s).ReplayBlocks(ctx)
 		if err != nil {
 			return nil, status.Error(codes.Internal, fmt.Sprintf("error replaying blocks for state at slot %d: %v", s, err))
 		}
@@ -391,7 +403,11 @@ func (bs *Server) GetValidator(
 func (bs *Server) GetValidatorActiveSetChanges(
 	ctx context.Context, req *ethpb.GetValidatorActiveSetChangesRequest,
 ) (*ethpb.ActiveSetChanges, error) {
-	currentEpoch := slots.ToEpoch(bs.GenesisTimeFetcher.CurrentSlot())
+	c, err := bs.ClockProvider.WaitForClock(ctx)
+	if err != nil {
+		return nil, status.Errorf(codes.Internal, "timeout waiting for genesis timestamp, %s", err)
+	}
+	currentEpoch := slots.ToEpoch(c.CurrentSlot())
 
 	var requestedEpoch types.Epoch
 	switch q := req.QueryFilter.(type) {
@@ -415,7 +431,11 @@ func (bs *Server) GetValidatorActiveSetChanges(
 	if err != nil {
 		return nil, err
 	}
-	requestedState, err := bs.ReplayerBuilder.ReplayerForSlot(s).ReplayBlocks(ctx)
+	b, err := bs.CanonicalHistoryWaiter.WaitForCanonicalHistory(ctx)
+	if err != nil {
+		return nil, status.Error(codes.Internal, err.Error())
+	}
+	requestedState, err := b.ReplayerForSlot(s).ReplayBlocks(ctx)
 	if err != nil {
 		return nil, status.Error(codes.Internal, fmt.Sprintf("error replaying blocks for state at slot %d: %v", s, err))
 	}
@@ -476,7 +496,11 @@ func (bs *Server) GetValidatorActiveSetChanges(
 func (bs *Server) GetValidatorParticipation(
 	ctx context.Context, req *ethpb.GetValidatorParticipationRequest,
 ) (*ethpb.ValidatorParticipationResponse, error) {
-	currentSlot := bs.GenesisTimeFetcher.CurrentSlot()
+	c, err := bs.ClockProvider.WaitForClock(ctx)
+	if err != nil {
+		return nil, status.Errorf(codes.Internal, "timeout waiting for genesis timestamp, %s", err)
+	}
+	currentSlot := c.CurrentSlot()
 	currentEpoch := slots.ToEpoch(currentSlot)
 
 	var requestedEpoch types.Epoch
@@ -512,7 +536,11 @@ func (bs *Server) GetValidatorParticipation(
 	}
 
 	// ReplayerBuilder ensures that a canonical chain is followed to the slot
-	beaconState, err := bs.ReplayerBuilder.ReplayerForSlot(endSlot).ReplayBlocks(ctx)
+	rb, err := bs.CanonicalHistoryWaiter.WaitForCanonicalHistory(ctx)
+	if err != nil {
+		return nil, status.Error(codes.Internal, err.Error())
+	}
+	beaconState, err := rb.ReplayerForSlot(endSlot).ReplayBlocks(ctx)
 	if err != nil {
 		return nil, status.Error(codes.Internal, fmt.Sprintf("error replaying blocks for state at slot %d: %v", endSlot, err))
 	}
@@ -660,12 +688,16 @@ func (bs *Server) GetValidatorPerformance(
 	if bs.SyncChecker.Syncing() {
 		return nil, status.Errorf(codes.Unavailable, "Syncing to latest head, not ready to respond")
 	}
+	c, err := bs.ClockProvider.WaitForClock(ctx)
+	if err != nil {
+		return nil, status.Errorf(codes.Internal, "timeout waiting for genesis timestamp, %s", err)
+	}
 
 	headState, err := bs.HeadFetcher.HeadState(ctx)
 	if err != nil {
 		return nil, status.Errorf(codes.Internal, "Could not get head state: %v", err)
 	}
-	currSlot := bs.GenesisTimeFetcher.CurrentSlot()
+	currSlot := c.CurrentSlot()
 
 	if currSlot > headState.Slot() {
 		headRoot, err := bs.HeadFetcher.HeadRoot(ctx)
@@ -817,7 +849,11 @@ func (bs *Server) GetIndividualVotes(
 	ctx context.Context,
 	req *ethpb.IndividualVotesRequest,
 ) (*ethpb.IndividualVotesRespond, error) {
-	currentEpoch := slots.ToEpoch(bs.GenesisTimeFetcher.CurrentSlot())
+	c, err := bs.ClockProvider.WaitForClock(ctx)
+	if err != nil {
+		return nil, status.Errorf(codes.Internal, "timeout waiting for genesis timestamp, %s", err)
+	}
+	currentEpoch := slots.ToEpoch(c.CurrentSlot())
 	if req.Epoch > currentEpoch {
 		return nil, status.Errorf(
 			codes.InvalidArgument,
@@ -831,7 +867,11 @@ func (bs *Server) GetIndividualVotes(
 	if err != nil {
 		return nil, err
 	}
-	st, err := bs.ReplayerBuilder.ReplayerForSlot(s).ReplayBlocks(ctx)
+	b, err := bs.CanonicalHistoryWaiter.WaitForCanonicalHistory(ctx)
+	if err != nil {
+		return nil, status.Error(codes.Internal, err.Error())
+	}
+	st, err := b.ReplayerForSlot(s).ReplayBlocks(ctx)
 	if err != nil {
 		return nil, status.Errorf(codes.Internal, "failed to replay blocks for state at epoch %d: %v", req.Epoch, err)
 	}

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

@@ -4,6 +4,7 @@ import (
 	"context"
 	"encoding/binary"
 	"fmt"
+	"github.com/prysmaticlabs/prysm/beacon-chain/blockchain"
 	"sort"
 	"strconv"
 	"testing"
@@ -51,19 +52,21 @@ func TestServer_GetValidatorActiveSetChanges_CannotRequestFutureEpoch(t *testing
 	require.NoError(t, err)
 	require.NoError(t, st.SetSlot(0))
 	bs := &Server{
-		GenesisTimeFetcher: &mock.ChainService{},
+		ClockProvider: &mock.ChainService{},
 		HeadFetcher: &mock.ChainService{
 			State: st,
 		},
 		BeaconDB: beaconDB,
 	}
 
+	c, err := bs.ClockProvider.WaitForClock(ctx)
+	require.NoError(t, err)
 	wanted := errNoEpochInfoError
 	_, err = bs.GetValidatorActiveSetChanges(
 		ctx,
 		&ethpb.GetValidatorActiveSetChangesRequest{
 			QueryFilter: &ethpb.GetValidatorActiveSetChangesRequest_Epoch{
-				Epoch: slots.ToEpoch(bs.GenesisTimeFetcher.CurrentSlot()) + 1,
+				Epoch: slots.ToEpoch(c.CurrentSlot()) + 1,
 			},
 		},
 	)
@@ -82,15 +85,17 @@ func TestServer_ListValidatorBalances_CannotRequestFutureEpoch(t *testing.T) {
 		HeadFetcher: &mock.ChainService{
 			State: st,
 		},
-		GenesisTimeFetcher: &mock.ChainService{},
+		ClockProvider: &mock.ChainService{},
 	}
 
 	wanted := errNoEpochInfoError
+	c, err := bs.ClockProvider.WaitForClock(ctx)
+	require.NoError(t, err)
 	_, err = bs.ListValidatorBalances(
 		ctx,
 		&ethpb.ListValidatorBalancesRequest{
 			QueryFilter: &ethpb.ListValidatorBalancesRequest_Epoch{
-				Epoch: slots.ToEpoch(bs.GenesisTimeFetcher.CurrentSlot()) + 1,
+				Epoch: slots.ToEpoch(c.CurrentSlot()) + 1,
 			},
 		},
 	)
@@ -105,7 +110,7 @@ func TestServer_ListValidatorBalances_NoResults(t *testing.T) {
 	require.NoError(t, err)
 	require.NoError(t, st.SetSlot(0))
 	bs := &Server{
-		GenesisTimeFetcher: &mock.ChainService{},
+		ClockProvider: &mock.ChainService{},
 		StateGen:           stategen.New(beaconDB),
 	}
 
@@ -172,7 +177,7 @@ func TestServer_ListValidatorBalances_DefaultResponse_NoArchive(t *testing.T) {
 	require.NoError(t, beaconDB.SaveGenesisBlockRoot(ctx, gRoot))
 	require.NoError(t, beaconDB.SaveState(ctx, st, gRoot))
 	bs := &Server{
-		GenesisTimeFetcher: &mock.ChainService{},
+		ClockProvider: &mock.ChainService{},
 		StateGen:           stategen.New(beaconDB),
 		HeadFetcher: &mock.ChainService{
 			State: st,
@@ -201,7 +206,7 @@ func TestServer_ListValidatorBalances_PaginationOutOfRange(t *testing.T) {
 	require.NoError(t, beaconDB.SaveState(ctx, headState, gRoot))
 
 	bs := &Server{
-		GenesisTimeFetcher: &mock.ChainService{},
+		ClockProvider: &mock.ChainService{},
 		StateGen:           stategen.New(beaconDB),
 		HeadFetcher: &mock.ChainService{
 			State: headState,
@@ -250,7 +255,7 @@ func TestServer_ListValidatorBalances_Pagination_Default(t *testing.T) {
 	require.NoError(t, beaconDB.SaveState(ctx, headState, gRoot))
 
 	bs := &Server{
-		GenesisTimeFetcher: &mock.ChainService{},
+		ClockProvider: &mock.ChainService{},
 		StateGen:           stategen.New(beaconDB),
 		HeadFetcher: &mock.ChainService{
 			State: headState,
@@ -334,7 +339,7 @@ func TestServer_ListValidatorBalances_Pagination_CustomPageSizes(t *testing.T) {
 	require.NoError(t, beaconDB.SaveState(ctx, headState, gRoot))
 
 	bs := &Server{
-		GenesisTimeFetcher: &mock.ChainService{},
+		ClockProvider: &mock.ChainService{},
 		StateGen:           stategen.New(beaconDB),
 		HeadFetcher: &mock.ChainService{
 			State: headState,
@@ -402,7 +407,7 @@ func TestServer_ListValidatorBalances_OutOfRange(t *testing.T) {
 	require.NoError(t, beaconDB.SaveState(ctx, headState, gRoot))
 
 	bs := &Server{
-		GenesisTimeFetcher: &mock.ChainService{},
+		ClockProvider: &mock.ChainService{},
 		StateGen:           stategen.New(beaconDB),
 		HeadFetcher: &mock.ChainService{
 			State: headState,
@@ -425,10 +430,7 @@ func TestServer_ListValidators_CannotRequestFutureEpoch(t *testing.T) {
 	require.NoError(t, st.SetSlot(0))
 	bs := &Server{
 		BeaconDB: beaconDB,
-		GenesisTimeFetcher: &mock.ChainService{
-			// We are in epoch 0.
-			Genesis: time.Now(),
-		},
+		ClockProvider: &mock.ChainService{},
 		HeadFetcher: &mock.ChainService{
 			State: st,
 		},
@@ -449,12 +451,10 @@ func TestServer_ListValidators_CannotRequestFutureEpoch(t *testing.T) {
 func TestServer_ListValidators_reqStateIsNil(t *testing.T) {
 	beaconDB := dbTest.SetupDB(t)
 	secondsPerEpoch := params.BeaconConfig().SecondsPerSlot * uint64(params.BeaconConfig().SlotsPerEpoch)
+	gent := time.Now().Add(time.Duration(-1*int64(secondsPerEpoch)) * time.Second)
 	bs := &Server{
 		BeaconDB: beaconDB,
-		GenesisTimeFetcher: &mock.ChainService{
-			// We are in epoch 1.
-			Genesis: time.Now().Add(time.Duration(-1*int64(secondsPerEpoch)) * time.Second),
-		},
+		ClockProvider: &mock.ChainService{Clock: blockchain.NewClock(gent)},
 		HeadFetcher: &mock.ChainService{
 			State: nil,
 		},
@@ -492,10 +492,7 @@ func TestServer_ListValidators_NoResults(t *testing.T) {
 	require.NoError(t, beaconDB.SaveState(ctx, st, gRoot))
 	bs := &Server{
 		BeaconDB: beaconDB,
-		GenesisTimeFetcher: &mock.ChainService{
-			// We are in epoch 0.
-			Genesis: time.Now(),
-		},
+		ClockProvider: &mock.ChainService{},
 		HeadFetcher: &mock.ChainService{
 			State: st,
 		},
@@ -562,10 +559,7 @@ func TestServer_ListValidators_OnlyActiveValidators(t *testing.T) {
 		HeadFetcher: &mock.ChainService{
 			State: st,
 		},
-		GenesisTimeFetcher: &mock.ChainService{
-			// We are in epoch 0.
-			Genesis: time.Now(),
-		},
+		ClockProvider: &mock.ChainService{},
 		StateGen: stategen.New(beaconDB),
 	}
 
@@ -630,10 +624,7 @@ func TestServer_ListValidators_InactiveInTheMiddle(t *testing.T) {
 		HeadFetcher: &mock.ChainService{
 			State: st,
 		},
-		GenesisTimeFetcher: &mock.ChainService{
-			// We are in epoch 0.
-			Genesis: time.Now(),
-		},
+		ClockProvider: &mock.ChainService{},
 		StateGen: stategen.New(beaconDB),
 	}
 
@@ -665,7 +656,7 @@ func TestServer_ListValidatorBalances_UnknownValidatorInResponse(t *testing.T) {
 	require.NoError(t, beaconDB.SaveState(ctx, headState, gRoot))
 
 	bs := &Server{
-		GenesisTimeFetcher: &mock.ChainService{},
+		ClockProvider: &mock.ChainService{},
 		StateGen:           stategen.New(beaconDB),
 		HeadFetcher: &mock.ChainService{
 			State: headState,
@@ -715,10 +706,7 @@ func TestServer_ListValidators_NoPagination(t *testing.T) {
 		HeadFetcher: &mock.ChainService{
 			State: headState,
 		},
-		GenesisTimeFetcher: &mock.ChainService{
-			// We are in epoch 0.
-			Genesis: time.Now(),
-		},
+		ClockProvider: &mock.ChainService{},
 		FinalizationFetcher: &mock.ChainService{
 			FinalizedCheckPoint: &ethpb.Checkpoint{
 				Epoch: 0,
@@ -748,10 +736,7 @@ func TestServer_ListValidators_StategenNotUsed(t *testing.T) {
 		HeadFetcher: &mock.ChainService{
 			State: headState,
 		},
-		GenesisTimeFetcher: &mock.ChainService{
-			// We are in epoch 0.
-			Genesis: time.Now(),
-		},
+		ClockProvider: &mock.ChainService{},
 	}
 
 	received, err := bs.ListValidators(context.Background(), &ethpb.ListValidatorsRequest{})
@@ -786,10 +771,7 @@ func TestServer_ListValidators_IndicesPubKeys(t *testing.T) {
 				Epoch: 0,
 			},
 		},
-		GenesisTimeFetcher: &mock.ChainService{
-			// We are in epoch 0.
-			Genesis: time.Now(),
-		},
+		ClockProvider: &mock.ChainService{},
 		StateGen: stategen.New(beaconDB),
 	}
 
@@ -822,10 +804,7 @@ func TestServer_ListValidators_Pagination(t *testing.T) {
 				Epoch: 0,
 			},
 		},
-		GenesisTimeFetcher: &mock.ChainService{
-			// We are in epoch 0.
-			Genesis: time.Now(),
-		},
+		ClockProvider: &mock.ChainService{},
 		StateGen: stategen.New(beaconDB),
 	}
 
@@ -959,10 +938,7 @@ func TestServer_ListValidators_PaginationOutOfRange(t *testing.T) {
 				Epoch: 0,
 			},
 		},
-		GenesisTimeFetcher: &mock.ChainService{
-			// We are in epoch 0.
-			Genesis: time.Now(),
-		},
+		ClockProvider: &mock.ChainService{},
 		StateGen: stategen.New(beaconDB),
 	}
 
@@ -1003,10 +979,7 @@ func TestServer_ListValidators_DefaultPageSize(t *testing.T) {
 				Epoch: 0,
 			},
 		},
-		GenesisTimeFetcher: &mock.ChainService{
-			// We are in epoch 0.
-			Genesis: time.Now(),
-		},
+		ClockProvider: &mock.ChainService{},
 		StateGen: stategen.New(beaconDB),
 	}
 
@@ -1045,13 +1018,12 @@ func TestServer_ListValidators_FromOldEpoch(t *testing.T) {
 	require.NoError(t, beaconDB.SaveGenesisBlockRoot(ctx, r))
 
 	secondsPerEpoch := params.BeaconConfig().SecondsPerSlot * uint64(params.BeaconConfig().SlotsPerEpoch)
+	gent := time.Now().Add(time.Duration(-1*int64(uint64(epochs)*secondsPerEpoch)) * time.Second)
 	bs := &Server{
 		HeadFetcher: &mock.ChainService{
 			State: st,
 		},
-		GenesisTimeFetcher: &mock.ChainService{
-			Genesis: time.Now().Add(time.Duration(-1*int64(uint64(epochs)*secondsPerEpoch)) * time.Second),
-		},
+		ClockProvider: &mock.ChainService{Clock: blockchain.NewClock(gent)},
 	}
 	addDefaultReplayerBuilder(bs, beaconDB)
 
@@ -1124,13 +1096,12 @@ func TestServer_ListValidators_ProcessHeadStateSlots(t *testing.T) {
 	require.NoError(t, beaconDB.SaveState(ctx, st, gRoot))
 	require.NoError(t, beaconDB.SaveGenesisBlockRoot(ctx, gRoot))
 	secondsPerEpoch := params.BeaconConfig().SecondsPerSlot * uint64(params.BeaconConfig().SlotsPerEpoch)
+	gent := time.Now().Add(time.Duration(-1*int64(secondsPerEpoch)) * time.Second)
 	bs := &Server{
 		HeadFetcher: &mock.ChainService{
 			State: st,
 		},
-		GenesisTimeFetcher: &mock.ChainService{
-			Genesis: time.Now().Add(time.Duration(-1*int64(secondsPerEpoch)) * time.Second),
-		},
+		ClockProvider: &mock.ChainService{Clock: blockchain.NewClock(gent)},
 		StateGen: stategen.New(beaconDB),
 	}
 
