Cache headers and logs using accepted depth instead of LRU (#387)

* save progress

* save progress

* saving more progress

* add more context

* more comments

* fix items

* fix removal

* passs config

* add additional comment

* move cache init

* remove TODO

* fix logs format

* nits

* insert into cache oldest first

* make bounded buffer generic

* cleanup FIFO cache

* cleanup comments

* simplify bounded buffer

* fix `Last`

* nits

* more comment nits

* fix min size of FIFOCache

* add NoOpFIFOCache

* move `FlattenLogs` to `types`

* fix off by 1

* revert LastBloomIndex

* fifo cache nits

* simplify bounded buffer

* move acceptedHeaderCache to headerchain

* remove unnecessary comment

accounts/abi/bind/backends/simulated.go

@@ -945,7 +945,6 @@ func (fb *filterBackend) SubscribePendingLogsEvent(ch chan<- []*types.Log) event
 }
 
 func (fb *filterBackend) BloomStatus() (uint64, uint64) { return 4096, 0 }
-func (fb *filterBackend) LastBloomIndex() uint64        { return 0 }
 
 func (fb *filterBackend) ServiceFilter(ctx context.Context, ms *bloombits.MatcherSession) {
 	panic("not supported")

core/blockchain.go

@@ -164,6 +164,7 @@ type CacheConfig struct {
 	SnapshotVerify                  bool          // Verify generated snapshots
 	SkipSnapshotRebuild             bool          // Whether to skip rebuilding the snapshot in favor of returning an error (only set to true for tests)
 	Preimages                       bool          // Whether to store preimage of trie key to the disk
+	AcceptedCacheSize               int           // Depth of accepted headers cache and accepted logs cache at the accepted tip
 }
 
 var DefaultCacheConfig = &CacheConfig{
@@ -174,6 +175,7 @@ var DefaultCacheConfig = &CacheConfig{
 	CommitInterval:        4096,
 	AcceptorQueueLimit:    64, // Provides 2 minutes of buffer (2s block target) for a commit delay
 	SnapshotLimit:         256,
+	AcceptedCacheSize:     32,
 }
 
 // BlockChain represents the canonical chain given a database with a genesis
@@ -276,6 +278,9 @@ type BlockChain struct {
 	// [flattenLock] prevents the [acceptor] from flattening snapshots while
 	// a block is being verified.
 	flattenLock sync.Mutex
+
+	// [acceptedLogsCache] stores recently accepted logs to improve the performance of eth_getLogs.
+	acceptedLogsCache FIFOCache[common.Hash, [][]*types.Log]
 }
 
 // NewBlockChain returns a fully initialised block chain using information
@@ -305,24 +310,25 @@ func NewBlockChain(
 			Preimages:   cacheConfig.Preimages,
 			StatsPrefix: trieCleanCacheStatsNamespace,
 		}),
-		bodyCache:      bodyCache,
-		receiptsCache:  receiptsCache,
-		blockCache:     blockCache,
-		txLookupCache:  txLookupCache,
-		feeConfigCache: feeConfigCache,
-		engine:         engine,
-		vmConfig:       vmConfig,
-		badBlocks:      badBlocks,
-		senderCacher:   newTxSenderCacher(runtime.NumCPU()),
-		acceptorQueue:  make(chan *types.Block, cacheConfig.AcceptorQueueLimit),
-		quit:           make(chan struct{}),
+		bodyCache:         bodyCache,
+		receiptsCache:     receiptsCache,
+		blockCache:        blockCache,
+		txLookupCache:     txLookupCache,
+		feeConfigCache:    feeConfigCache,
+		engine:            engine,
+		vmConfig:          vmConfig,
+		badBlocks:         badBlocks,
+		senderCacher:      newTxSenderCacher(runtime.NumCPU()),
+		acceptorQueue:     make(chan *types.Block, cacheConfig.AcceptorQueueLimit),
+		quit:              make(chan struct{}),
+		acceptedLogsCache: NewFIFOCache[common.Hash, [][]*types.Log](cacheConfig.AcceptedCacheSize),
 	}
 	bc.validator = NewBlockValidator(chainConfig, bc, engine)
 	bc.prefetcher = newStatePrefetcher(chainConfig, bc, engine)
 	bc.processor = NewStateProcessor(chainConfig, bc, engine)
 
 	var err error
-	bc.hc, err = NewHeaderChain(db, chainConfig, engine)
+	bc.hc, err = NewHeaderChain(db, chainConfig, cacheConfig, engine)
 	if err != nil {
 		return nil, err
 	}
@@ -373,6 +379,9 @@ func NewBlockChain(
 		bc.initSnapshot(head)
 	}
 
