Track optimistic status on head (#12552)

beacon-chain/blockchain/chain_info.go

@@ -340,7 +340,13 @@ func (s *Service) IsOptimistic(_ context.Context) (bool, error) {
 	}
 	s.headLock.RLock()
 	headRoot := s.head.root
+	headSlot := s.head.slot
+	headOptimistic := s.head.optimistic
 	s.headLock.RUnlock()
+	// we trust the head package for recent head slots, otherwise fallback to forkchoice
+	if headSlot+2 >= s.CurrentSlot() {
+		return headOptimistic, nil
+	}
 
 	s.cfg.ForkChoiceStore.RLock()
 	defer s.cfg.ForkChoiceStore.RUnlock()

beacon-chain/blockchain/chain_info_test.go

@@ -422,6 +422,12 @@ func TestService_IsOptimistic(t *testing.T) {
 
 	opt, err := c.IsOptimistic(ctx)
 	require.NoError(t, err)
+	require.Equal(t, primitives.Slot(0), c.CurrentSlot())
+	require.Equal(t, false, opt)
+
+	c.SetGenesisTime(time.Now().Add(-time.Second * time.Duration(4*params.BeaconConfig().SecondsPerSlot)))
+	opt, err = c.IsOptimistic(ctx)
+	require.NoError(t, err)
 	require.Equal(t, true, opt)
 }
 

beacon-chain/blockchain/head.go

@@ -47,9 +47,11 @@ func (s *Service) UpdateAndSaveHeadWithBalances(ctx context.Context) error {
 
 // This defines the current chain service's view of head.
 type head struct {
-	root  [32]byte                             // current head root.
-	block interfaces.ReadOnlySignedBeaconBlock // current head block.
-	state state.BeaconState                    // current head state.
+	root       [32]byte                             // current head root.
+	block      interfaces.ReadOnlySignedBeaconBlock // current head block.
+	state      state.BeaconState                    // current head state.
+	slot       primitives.Slot                      // the head block slot number
+	optimistic bool                                 // optimistic status when saved head
 }
 
 // This saves head info to the local service cache, it also saves the
@@ -94,6 +96,10 @@ func (s *Service) saveHead(ctx context.Context, newHeadRoot [32]byte, headBlock
 		return errors.Wrap(err, "could not get old head root")
 	}
 	oldHeadRoot := bytesutil.ToBytes32(r)
+	isOptimistic, err := s.cfg.ForkChoiceStore.IsOptimistic(newHeadRoot)
+	if err != nil {
+		log.WithError(err).Error("could not check if node is optimistically synced")
+	}
 	if headBlock.Block().ParentRoot() != oldHeadRoot {
 		// A chain re-org occurred, so we fire an event notifying the rest of the services.
 		commonRoot, forkSlot, err := s.cfg.ForkChoiceStore.CommonAncestor(ctx, oldHeadRoot, newHeadRoot)
@@ -125,10 +131,6 @@ func (s *Service) saveHead(ctx context.Context, newHeadRoot [32]byte, headBlock
 		reorgDistance.Observe(float64(dis))
 		reorgDepth.Observe(float64(dep))
 
-		isOptimistic, err := s.cfg.ForkChoiceStore.IsOptimistic(newHeadRoot)
-		if err != nil {
-			return errors.Wrap(err, "could not check if node is optimistically synced")
-		}
 		s.cfg.StateNotifier.StateFeed().Send(&feed.Event{
 			Type: statefeed.Reorg,
 			Data: &ethpbv1.EventChainReorg{
@@ -150,7 +152,14 @@ func (s *Service) saveHead(ctx context.Context, newHeadRoot [32]byte, headBlock
 	}
 
 	// Cache the new head info.
-	if err := s.setHead(newHeadRoot, headBlock, headState); err != nil {
+	newHead := &head{
+		root:       newHeadRoot,
+		block:      headBlock,
+		state:      headState,
+		optimistic: isOptimistic,
+		slot:       headBlock.Block().Slot(),
+	}
+	if err := s.setHead(newHead); err != nil {
 		return errors.Wrap(err, "could not set head")
 	}
 
@@ -195,20 +204,22 @@ func (s *Service) saveHeadNoDB(ctx context.Context, b interfaces.ReadOnlySignedB
 	return nil
 }
 
-// This sets head view object which is used to track the head slot, root, block and state.
-func (s *Service) setHead(root [32]byte, block interfaces.ReadOnlySignedBeaconBlock, state state.BeaconState) error {
+// This sets head view object which is used to track the head slot, root, block, state and optimistic status
+func (s *Service) setHead(newHead *head) error {
 	s.headLock.Lock()
 	defer s.headLock.Unlock()
 
 	// This does a full copy of the block and state.
-	bCp, err := block.Copy()
+	bCp, err := newHead.block.Copy()
 	if err != nil {
 		return err
 	}
 	s.head = &head{
-		root:  root,
-		block: bCp,
-		state: state.Copy(),
+		root:       newHead.root,
+		block:      bCp,
+		state:      newHead.state.Copy(),
+		optimistic: newHead.optimistic,
+		slot:       newHead.slot,
 	}
 	return nil
 }

beacon-chain/blockchain/service.go

@@ -308,7 +308,13 @@ func (s *Service) initializeHeadFromDB(ctx context.Context) error {
 	if err != nil {
 		return errors.Wrap(err, "could not get finalized block")
 	}
-	if err := s.setHead(finalizedRoot, finalizedBlock, finalizedState); err != nil {
+	if err := s.setHead(&head{
+		finalizedRoot,
+		finalizedBlock,
+		finalizedState,
+		finalizedBlock.Block().Slot(),
+		false,
+	}); err != nil {
 		return errors.Wrap(err, "could not set head")
 	}
 
@@ -440,7 +446,13 @@ func (s *Service) saveGenesisData(ctx context.Context, genesisState state.Beacon
 	}
 	s.cfg.ForkChoiceStore.SetGenesisTime(uint64(s.genesisTime.Unix()))
 
-	if err := s.setHead(genesisBlkRoot, genesisBlk, genesisState); err != nil {
+	if err := s.setHead(&head{
+		genesisBlkRoot,
+		genesisBlk,
+		genesisState,
+		genesisBlk.Block().Slot(),
+		false,
+	}); err != nil {
 		log.WithError(err).Fatal("Could not set head")
 	}
 	return nil