@@ -1283,7 +1254,7 @@ func TestServer_GetValidatorActiveSetChanges(t *testing.T) {
 		FinalizationFetcher: &mock.ChainService{
 			FinalizedCheckPoint: &ethpb.Checkpoint{Epoch: 0, Root: make([]byte, fieldparams.RootLength)},
 		},
-		GenesisTimeFetcher: &mock.ChainService{},
+		ClockProvider: &mock.ChainService{},
 	}
 	addDefaultReplayerBuilder(bs, beaconDB)
 	res, err := bs.GetValidatorActiveSetChanges(ctx, &ethpb.GetValidatorActiveSetChangesRequest{
@@ -1487,16 +1458,18 @@ func TestServer_GetValidatorParticipation_CannotRequestFutureEpoch(t *testing.T)
 		HeadFetcher: &mock.ChainService{
 			State: headState,
 		},
-		GenesisTimeFetcher: &mock.ChainService{},
+		ClockProvider: &mock.ChainService{},
 		StateGen:           stategen.New(beaconDB),
 	}
 
 	wanted := "Cannot retrieve information about an epoch"
+	c, err := bs.ClockProvider.WaitForClock(ctx)
+	require.NoError(t, err)
 	_, err = bs.GetValidatorParticipation(
 		ctx,
 		&ethpb.GetValidatorParticipationRequest{
 			QueryFilter: &ethpb.GetValidatorParticipationRequest_Epoch{
-				Epoch: slots.ToEpoch(bs.GenesisTimeFetcher.CurrentSlot()) + 1,
+				Epoch: slots.ToEpoch(c.CurrentSlot()) + 1,
 			},
 		},
 	)
@@ -1550,13 +1523,12 @@ func TestServer_GetValidatorParticipation_CurrentAndPrevEpoch(t *testing.T) {
 
 	m := &mock.ChainService{State: headState}
 	offset := int64(params.BeaconConfig().SlotsPerEpoch.Mul(params.BeaconConfig().SecondsPerSlot))
+	gent := prysmTime.Now().Add(time.Duration(-1*offset) * time.Second)
 	bs := &Server{
 		BeaconDB:    beaconDB,
 		HeadFetcher: m,
 		StateGen:    stategen.New(beaconDB),
-		GenesisTimeFetcher: &mock.ChainService{
-			Genesis: prysmTime.Now().Add(time.Duration(-1*offset) * time.Second),
-		},
+		ClockProvider: &mock.ChainService{Clock: blockchain.NewClock(gent)},
 		CanonicalFetcher: &mock.ChainService{
 			CanonicalRoots: map[[32]byte]bool{
 				bRoot: true,
@@ -1629,13 +1601,12 @@ func TestServer_GetValidatorParticipation_OrphanedUntilGenesis(t *testing.T) {
 
 	m := &mock.ChainService{State: headState}
 	offset := int64(params.BeaconConfig().SlotsPerEpoch.Mul(params.BeaconConfig().SecondsPerSlot))
+	gent := prysmTime.Now().Add(time.Duration(-1*offset) * time.Second)
 	bs := &Server{
 		BeaconDB:    beaconDB,
 		HeadFetcher: m,
 		StateGen:    stategen.New(beaconDB),
-		GenesisTimeFetcher: &mock.ChainService{
-			Genesis: prysmTime.Now().Add(time.Duration(-1*offset) * time.Second),
-		},
+		ClockProvider: &mock.ChainService{Clock: blockchain.NewClock(gent),
 		CanonicalFetcher: &mock.ChainService{
 			CanonicalRoots: map[[32]byte]bool{
 				bRoot: true,
@@ -1726,13 +1697,12 @@ func runGetValidatorParticipationCurrentAndPrevEpoch(t *testing.T, genState stat
 
 	m := &mock.ChainService{State: genState}
 	offset := int64(params.BeaconConfig().SlotsPerEpoch.Mul(params.BeaconConfig().SecondsPerSlot))
+	gent := prysmTime.Now().Add(time.Duration(-1*offset) * time.Second)
 	bs := &Server{
 		BeaconDB:    beaconDB,
 		HeadFetcher: m,
 		StateGen:    stategen.New(beaconDB),
-		GenesisTimeFetcher: &mock.ChainService{
-			Genesis: prysmTime.Now().Add(time.Duration(-1*offset) * time.Second),
-		},
+		ClockProvider: &mock.ChainService{Clock: blockchain.NewClock(gent)},
 		FinalizationFetcher: &mock.ChainService{FinalizedCheckPoint: &ethpb.Checkpoint{Epoch: 100}},
 	}
 	addDefaultReplayerBuilder(bs, beaconDB)
@@ -1837,11 +1807,12 @@ func TestGetValidatorPerformance_OK(t *testing.T) {
 	require.NoError(t, headState.SetValidators(validators))
 	require.NoError(t, headState.SetBalances([]uint64{100, 101, 102}))
 	offset := int64(headState.Slot().Mul(params.BeaconConfig().SecondsPerSlot))
+	gent := time.Now().Add(time.Duration(-1*offset) * time.Second)
 	bs := &Server{
 		HeadFetcher: &mock.ChainService{
 			State: headState,
 		},
-		GenesisTimeFetcher: &mock.ChainService{Genesis: time.Now().Add(time.Duration(-1*offset) * time.Second)},
+		ClockProvider: &mock.ChainService{Clock: blockchain.NewClock(gent)},
 		SyncChecker:        &mockSync.Sync{IsSyncing: false},
 	}
 	farFuture := params.BeaconConfig().FarFutureSlot
@@ -1901,13 +1872,14 @@ func TestGetValidatorPerformance_Indices(t *testing.T) {
 	}
 	require.NoError(t, headState.SetValidators(validators))
 	offset := int64(headState.Slot().Mul(params.BeaconConfig().SecondsPerSlot))
+	gent := time.Now().Add(time.Duration(-1*offset) * time.Second)
 	bs := &Server{
 		HeadFetcher: &mock.ChainService{
 			// 10 epochs into the future.
 			State: headState,
 		},
 		SyncChecker:        &mockSync.Sync{IsSyncing: false},
-		GenesisTimeFetcher: &mock.ChainService{Genesis: time.Now().Add(time.Duration(-1*offset) * time.Second)},
+		ClockProvider: &mock.ChainService{Clock: blockchain.NewClock(gent)},
 	}
 	c := headState.Copy()
 	vp, bp, err := precompute.New(ctx, c)
@@ -1974,13 +1946,14 @@ func TestGetValidatorPerformance_IndicesPubkeys(t *testing.T) {
 	require.NoError(t, headState.SetValidators(validators))
 
 	offset := int64(headState.Slot().Mul(params.BeaconConfig().SecondsPerSlot))
+	gent := time.Now().Add(time.Duration(-1*offset) * time.Second)
 	bs := &Server{
 		HeadFetcher: &mock.ChainService{
 			// 10 epochs into the future.
 			State: headState,
 		},
 		SyncChecker:        &mockSync.Sync{IsSyncing: false},
-		GenesisTimeFetcher: &mock.ChainService{Genesis: time.Now().Add(time.Duration(-1*offset) * time.Second)},
+		ClockProvider: &mock.ChainService{Clock: blockchain.NewClock(gent)},
 	}
 	c := headState.Copy()
 	vp, bp, err := precompute.New(ctx, c)
@@ -2053,11 +2026,12 @@ func TestGetValidatorPerformanceAltair_OK(t *testing.T) {
 	require.NoError(t, headState.SetInactivityScores([]uint64{0, 0, 0}))
 	require.NoError(t, headState.SetBalances([]uint64{100, 101, 102}))
 	offset := int64(headState.Slot().Mul(params.BeaconConfig().SecondsPerSlot))
+	gent := time.Now().Add(time.Duration(-1*offset) * time.Second)
 	bs := &Server{
 		HeadFetcher: &mock.ChainService{
 			State: headState,
 		},
-		GenesisTimeFetcher: &mock.ChainService{Genesis: time.Now().Add(time.Duration(-1*offset) * time.Second)},
+		ClockProvider: &mock.ChainService{Clock: blockchain.NewClock(gent)},
 		SyncChecker:        &mockSync.Sync{IsSyncing: false},
 	}
 	want := &ethpb.ValidatorPerformanceResponse{
@@ -2123,11 +2097,13 @@ func TestGetValidatorPerformanceBellatrix_OK(t *testing.T) {
 	require.NoError(t, headState.SetInactivityScores([]uint64{0, 0, 0}))
 	require.NoError(t, headState.SetBalances([]uint64{100, 101, 102}))
 	offset := int64(headState.Slot().Mul(params.BeaconConfig().SecondsPerSlot))
+	gent := time.Now().Add(time.Duration(-1*offset) * time.Second)
+	clock := blockchain.NewClock(gent)
 	bs := &Server{
 		HeadFetcher: &mock.ChainService{
 			State: headState,
 		},
-		GenesisTimeFetcher: &mock.ChainService{Genesis: time.Now().Add(time.Duration(-1*offset) * time.Second)},
+		ClockProvider: &mock.ChainService{Clock: clock},
 		SyncChecker:        &mockSync.Sync{IsSyncing: false},
 	}
 	want := &ethpb.ValidatorPerformanceResponse{
@@ -2194,12 +2170,14 @@ func setupValidators(t testing.TB, _ db.Database, count int) ([]*ethpb.Validator
 }
 
 func TestServer_GetIndividualVotes_RequestFutureSlot(t *testing.T) {
-	ds := &Server{GenesisTimeFetcher: &mock.ChainService{}}
+	ds := &Server{ClockProvider: &mock.ChainService{}}
+	c, err := ds.ClockProvider.WaitForClock(context.Background())
+	require.NoError(t, err)
 	req := &ethpb.IndividualVotesRequest{
-		Epoch: slots.ToEpoch(ds.GenesisTimeFetcher.CurrentSlot()) + 1,
+		Epoch: slots.ToEpoch(c.CurrentSlot()) + 1,
 	}
 	wanted := errNoEpochInfoError
-	_, err := ds.GetIndividualVotes(context.Background(), req)
+	_, err = ds.GetIndividualVotes(context.Background(), req)
 	assert.ErrorContains(t, wanted, err)
 }
 
@@ -2229,7 +2207,7 @@ func TestServer_GetIndividualVotes_ValidatorsDontExist(t *testing.T) {
 	require.NoError(t, beaconDB.SaveGenesisBlockRoot(ctx, gRoot))
 	bs := &Server{
 		StateGen:           gen,
-		GenesisTimeFetcher: &mock.ChainService{},
+		ClockProvider: &mock.ChainService{},
 	}
 	addDefaultReplayerBuilder(bs, beaconDB)
 
@@ -2325,7 +2303,7 @@ func TestServer_GetIndividualVotes_Working(t *testing.T) {
 	require.NoError(t, beaconDB.SaveGenesisBlockRoot(ctx, gRoot))
 	bs := &Server{
 		StateGen:           gen,
-		GenesisTimeFetcher: &mock.ChainService{},
+		ClockProvider: &mock.ChainService{},
 	}
 	addDefaultReplayerBuilder(bs, beaconDB)
 
@@ -2390,7 +2368,7 @@ func TestServer_GetIndividualVotes_WorkingAltair(t *testing.T) {
 	require.NoError(t, beaconDB.SaveGenesisBlockRoot(ctx, gRoot))
 	bs := &Server{
 		StateGen:           gen,
-		GenesisTimeFetcher: &mock.ChainService{},
+		ClockProvider: &mock.ChainService{},
 	}
 	addDefaultReplayerBuilder(bs, beaconDB)
 
@@ -2476,7 +2454,7 @@ func TestServer_GetIndividualVotes_AltairEndOfEpoch(t *testing.T) {
 	require.NoError(t, beaconDB.SaveState(ctx, beaconState, gRoot))
 	bs := &Server{
 		StateGen:           gen,
-		GenesisTimeFetcher: &mock.ChainService{},
+		ClockProvider: &mock.ChainService{},
 	}
 	addDefaultReplayerBuilder(bs, beaconDB)
 
@@ -2564,7 +2542,7 @@ func TestServer_GetIndividualVotes_BellatrixEndOfEpoch(t *testing.T) {
 	require.NoError(t, beaconDB.SaveState(ctx, beaconState, gRoot))
 	bs := &Server{
 		StateGen:           gen,
-		GenesisTimeFetcher: &mock.ChainService{},
+		ClockProvider: &mock.ChainService{},
 	}
 	addDefaultReplayerBuilder(bs, beaconDB)
 

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

@@ -45,6 +45,7 @@ go_test(
     ],
     embed = [":go_default_library"],
     deps = [
+        "//beacon-chain/blockchain:go_default_library",
         "//beacon-chain/blockchain/testing:go_default_library",
         "//beacon-chain/core/helpers:go_default_library",
         "//beacon-chain/db/testing:go_default_library",

beacon-chain/rpc/prysm/v1alpha1/debug/block.go

@@ -41,12 +41,14 @@ func (ds *Server) GetBlock(
 
 // GetInclusionSlot of an attestation in block.
 func (ds *Server) GetInclusionSlot(ctx context.Context, req *pbrpc.InclusionSlotRequest) (*pbrpc.InclusionSlotResponse, error) {
-	ds.GenesisTimeFetcher.CurrentSlot()
-
+	c, err := ds.ClockProvider.WaitForClock(ctx)
+	if err != nil {
+		return nil, status.Errorf(codes.Internal, "timeout while waiting for genesis timestamp, %s", err)
+	}
 	// Attestation has one epoch to get included in the chain. This blocks users from requesting too soon.
 	epochBack := types.Slot(0)
-	if ds.GenesisTimeFetcher.CurrentSlot() > params.BeaconConfig().SlotsPerEpoch {
-		epochBack = ds.GenesisTimeFetcher.CurrentSlot() - params.BeaconConfig().SlotsPerEpoch
+	if c.CurrentSlot() > params.BeaconConfig().SlotsPerEpoch {
+		epochBack = c.CurrentSlot() - params.BeaconConfig().SlotsPerEpoch
 	}
 	if epochBack < req.Slot {
 		return nil, fmt.Errorf("attestation has one epoch window, please request slot older than %d", epochBack)

beacon-chain/rpc/prysm/v1alpha1/debug/block_test.go

@@ -6,6 +6,7 @@ import (
 	"time"
 
 	"github.com/prysmaticlabs/go-bitfield"
+	"github.com/prysmaticlabs/prysm/beacon-chain/blockchain"
 	mock "github.com/prysmaticlabs/prysm/beacon-chain/blockchain/testing"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
 	dbTest "github.com/prysmaticlabs/prysm/beacon-chain/db/testing"
@@ -51,10 +52,11 @@ func TestServer_GetAttestationInclusionSlot(t *testing.T) {
 	db := dbTest.SetupDB(t)
 	ctx := context.Background()
 	offset := int64(2 * params.BeaconConfig().SlotsPerEpoch.Mul(params.BeaconConfig().SecondsPerSlot))
+	gent := time.Now().Add(time.Duration(-1*offset) * time.Second)
 	bs := &Server{
 		BeaconDB:           db,
 		StateGen:           stategen.New(db),
-		GenesisTimeFetcher: &mock.ChainService{Genesis: time.Now().Add(time.Duration(-1*offset) * time.Second)},
+		ClockProvider: &mock.ChainService{Clock: blockchain.NewClock(gent)},
 	}
 
 	s, _ := util.DeterministicGenesisState(t, 2048)

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

@@ -25,13 +25,13 @@ import (
 // gated behind the feature flag --enable-debug-rpc-endpoints.
 type Server struct {
 	BeaconDB           db.NoHeadAccessDatabase
-	GenesisTimeFetcher blockchain.TimeFetcher
 	StateGen           *stategen.State
 	HeadFetcher        blockchain.HeadFetcher
 	ForkFetcher        blockchain.ForkFetcher
 	PeerManager        p2p.PeerManager
-	PeersFetcher       p2p.PeersProvider
-	ReplayerBuilder    stategen.ReplayerBuilder
+	PeersFetcher           p2p.PeersProvider
+	CanonicalHistoryWaiter stategen.CanonicalHistoryWaiter
+	ClockProvider          blockchain.ClockProvider
 }
 
 // SetLoggingLevel of a beacon node according to a request type,

beacon-chain/rpc/prysm/v1alpha1/debug/state.go

@@ -18,7 +18,11 @@ func (ds *Server) GetBeaconState(
 ) (*pbrpc.SSZResponse, error) {
 	switch q := req.QueryFilter.(type) {
 	case *pbrpc.BeaconStateRequest_Slot:
-		currentSlot := ds.GenesisTimeFetcher.CurrentSlot()
+		c, err := ds.ClockProvider.WaitForClock(ctx)
+		if err != nil {
+			return nil, status.Errorf(codes.Internal, "timeout waiting for genesis timestamp, %s", err)
+		}
+		currentSlot := c.CurrentSlot()
 		requestedSlot := q.Slot
 		if requestedSlot > currentSlot {
 			return nil, status.Errorf(
@@ -29,7 +33,11 @@ func (ds *Server) GetBeaconState(
 			)
 		}
 