+	// Warm up [hc.acceptedNumberCache] and [acceptedLogsCache]
+	bc.warmAcceptedCaches()
+
 	// Start processing accepted blocks effects in the background
 	go bc.startAcceptor()
 
@@ -435,6 +444,41 @@ func (bc *BlockChain) flattenSnapshot(postAbortWork func() error, hash common.Ha
 	return bc.snaps.Flatten(hash)
 }
 
+// warmAcceptedCaches fetches previously accepted headers and logs from disk to
+// pre-populate [hc.acceptedNumberCache] and [acceptedLogsCache].
+func (bc *BlockChain) warmAcceptedCaches() {
+	var (
+		startTime       = time.Now()
+		lastAccepted    = bc.LastAcceptedBlock().NumberU64()
+		startIndex      = uint64(1)
+		targetCacheSize = uint64(bc.cacheConfig.AcceptedCacheSize)
+	)
+	if targetCacheSize == 0 {
+		log.Info("Not warming accepted cache because disabled")
+		return
+	}
+	if lastAccepted < startIndex {
+		// This could occur if we haven't accepted any blocks yet
+		log.Info("Not warming accepted cache because there are no accepted blocks")
+		return
+	}
+	cacheDiff := targetCacheSize - 1 // last accepted lookback is inclusive, so we reduce size by 1
+	if cacheDiff < lastAccepted {
+		startIndex = lastAccepted - cacheDiff
+	}
+	for i := startIndex; i <= lastAccepted; i++ {
+		header := bc.GetHeaderByNumber(i)
+		if header == nil {
+			// This could happen if a node state-synced
+			log.Info("Exiting accepted cache warming early because header is nil", "height", i, "t", time.Since(startTime))
+			break
+		}
+		bc.hc.acceptedNumberCache.Put(header.Number.Uint64(), header)
+		bc.acceptedLogsCache.Put(header.Hash(), rawdb.ReadLogs(bc.db, header.Hash(), header.Number.Uint64()))
+	}
+	log.Info("Warmed accepted caches", "start", startIndex, "end", lastAccepted, "t", time.Since(startTime))
+}
+
 // startAcceptor starts processing items on the [acceptorQueue]. If a [nil]
 // object is placed on the [acceptorQueue], the [startAcceptor] will exit.
 func (bc *BlockChain) startAcceptor() {
@@ -455,13 +499,16 @@ func (bc *BlockChain) startAcceptor() {
 			log.Crit("failed to write accepted block effects", "err", err)
 		}
 
-		// Fetch block logs
-		logs := bc.gatherBlockLogs(next.Hash(), next.NumberU64(), false)
+		// Ensure [hc.acceptedNumberCache] and [acceptedLogsCache] have latest content
+		bc.hc.acceptedNumberCache.Put(next.NumberU64(), next.Header())
+		logs := rawdb.ReadLogs(bc.db, next.Hash(), next.NumberU64())
+		bc.acceptedLogsCache.Put(next.Hash(), logs)
 
 		// Update accepted feeds
-		bc.chainAcceptedFeed.Send(ChainEvent{Block: next, Hash: next.Hash(), Logs: logs})
-		if len(logs) > 0 {
-			bc.logsAcceptedFeed.Send(logs)
+		flattenedLogs := types.FlattenLogs(logs)
+		bc.chainAcceptedFeed.Send(ChainEvent{Block: next, Hash: next.Hash(), Logs: flattenedLogs})
+		if len(flattenedLogs) > 0 {
+			bc.logsAcceptedFeed.Send(flattenedLogs)
 		}
 		if len(next.Transactions()) != 0 {
 			bc.txAcceptedFeed.Send(NewTxsEvent{next.Transactions()})
@@ -911,6 +958,7 @@ func (bc *BlockChain) Accept(block *types.Block) error {
 		}
 	}
 
