Cache filtered block tree (#4515)

* Cache filtered block tree
* Merge refs/heads/master into cache-filtered-tree
* Merge refs/heads/master into cache-filtered-tree
* Add locks
* Merge branch 'cache-filtered-tree' of git+ssh://github.com/prysmaticlabs/prysm into cache-filtered-tree
* Confligt
* Merge refs/heads/master into cache-filtered-tree
* Merge refs/heads/master into cache-filtered-tree
* Update shared/featureconfig/flags.go

Co-Authored-By: Preston Van Loon <preston@prysmaticlabs.com>
* Rlock
* Merge branch 'master' of git+ssh://github.com/prysmaticlabs/prysm into cache-filtered-tree
* Merge branch 'cache-filtered-tree' of git+ssh://github.com/prysmaticlabs/prysm into cache-filtered-tree

beacon-chain/blockchain/forkchoice/process_block.go

@@ -93,6 +93,16 @@ func (s *Store) OnBlock(ctx context.Context, signed *ethpb.SignedBeaconBlock) er
 		return errors.Wrap(err, "could not save state")
 	}
 
+	if featureconfig.Get().EnableBlockTreeCache {
+		tree, err := s.getFilterBlockTree(ctx)
+		if err != nil {
+			return errors.Wrap(err, "could not calculate filtered block tree")
+		}
+		s.filteredBlockTreeLock.Lock()
+		s.filteredBlockTree = tree
+		s.filteredBlockTreeLock.Unlock()
+	}
+
 	// Update justified check point.
 	if postState.CurrentJustifiedCheckpoint.Epoch > s.justifiedCheckpt.Epoch {
 		if err := s.updateJustified(ctx, postState); err != nil {

beacon-chain/blockchain/forkchoice/service.go

@@ -52,6 +52,8 @@ type Store struct {
 	initSyncState         map[[32]byte]*pb.BeaconState
 	initSyncStateLock     sync.RWMutex
 	nextEpochBoundarySlot uint64
+	filteredBlockTree     map[[32]byte]*ethpb.BeaconBlock
+	filteredBlockTreeLock   sync.RWMutex
 }
 
 // NewForkChoiceService instantiates a new service instance that will
@@ -262,9 +264,17 @@ func (s *Store) Head(ctx context.Context) ([]byte, error) {
 	defer span.End()
 
 	head := s.JustifiedCheckpt().Root
-	filteredBlocks, err := s.getFilterBlockTree(ctx)
+	filteredBlocks := make(map[[32]byte]*ethpb.BeaconBlock)
-	if err != nil {
+	var err error
-		return nil, err
+	if featureconfig.Get().EnableBlockTreeCache {
+		s.filteredBlockTreeLock.RLock()
+		filteredBlocks = s.filteredBlockTree
+		s.filteredBlockTreeLock.RUnlock()
+	} else {
+		filteredBlocks, err = s.getFilterBlockTree(ctx)
+		if err != nil {
+			return nil, err
+		}
 	}
 
 	justifiedSlot := helpers.StartSlot(s.justifiedCheckpt.Epoch)

shared/featureconfig/config.go

@@ -38,10 +38,11 @@ type Flags struct {
 	EnableSavingOfDepositData bool   // EnableSavingOfDepositData allows the saving of eth1 related data such as deposits,chain data to be saved.
 
 	// Cache toggles.
-	EnableAttestationCache  bool // EnableAttestationCache; see https://github.com/prysmaticlabs/prysm/issues/3106.
+	EnableAttestationCache   bool // EnableAttestationCache; see https://github.com/prysmaticlabs/prysm/issues/3106.
-	EnableEth1DataVoteCache bool // EnableEth1DataVoteCache; see https://github.com/prysmaticlabs/prysm/issues/3106.
+	EnableEth1DataVoteCache  bool // EnableEth1DataVoteCache; see https://github.com/prysmaticlabs/prysm/issues/3106.
-	EnableSkipSlotsCache    bool // EnableSkipSlotsCache caches the state in skipped slots.
+	EnableSkipSlotsCache     bool // EnableSkipSlotsCache caches the state in skipped slots.
-	EnableSlasherConnection bool // EnableSlasher enable retrieval of slashing events from a slasher instance.
+	EnableSlasherConnection  bool // EnableSlasher enable retrieval of slashing events from a slasher instance.
+	EnableBlockTreeCache     bool // EnableBlockTreeCache enable fork choice service to maintain latest filtered block tree.
 }
 
 var featureConfig *Flags
@@ -118,6 +119,10 @@ func ConfigureBeaconChain(ctx *cli.Context) {
 		log.Warn("Enable slasher connection.")
 		cfg.EnableSlasherConnection = true
 	}
+	if ctx.GlobalBool(cacheFilteredBlockTree.Name) {
+		log.Warn("Enabled filtered block tree cache for fork choice.")
+		cfg.EnableBlockTreeCache = true
+	}
 	Init(cfg)
 }
 

shared/featureconfig/flags.go

@@ -69,6 +69,11 @@ var (
 			"triggered the genesis as the genesis time. This flag should be used for local " +
 			"development and testing only.",
 	}
+	cacheFilteredBlockTree = cli.BoolFlag{
+		Name: "cache-filtered-block-tree",
+		Usage: "Cache filtered block tree by maintaining it rather than continually recalculating on the fly, " +
+			"this is used for fork choice.",
+	}
 )
 
 // Deprecated flags list.
@@ -192,4 +197,5 @@ var BeaconChainFlags = append(deprecatedFlags, []cli.Flag{
 	enableSkipSlotsCache,
 	saveDepositData,
 	enableSlasherFlag,
+	cacheFilteredBlockTree,
 }...)