-		st, err := ds.ReplayerBuilder.ReplayerForSlot(q.Slot).ReplayBlocks(ctx)
+		b, err := ds.CanonicalHistoryWaiter.WaitForCanonicalHistory(ctx)
+		if err != nil {
+			return nil, status.Errorf(codes.Internal, err.Error())
+		}
+		st, err := b.ReplayerForSlot(q.Slot).ReplayBlocks(ctx)
 		if err != nil {
 			return nil, status.Error(codes.Internal, fmt.Sprintf("error replaying blocks for state at slot %d: %v", q.Slot, err))
 		}

beacon-chain/rpc/prysm/v1alpha1/debug/state_test.go

@@ -39,7 +39,7 @@ func TestServer_GetBeaconState(t *testing.T) {
 	require.NoError(t, db.SaveState(ctx, st, gRoot))
 	bs := &Server{
 		StateGen:           gen,
-		GenesisTimeFetcher: &mock.ChainService{},
+		ClockProvider: &mock.ChainService{},
 	}
 	addDefaultReplayerBuilder(bs, db)
 	_, err = bs.GetBeaconState(ctx, &pbrpc.BeaconStateRequest{})
@@ -95,13 +95,15 @@ func TestServer_GetBeaconState(t *testing.T) {
 }
 
 func TestServer_GetBeaconState_RequestFutureSlot(t *testing.T) {
-	ds := &Server{GenesisTimeFetcher: &mock.ChainService{}}
+	ds := &Server{ClockProvider: &mock.ChainService{}}
+	c, err := ds.ClockProvider.WaitForClock(context.Background())
+	require.NoError(t, err)
 	req := &pbrpc.BeaconStateRequest{
 		QueryFilter: &pbrpc.BeaconStateRequest_Slot{
-			Slot: ds.GenesisTimeFetcher.CurrentSlot() + 1,
+			Slot: c.CurrentSlot() + 1,
 		},
 	}
 	wanted := "Cannot retrieve information about a slot in the future"
-	_, err := ds.GetBeaconState(context.Background(), req)
+	_, err = ds.GetBeaconState(context.Background(), req)
 	assert.ErrorContains(t, wanted, err)
 }

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

@@ -30,6 +30,7 @@ go_test(
     srcs = ["server_test.go"],
     embed = [":go_default_library"],
     deps = [
+        "//beacon-chain/blockchain:go_default_library",
         "//beacon-chain/blockchain/testing:go_default_library",
         "//beacon-chain/db/testing:go_default_library",
         "//beacon-chain/p2p:go_default_library",

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

@@ -38,11 +38,11 @@ type Server struct {
 	BeaconDB             db.ReadOnlyDatabase
 	PeersFetcher         p2p.PeersProvider
 	PeerManager          p2p.PeerManager
-	GenesisTimeFetcher   blockchain.TimeFetcher
 	GenesisFetcher       blockchain.GenesisFetcher
 	POWChainInfoFetcher  powchain.ChainInfoFetcher
 	BeaconMonitoringHost string
 	BeaconMonitoringPort int
+	ClockProvider blockchain.ClockProvider
 }
 
 // GetSyncStatus checks the current network sync status of the node.
@@ -59,7 +59,11 @@ func (ns *Server) GetGenesis(ctx context.Context, _ *empty.Empty) (*ethpb.Genesi
 	if err != nil {
 		return nil, status.Errorf(codes.Internal, "Could not retrieve contract address from db: %v", err)
 	}
-	genesisTime := ns.GenesisTimeFetcher.GenesisTime()
+	c, err := ns.ClockProvider.WaitForClock(ctx)
+	if err != nil {
+		return nil, status.Errorf(codes.Internal, "timeout while waiting for genesis timestamp, %s", err)
+	}
+	genesisTime := c.GenesisTime()
 	var defaultGenesisTime time.Time
 	var gt *timestamp.Timestamp
 	if genesisTime == defaultGenesisTime {

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

@@ -3,6 +3,7 @@ package node
 import (
 	"context"
 	"fmt"
+	"github.com/prysmaticlabs/prysm/beacon-chain/blockchain"
 	"testing"
 	"time"
 
@@ -51,7 +52,7 @@ func TestNodeServer_GetGenesis(t *testing.T) {
 	genValRoot := bytesutil.ToBytes32([]byte("I am root"))
 	ns := &Server{
 		BeaconDB:           db,
-		GenesisTimeFetcher: &mock.ChainService{},
+		ClockProvider: &mock.ChainService{},
 		GenesisFetcher: &mock.ChainService{
 			State:          st,
 			ValidatorsRoot: genValRoot,
@@ -64,7 +65,7 @@ func TestNodeServer_GetGenesis(t *testing.T) {
 	assert.Equal(t, res.GenesisTime.Seconds, pUnix.Seconds)
 	assert.DeepEqual(t, genValRoot[:], res.GenesisValidatorsRoot)
 
-	ns.GenesisTimeFetcher = &mock.ChainService{Genesis: time.Unix(10, 0)}
+	ns.ClockProvider = &mock.ChainService{Clock: blockchain.NewClock(time.Unix(10, 0))}
 	res, err = ns.GetGenesis(context.Background(), &emptypb.Empty{})
 	require.NoError(t, err)
 	pUnix = timestamppb.New(time.Unix(10, 0))

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

@@ -117,6 +117,7 @@ go_test(
     embed = [":go_default_library"],
     deps = [
         "//async/event:go_default_library",
+        "//beacon-chain/blockchain:go_default_library",
         "//beacon-chain/blockchain/testing:go_default_library",
         "//beacon-chain/builder/testing:go_default_library",
         "//beacon-chain/cache:go_default_library",

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

@@ -129,9 +129,13 @@ func (vs *Server) SubmitSignedAggregateSelectionProof(
 		return nil, status.Error(codes.InvalidArgument, "Signed signatures can't be zero hashes")
 	}
 
+	c, err := vs.ClockProvider.WaitForClock(ctx)
+	if err != nil {
+		return nil, status.Errorf(codes.Internal, "timeout waiting for genesis time initialization, %s", err)
+	}
 	// As a preventive measure, a beacon node shouldn't broadcast an attestation whose slot is out of range.
 	if err := helpers.ValidateAttestationTime(req.SignedAggregateAndProof.Message.Aggregate.Data.Slot,
-		vs.TimeFetcher.GenesisTime(), params.BeaconNetworkConfig().MaximumGossipClockDisparity); err != nil {
+		c.GenesisTime(), params.BeaconNetworkConfig().MaximumGossipClockDisparity); err != nil {
 		return nil, status.Error(codes.InvalidArgument, "Attestation slot is no longer valid from current time")
 	}
 

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

@@ -2,6 +2,7 @@ package validator
 
 import (
 	"context"
+	"github.com/prysmaticlabs/prysm/beacon-chain/blockchain"
 	"reflect"
 	"testing"
 	"time"
@@ -55,7 +56,7 @@ func TestSubmitAggregateAndProof_CantFindValidatorIndex(t *testing.T) {
 	server := &Server{
 		HeadFetcher: &mock.ChainService{State: s},
 		SyncChecker: &mockSync.Sync{IsSyncing: false},
-		TimeFetcher: &mock.ChainService{Genesis: time.Now()},
+		ClockProvider: &mock.ChainService{Clock: blockchain.NewClock(time.Now())},
 	}
 
 	priv, err := bls.RandKey()
@@ -83,7 +84,7 @@ func TestSubmitAggregateAndProof_IsAggregatorAndNoAtts(t *testing.T) {
 		HeadFetcher: &mock.ChainService{State: s},
 		SyncChecker: &mockSync.Sync{IsSyncing: false},
 		AttPool:     attestations.NewPool(),
-		TimeFetcher: &mock.ChainService{Genesis: time.Now()},
+		ClockProvider: &mock.ChainService{Clock: blockchain.NewClock(time.Now())},
 	}
 
 	priv, err := bls.RandKey()
@@ -117,7 +118,7 @@ func TestSubmitAggregateAndProof_UnaggregateOk(t *testing.T) {
 		SyncChecker: &mockSync.Sync{IsSyncing: false},
 		AttPool:     attestations.NewPool(),
 		P2P:         &mockp2p.MockBroadcaster{},
-		TimeFetcher: &mock.ChainService{Genesis: time.Now()},
+		ClockProvider: &mock.ChainService{Clock: blockchain.NewClock(time.Now())},
 	}
 
 	priv, err := bls.RandKey()
@@ -155,7 +156,7 @@ func TestSubmitAggregateAndProof_AggregateOk(t *testing.T) {
 		SyncChecker: &mockSync.Sync{IsSyncing: false},
 		AttPool:     attestations.NewPool(),
 		P2P:         &mockp2p.MockBroadcaster{},
-		TimeFetcher: &mock.ChainService{Genesis: time.Now()},
+		ClockProvider: &mock.ChainService{Clock: blockchain.NewClock(time.Now())},
 	}
 
 	priv, err := bls.RandKey()
@@ -195,7 +196,7 @@ func TestSubmitAggregateAndProof_AggregateNotOk(t *testing.T) {
 		SyncChecker: &mockSync.Sync{IsSyncing: false},
 		AttPool:     attestations.NewPool(),
 		P2P:         &mockp2p.MockBroadcaster{},
-		TimeFetcher: &mock.ChainService{Genesis: time.Now()},
+		ClockProvider: &mock.ChainService{Clock: blockchain.NewClock(time.Now())},
 	}
 
 	priv, err := bls.RandKey()
@@ -324,7 +325,7 @@ func TestSubmitAggregateAndProof_PreferOwnAttestation(t *testing.T) {
 		SyncChecker: &mockSync.Sync{IsSyncing: false},
 		AttPool:     attestations.NewPool(),
 		P2P:         &mockp2p.MockBroadcaster{},
-		TimeFetcher: &mock.ChainService{Genesis: time.Now()},
+		ClockProvider: &mock.ChainService{Clock: blockchain.NewClock(time.Now())},
 	}
 
 	priv, err := bls.RandKey()
@@ -375,7 +376,7 @@ func TestSubmitAggregateAndProof_SelectsMostBitsWhenOwnAttestationNotPresent(t *
 		SyncChecker: &mockSync.Sync{IsSyncing: false},
 		AttPool:     attestations.NewPool(),
 		P2P:         &mockp2p.MockBroadcaster{},
-		TimeFetcher: &mock.ChainService{Genesis: time.Now()},
+		ClockProvider: &mock.ChainService{Clock: blockchain.NewClock(time.Now())},
 	}
 
 	priv, err := bls.RandKey()
@@ -428,8 +429,8 @@ func TestSubmitSignedAggregateSelectionProof_ZeroHashesSignatures(t *testing.T)
 }
 
 func TestSubmitSignedAggregateSelectionProof_InvalidSlot(t *testing.T) {
-	c := &mock.ChainService{Genesis: time.Now()}
-	aggregatorServer := &Server{TimeFetcher: c}
+	c := &mock.ChainService{Clock: blockchain.NewClock(time.Now())}
+	aggregatorServer := &Server{ClockProvider: c}
 	req := &ethpb.SignedAggregateSubmitRequest{
 		SignedAggregateAndProof: &ethpb.SignedAggregateAttestationAndProof{
 			Signature: []byte{'a'},

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

@@ -41,15 +41,16 @@ func (vs *Server) StreamDuties(req *ethpb.DutiesRequest, stream ethpb.BeaconNode
 		return status.Error(codes.Unavailable, "Syncing to latest head, not ready to respond")
 	}
 
+	c, err := vs.ClockProvider.WaitForClock(stream.Context())
+	if err != nil {
+		return status.Errorf(codes.Internal, "timeout waiting for genesis timestamp, %s", err)
+	}
 	// If we are post-genesis time, then set the current epoch to
 	// the number epochs since the genesis time, otherwise 0 by default.
-	genesisTime := vs.TimeFetcher.GenesisTime()
-	if genesisTime.IsZero() {
-		return status.Error(codes.Unavailable, "genesis time is not set")
-	}
+	genesisTime := c.GenesisTime()
 	var currentEpoch types.Epoch
-	if genesisTime.Before(prysmTime.Now()) {
-		currentEpoch = slots.EpochsSinceGenesis(vs.TimeFetcher.GenesisTime())
+	if genesisTime.Before(c.Now()) {
+		currentEpoch = slots.EpochsSinceGenesis(genesisTime)
 	}
 	req.Epoch = currentEpoch
 	res, err := vs.duties(stream.Context(), req)
@@ -66,7 +67,7 @@ func (vs *Server) StreamDuties(req *ethpb.DutiesRequest, stream ethpb.BeaconNode
 	defer stateSub.Unsubscribe()
 
 	secondsPerEpoch := params.BeaconConfig().SecondsPerSlot * uint64(params.BeaconConfig().SlotsPerEpoch)
-	epochTicker := slots.NewSlotTicker(vs.TimeFetcher.GenesisTime(), secondsPerEpoch)
+	epochTicker := slots.NewSlotTicker(genesisTime, secondsPerEpoch)
 	for {
 		select {
 		// Ticks every epoch to submit assignments to connected validator clients.
@@ -82,7 +83,7 @@ func (vs *Server) StreamDuties(req *ethpb.DutiesRequest, stream ethpb.BeaconNode
 		case ev := <-stateChannel:
 			// If a reorg occurred, we recompute duties for the connected validator clients
 			// and send another response over the server stream right away.
-			currentEpoch = slots.EpochsSinceGenesis(vs.TimeFetcher.GenesisTime())
+			currentEpoch = slots.EpochsSinceGenesis(genesisTime)
 			if ev.Type == statefeed.Reorg {
 				data, ok := ev.Data.(*ethpbv1.EventChainReorg)
 				if !ok {
@@ -108,7 +109,11 @@ func (vs *Server) StreamDuties(req *ethpb.DutiesRequest, stream ethpb.BeaconNode
 // Compute the validator duties from the head state's corresponding epoch
 // for validators public key / indices requested.
 func (vs *Server) duties(ctx context.Context, req *ethpb.DutiesRequest) (*ethpb.DutiesResponse, error) {
-	currentEpoch := slots.ToEpoch(vs.TimeFetcher.CurrentSlot())
+	c, err := vs.ClockProvider.WaitForClock(ctx)
+	if err != nil {
+		return nil, status.Errorf(codes.Internal, "timeout while waiting for genesis timestamp, %s", err)
+	}
+	currentEpoch := slots.ToEpoch(c.CurrentSlot())
 	if req.Epoch > currentEpoch+1 {
 		return nil, status.Errorf(codes.Unavailable, "Request epoch %d can not be greater than next epoch %d", req.Epoch, currentEpoch+1)
 	}

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

@@ -3,6 +3,7 @@ package validator
 import (
 	"context"
 	"encoding/binary"
+	"github.com/prysmaticlabs/prysm/beacon-chain/blockchain"
 	"testing"
 	"time"
 
@@ -57,11 +58,13 @@ func TestGetDuties_OK(t *testing.T) {
 	}
 
 	chain := &mockChain.ChainService{
-		State: bs, Root: genesisRoot[:], Genesis: time.Now(),
+		State: bs,
+		Root: genesisRoot[:],
+		Clock: blockchain.NewClock(time.Now()),
 	}
 	vs := &Server{
 		HeadFetcher:            chain,
-		TimeFetcher:            chain,
+		ClockProvider:            chain,
 		SyncChecker:            &mockSync.Sync{IsSyncing: false},
 		ProposerSlotIndexCache: cache.NewProposerPayloadIDsCache(),
 	}
@@ -141,12 +144,15 @@ func TestGetAltairDuties_SyncCommitteeOK(t *testing.T) {
 	}
 
 	slot := uint64(params.BeaconConfig().SlotsPerEpoch) * uint64(params.BeaconConfig().EpochsPerSyncCommitteePeriod) * params.BeaconConfig().SecondsPerSlot
+	gent := time.Now().Add(time.Duration(-1*int64(slot-1)) * time.Second)
 	chain := &mockChain.ChainService{
-		State: bs, Root: genesisRoot[:], Genesis: time.Now().Add(time.Duration(-1*int64(slot-1)) * time.Second),
+		State: bs,
+		Root: genesisRoot[:],
+		Clock: blockchain.NewClock(gent),
 	}
 	vs := &Server{
 		HeadFetcher:            chain,
-		TimeFetcher:            chain,
+		ClockProvider:          chain,
 		Eth1InfoFetcher:        &mockPOW.POWChain{},
 		SyncChecker:            &mockSync.Sync{IsSyncing: false},
 		ProposerSlotIndexCache: cache.NewProposerPayloadIDsCache(),
@@ -247,12 +253,15 @@ func TestGetBellatrixDuties_SyncCommitteeOK(t *testing.T) {
 	}
 
 	slot := uint64(params.BeaconConfig().SlotsPerEpoch) * uint64(params.BeaconConfig().EpochsPerSyncCommitteePeriod) * params.BeaconConfig().SecondsPerSlot
+	gent := time.Now().Add(time.Duration(-1*int64(slot-1)) * time.Second)
 	chain := &mockChain.ChainService{
-		State: bs, Root: genesisRoot[:], Genesis: time.Now().Add(time.Duration(-1*int64(slot-1)) * time.Second),
+		State: bs,
+		Root: genesisRoot[:],
+		Clock: blockchain.NewClock(gent),
 	}
 	vs := &Server{
 		HeadFetcher:            chain,
-		TimeFetcher:            chain,
+		ClockProvider:            chain,
 		Eth1InfoFetcher:        &mockPOW.POWChain{},
 		SyncChecker:            &mockSync.Sync{IsSyncing: false},
 		ProposerSlotIndexCache: cache.NewProposerPayloadIDsCache(),
@@ -336,15 +345,18 @@ func TestGetAltairDuties_UnknownPubkey(t *testing.T) {
 	require.NoError(t, helpers.UpdateSyncCommitteeCache(bs))
 
 	slot := uint64(params.BeaconConfig().SlotsPerEpoch) * uint64(params.BeaconConfig().EpochsPerSyncCommitteePeriod) * params.BeaconConfig().SecondsPerSlot
+	gent := time.Now().Add(time.Duration(-1*int64(slot-1)) * time.Second)
 	chain := &mockChain.ChainService{
-		State: bs, Root: genesisRoot[:], Genesis: time.Now().Add(time.Duration(-1*int64(slot-1)) * time.Second),
+		State: bs,
+		Root: genesisRoot[:],
+		Clock: blockchain.NewClock(gent),
 	}
 	depositCache, err := depositcache.New()
 	require.NoError(t, err)
 
 	vs := &Server{
 		HeadFetcher:            chain,
-		TimeFetcher:            chain,
+		ClockProvider:            chain,
 		Eth1InfoFetcher:        &mockPOW.POWChain{},
 		SyncChecker:            &mockSync.Sync{IsSyncing: false},
 		DepositFetcher:         depositCache,
@@ -365,10 +377,10 @@ func TestGetAltairDuties_UnknownPubkey(t *testing.T) {
 