+	// Enqueue block in the acceptor
 	bc.lastAccepted = block
 	bc.addAcceptorQueue(block)
 	acceptedBlockGasUsedCounter.Inc(int64(block.GasUsed()))

core/blockchain_reader.go

@@ -405,3 +405,12 @@ func (bc *BlockChain) GetCoinbaseAt(parent *types.Header) (common.Address, bool,
 	rewardAddress, feeRecipients := precompile.GetStoredRewardAddress(stateDB)
 	return rewardAddress, feeRecipients, nil
 }
+
+// GetLogs fetches all logs from a given block.
+func (bc *BlockChain) GetLogs(hash common.Hash, number uint64) [][]*types.Log {
+	logs, ok := bc.acceptedLogsCache.Get(hash) // this cache is thread-safe
+	if ok {
+		return logs
+	}
+	return rawdb.ReadLogs(bc.db, hash, number)
+}

core/bounded_buffer.go

@@ -3,45 +3,55 @@
 
 package core
 
-import (
-	"github.com/ethereum/go-ethereum/common"
-)
-
-// BoundedBuffer keeps [size] common.Hash entries in a buffer and calls
-// [callback] on any item that is evicted. This is typically used for
+// BoundedBuffer keeps [size] entries of type [K] in a buffer and calls
+// [callback] on any item that is overwritten. This is typically used for
 // dereferencing old roots during block processing.
-type BoundedBuffer struct {
+//
+// BoundedBuffer is not thread-safe and requires the caller synchronize usage.
+type BoundedBuffer[K any] struct {
 	lastPos  int
 	size     int
-	callback func(common.Hash)
-	buffer   []common.Hash
+	callback func(K)
+	buffer   []K
+
+	cycled bool
 }
 
 // NewBoundedBuffer creates a new [BoundedBuffer].
-func NewBoundedBuffer(size int, callback func(common.Hash)) *BoundedBuffer {
-	return &BoundedBuffer{
+func NewBoundedBuffer[K any](size int, callback func(K)) *BoundedBuffer[K] {
+	return &BoundedBuffer[K]{
+		lastPos:  -1,
 		size:     size,
 		callback: callback,
-		buffer:   make([]common.Hash, size),
+		buffer:   make([]K, size),
 	}
 }
 
-// Insert adds a new common.Hash to the buffer. If the buffer is full, the
-// oldest common.Hash will be evicted and [callback] will be invoked.
-//
-// WARNING: BoundedBuffer does not support the insertion of empty common.Hash.
-// Inserting such data will cause unintended behavior.
-func (b *BoundedBuffer) Insert(h common.Hash) {
-	nextPos := (b.lastPos + 1) % b.size // the first item added to the buffer will be at position 1
-	if b.buffer[nextPos] != (common.Hash{}) {
+// Insert adds a new value to the buffer. If the buffer is full, the
+// oldest value will be overwritten and [callback] will be invoked.
+func (b *BoundedBuffer[K]) Insert(h K) {
+	nextPos := b.lastPos + 1 // the first item added to the buffer will be at position 0
+	if nextPos == b.size {
+		nextPos = 0
+		// Set [cycled] since we are back to the 0th element
+		b.cycled = true
+	}
+	if b.cycled {
+		// We ensure we have cycled through the buffer once before invoking the
+		// [callback] to ensure we don't call it with unset values.
 		b.callback(b.buffer[nextPos])
 	}
 	b.buffer[nextPos] = h
 	b.lastPos = nextPos
 }
 
 // Last retrieves the last item added to the buffer.
-// If no items have been added to the buffer, Last returns an empty hash.
-func (b *BoundedBuffer) Last() common.Hash {
-	return b.buffer[b.lastPos]
+//
+// If no items have been added to the buffer, Last returns the default value of
+// [K] and [false].
+func (b *BoundedBuffer[K]) Last() (K, bool) {
+	if b.lastPos == -1 {
+		return *new(K), false
+	}
+	return b.buffer[b.lastPos], true
 }