 func TestGetDuties_SlotOutOfUpperBound(t *testing.T) {
 	chain := &mockChain.ChainService{
-		Genesis: time.Now(),
+		Clock: blockchain.NewClock(time.Now()),
 	}
 	vs := &Server{
-		TimeFetcher: chain,
+		ClockProvider: chain,
 	}
 	req := &ethpb.DutiesRequest{
 		Epoch: types.Epoch(chain.CurrentSlot()/params.BeaconConfig().SlotsPerEpoch + 2),
@@ -400,11 +412,13 @@ func TestGetDuties_CurrentEpoch_ShouldNotFail(t *testing.T) {
 	}
 
 	chain := &mockChain.ChainService{
-		State: bState, Root: genesisRoot[:], Genesis: time.Now(),
+		State: bState,
+		Root: genesisRoot[:],
+		Clock: blockchain.NewClock(time.Now()),
 	}
 	vs := &Server{
 		HeadFetcher:            chain,
-		TimeFetcher:            chain,
+		ClockProvider:            chain,
 		SyncChecker:            &mockSync.Sync{IsSyncing: false},
 		ProposerSlotIndexCache: cache.NewProposerPayloadIDsCache(),
 	}
@@ -439,11 +453,12 @@ func TestGetDuties_MultipleKeys_OK(t *testing.T) {
 	}
 
 	chain := &mockChain.ChainService{
-		State: bs, Root: genesisRoot[:], Genesis: time.Now(),
+		State: bs, Root: genesisRoot[:],
+		Clock: blockchain.NewClock(time.Now()),
 	}
 	vs := &Server{
 		HeadFetcher:            chain,
-		TimeFetcher:            chain,
+		ClockProvider:          chain,
 		SyncChecker:            &mockSync.Sync{IsSyncing: false},
 		ProposerSlotIndexCache: cache.NewProposerPayloadIDsCache(),
 	}
@@ -506,13 +521,13 @@ func TestStreamDuties_OK(t *testing.T) {
 
 	ctx, cancel := context.WithCancel(context.Background())
 	c := &mockChain.ChainService{
-		Genesis: time.Now(),
+		Clock: blockchain.NewClock(time.Now()),
 	}
 	vs := &Server{
 		Ctx:                    ctx,
 		HeadFetcher:            &mockChain.ChainService{State: bs, Root: genesisRoot[:]},
 		SyncChecker:            &mockSync.Sync{IsSyncing: false},
-		TimeFetcher:            c,
+		ClockProvider:            c,
 		StateNotifier:          &mockChain.MockStateNotifier{},
 		ProposerSlotIndexCache: cache.NewProposerPayloadIDsCache(),
 	}
@@ -564,13 +579,13 @@ func TestStreamDuties_OK_ChainReorg(t *testing.T) {
 
 	ctx, cancel := context.WithCancel(context.Background())
 	c := &mockChain.ChainService{
-		Genesis: time.Now(),
+		Clock: blockchain.NewClock(time.Now()),
 	}
 	vs := &Server{
 		Ctx:                    ctx,
 		HeadFetcher:            &mockChain.ChainService{State: bs, Root: genesisRoot[:]},
 		SyncChecker:            &mockSync.Sync{IsSyncing: false},
-		TimeFetcher:            c,
+		ClockProvider:            c,
 		StateNotifier:          &mockChain.MockStateNotifier{},
 		ProposerSlotIndexCache: cache.NewProposerPayloadIDsCache(),
 	}

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

@@ -42,7 +42,11 @@ func (vs *Server) GetAttestationData(ctx context.Context, req *ethpb.Attestation
 		return nil, err
 	}
 
-	if err := helpers.ValidateAttestationTime(req.Slot, vs.TimeFetcher.GenesisTime(),
+	c, err := vs.ClockProvider.WaitForClock(ctx)
+	if err != nil {
+		return nil, status.Errorf(codes.Internal, "timeout while waiting for genesis timestamp, %s", err)
+	}
+	if err := helpers.ValidateAttestationTime(req.Slot, c.GenesisTime(),
 		params.BeaconNetworkConfig().MaximumGossipClockDisparity); err != nil {
 		return nil, status.Error(codes.InvalidArgument, fmt.Sprintf("invalid request: %v", err))
 	}

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

@@ -2,6 +2,7 @@ package validator
 
 import (
 	"context"
+	"github.com/prysmaticlabs/prysm/beacon-chain/blockchain"
 	"math/rand"
 	"sync"
 	"testing"
@@ -121,6 +122,7 @@ func TestGetAttestationData_OK(t *testing.T) {
 		Genesis: time.Now(),
 	}
 	offset := int64(slot.Mul(params.BeaconConfig().SecondsPerSlot))
+	gent := time.Now().Add(time.Duration(-1*offset) * time.Second)
 	attesterServer := &Server{
 		P2P:              &mockp2p.MockBroadcaster{},
 		SyncChecker:      &mockSync.Sync{IsSyncing: false},
@@ -131,8 +133,8 @@ func TestGetAttestationData_OK(t *testing.T) {
 		FinalizationFetcher: &mock.ChainService{
 			CurrentJustifiedCheckPoint: beaconState.CurrentJustifiedCheckpoint(),
 		},
-		TimeFetcher: &mock.ChainService{
-			Genesis: time.Now().Add(time.Duration(-1*offset) * time.Second),
+		ClockProvider: &mock.ChainService{
+			Clock: blockchain.NewClock(gent),
 		},
 		StateNotifier: chainService.StateNotifier(),
 	}
@@ -178,7 +180,7 @@ func TestGetAttestationData_Optimistic(t *testing.T) {
 
 	as := &Server{
 		SyncChecker:           &mockSync.Sync{},
-		TimeFetcher:           &mock.ChainService{Genesis: time.Now()},
+		ClockProvider:         &mock.ChainService{Clock: blockchain.NewClock(time.Now())},
 		HeadFetcher:           &mock.ChainService{},
 		OptimisticModeFetcher: &mock.ChainService{Optimistic: true},
 	}
@@ -192,7 +194,7 @@ func TestGetAttestationData_Optimistic(t *testing.T) {
 	require.NoError(t, err)
 	as = &Server{
 		SyncChecker:           &mockSync.Sync{},
-		TimeFetcher:           &mock.ChainService{Genesis: time.Now()},
+		ClockProvider:         &mock.ChainService{Clock: blockchain.NewClock(time.Now())},
 		HeadFetcher:           &mock.ChainService{Optimistic: false, State: beaconState},
 		OptimisticModeFetcher: &mock.ChainService{Optimistic: false},
 		AttestationCache:      cache.NewAttestationCache(),
@@ -252,6 +254,8 @@ func TestAttestationDataAtSlot_HandlesFarAwayJustifiedEpoch(t *testing.T) {
 		Genesis: time.Now(),
 	}
 	offset := int64(slot.Mul(params.BeaconConfig().SecondsPerSlot))
+	gent := time.Now().Add(time.Duration(-1*offset) * time.Second)
+	clock := blockchain.NewClock(gent)
 	attesterServer := &Server{
 		P2P:              &mockp2p.MockBroadcaster{},
 		AttestationCache: cache.NewAttestationCache(),
@@ -260,7 +264,7 @@ func TestAttestationDataAtSlot_HandlesFarAwayJustifiedEpoch(t *testing.T) {
 			CurrentJustifiedCheckPoint: beaconState.CurrentJustifiedCheckpoint(),
 		},
 		SyncChecker:   &mockSync.Sync{IsSyncing: false},
-		TimeFetcher:   &mock.ChainService{Genesis: time.Now().Add(time.Duration(-1*offset) * time.Second)},
+		ClockProvider:   &mock.ChainService{Clock: clock},
 		StateNotifier: chainService.StateNotifier(),
 	}
 
@@ -299,11 +303,13 @@ func TestAttestationDataSlot_handlesInProgressRequest(t *testing.T) {
 	}
 	slot := types.Slot(2)
 	offset := int64(slot.Mul(params.BeaconConfig().SecondsPerSlot))
+	gent := time.Now().Add(time.Duration(-1*offset) * time.Second)
+	clock := blockchain.NewClock(gent)
 	server := &Server{
 		HeadFetcher:      &mock.ChainService{State: state},
 		AttestationCache: cache.NewAttestationCache(),
 		SyncChecker:      &mockSync.Sync{IsSyncing: false},
-		TimeFetcher:      &mock.ChainService{Genesis: time.Now().Add(time.Duration(-1*offset) * time.Second)},
+		ClockProvider:      &mock.ChainService{Clock: clock},
 		StateNotifier:    chainService.StateNotifier(),
 	}
 
@@ -347,10 +353,12 @@ func TestServer_GetAttestationData_InvalidRequestSlot(t *testing.T) {
 
 	slot := 3*params.BeaconConfig().SlotsPerEpoch + 1
 	offset := int64(slot.Mul(params.BeaconConfig().SecondsPerSlot))
+	gent := time.Now().Add(time.Duration(-1*offset) * time.Second)
+	clock := blockchain.NewClock(gent)
 	attesterServer := &Server{
 		SyncChecker: &mockSync.Sync{IsSyncing: false},
 		HeadFetcher: &mock.ChainService{},
-		TimeFetcher: &mock.ChainService{Genesis: time.Now().Add(time.Duration(-1*offset) * time.Second)},
+		ClockProvider: &mock.ChainService{Clock: clock},
 	}
 
 	req := &ethpb.AttestationDataRequest{
@@ -411,17 +419,19 @@ func TestServer_GetAttestationData_HeadStateSlotGreaterThanRequestSlot(t *testin
 	beaconstate := beaconState.Copy()
 	require.NoError(t, beaconstate.SetSlot(beaconstate.Slot()-1))
 	require.NoError(t, db.SaveState(ctx, beaconstate, blockRoot2))
-	chainService := &mock.ChainService{
-		Genesis: time.Now(),
-	}
 	offset = int64(slot.Mul(params.BeaconConfig().SecondsPerSlot))
+	gent := time.Now().Add(time.Duration(-1*offset) * time.Second)
+	clock := blockchain.NewClock(gent)
+	chainService := &mock.ChainService{
+		Clock: clock,
+	}
 	attesterServer := &Server{
 		P2P:                 &mockp2p.MockBroadcaster{},
 		SyncChecker:         &mockSync.Sync{IsSyncing: false},
 		AttestationCache:    cache.NewAttestationCache(),
 		HeadFetcher:         &mock.ChainService{State: beaconState, Root: blockRoot[:]},
 		FinalizationFetcher: &mock.ChainService{CurrentJustifiedCheckPoint: beaconState.CurrentJustifiedCheckpoint()},
-		TimeFetcher:         &mock.ChainService{Genesis: time.Now().Add(time.Duration(-1*offset) * time.Second)},
+		ClockProvider:       chainService,
 		StateNotifier:       chainService.StateNotifier(),
 		StateGen:            stategen.New(db),
 	}
@@ -486,6 +496,8 @@ func TestGetAttestationData_SucceedsInFirstEpoch(t *testing.T) {
 		Genesis: time.Now(),
 	}
 	offset := int64(slot.Mul(params.BeaconConfig().SecondsPerSlot))
+	gent := prysmTime.Now().Add(time.Duration(-1*offset) * time.Second)
+	clock := blockchain.NewClock(gent)
 	attesterServer := &Server{
 		P2P:              &mockp2p.MockBroadcaster{},
 		SyncChecker:      &mockSync.Sync{IsSyncing: false},
@@ -496,7 +508,7 @@ func TestGetAttestationData_SucceedsInFirstEpoch(t *testing.T) {
 		FinalizationFetcher: &mock.ChainService{
 			CurrentJustifiedCheckPoint: beaconState.CurrentJustifiedCheckpoint(),
 		},
-		TimeFetcher:   &mock.ChainService{Genesis: prysmTime.Now().Add(time.Duration(-1*offset) * time.Second)},
+		ClockProvider:   &mock.ChainService{Clock: clock},
 		StateNotifier: chainService.StateNotifier(),
 	}
 

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

@@ -2,6 +2,7 @@ package validator
 
 import (
 	"context"
+	"github.com/prysmaticlabs/prysm/beacon-chain/blockchain"
 	"testing"
 	"time"
 
@@ -39,11 +40,15 @@ func TestProposeExit_Notification(t *testing.T) {
 	// Set genesis time to be 100 epochs ago.
 	offset := int64(params.BeaconConfig().SlotsPerEpoch.Mul(params.BeaconConfig().SecondsPerSlot))
 	genesisTime := time.Now().Add(time.Duration(-100*offset) * time.Second)
-	mockChainService := &mockChain.ChainService{State: beaconState, Root: genesisRoot[:], Genesis: genesisTime}
+	mockChainService := &mockChain.ChainService{
+		State: beaconState,
+		Root: genesisRoot[:],
+		Clock: blockchain.NewClock(genesisTime),
+	}
 	server := &Server{
 		HeadFetcher:       mockChainService,
 		SyncChecker:       &mockSync.Sync{IsSyncing: false},
-		TimeFetcher:       mockChainService,
+		ClockProvider:     mockChainService,
 		StateNotifier:     mockChainService.StateNotifier(),
 		OperationNotifier: mockChainService.OperationNotifier(),
 		ExitPool:          voluntaryexits.NewPool(),
@@ -106,11 +111,15 @@ func TestProposeExit_NoPanic(t *testing.T) {
 	// Set genesis time to be 100 epochs ago.
 	offset := int64(params.BeaconConfig().SlotsPerEpoch.Mul(params.BeaconConfig().SecondsPerSlot))
 	genesisTime := time.Now().Add(time.Duration(-100*offset) * time.Second)
-	mockChainService := &mockChain.ChainService{State: beaconState, Root: genesisRoot[:], Genesis: genesisTime}
+	mockChainService := &mockChain.ChainService{
+		State: beaconState,
+		Root: genesisRoot[:],
+		Clock: blockchain.NewClock(genesisTime),
+	}
 	server := &Server{
 		HeadFetcher:       mockChainService,
 		SyncChecker:       &mockSync.Sync{IsSyncing: false},
-		TimeFetcher:       mockChainService,
+		ClockProvider:     mockChainService,
 		StateNotifier:     mockChainService.StateNotifier(),
 		OperationNotifier: mockChainService.OperationNotifier(),
 		ExitPool:          voluntaryexits.NewPool(),

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

@@ -2,6 +2,7 @@ package validator
 
 import (
 	"context"
+	"github.com/prysmaticlabs/prysm/beacon-chain/blockchain"
 	"testing"
 	"time"
 
@@ -441,7 +442,7 @@ func TestServer_GetBellatrixBeaconBlock_HappyCase(t *testing.T) {
 
 	proposerServer := &Server{
 		HeadFetcher:       &blockchainTest.ChainService{State: beaconState, Root: parentRoot[:], Optimistic: false},
-		TimeFetcher:       &blockchainTest.ChainService{Genesis: time.Now()},
+		ClockProvider:     &blockchainTest.ChainService{Clock: blockchain.NewClock(time.Now())},
 		SyncChecker:       &mockSync.Sync{IsSyncing: false},
 		BlockReceiver:     &blockchainTest.ChainService{},
 		HeadUpdater:       &blockchainTest.ChainService{},
@@ -570,7 +571,7 @@ func TestServer_GetBellatrixBeaconBlock_BuilderCase(t *testing.T) {
 	proposerServer := &Server{
 		FinalizationFetcher: &blockchainTest.ChainService{FinalizedCheckPoint: &ethpb.Checkpoint{Root: wbr1[:]}},
 		HeadFetcher:         &blockchainTest.ChainService{State: beaconState, Root: parentRoot[:], Optimistic: false, Block: wb1},
-		TimeFetcher:         &blockchainTest.ChainService{Genesis: time.Unix(int64(beaconState.GenesisTime()), 0)},
+		ClockProvider:       &blockchainTest.ChainService{Clock: blockchain.NewClock(time.Unix(int64(beaconState.GenesisTime()), 0))},
 		SyncChecker:         &mockSync.Sync{IsSyncing: false},
 		BlockReceiver:       &blockchainTest.ChainService{},
 		HeadUpdater:         &blockchainTest.ChainService{},

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

@@ -2,6 +2,7 @@ package validator
 
 import (
 	"context"
+	"github.com/prysmaticlabs/prysm/beacon-chain/blockchain"
 	"math/big"
 	"testing"
 	"time"
@@ -2329,7 +2330,7 @@ func TestProposer_GetBeaconBlock_BellatrixEpoch(t *testing.T) {
 	}
 	proposerServer := &Server{
 		HeadFetcher:       &mock.ChainService{State: beaconState, Root: parentRoot[:], Optimistic: false},
-		TimeFetcher:       &mock.ChainService{Genesis: time.Now()},
+		ClockProvider:     &mock.ChainService{Clock: blockchain.NewClock(time.Now())},
 		SyncChecker:       &mockSync.Sync{IsSyncing: false},
 		BlockReceiver:     &mock.ChainService{},
 		HeadUpdater:       &mock.ChainService{},
@@ -2394,8 +2395,8 @@ func TestProposer_GetBeaconBlock_Optimistic(t *testing.T) {
 
 	bellatrixSlot, err := slots.EpochStart(params.BeaconConfig().BellatrixForkEpoch)
 	require.NoError(t, err)
-
-	proposerServer := &Server{OptimisticModeFetcher: &mock.ChainService{Optimistic: true}, TimeFetcher: &mock.ChainService{}}
+	clockp := &mock.ChainService{Clock: blockchain.NewClock(time.Now())}
+	proposerServer := &Server{OptimisticModeFetcher: &mock.ChainService{Optimistic: true}, ClockProvider: clockp}
 	req := &ethpb.BlockRequest{
 		Slot: bellatrixSlot + 1,
 	}

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

@@ -47,7 +47,6 @@ type Server struct {
 	HeadUpdater            blockchain.HeadUpdater
 	ForkFetcher            blockchain.ForkFetcher
 	FinalizationFetcher    blockchain.FinalizationFetcher
-	TimeFetcher            blockchain.TimeFetcher
 	BlockFetcher           powchain.POWBlockFetcher
 	DepositFetcher         depositcache.DepositFetcher
 	ChainStartFetcher      powchain.ChainStartFetcher
@@ -67,10 +66,11 @@ type Server struct {
 	PendingDepositsFetcher depositcache.PendingDepositsFetcher
 	OperationNotifier      opfeed.Notifier
 	StateGen               stategen.StateManager
-	ReplayerBuilder        stategen.ReplayerBuilder
+	CanonicalHistoryWaiter stategen.CanonicalHistoryWaiter
 	BeaconDB               db.HeadAccessDatabase
 	ExecutionEngineCaller  powchain.EngineCaller
 	BlockBuilder           builder.BlockBuilder
+	ClockProvider          blockchain.ClockProvider
 }
 
 // WaitForActivation checks if a validator public key exists in the active validator registry of the current
@@ -124,7 +124,7 @@ func (vs *Server) ValidatorIndex(ctx context.Context, req *ethpb.ValidatorIndexR
 	}
 	index, ok := st.ValidatorIndexByPubkey(bytesutil.ToBytes48(req.PublicKey))
 	if !ok {
-		return nil, status.Errorf(codes.Internal, "Could not find validator index for public key %#x not found", req.PublicKey)
+		return nil, status.Errorf(codes.NotFound, "Could not find validator index for public key %#x not found", req.PublicKey)
 	}
 
 	return &ethpb.ValidatorIndexResponse{Index: index}, nil

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

@@ -146,7 +146,11 @@ func (vs *Server) CheckDoppelGanger(ctx context.Context, req *ethpb.DoppelGanger
 	if err != nil {
 		return nil, status.Error(codes.Internal, "Could not get previous epoch's end")
 	}
-	prevState, err := vs.ReplayerBuilder.ReplayerForSlot(prevEpochEnd).ReplayBlocks(ctx)
+	b, err := vs.CanonicalHistoryWaiter.WaitForCanonicalHistory(ctx)
+	if err != nil {
+		return nil, status.Error(codes.Internal, err.Error())
+	}
+	prevState, err := b.ReplayerForSlot(prevEpochEnd).ReplayBlocks(ctx)
 	if err != nil {
 		return nil, status.Error(codes.Internal, "Could not get previous state")
 	}
@@ -252,7 +256,11 @@ func (vs *Server) activationStatus(
 // Spec:
 // https://github.com/ethereum/consensus-specs/blob/dev/sync/optimistic.md
 func (vs *Server) optimisticStatus(ctx context.Context) error {
-	if slots.ToEpoch(vs.TimeFetcher.CurrentSlot()) < params.BeaconConfig().BellatrixForkEpoch {
+	c, err := vs.ClockProvider.WaitForClock(ctx)
+	if err != nil {
+		return status.Errorf(codes.Internal, "timeout while waiting for genesis timestamp, %s", err)
+	}
+	if slots.ToEpoch(c.CurrentSlot()) < params.BeaconConfig().BellatrixForkEpoch {
 		return nil
 	}
 	optimistic, err := vs.OptimisticModeFetcher.IsOptimistic(ctx)
@@ -363,15 +371,6 @@ func (vs *Server) validatorStatus(
 	}
 }
 
-func (vs *Server) retrieveAfterEpochTransition(ctx context.Context, epoch types.Epoch) (state.BeaconState, error) {
-	endSlot, err := slots.EpochEnd(epoch)
-	if err != nil {
-		return nil, err
-	}
-	// replay to first slot of following epoch
-	return vs.ReplayerBuilder.ReplayerForSlot(endSlot).ReplayToSlot(ctx, endSlot+1)
-}
-
 func checkValidatorsAreRecent(headEpoch types.Epoch, req *ethpb.DoppelGangerRequest) (bool, *ethpb.DoppelGangerResponse) {
 	validatorsAreRecent := true
 	resp := &ethpb.DoppelGangerResponse{

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

@@ -2,6 +2,7 @@ package validator
 
 import (
 	"context"
+	"github.com/prysmaticlabs/prysm/beacon-chain/blockchain"
 	"reflect"
 	"testing"
 	"time"
@@ -604,7 +605,8 @@ func TestActivationStatus_OK(t *testing.T) {
 
 func TestOptimisticStatus(t *testing.T) {
 	params.SetupTestConfigCleanup(t)
-	server := &Server{OptimisticModeFetcher: &mockChain.ChainService{}, TimeFetcher: &mockChain.ChainService{}}
+	clockp := &mockChain.ChainService{Clock: blockchain.NewClock(time.Now())}
+	server := &Server{OptimisticModeFetcher: &mockChain.ChainService{}, ClockProvider: clockp}
 	err := server.optimisticStatus(context.Background())
 	require.NoError(t, err)
 
@@ -612,14 +614,14 @@ func TestOptimisticStatus(t *testing.T) {
 	cfg.BellatrixForkEpoch = 2
 	params.OverrideBeaconConfig(cfg)
 
-	server = &Server{OptimisticModeFetcher: &mockChain.ChainService{Optimistic: true}, TimeFetcher: &mockChain.ChainService{}}
+	server = &Server{OptimisticModeFetcher: &mockChain.ChainService{Optimistic: true}, ClockProvider: clockp}
 	err = server.optimisticStatus(context.Background())
 	s, ok := status.FromError(err)
 	require.Equal(t, true, ok)
 	require.DeepEqual(t, codes.Unavailable, s.Code())
 	require.ErrorContains(t, errOptimisticMode.Error(), err)
 
-	server = &Server{OptimisticModeFetcher: &mockChain.ChainService{Optimistic: false}, TimeFetcher: &mockChain.ChainService{}}
+	server = &Server{OptimisticModeFetcher: &mockChain.ChainService{Optimistic: false}, ClockProvider: clockp}
 	err = server.optimisticStatus(context.Background())
 	require.NoError(t, err)
 }

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

@@ -5,6 +5,7 @@ import (
 	"testing"
 	"time"
 
+	"github.com/prysmaticlabs/prysm/beacon-chain/blockchain"
 	mock "github.com/prysmaticlabs/prysm/beacon-chain/blockchain/testing"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/feed"
 	opfeed "github.com/prysmaticlabs/prysm/beacon-chain/core/feed/operation"
@@ -27,8 +28,8 @@ import (
 func TestGetSyncMessageBlockRoot_OK(t *testing.T) {
 	r := []byte{'a'}
 	server := &Server{
-		HeadFetcher: &mock.ChainService{Root: r},
-		TimeFetcher: &mock.ChainService{Genesis: time.Now()},
+		HeadFetcher:   &mock.ChainService{Root: r},
+		ClockProvider: &mock.ChainService{Clock: blockchain.NewClock(time.Now())},
 	}
 	res, err := server.GetSyncMessageBlockRoot(context.Background(), &emptypb.Empty{})
 	require.NoError(t, err)
@@ -43,7 +44,7 @@ func TestGetSyncMessageBlockRoot_Optimistic(t *testing.T) {
 
 	server := &Server{
 		HeadFetcher:           &mock.ChainService{},
-		TimeFetcher:           &mock.ChainService{Genesis: time.Now()},
+		ClockProvider:         &mock.ChainService{Clock: blockchain.NewClock(time.Now())},
 		OptimisticModeFetcher: &mock.ChainService{Optimistic: true},
 	}
 	_, err := server.GetSyncMessageBlockRoot(context.Background(), &emptypb.Empty{})
@@ -54,7 +55,7 @@ func TestGetSyncMessageBlockRoot_Optimistic(t *testing.T) {
 
 	server = &Server{
 		HeadFetcher:           &mock.ChainService{},
-		TimeFetcher:           &mock.ChainService{Genesis: time.Now()},
+		ClockProvider:         &mock.ChainService{Clock: blockchain.NewClock(time.Now())},
 		OptimisticModeFetcher: &mock.ChainService{Optimistic: false},
 	}
 	_, err = server.GetSyncMessageBlockRoot(context.Background(), &emptypb.Empty{})
@@ -103,14 +104,16 @@ func TestGetSyncSubcommitteeIndex_Ok(t *testing.T) {
 
 func TestGetSyncCommitteeContribution_FiltersDuplicates(t *testing.T) {
 	st, _ := util.DeterministicGenesisStateAltair(t, 10)
+	chain := &mock.ChainService{
+		State:                st,
+		SyncCommitteeIndices: []types.CommitteeIndex{10},
+		Clock: blockchain.NewClock(time.Now()),
+	}
 	server := &Server{
 		SyncCommitteePool: synccommittee.NewStore(),
 		P2P:               &mockp2p.MockBroadcaster{},
-		HeadFetcher: &mock.ChainService{
-			State:                st,
-			SyncCommitteeIndices: []types.CommitteeIndex{10},
-		},
-		TimeFetcher: &mock.ChainService{Genesis: time.Now()},
+		HeadFetcher: chain,
+		ClockProvider: chain,
 	}
 	secKey, err := bls.RandKey()
 	require.NoError(t, err)

beacon-chain/rpc/service.go

@@ -4,7 +4,6 @@ package rpc
 
 import (
 	"context"
-	"errors"
 	"fmt"
 	"net"
 	"sync"
@@ -13,6 +12,7 @@ import (
 	recovery "github.com/grpc-ecosystem/go-grpc-middleware/recovery"
 	grpcopentracing "github.com/grpc-ecosystem/go-grpc-middleware/tracing/opentracing"
 	grpcprometheus "github.com/grpc-ecosystem/go-grpc-prometheus"
+	"github.com/pkg/errors"
 	"github.com/prysmaticlabs/prysm/beacon-chain/blockchain"
 	"github.com/prysmaticlabs/prysm/beacon-chain/builder"
 	"github.com/prysmaticlabs/prysm/beacon-chain/cache"
@@ -90,7 +90,6 @@ type Config struct {
 	POWChainService               powchain.Chain
 	ChainStartFetcher             powchain.ChainStartFetcher
 	POWChainInfoFetcher           powchain.ChainInfoFetcher
-	GenesisTimeFetcher            blockchain.TimeFetcher
 	GenesisFetcher                blockchain.GenesisFetcher
 	EnableDebugRPCEndpoints       bool
 	MockEth1Votes                 bool
@@ -115,6 +114,7 @@ type Config struct {
 	ProposerIdsCache              *cache.ProposerPayloadIDsCache
 	OptimisticModeFetcher         blockchain.OptimisticModeFetcher
 	BlockBuilder                  builder.BlockBuilder
+	ClockProvider                 blockchain.ClockProvider
 }
 
 // NewService instantiates a new RPC service instance that will
@@ -175,7 +175,6 @@ func NewService(ctx context.Context, cfg *Config) *Service {
 
 // paranoid build time check to ensure ChainInfoFetcher implements required interfaces
 var _ stategen.CanonicalChecker = blockchain.ChainInfoFetcher(nil)
-var _ stategen.CurrentSlotter = blockchain.ChainInfoFetcher(nil)
 
 // Start the gRPC server.
 func (s *Service) Start() {
@@ -186,7 +185,8 @@ func (s *Service) Start() {
 		stateCache = s.cfg.StateGen.CombinedCache()
 	}
 	withCache := stategen.WithCache(stateCache)
-	ch := stategen.NewCanonicalHistory(s.cfg.BeaconDB, s.cfg.ChainInfoFetcher, s.cfg.ChainInfoFetcher, withCache)
+	//ch := stategen.NewCanonicalHistory(s.cfg.BeaconDB, s.cfg.ChainInfoFetcher, s.cfg.ChainInfoFetcher, withCache)
+	rbw := NewCanonicalHistoryWaiter(s.cfg.ChainInfoFetcher, s.cfg.BeaconDB, s.cfg.ChainInfoFetcher, withCache)
 
 	validatorServer := &validatorv1alpha1.Server{
 		Ctx:                    s.ctx,
@@ -197,7 +197,6 @@ func (s *Service) Start() {
 		HeadUpdater:            s.cfg.HeadUpdater,
 		ForkFetcher:            s.cfg.ForkFetcher,
 		FinalizationFetcher:    s.cfg.FinalizationFetcher,
-		TimeFetcher:            s.cfg.GenesisTimeFetcher,
 		BlockFetcher:           s.cfg.POWChainService,
 		DepositFetcher:         s.cfg.DepositFetcher,
 		ChainStartFetcher:      s.cfg.ChainStartFetcher,
@@ -215,16 +214,16 @@ func (s *Service) Start() {
 		SlashingsPool:          s.cfg.SlashingsPool,
 		StateGen:               s.cfg.StateGen,
 		SyncCommitteePool:      s.cfg.SyncCommitteeObjectPool,
-		ReplayerBuilder:        ch,
+		CanonicalHistoryWaiter: rbw,
 		ExecutionEngineCaller:  s.cfg.ExecutionEngineCaller,
 		BeaconDB:               s.cfg.BeaconDB,
 		ProposerSlotIndexCache: s.cfg.ProposerIdsCache,
 		BlockBuilder:           s.cfg.BlockBuilder,
+		ClockProvider:          s.cfg.ClockProvider,
 	}
 	validatorServerV1 := &validator.Server{
 		HeadFetcher:           s.cfg.HeadFetcher,
 		HeadUpdater:           s.cfg.HeadUpdater,
-		TimeFetcher:           s.cfg.GenesisTimeFetcher,
 		SyncChecker:           s.cfg.SyncService,
 		OptimisticModeFetcher: s.cfg.OptimisticModeFetcher,
 		AttestationsPool:      s.cfg.AttestationsPool,
@@ -232,13 +231,14 @@ func (s *Service) Start() {
 		Broadcaster:           s.cfg.Broadcaster,
 		V1Alpha1Server:        validatorServer,
 		StateFetcher: &statefetcher.StateProvider{
-			BeaconDB:           s.cfg.BeaconDB,
-			ChainInfoFetcher:   s.cfg.ChainInfoFetcher,
-			GenesisTimeFetcher: s.cfg.GenesisTimeFetcher,
-			StateGenService:    s.cfg.StateGen,
-			ReplayerBuilder:    ch,
+			BeaconDB:               s.cfg.BeaconDB,
+			ChainInfoFetcher:       s.cfg.ChainInfoFetcher,
+			StateGenService:        s.cfg.StateGen,
+			CanonicalHistoryWaiter: rbw,
+			ClockProvider:          s.cfg.ClockProvider,
 		},
 		SyncCommitteePool: s.cfg.SyncCommitteeObjectPool,
+		ClockProvider: s.cfg.ClockProvider,
 	}
 
 	nodeServer := &nodev1alpha1.Server{
@@ -247,24 +247,24 @@ func (s *Service) Start() {
 		BeaconDB:             s.cfg.BeaconDB,
 		Server:               s.grpcServer,
 		SyncChecker:          s.cfg.SyncService,
-		GenesisTimeFetcher:   s.cfg.GenesisTimeFetcher,
 		PeersFetcher:         s.cfg.PeersFetcher,
 		PeerManager:          s.cfg.PeerManager,
 		GenesisFetcher:       s.cfg.GenesisFetcher,
 		POWChainInfoFetcher:  s.cfg.POWChainInfoFetcher,
 		BeaconMonitoringHost: s.cfg.BeaconMonitoringHost,
 		BeaconMonitoringPort: s.cfg.BeaconMonitoringPort,
+		ClockProvider: s.cfg.ClockProvider,
 	}
 	nodeServerV1 := &node.Server{
 		BeaconDB:              s.cfg.BeaconDB,
 		Server:                s.grpcServer,
 		SyncChecker:           s.cfg.SyncService,
 		OptimisticModeFetcher: s.cfg.OptimisticModeFetcher,
-		GenesisTimeFetcher:    s.cfg.GenesisTimeFetcher,
 		PeersFetcher:          s.cfg.PeersFetcher,
 		PeerManager:           s.cfg.PeerManager,
 		MetadataProvider:      s.cfg.MetadataProvider,
 		HeadFetcher:           s.cfg.HeadFetcher,
+		ClockProvider:         s.cfg.ClockProvider,
 	}
 