core/fifo_cache.go

@@ -0,0 +1,72 @@
+// (c) 2021, Ava Labs, Inc. All rights reserved.
+// See the file LICENSE for licensing terms.
+
+package core
+
+import (
+	"sync"
+)
+
+var (
+	_ FIFOCache[int, int] = (*BufferFIFOCache[int, int])(nil)
+	_ FIFOCache[int, int] = (*NoOpFIFOCache[int, int])(nil)
+)
+
+// FIFOCache evicts the oldest element added to it after [limit] items are
+// added.
+type FIFOCache[K comparable, V any] interface {
+	Put(K, V)
+	Get(K) (V, bool)
+}
+
+// NewFIFOCache creates a new First-In-First-Out cache of size [limit].
+//
+// If a [limit] of 0 is passed as an argument, a no-op cache is returned that
+// does nothing.
+func NewFIFOCache[K comparable, V any](limit int) FIFOCache[K, V] {
+	if limit <= 0 {
+		return &NoOpFIFOCache[K, V]{}
+	}
+
+	c := &BufferFIFOCache[K, V]{
+		m: make(map[K]V, limit),
+	}
+	c.buffer = NewBoundedBuffer(limit, c.remove)
+	return c
+}
+
+type BufferFIFOCache[K comparable, V any] struct {
+	l sync.RWMutex
+
+	buffer *BoundedBuffer[K]
+	m      map[K]V
+}
+
+func (f *BufferFIFOCache[K, V]) Put(key K, val V) {
+	f.l.Lock()
+	defer f.l.Unlock()
+
+	f.buffer.Insert(key) // Insert will remove the oldest [K] if we are at the [limit]
+	f.m[key] = val
+}
+
+func (f *BufferFIFOCache[K, V]) Get(key K) (V, bool) {
+	f.l.RLock()
+	defer f.l.RUnlock()
+
+	v, ok := f.m[key]
+	return v, ok
+}
+
+// remove is used as the callback in [BoundedBuffer]. It is assumed that the
+// [WriteLock] is held when this is accessed.
+func (f *BufferFIFOCache[K, V]) remove(key K) {
+	delete(f.m, key)
+}
+
+type NoOpFIFOCache[K comparable, V any] struct{}
+
+func (f *NoOpFIFOCache[K, V]) Put(_ K, _ V) {}
+func (f *NoOpFIFOCache[K, V]) Get(_ K) (V, bool) {
+	return *new(V), false
+}

core/headerchain.go

@@ -70,20 +70,22 @@ type HeaderChain struct {
 	currentHeader     atomic.Value // Current head of the header chain (may be above the block chain!)
 	currentHeaderHash common.Hash  // Hash of the current head of the header chain (prevent recomputing all the time)
 
-	headerCache *lru.Cache // Cache for the most recent block headers
-	tdCache     *lru.Cache // Cache for the most recent block total difficulties
-	numberCache *lru.Cache // Cache for the most recent block numbers
+	headerCache         *lru.Cache                       // Cache for the most recent block headers
+	tdCache             *lru.Cache                       // Cache for the most recent block total difficulties
+	numberCache         *lru.Cache                       // Cache for the most recent block numbers
+	acceptedNumberCache FIFOCache[uint64, *types.Header] // Cache for most recent accepted heights to headers (only modified in accept)
 
 	rand   *mrand.Rand
 	engine consensus.Engine
 }
 
 // NewHeaderChain creates a new HeaderChain structure. ProcInterrupt points
 // to the parent's interrupt semaphore.
-func NewHeaderChain(chainDb ethdb.Database, config *params.ChainConfig, engine consensus.Engine) (*HeaderChain, error) {
+func NewHeaderChain(chainDb ethdb.Database, config *params.ChainConfig, cacheConfig *CacheConfig, engine consensus.Engine) (*HeaderChain, error) {
 	headerCache, _ := lru.New(headerCacheLimit)
 	tdCache, _ := lru.New(tdCacheLimit)
 	numberCache, _ := lru.New(numberCacheLimit)
+	acceptedNumberCache := NewFIFOCache[uint64, *types.Header](cacheConfig.AcceptedCacheSize)
 
 	// Seed a fast but crypto originating random generator
 	seed, err := crand.Int(crand.Reader, big.NewInt(math.MaxInt64))
@@ -92,13 +94,14 @@ func NewHeaderChain(chainDb ethdb.Database, config *params.ChainConfig, engine c
 	}
 
 	hc := &HeaderChain{
-		config:      config,
-		chainDb:     chainDb,
-		headerCache: headerCache,
-		tdCache:     tdCache,
-		numberCache: numberCache,
-		rand:        mrand.New(mrand.NewSource(seed.Int64())),
-		engine:      engine,
+		config:              config,
+		chainDb:             chainDb,
+		headerCache:         headerCache,
+		tdCache:             tdCache,
+		numberCache:         numberCache,
+		acceptedNumberCache: acceptedNumberCache,
+		rand:                mrand.New(mrand.NewSource(seed.Int64())),
+		engine:              engine,
 	}
 
 	hc.genesisHeader = hc.GetHeaderByNumber(0)
@@ -170,6 +173,9 @@ func (hc *HeaderChain) HasHeader(hash common.Hash, number uint64) bool {
 // GetHeaderByNumber retrieves a block header from the database by number,
 // caching it (associated with its hash) if found.
 func (hc *HeaderChain) GetHeaderByNumber(number uint64) *types.Header {
+	if cachedHeader, ok := hc.acceptedNumberCache.Get(number); ok {
+		return cachedHeader
+	}
 	hash := rawdb.ReadCanonicalHash(hc.chainDb, number)
 	if hash == (common.Hash{}) {
 		return nil