 	beaconChainServer := &beaconv1alpha1.Server{
@@ -280,7 +280,6 @@ func (s *Service) Start() {
 		ChainStartFetcher:           s.cfg.ChainStartFetcher,
 		DepositFetcher:              s.cfg.DepositFetcher,
 		BlockFetcher:                s.cfg.POWChainService,
-		GenesisTimeFetcher:          s.cfg.GenesisTimeFetcher,
 		StateNotifier:               s.cfg.StateNotifier,
 		BlockNotifier:               s.cfg.BlockNotifier,
 		AttestationNotifier:         s.cfg.OperationNotifier,
@@ -289,26 +288,26 @@ func (s *Service) Start() {
 		SyncChecker:                 s.cfg.SyncService,
 		ReceivedAttestationsBuffer:  make(chan *ethpbv1alpha1.Attestation, attestationBufferSize),
 		CollectedAttestationsBuffer: make(chan []*ethpbv1alpha1.Attestation, attestationBufferSize),
-		ReplayerBuilder:             ch,
+		CanonicalHistoryWaiter:      rbw,
+		ClockProvider:               s.cfg.ClockProvider,
 	}
 	beaconChainServerV1 := &beacon.Server{
-		CanonicalHistory:   ch,
-		BeaconDB:           s.cfg.BeaconDB,
-		AttestationsPool:   s.cfg.AttestationsPool,
-		SlashingsPool:      s.cfg.SlashingsPool,
-		ChainInfoFetcher:   s.cfg.ChainInfoFetcher,
-		GenesisTimeFetcher: s.cfg.GenesisTimeFetcher,
-		BlockNotifier:      s.cfg.BlockNotifier,
-		OperationNotifier:  s.cfg.OperationNotifier,
-		Broadcaster:        s.cfg.Broadcaster,
-		BlockReceiver:      s.cfg.BlockReceiver,
-		StateGenService:    s.cfg.StateGen,
+		CanonicalHistoryWaiter: rbw,
+		BeaconDB:               s.cfg.BeaconDB,
+		AttestationsPool:       s.cfg.AttestationsPool,
+		SlashingsPool:          s.cfg.SlashingsPool,
+		ChainInfoFetcher:       s.cfg.ChainInfoFetcher,
+		BlockNotifier:          s.cfg.BlockNotifier,
+		OperationNotifier:      s.cfg.OperationNotifier,
+		Broadcaster:            s.cfg.Broadcaster,
+		BlockReceiver:          s.cfg.BlockReceiver,
+		StateGenService:        s.cfg.StateGen,
 		StateFetcher: &statefetcher.StateProvider{
-			BeaconDB:           s.cfg.BeaconDB,
-			ChainInfoFetcher:   s.cfg.ChainInfoFetcher,
-			GenesisTimeFetcher: s.cfg.GenesisTimeFetcher,
-			StateGenService:    s.cfg.StateGen,
-			ReplayerBuilder:    ch,
+			BeaconDB:               s.cfg.BeaconDB,
+			ChainInfoFetcher:       s.cfg.ChainInfoFetcher,
+			StateGenService:        s.cfg.StateGen,
+			CanonicalHistoryWaiter: rbw,
+			ClockProvider:          s.cfg.ClockProvider,
 		},
 		OptimisticModeFetcher:         s.cfg.OptimisticModeFetcher,
 		HeadFetcher:                   s.cfg.HeadFetcher,
@@ -316,6 +315,7 @@ func (s *Service) Start() {
 		V1Alpha1ValidatorServer:       validatorServer,
 		SyncChecker:                   s.cfg.SyncService,
 		ExecutionPayloadReconstructor: s.cfg.ExecutionPayloadReconstructor,
+		ClockProvider:         s.cfg.ClockProvider,
 	}
 	ethpbv1alpha1.RegisterNodeServer(s.grpcServer, nodeServer)
 	ethpbservice.RegisterBeaconNodeServer(s.grpcServer, nodeServerV1)
@@ -331,24 +331,24 @@ func (s *Service) Start() {
 	if s.cfg.EnableDebugRPCEndpoints {
 		log.Info("Enabled debug gRPC endpoints")
 		debugServer := &debugv1alpha1.Server{
-			GenesisTimeFetcher: s.cfg.GenesisTimeFetcher,
-			BeaconDB:           s.cfg.BeaconDB,
-			StateGen:           s.cfg.StateGen,
-			HeadFetcher:        s.cfg.HeadFetcher,
-			ForkFetcher:        s.cfg.ForkFetcher,
-			PeerManager:        s.cfg.PeerManager,
-			PeersFetcher:       s.cfg.PeersFetcher,
-			ReplayerBuilder:    ch,
+			BeaconDB:               s.cfg.BeaconDB,
+			StateGen:               s.cfg.StateGen,
+			HeadFetcher:            s.cfg.HeadFetcher,
+			ForkFetcher:            s.cfg.ForkFetcher,
+			PeerManager:            s.cfg.PeerManager,
+			PeersFetcher:           s.cfg.PeersFetcher,
+			CanonicalHistoryWaiter: rbw,
+			ClockProvider:          s.cfg.ClockProvider,
 		}
 		debugServerV1 := &debug.Server{
 			BeaconDB:    s.cfg.BeaconDB,
 			HeadFetcher: s.cfg.HeadFetcher,
 			StateFetcher: &statefetcher.StateProvider{
-				BeaconDB:           s.cfg.BeaconDB,
-				ChainInfoFetcher:   s.cfg.ChainInfoFetcher,
-				GenesisTimeFetcher: s.cfg.GenesisTimeFetcher,
-				StateGenService:    s.cfg.StateGen,
-				ReplayerBuilder:    ch,
+				BeaconDB:               s.cfg.BeaconDB,
+				ChainInfoFetcher:       s.cfg.ChainInfoFetcher,
+				StateGenService:        s.cfg.StateGen,
+				CanonicalHistoryWaiter: rbw,
+				ClockProvider:          s.cfg.ClockProvider,
 			},
 			OptimisticModeFetcher: s.cfg.OptimisticModeFetcher,
 		}
@@ -429,3 +429,27 @@ func (s *Service) logNewClientConnection(ctx context.Context) {
 		}
 	}
 }
+
+func NewCanonicalHistoryWaiter(c blockchain.ClockProvider, h stategen.HistoryAccessor, cc stategen.CanonicalChecker, opts ...stategen.CanonicalHistoryOption) stategen.CanonicalHistoryWaiter {
+	return &canonicalHistoryWaiter{
+		c:    c,
+		h:    h,
+		cc:   cc,
+		opts: opts,
+	}
+}
+
+type canonicalHistoryWaiter struct {
+	c blockchain.ClockProvider
+	h stategen.HistoryAccessor
+	cc stategen.CanonicalChecker
+	opts []stategen.CanonicalHistoryOption
+}
+
+func (w *canonicalHistoryWaiter) WaitForCanonicalHistory(ctx context.Context) (*stategen.CanonicalHistory, error) {
+	c, err := w.c.WaitForClock(ctx)
+	if err != nil {
+		return nil, errors.Wrap(err, "timeout waiting for genesis timestamp")
+	}
+	return stategen.NewCanonicalHistory(w.h, w.cc, c, w.opts...), nil
+}

beacon-chain/rpc/service_test.go

@@ -3,6 +3,7 @@ package rpc
 import (
 	"context"
 	"errors"
+	"github.com/prysmaticlabs/prysm/beacon-chain/blockchain"
 	"io"
 	"testing"
 	"time"
@@ -24,7 +25,7 @@ func init() {
 func TestLifecycle_OK(t *testing.T) {
 	hook := logTest.NewGlobal()
 	chainService := &mock.ChainService{
-		Genesis: time.Now(),
+		Clock: blockchain.NewClock(time.Now()),
 	}
 	rpcService := NewService(context.Background(), &Config{
 		Port:                "7348",
@@ -32,9 +33,9 @@ func TestLifecycle_OK(t *testing.T) {
 		BlockReceiver:       chainService,
 		AttestationReceiver: chainService,
 		HeadFetcher:         chainService,
-		GenesisTimeFetcher:  chainService,
 		POWChainService:     &mockPOW.POWChain{},
 		StateNotifier:       chainService.StateNotifier(),
+		ClockProvider:       chainService,
 	})
 
 	rpcService.Start()
@@ -55,12 +56,12 @@ func TestStatus_CredentialError(t *testing.T) {
 
 func TestRPC_InsecureEndpoint(t *testing.T) {
 	hook := logTest.NewGlobal()
-	chainService := &mock.ChainService{Genesis: time.Now()}
+	chainService := &mock.ChainService{Clock: blockchain.NewClock(time.Now())}
 	rpcService := NewService(context.Background(), &Config{
 		Port:                "7777",
 		SyncService:         &mockSync.Sync{IsSyncing: false},
 		BlockReceiver:       chainService,
-		GenesisTimeFetcher:  chainService,
+		ClockProvider:       chainService,
 		AttestationReceiver: chainService,
 		HeadFetcher:         chainService,
 		POWChainService:     &mockPOW.POWChain{},

beacon-chain/rpc/statefetcher/BUILD.bazel

@@ -24,6 +24,7 @@ go_test(
     srcs = ["fetcher_test.go"],
     embed = [":go_default_library"],
     deps = [
+        "//beacon-chain/blockchain:go_default_library",
         "//beacon-chain/blockchain/testing:go_default_library",
         "//beacon-chain/db/testing:go_default_library",
         "//beacon-chain/state/state-native:go_default_library",

beacon-chain/rpc/statefetcher/fetcher.go

@@ -81,9 +81,9 @@ type Fetcher interface {
 type StateProvider struct {
 	BeaconDB           db.ReadOnlyDatabase
 	ChainInfoFetcher   blockchain.ChainInfoFetcher
-	GenesisTimeFetcher blockchain.TimeFetcher
-	StateGenService    stategen.StateManager
-	ReplayerBuilder    stategen.ReplayerBuilder
+	StateGenService        stategen.StateManager
+	CanonicalHistoryWaiter stategen.CanonicalHistoryWaiter
+	ClockProvider          blockchain.ClockProvider
 }
 
 // State returns the BeaconState for a given identifier. The identifier can be one of:
@@ -200,14 +200,22 @@ func (p *StateProvider) StateBySlot(ctx context.Context, target types.Slot) (sta
 	ctx, span := trace.StartSpan(ctx, "statefetcher.StateBySlot")
 	defer span.End()
 
-	if target > p.GenesisTimeFetcher.CurrentSlot() {
+	c, err := p.ClockProvider.WaitForClock(ctx)
+	if err != nil {
+		return nil, errors.Wrap(err, "timeout while waiting for genesis timestamp")
+	}
+	if target > c.CurrentSlot() {
 		return nil, errors.New("requested slot is in the future")
 	}
 	if target > p.ChainInfoFetcher.HeadSlot() {
 		return nil, errors.New("requested slot number is higher than head slot number")
 	}
 
-	st, err := p.ReplayerBuilder.ReplayerForSlot(target).ReplayBlocks(ctx)
+	b, err := p.ReplayerBuilder(ctx)
+	if err != nil {
+		return nil, err
+	}
+	st, err := b.ReplayerForSlot(target).ReplayBlocks(ctx)
 	if err != nil {
 		msg := fmt.Sprintf("error while replaying history to slot=%d", target)
 		return nil, errors.Wrap(err, msg)
@@ -285,7 +293,11 @@ func (p *StateProvider) stateRootByHex(ctx context.Context, stateId []byte) ([]b
 }
 
 func (p *StateProvider) stateRootBySlot(ctx context.Context, slot types.Slot) ([]byte, error) {
-	currentSlot := p.GenesisTimeFetcher.CurrentSlot()
+	c, err := p.ClockProvider.WaitForClock(ctx)
+	if err != nil {
+		return nil, errors.Wrap(err, "timeout waiting for genesis time")
+	}
+	currentSlot := c.CurrentSlot()
 	if slot > currentSlot {
 		return nil, errors.New("slot cannot be in the future")
 	}
@@ -304,3 +316,7 @@ func (p *StateProvider) stateRootBySlot(ctx context.Context, slot types.Slot) ([
 	}
 	return blks[0].Block().StateRoot(), nil
 }
+
+func (p *StateProvider) ReplayerBuilder(ctx context.Context) (stategen.ReplayerBuilder, error) {
+	return p.CanonicalHistoryWaiter.WaitForCanonicalHistory(ctx)
+}

beacon-chain/rpc/statefetcher/fetcher_test.go

@@ -2,6 +2,7 @@ package statefetcher
 
 import (
 	"context"
+	"github.com/prysmaticlabs/prysm/beacon-chain/blockchain"
 	"strconv"
 	"strings"
 	"testing"
@@ -77,11 +78,11 @@ func TestGetState(t *testing.T) {
 		cc := &mockstategen.MockCanonicalChecker{Is: true}
 		cs := &mockstategen.MockCurrentSlotter{Slot: bs.Slot() + 1}
 		ch := stategen.NewCanonicalHistory(db, cc, cs)
-		currentSlot := types.Slot(0)
+		clock := blockchain.NewClock(time.Now())
 		p := StateProvider{
 			BeaconDB:           db,
 			ReplayerBuilder:    ch,
-			GenesisTimeFetcher: &chainMock.ChainService{Slot: &currentSlot},
+			ClockProvider: &chainMock.ChainService{Clock: clock},
 			ChainInfoFetcher:   &chainMock.ChainService{State: bs},
 		}
 
@@ -161,8 +162,10 @@ func TestGetState(t *testing.T) {
 	})
 
 	t.Run("slot", func(t *testing.T) {
+
+		clock := NewMockClock(time.Now(), headSlot)
 		p := StateProvider{
-			GenesisTimeFetcher: &chainMock.ChainService{Slot: &headSlot},
+			ClockProvider: &chainMock.ChainService{Clock: clock},
 			ChainInfoFetcher: &chainMock.ChainService{
 				CanonicalRoots: map[[32]byte]bool{
 					bytesutil.ToBytes32(newBeaconState.LatestBlockHeader().ParentRoot): true,
@@ -346,8 +349,9 @@ func TestGetStateRoot(t *testing.T) {
 		require.NoError(t, db.SaveState(ctx, st, root))
 
 		slot := types.Slot(40)
+		clock := NewMockClock(time.Now(), slot)
 		p := StateProvider{
-			GenesisTimeFetcher: &chainMock.ChainService{Slot: &slot},
+			ClockProvider: &chainMock.ChainService{Clock: clock},
 			BeaconDB:           db,
 		}
 
@@ -357,11 +361,7 @@ func TestGetStateRoot(t *testing.T) {
 	})
 
 	t.Run("slot_too_big", func(t *testing.T) {
-		p := StateProvider{
-			GenesisTimeFetcher: &chainMock.ChainService{
-				Genesis: time.Now(),
-			},
-		}
+		p := StateProvider{ClockProvider: &chainMock.ChainService{Clock: blockchain.NewClock(time.Now())}}
 		_, err := p.StateRoot(ctx, []byte(strconv.FormatUint(1, 10)))
 		assert.ErrorContains(t, "slot cannot be in the future", err)
 	})
@@ -380,7 +380,8 @@ func TestNewStateNotFoundError(t *testing.T) {
 
 func TestStateBySlot_FutureSlot(t *testing.T) {
 	slot := types.Slot(100)
-	p := StateProvider{GenesisTimeFetcher: &chainMock.ChainService{Slot: &slot}}
+	clock := NewMockClock(time.Now(), slot)
+	p := StateProvider{ClockProvider: &chainMock.ChainService{Clock: clock}}
 	_, err := p.StateBySlot(context.Background(), 101)
 	assert.ErrorContains(t, "requested slot is in the future", err)
 }
@@ -389,8 +390,17 @@ func TestStateBySlot_AfterHeadSlot(t *testing.T) {
 	st, err := statenative.InitializeFromProtoPhase0(&ethpb.BeaconState{Slot: 100})
 	require.NoError(t, err)
 	currentSlot := types.Slot(102)
-	mock := &chainMock.ChainService{State: st, Slot: &currentSlot}
-	p := StateProvider{ChainInfoFetcher: mock, GenesisTimeFetcher: mock}
+	clock := NewMockClock(time.Now(), currentSlot)
+	mock := &chainMock.ChainService{State: st, Slot: &currentSlot, Clock: clock}
+	p := StateProvider{ChainInfoFetcher: mock, ClockProvider: mock}
 	_, err = p.StateBySlot(context.Background(), 101)
 	assert.ErrorContains(t, "requested slot number is higher than head slot number", err)
 }
+
+func NewMockClock(now time.Time, slotsAfterGenesis types.Slot) blockchain.Clock {
+	offset := uint64(slotsAfterGenesis) * params.BeaconConfig().SecondsPerSlot
+	genesis := now.Add(-1 * time.Second * time.Duration(offset))
+	return blockchain.NewClock(genesis, blockchain.WithNow(func() time.Time {
+		return genesis
+	}))
+}

beacon-chain/rpc/testutil/BUILD.bazel

@@ -4,7 +4,6 @@ go_library(
     name = "go_default_library",
     testonly = True,
     srcs = [
-        "mock_genesis_timefetcher.go",
         "mock_powchain_info_fetcher.go",
         "mock_state_fetcher.go",
     ],
@@ -12,7 +11,6 @@ go_library(
     visibility = ["//beacon-chain:__subpackages__"],
     deps = [
         "//beacon-chain/state:go_default_library",
-        "//config/params:go_default_library",
         "//consensus-types/primitives:go_default_library",
     ],
 )

beacon-chain/rpc/testutil/mock_genesis_timefetcher.go

@@ -1,21 +0,0 @@
-package testutil
-
-import (
-	"time"
-
-	"github.com/prysmaticlabs/prysm/config/params"
-	types "github.com/prysmaticlabs/prysm/consensus-types/primitives"
-)
-
-// MockGenesisTimeFetcher is a fake implementation of the blockchain.TimeFetcher
-type MockGenesisTimeFetcher struct {
-	Genesis time.Time
-}
-
-func (m *MockGenesisTimeFetcher) GenesisTime() time.Time {
-	return m.Genesis
-}
-
-func (m *MockGenesisTimeFetcher) CurrentSlot() types.Slot {
-	return types.Slot(uint64(time.Now().Unix()-m.Genesis.Unix()) / params.BeaconConfig().SecondsPerSlot)
-}

beacon-chain/state/stategen/BUILD.bazel

@@ -26,6 +26,7 @@ go_library(
         "//beacon-chain/core/transition:go_default_library",
         "//beacon-chain/db:go_default_library",
         "//beacon-chain/db/filters:go_default_library",
+        "//beacon-chain/forkchoice/types:go_default_library",
         "//beacon-chain/state:go_default_library",
         "//beacon-chain/sync/backfill:go_default_library",
         "//cache/lru:go_default_library",
@@ -70,6 +71,7 @@ go_test(
         "//beacon-chain/core/transition:go_default_library",
         "//beacon-chain/db:go_default_library",
         "//beacon-chain/db/testing:go_default_library",
+        "//beacon-chain/forkchoice/types:go_default_library",
         "//beacon-chain/state:go_default_library",
         "//beacon-chain/state/v1:go_default_library",
         "//config/params:go_default_library",

beacon-chain/state/stategen/getter.go

@@ -17,7 +17,7 @@ var ErrNoDataForSlot = errors.New("cannot retrieve data for slot")
 
 // HasState returns true if the state exists in cache or in DB.
 func (s *State) HasState(ctx context.Context, blockRoot [32]byte) (bool, error) {
-	has, err := s.HasStateInCache(ctx, blockRoot)
+	has, err := s.hasStateInCache(ctx, blockRoot)
 	if err != nil {
 		return false, err
 	}
@@ -27,8 +27,8 @@ func (s *State) HasState(ctx context.Context, blockRoot [32]byte) (bool, error)
 	return s.beaconDB.HasState(ctx, blockRoot), nil
 }
 
-// HasStateInCache returns true if the state exists in cache.
-func (s *State) HasStateInCache(_ context.Context, blockRoot [32]byte) (bool, error) {
+// hasStateInCache returns true if the state exists in cache.
+func (s *State) hasStateInCache(_ context.Context, blockRoot [32]byte) (bool, error) {
 	if s.hotStateCache.has(blockRoot) {
 		return true, nil
 	}
@@ -87,7 +87,7 @@ func (s *State) StateByRootInitialSync(ctx context.Context, blockRoot [32]byte)
 		return cachedInfo.state, nil
 	}
 
-	startState, err := s.LastAncestorState(ctx, blockRoot)
+	startState, err := s.latestAncestor(ctx, blockRoot)
 	if err != nil {
 		return nil, errors.Wrap(err, "could not get ancestor state")
 	}
@@ -102,11 +102,11 @@ func (s *State) StateByRootInitialSync(ctx context.Context, blockRoot [32]byte)
 		return startState, nil
 	}
 
-	blks, err := s.LoadBlocks(ctx, startState.Slot()+1, summary.Slot, bytesutil.ToBytes32(summary.Root))
+	blks, err := s.loadBlocks(ctx, startState.Slot()+1, summary.Slot, bytesutil.ToBytes32(summary.Root))
 	if err != nil {
 		return nil, errors.Wrap(err, "could not load blocks")
 	}
-	startState, err = s.ReplayBlocks(ctx, startState, blks, summary.Slot)
+	startState, err = s.replayBlocks(ctx, startState, blks, summary.Slot)
 	if err != nil {
 		return nil, errors.Wrap(err, "could not replay blocks")
 	}
@@ -125,13 +125,13 @@ func (s *State) stateSummary(ctx context.Context, blockRoot [32]byte) (*ethpb.St
 	}
 
 	if summary == nil {
-		return s.RecoverStateSummary(ctx, blockRoot)
+		return s.recoverStateSummary(ctx, blockRoot)
 	}
 	return summary, nil
 }
 
 // RecoverStateSummary recovers state summary object of a given block root by using the saved block in DB.
-func (s *State) RecoverStateSummary(ctx context.Context, blockRoot [32]byte) (*ethpb.StateSummary, error) {
+func (s *State) recoverStateSummary(ctx context.Context, blockRoot [32]byte) (*ethpb.StateSummary, error) {
 	if s.beaconDB.HasBlock(ctx, blockRoot) {
 		b, err := s.beaconDB.Block(ctx, blockRoot)
 		if err != nil {
@@ -185,7 +185,7 @@ func (s *State) loadStateByRoot(ctx context.Context, blockRoot [32]byte) (state.
 
 	// Since the requested state is not in caches or DB, start replaying using the last
 	// available ancestor state which is retrieved using input block's root.
-	startState, err := s.LastAncestorState(ctx, blockRoot)
+	startState, err := s.latestAncestor(ctx, blockRoot)
 	if err != nil {
 		return nil, errors.Wrap(err, "could not get ancestor state")
 	}
@@ -197,17 +197,17 @@ func (s *State) loadStateByRoot(ctx context.Context, blockRoot [32]byte) (state.
 		return startState, nil
 	}
 
-	blks, err := s.LoadBlocks(ctx, startState.Slot()+1, targetSlot, bytesutil.ToBytes32(summary.Root))
+	blks, err := s.loadBlocks(ctx, startState.Slot()+1, targetSlot, bytesutil.ToBytes32(summary.Root))
 	if err != nil {
 		return nil, errors.Wrap(err, "could not load blocks for hot state using root")
 	}
 
 	replayBlockCount.Observe(float64(len(blks)))
 
-	return s.ReplayBlocks(ctx, startState, blks, targetSlot)
+	return s.replayBlocks(ctx, startState, blks, targetSlot)
 }
 
-// LastAncestorState returns the highest available ancestor state of the input block root.
+// latestAncestor returns the highest available ancestor state of the input block root.
 // It recursively looks up block's parent until a corresponding state of the block root
 // is found in the caches or DB.
 //
@@ -215,8 +215,8 @@ func (s *State) loadStateByRoot(ctx context.Context, blockRoot [32]byte) (state.
 // 1) block parent state is the last finalized state
 // 2) block parent state is the epoch boundary state and exists in epoch boundary cache
 // 3) block parent state is in DB
-func (s *State) LastAncestorState(ctx context.Context, blockRoot [32]byte) (state.BeaconState, error) {
-	ctx, span := trace.StartSpan(ctx, "stateGen.LastAncestorState")
+func (s *State) latestAncestor(ctx context.Context, blockRoot [32]byte) (state.BeaconState, error) {
+	ctx, span := trace.StartSpan(ctx, "stateGen.latestAncestor")
 	defer span.End()
 
 	if s.isFinalizedRoot(blockRoot) && s.finalizedState() != nil {

beacon-chain/state/stategen/getter_test.go

@@ -385,7 +385,7 @@ func TestLastAncestorState_CanGetUsingDB(t *testing.T) {
 	util.SaveBlock(t, ctx, service.beaconDB, b3)
 	require.NoError(t, service.beaconDB.SaveState(ctx, b1State, r1))
 
-	lastState, err := service.LastAncestorState(ctx, r3)
+	lastState, err := service.latestAncestor(ctx, r3)
 	require.NoError(t, err)
 	assert.Equal(t, b1State.Slot(), lastState.Slot(), "Did not get wanted state")
 }
@@ -425,7 +425,7 @@ func TestLastAncestorState_CanGetUsingCache(t *testing.T) {
 	util.SaveBlock(t, ctx, service.beaconDB, b3)
 	service.hotStateCache.put(r1, b1State)
 
-	lastState, err := service.LastAncestorState(ctx, r3)
+	lastState, err := service.latestAncestor(ctx, r3)
 	require.NoError(t, err)
 	assert.Equal(t, b1State.Slot(), lastState.Slot(), "Did not get wanted state")
 }
@@ -483,7 +483,7 @@ func TestState_HasStateInCache(t *testing.T) {
 		{rMiss, false},
 	}
 	for _, tc := range tt {
-		got, err := service.HasStateInCache(ctx, tc.root)
+		got, err := service.hasStateInCache(ctx, tc.root)
 		require.NoError(t, err)
 		require.Equal(t, tc.want, got)
 	}

beacon-chain/state/stategen/mock/BUILD.bazel

@@ -12,8 +12,6 @@ go_library(
     deps = [
         "//beacon-chain/state:go_default_library",
         "//beacon-chain/state/stategen:go_default_library",
-        "//consensus-types/interfaces:go_default_library",
         "//consensus-types/primitives:go_default_library",
-        "//proto/prysm/v1alpha1:go_default_library",
     ],
 )

beacon-chain/state/stategen/mock/mock.go

@@ -4,9 +4,7 @@ import (
 	"context"
 
 	"github.com/prysmaticlabs/prysm/beacon-chain/state"
-	"github.com/prysmaticlabs/prysm/consensus-types/interfaces"
 	types "github.com/prysmaticlabs/prysm/consensus-types/primitives"
-	ethpb "github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1"
 )
 
 // MockStateManager is a fake implementation of StateManager.
@@ -43,35 +41,11 @@ func (_ *MockStateManager) MigrateToCold(_ context.Context, _ [32]byte) error {
 	panic("implement me")
 }
 
-// ReplayBlocks --
-func (_ *MockStateManager) ReplayBlocks(
-	_ context.Context,
-	_ state.BeaconState,
-	_ []interfaces.SignedBeaconBlock,
-	_ types.Slot,
-) (state.BeaconState, error) {
-	panic("implement me")
-}
-
-// LoadBlocks --
-func (_ *MockStateManager) LoadBlocks(
-	_ context.Context,
-	_, _ types.Slot,
-	_ [32]byte,
-) ([]interfaces.SignedBeaconBlock, error) {
-	panic("implement me")
-}
-
 // HasState --
 func (_ *MockStateManager) HasState(_ context.Context, _ [32]byte) (bool, error) {
 	panic("implement me")
 }
 
-// HasStateInCache --
-func (_ *MockStateManager) HasStateInCache(_ context.Context, _ [32]byte) (bool, error) {
-	panic("implement me")
-}
-
 // StateByRoot --
 func (m *MockStateManager) StateByRoot(_ context.Context, blockRoot [32]byte) (state.BeaconState, error) {
 	return m.StatesByRoot[blockRoot], nil
@@ -87,14 +61,6 @@ func (m *MockStateManager) StateBySlot(_ context.Context, slot types.Slot) (stat
 	return m.StatesBySlot[slot], nil
 }
 
-// RecoverStateSummary --
-func (_ *MockStateManager) RecoverStateSummary(
-	_ context.Context,
-	_ [32]byte,
-) (*ethpb.StateSummary, error) {
-	panic("implement me")
-}
-
 // SaveState --
 func (_ *MockStateManager) SaveState(_ context.Context, _ [32]byte, _ state.BeaconState) error {
 	panic("implement me")
@@ -105,16 +71,6 @@ func (_ *MockStateManager) ForceCheckpoint(_ context.Context, _ []byte) error {
 	panic("implement me")
 }
 
-// EnableSaveHotStateToDB --
-func (_ *MockStateManager) EnableSaveHotStateToDB(_ context.Context) {
-	panic("implement me")
-}
-
-// DisableSaveHotStateToDB --
-func (_ *MockStateManager) DisableSaveHotStateToDB(_ context.Context) error {
-	panic("implement me")
-}
-
 // AddStateForRoot --
 func (m *MockStateManager) AddStateForRoot(state state.BeaconState, blockRoot [32]byte) {
 	m.StatesByRoot[blockRoot] = state

beacon-chain/state/stategen/replay.go

@@ -25,13 +25,13 @@ import (
 // ReplayBlocks replays the input blocks on the input state until the target slot is reached.
 //
 // WARNING Blocks passed to the function must be in decreasing slots order.
-func (_ *State) ReplayBlocks(
+func (_ *State) replayBlocks(
 	ctx context.Context,
 	state state.BeaconState,
 	signed []interfaces.SignedBeaconBlock,
 	targetSlot types.Slot,
 ) (state.BeaconState, error) {
-	ctx, span := trace.StartSpan(ctx, "stateGen.ReplayBlocks")
+	ctx, span := trace.StartSpan(ctx, "stateGen.replayBlocks")
 	defer span.End()
 	var err error
 
@@ -77,9 +77,9 @@ func (_ *State) ReplayBlocks(
 	return state, nil
 }
 
-// LoadBlocks loads the blocks between start slot and end slot by recursively fetching from end block root.
+// loadBlocks loads the blocks between start slot and end slot by recursively fetching from end block root.
 // The Blocks are returned in slot-descending order.
-func (s *State) LoadBlocks(ctx context.Context, startSlot, endSlot types.Slot, endBlockRoot [32]byte) ([]interfaces.SignedBeaconBlock, error) {
+func (s *State) loadBlocks(ctx context.Context, startSlot, endSlot types.Slot, endBlockRoot [32]byte) ([]interfaces.SignedBeaconBlock, error) {
 	// Nothing to load for invalid range.
 	if endSlot < startSlot {
 		return nil, fmt.Errorf("start slot %d >= end slot %d", startSlot, endSlot)

beacon-chain/state/stategen/replay_test.go

@@ -43,7 +43,7 @@ func TestReplayBlocks_AllSkipSlots(t *testing.T) {
 
 	service := New(beaconDB)
 	targetSlot := params.BeaconConfig().SlotsPerEpoch - 1
-	newState, err := service.ReplayBlocks(context.Background(), beaconState, []interfaces.SignedBeaconBlock{}, targetSlot)
+	newState, err := service.replayBlocks(context.Background(), beaconState, []interfaces.SignedBeaconBlock{}, targetSlot)
 	require.NoError(t, err)
 	assert.Equal(t, targetSlot, newState.Slot(), "Did not advance slots")
 }
@@ -72,7 +72,7 @@ func TestReplayBlocks_SameSlot(t *testing.T) {
 
 	service := New(beaconDB)
 	targetSlot := beaconState.Slot()
-	newState, err := service.ReplayBlocks(context.Background(), beaconState, []interfaces.SignedBeaconBlock{}, targetSlot)
+	newState, err := service.replayBlocks(context.Background(), beaconState, []interfaces.SignedBeaconBlock{}, targetSlot)
 	require.NoError(t, err)
 	assert.Equal(t, targetSlot, newState.Slot(), "Did not advance slots")
 }
@@ -106,7 +106,7 @@ func TestReplayBlocks_LowerSlotBlock(t *testing.T) {
 	b.Block.Slot = beaconState.Slot() - 1
 	wsb, err := wrapper.WrappedSignedBeaconBlock(b)
 	require.NoError(t, err)
-	newState, err := service.ReplayBlocks(context.Background(), beaconState, []interfaces.SignedBeaconBlock{wsb}, targetSlot)
+	newState, err := service.replayBlocks(context.Background(), beaconState, []interfaces.SignedBeaconBlock{wsb}, targetSlot)
 	require.NoError(t, err)
 	assert.Equal(t, targetSlot, newState.Slot(), "Did not advance slots")
 }
@@ -132,7 +132,7 @@ func TestReplayBlocks_ThroughForkBoundary(t *testing.T) {
 
 	service := New(testDB.SetupDB(t))
 	targetSlot := params.BeaconConfig().SlotsPerEpoch
-	newState, err := service.ReplayBlocks(context.Background(), beaconState, []interfaces.SignedBeaconBlock{}, targetSlot)
+	newState, err := service.replayBlocks(context.Background(), beaconState, []interfaces.SignedBeaconBlock{}, targetSlot)
 	require.NoError(t, err)
 
 	// Verify state is version Altair.
@@ -162,7 +162,7 @@ func TestReplayBlocks_ThroughBellatrixForkBoundary(t *testing.T) {
 
 	service := New(testDB.SetupDB(t))
 	targetSlot := params.BeaconConfig().SlotsPerEpoch * 2
-	newState, err := service.ReplayBlocks(context.Background(), beaconState, []interfaces.SignedBeaconBlock{}, targetSlot)
+	newState, err := service.replayBlocks(context.Background(), beaconState, []interfaces.SignedBeaconBlock{}, targetSlot)
 	require.NoError(t, err)
 
 	// Verify state is version Altair.
@@ -179,7 +179,7 @@ func TestLoadBlocks_FirstBranch(t *testing.T) {
 	roots, savedBlocks, err := tree1(t, beaconDB, bytesutil.PadTo([]byte{'A'}, 32))
 	require.NoError(t, err)
 
-	filteredBlocks, err := s.LoadBlocks(ctx, 0, 8, roots[len(roots)-1])
+	filteredBlocks, err := s.loadBlocks(ctx, 0, 8, roots[len(roots)-1])
 	require.NoError(t, err)
 
 	wanted := []*ethpb.SignedBeaconBlock{
@@ -208,7 +208,7 @@ func TestLoadBlocks_SecondBranch(t *testing.T) {
 	roots, savedBlocks, err := tree1(t, beaconDB, bytesutil.PadTo([]byte{'A'}, 32))
 	require.NoError(t, err)
 
-	filteredBlocks, err := s.LoadBlocks(ctx, 0, 5, roots[5])
+	filteredBlocks, err := s.loadBlocks(ctx, 0, 5, roots[5])
 	require.NoError(t, err)
 
 	wanted := []*ethpb.SignedBeaconBlock{
@@ -235,7 +235,7 @@ func TestLoadBlocks_ThirdBranch(t *testing.T) {
 	roots, savedBlocks, err := tree1(t, beaconDB, bytesutil.PadTo([]byte{'A'}, 32))
 	require.NoError(t, err)
 
-	filteredBlocks, err := s.LoadBlocks(ctx, 0, 7, roots[7])
+	filteredBlocks, err := s.loadBlocks(ctx, 0, 7, roots[7])
 	require.NoError(t, err)
 
 	wanted := []*ethpb.SignedBeaconBlock{
@@ -264,7 +264,7 @@ func TestLoadBlocks_SameSlots(t *testing.T) {
 	roots, savedBlocks, err := tree2(t, beaconDB, bytesutil.PadTo([]byte{'A'}, 32))
 	require.NoError(t, err)
 
-	filteredBlocks, err := s.LoadBlocks(ctx, 0, 3, roots[6])
+	filteredBlocks, err := s.loadBlocks(ctx, 0, 3, roots[6])
 	require.NoError(t, err)
 
 	wanted := []*ethpb.SignedBeaconBlock{
@@ -291,7 +291,7 @@ func TestLoadBlocks_SameEndSlots(t *testing.T) {
 	roots, savedBlocks, err := tree3(t, beaconDB, bytesutil.PadTo([]byte{'A'}, 32))
 	require.NoError(t, err)
 
-	filteredBlocks, err := s.LoadBlocks(ctx, 0, 2, roots[2])
+	filteredBlocks, err := s.loadBlocks(ctx, 0, 2, roots[2])
 	require.NoError(t, err)
 
 	wanted := []*ethpb.SignedBeaconBlock{
@@ -317,7 +317,7 @@ func TestLoadBlocks_SameEndSlotsWith2blocks(t *testing.T) {
 	roots, savedBlocks, err := tree4(t, beaconDB, bytesutil.PadTo([]byte{'A'}, 32))
 	require.NoError(t, err)
 
-	filteredBlocks, err := s.LoadBlocks(ctx, 0, 2, roots[1])
+	filteredBlocks, err := s.loadBlocks(ctx, 0, 2, roots[1])
 	require.NoError(t, err)
 
 	wanted := []*ethpb.SignedBeaconBlock{
@@ -341,7 +341,7 @@ func TestLoadBlocks_BadStart(t *testing.T) {
 
 	roots, _, err := tree1(t, beaconDB, bytesutil.PadTo([]byte{'A'}, 32))
 	require.NoError(t, err)
-	_, err = s.LoadBlocks(ctx, 0, 5, roots[8])
+	_, err = s.loadBlocks(ctx, 0, 5, roots[8])
 	assert.ErrorContains(t, "end block roots don't match", err)
 }
 

beacon-chain/state/stategen/replayer.go

@@ -173,3 +173,10 @@ type ReplayerBuilder interface {
 	// slots via process_slots.
 	ReplayerForSlot(target types.Slot) Replayer
 }
+
+// ReplayerBuiilderWaiter is designed for situations where services need to start up before it is possible to init
+// a ReplayerBuilder. When WaitForReplayerBuilder is called,
+// it will block until prerequisites for a replayer are available, or the parent context is canceled.
+type CanonicalHistoryWaiter interface {
+	WaitForCanonicalHistory(context.Context) (*CanonicalHistory, error)
+}

beacon-chain/state/stategen/service.go

@@ -6,16 +6,15 @@ package stategen
 import (
 	"context"
 	"errors"
+	forkchoicetypes "github.com/prysmaticlabs/prysm/beacon-chain/forkchoice/types"
 	"sync"
 
 	"github.com/prysmaticlabs/prysm/beacon-chain/db"
 	"github.com/prysmaticlabs/prysm/beacon-chain/state"
 	"github.com/prysmaticlabs/prysm/beacon-chain/sync/backfill"
 	"github.com/prysmaticlabs/prysm/config/params"
-	"github.com/prysmaticlabs/prysm/consensus-types/interfaces"
 	types "github.com/prysmaticlabs/prysm/consensus-types/primitives"
 	"github.com/prysmaticlabs/prysm/encoding/bytesutil"
-	ethpb "github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1"
 	"go.opencensus.io/trace"
 )
 
@@ -25,21 +24,15 @@ var defaultHotStateDBInterval types.Slot = 128
 // logic of maintaining both hot and cold states in DB.
 type StateManager interface {
 	Resume(ctx context.Context, fState state.BeaconState) (state.BeaconState, error)
+	HasState(ctx context.Context, blockRoot [32]byte) (bool, error)
+	DeleteStateFromCaches(ctx context.Context, blockRoot [32]byte) error
+	ForceCheckpoint(ctx context.Context, root []byte) error
+	SaveState(ctx context.Context, blockRoot [32]byte, st state.BeaconState) error
 	SaveFinalizedState(fSlot types.Slot, fRoot [32]byte, fState state.BeaconState)
 	MigrateToCold(ctx context.Context, fRoot [32]byte) error
-	ReplayBlocks(ctx context.Context, state state.BeaconState, signed []interfaces.SignedBeaconBlock, targetSlot types.Slot) (state.BeaconState, error)
-	LoadBlocks(ctx context.Context, startSlot, endSlot types.Slot, endBlockRoot [32]byte) ([]interfaces.SignedBeaconBlock, error)
-	HasState(ctx context.Context, blockRoot [32]byte) (bool, error)
-	HasStateInCache(ctx context.Context, blockRoot [32]byte) (bool, error)
 	StateByRoot(ctx context.Context, blockRoot [32]byte) (state.BeaconState, error)
 	StateByRootIfCachedNoCopy(blockRoot [32]byte) state.BeaconState
 	StateByRootInitialSync(ctx context.Context, blockRoot [32]byte) (state.BeaconState, error)
-	RecoverStateSummary(ctx context.Context, blockRoot [32]byte) (*ethpb.StateSummary, error)
-	SaveState(ctx context.Context, blockRoot [32]byte, st state.BeaconState) error
-	ForceCheckpoint(ctx context.Context, root []byte) error
-	EnableSaveHotStateToDB(_ context.Context)
-	DisableSaveHotStateToDB(ctx context.Context) error
-	DeleteStateFromCaches(ctx context.Context, blockRoot [32]byte) error
 }
 
 // State is a concrete implementation of StateManager.
@@ -51,6 +44,12 @@ type State struct {
 	epochBoundaryStateCache *epochBoundaryState
 	saveHotStateDB          *saveHotStateDbConfig
 	backfillStatus          *backfill.Status
+	fc minimumForkChoicer
+	cs CurrentSlotter
+}
+
+type minimumForkChoicer interface {
+	FinalizedCheckpoint() *forkchoicetypes.Checkpoint
 }
 
 // This tracks the config in the event of long non-finality,
@@ -81,6 +80,18 @@ func WithBackfillStatus(bfs *backfill.Status) StateGenOption {
 	}
 }
 
+func WithMinimumForkChoicer(fc minimumForkChoicer) StateGenOption {
+	return func(sg *State) {
+		sg.fc = fc
+	}
+}
+
+func WithCurrentSlotter(cs CurrentSlotter) StateGenOption {
+	return func(sg *State) {
+		sg.cs = cs
+	}
+}
+
 // New returns a new state management object.
 func New(beaconDB db.NoHeadAccessDatabase, opts ...StateGenOption) *State {
 	s := &State{

beacon-chain/state/stategen/setter.go

@@ -2,6 +2,8 @@ package stategen
 
 import (
 	"context"
+	"github.com/pkg/errors"
+	types "github.com/prysmaticlabs/prysm/consensus-types/primitives"
 	"math"
 
 	"github.com/prysmaticlabs/prysm/beacon-chain/state"
@@ -13,12 +15,38 @@ import (
 	"go.opencensus.io/trace"
 )
 
+
+var errForkChoiceFinalizedNil = errors.New("nil finalized checkpoint returned from forkchoice store")
+
+// number of epochs of non-finality before the hot state store will begin saving snapshots for faster recovery.
+var hotStateSaveThreshold = types.Epoch(100)
+
 // SaveState saves the state in the cache and/or DB.
 func (s *State) SaveState(ctx context.Context, blockRoot [32]byte, st state.BeaconState) error {
 	ctx, span := trace.StartSpan(ctx, "stateGen.SaveState")
 	defer span.End()
 
-	return s.saveStateByRoot(ctx, blockRoot, st)
+	if err := s.saveStateByRoot(ctx, blockRoot, st); err != nil {
+		return err
+	}
+	return s.toggleHotStateSaving(ctx)
+}
+
+func (s *State) toggleHotStateSaving(ctx context.Context) error {
+	finalized := s.fc.FinalizedCheckpoint()
+	if finalized == nil {
+		return errForkChoiceFinalizedNil
+	}
+
+	currentEpoch := slots.ToEpoch(s.cs.CurrentSlot())
+	if currentEpoch > finalized.Epoch {
+		if currentEpoch - finalized.Epoch > hotStateSaveThreshold {
+			s.EnableSaveHotStateToDB(ctx)
+			return nil
+		}
+	}
+
+	return s.DisableSaveHotStateToDB(ctx)
 }
 
 // ForceCheckpoint initiates a cold state save of the given block root's state. This method does not update the

beacon-chain/state/stategen/setter_test.go

@@ -2,14 +2,14 @@ package stategen
 
 import (
 	"context"
-	"testing"
-
 	testDB "github.com/prysmaticlabs/prysm/beacon-chain/db/testing"
+	forkchoicetypes "github.com/prysmaticlabs/prysm/beacon-chain/forkchoice/types"
 	"github.com/prysmaticlabs/prysm/config/params"
 	"github.com/prysmaticlabs/prysm/testing/assert"
 	"github.com/prysmaticlabs/prysm/testing/require"
 	"github.com/prysmaticlabs/prysm/testing/util"
 	logTest "github.com/sirupsen/logrus/hooks/test"
+	"testing"
 )
 
 func TestSaveState_HotStateCanBeSaved(t *testing.T) {
@@ -201,3 +201,28 @@ func TestEnableSaveHotStateToDB_AlreadyDisabled(t *testing.T) {
 	require.LogsDoNotContain(t, hook, "Exiting mode to save hot states in DB")
 	require.Equal(t, false, service.saveHotStateDB.enabled)
 }
+
+type mockMinForkChoicer struct {
+	finalizedCheckpoint *forkchoicetypes.Checkpoint
+}
+
+var _ minimumForkChoicer = &mockMinForkChoicer{}
+
+func (fc *mockMinForkChoicer) FinalizedCheckpoint() *forkchoicetypes.Checkpoint {
+	return fc.finalizedCheckpoint
+}
+
+func TestCheckSaveHotStateDB_EnableDisable(t *testing.T) {
+	beaconDB := testDB.SetupDB(t)
+	service := New(beaconDB)
+	// the zero value will return a finalized checkpoint at slot 0 with zero-value for root - this is fine!
+	service.fc = &mockMinForkChoicer{}
+	// set current slot as over the threshhold for hot state to be enabled
+	service.cs = &mockCurrentSlotter{Slot: params.BeaconConfig().SlotsPerEpoch.Mul(uint64(hotStateSaveThreshold))}
+
+	require.NoError(t, service.toggleHotStateSaving(context.Background()))
+	require.Equal(t, true, service.saveHotStateDB.enabled)
+	// set the finalized checkpoint to the same slot as the current slotter, assert that hot state saving is now disabled
+	service.fc = &mockMinForkChoicer{finalizedCheckpoint: &forkchoicetypes.Checkpoint{Epoch: hotStateSaveThreshold}}
+	require.Equal(t, false, service.saveHotStateDB.enabled)
+}

beacon-chain/sync/fork_watcher.go

@@ -12,7 +12,11 @@ import (
 // Is a background routine that observes for new incoming forks. Depending on the epoch
 // it will be in charge of subscribing/unsubscribing the relevant topics at the fork boundaries.
 func (s *Service) forkWatcher() {
-	slotTicker := slots.NewSlotTicker(s.cfg.chain.GenesisTime(), params.BeaconConfig().SecondsPerSlot)
+	clock, err := s.cfg.chain.WaitForClock(s.ctx)
+	if err != nil {
+		log.WithError(err).Error("timeout waiting for genesis time in forkWatcher()")
+	}
+	slotTicker := slots.NewSlotTicker(clock.GenesisTime(), params.BeaconConfig().SecondsPerSlot)
 	for {
 		select {
 		// In the event of a node restart, we will still end up subscribing to the correct
@@ -40,7 +44,11 @@ func (s *Service) forkWatcher() {
 // it registers the appropriate gossip and rpc topics.
 func (s *Service) registerForUpcomingFork(currEpoch types.Epoch) error {
 	genRoot := s.cfg.chain.GenesisValidatorsRoot()
-	isNextForkEpoch, err := forks.IsForkNextEpoch(s.cfg.chain.GenesisTime(), genRoot[:])
+	clock, err := s.cfg.chain.WaitForClock(s.ctx)
+	if err != nil {
+		return errors.Wrap(err, "timeout waiting for genesis time in registerForUpcomingFork")
+	}
+	isNextForkEpoch, err := forks.IsForkNextEpoch(clock.GenesisTime(), genRoot[:])
 	if err != nil {
 		return errors.Wrap(err, "Could not retrieve next fork epoch")
 	}

beacon-chain/sync/metrics.go

@@ -2,6 +2,7 @@ package sync
 
 import (
 	"fmt"
+	"github.com/prysmaticlabs/prysm/async"
 	"reflect"
 	"strings"
 
@@ -91,57 +92,61 @@ var (
 	)
 )
 
-func (s *Service) updateMetrics() {
-	// do not update metrics if genesis time
-	// has not been initialized
-	if s.cfg.chain.GenesisTime().IsZero() {
+func (s *Service) spawnUpdateMetrics() {
+	// do not update metrics if genesis time has not been initialized
+	c, err := s.cfg.chain.WaitForClock(s.ctx)
+	if err != nil {
+		log.WithError(err).Error("timeout while waiting for geenesis time in spawnUpdateMetrics")
 		return
 	}
-	// We update the dynamic subnet topics.
-	digest, err := s.currentForkDigest()
-	if err != nil {
-		log.WithError(err).Debugf("Could not compute fork digest")
-	}
-	indices := s.aggregatorSubnetIndices(s.cfg.chain.CurrentSlot())
-	syncIndices := cache.SyncSubnetIDs.GetAllSubnets(slots.ToEpoch(s.cfg.chain.CurrentSlot()))
-	attTopic := p2p.GossipTypeMapping[reflect.TypeOf(&pb.Attestation{})]
-	syncTopic := p2p.GossipTypeMapping[reflect.TypeOf(&pb.SyncCommitteeMessage{})]
-	attTopic += s.cfg.p2p.Encoding().ProtocolSuffix()
-	syncTopic += s.cfg.p2p.Encoding().ProtocolSuffix()
-	if flags.Get().SubscribeToAllSubnets {
-		for i := uint64(0); i < params.BeaconNetworkConfig().AttestationSubnetCount; i++ {
-			s.collectMetricForSubnet(attTopic, digest, i)
+	async.RunEvery(s.ctx, syncMetricsInterval, func() {
+		// We update the dynamic subnet topics.
+		digest, err := s.currentForkDigest()
+		if err != nil {
+			log.WithError(err).Debugf("Could not compute fork digest")
 		}
-		for i := uint64(0); i < params.BeaconConfig().SyncCommitteeSubnetCount; i++ {
-			s.collectMetricForSubnet(syncTopic, digest, i)
+		indices := s.aggregatorSubnetIndices(c.CurrentSlot())
+		syncIndices := cache.SyncSubnetIDs.GetAllSubnets(slots.ToEpoch(c.CurrentSlot()))
+		attTopic := p2p.GossipTypeMapping[reflect.TypeOf(&pb.Attestation{})]
+		syncTopic := p2p.GossipTypeMapping[reflect.TypeOf(&pb.SyncCommitteeMessage{})]
+		attTopic += s.cfg.p2p.Encoding().ProtocolSuffix()
+		syncTopic += s.cfg.p2p.Encoding().ProtocolSuffix()
+		if flags.Get().SubscribeToAllSubnets {
+			for i := uint64(0); i < params.BeaconNetworkConfig().AttestationSubnetCount; i++ {
+				s.collectMetricForSubnet(attTopic, digest, i)
+			}
+			for i := uint64(0); i < params.BeaconConfig().SyncCommitteeSubnetCount; i++ {
+				s.collectMetricForSubnet(syncTopic, digest, i)
+			}
+		} else {
+			for _, committeeIdx := range indices {
+				s.collectMetricForSubnet(attTopic, digest, committeeIdx)
+			}
+			for _, committeeIdx := range syncIndices {
+				s.collectMetricForSubnet(syncTopic, digest, committeeIdx)
+			}
 		}
-	} else {
-		for _, committeeIdx := range indices {
-			s.collectMetricForSubnet(attTopic, digest, committeeIdx)
-		}
-		for _, committeeIdx := range syncIndices {
-			s.collectMetricForSubnet(syncTopic, digest, committeeIdx)
-		}
-	}
 
-	// We update all other gossip topics.
-	for _, topic := range p2p.AllTopics() {
-		// We already updated attestation subnet topics.
-		if strings.Contains(topic, p2p.GossipAttestationMessage) || strings.Contains(topic, p2p.GossipSyncCommitteeMessage) {
-			continue
+		// We update all other gossip topics.
+		for _, topic := range p2p.AllTopics() {
+			// We already updated attestation subnet topics.
+			if strings.Contains(topic, p2p.GossipAttestationMessage) || strings.Contains(topic, p2p.GossipSyncCommitteeMessage) {
+				continue
+			}
+			topic += s.cfg.p2p.Encoding().ProtocolSuffix()
+			if !strings.Contains(topic, "%x") {
+				topicPeerCount.WithLabelValues(topic).Set(float64(len(s.cfg.p2p.PubSub().ListPeers(topic))))
+				continue
+			}
+			formattedTopic := fmt.Sprintf(topic, digest)
+			topicPeerCount.WithLabelValues(formattedTopic).Set(float64(len(s.cfg.p2p.PubSub().ListPeers(formattedTopic))))
 		}
-		topic += s.cfg.p2p.Encoding().ProtocolSuffix()
-		if !strings.Contains(topic, "%x") {
-			topicPeerCount.WithLabelValues(topic).Set(float64(len(s.cfg.p2p.PubSub().ListPeers(topic))))
-			continue
-		}
-		formattedTopic := fmt.Sprintf(topic, digest)
-		topicPeerCount.WithLabelValues(formattedTopic).Set(float64(len(s.cfg.p2p.PubSub().ListPeers(formattedTopic))))
-	}
 
-	for _, topic := range s.cfg.p2p.PubSub().GetTopics() {
-		subscribedTopicPeerCount.WithLabelValues(topic).Set(float64(len(s.cfg.p2p.PubSub().ListPeers(topic))))
-	}
+		for _, topic := range s.cfg.p2p.PubSub().GetTopics() {
+			subscribedTopicPeerCount.WithLabelValues(topic).Set(float64(len(s.cfg.p2p.PubSub().ListPeers(topic))))
+		}
+	})
+
 }
 
 func (s *Service) collectMetricForSubnet(topic string, digest [4]byte, index uint64) {

beacon-chain/sync/pending_attestations_queue.go

@@ -3,6 +3,7 @@ package sync
 import (
 	"context"
 	"encoding/hex"
+	"github.com/pkg/errors"
 	"sync"
 
 	pubsub "github.com/libp2p/go-libp2p-pubsub"
@@ -42,10 +43,14 @@ func (s *Service) processPendingAtts(ctx context.Context) error {
 	ctx, span := trace.StartSpan(ctx, "processPendingAtts")
 	defer span.End()
 
+	c, err := s.cfg.chain.WaitForClock(ctx)
+	if err != nil {
+		return errors.Wrap(err, "timeout while waiting for genesis timestamp")
+	}
 	// Before a node processes pending attestations queue, it verifies
 	// the attestations in the queue are still valid. Attestations will
 	// be deleted from the queue if invalid (ie. getting staled from falling too many slots behind).
-	s.validatePendingAtts(ctx, s.cfg.chain.CurrentSlot())
+	s.validatePendingAtts(ctx, c.CurrentSlot())
 
 	s.pendingAttsLock.RLock()
 	roots := make([][32]byte, 0, len(s.blkRootToPendingAtts))
@@ -75,7 +80,7 @@ func (s *Service) processPendingAtts(ctx context.Context) error {
 		} else {
 			// Pending attestation's missing block has not arrived yet.
 			log.WithFields(logrus.Fields{
-				"currentSlot": s.cfg.chain.CurrentSlot(),
+				"currentSlot": c.CurrentSlot(),
 				"attSlot":     attestations[0].Message.Aggregate.Data.Slot,
 				"attCount":    len(attestations),
 				"blockRoot":   hex.EncodeToString(bytesutil.Trunc(bRoot[:])),