Merge pull request #18087 from karalabe/trie-read-cacher

cmd, core, eth, light, trie: add trie read caching layer
2018-11-15 14:42:19 +02:00 · 2018-11-15 14:42:19 +02:00 · 17d67c5834
commit 17d67c5834
parent 14346e4ef9 434dd5bc00
33 changed files with 1660 additions and 127 deletions
--- a/cmd/geth/main.go
+++ b/cmd/geth/main.go
@ -89,6 +89,7 @@ var (
 		utils.LightKDFFlag,
 		utils.CacheFlag,
 		utils.CacheDatabaseFlag,
+		utils.CacheTrieFlag,
 		utils.CacheGCFlag,
 		utils.TrieCacheGenFlag,
 		utils.ListenPortFlag,
--- a/cmd/geth/usage.go
+++ b/cmd/geth/usage.go
@ -132,6 +132,7 @@ var AppHelpFlagGroups = []flagGroup{
 		Flags: []cli.Flag{
 			utils.CacheFlag,
 			utils.CacheDatabaseFlag,
+			utils.CacheTrieFlag,
 			utils.CacheGCFlag,
 			utils.TrieCacheGenFlag,
 		},
--- a/cmd/utils/flags.go
+++ b/cmd/utils/flags.go
@ -295,7 +295,12 @@ var (
 	CacheDatabaseFlag = cli.IntFlag{
 		Name:  "cache.database",
 		Usage: "Percentage of cache memory allowance to use for database io",
-		Value: 75,
+		Value: 50,
+	}
+	CacheTrieFlag = cli.IntFlag{
+		Name:  "cache.trie",
+		Usage: "Percentage of cache memory allowance to use for trie caching",
+		Value: 25,
 	}
 	CacheGCFlag = cli.IntFlag{
 		Name:  "cache.gc",
@ -1157,8 +1162,11 @@ func SetEthConfig(ctx *cli.Context, stack *node.Node, cfg *eth.Config) {
 	}
 	cfg.NoPruning = ctx.GlobalString(GCModeFlag.Name) == "archive"

+	if ctx.GlobalIsSet(CacheFlag.Name) || ctx.GlobalIsSet(CacheTrieFlag.Name) {
+		cfg.TrieCleanCache = ctx.GlobalInt(CacheFlag.Name) * ctx.GlobalInt(CacheTrieFlag.Name) / 100
+	}
 	if ctx.GlobalIsSet(CacheFlag.Name) || ctx.GlobalIsSet(CacheGCFlag.Name) {
-		cfg.TrieCache = ctx.GlobalInt(CacheFlag.Name) * ctx.GlobalInt(CacheGCFlag.Name) / 100
+		cfg.TrieDirtyCache = ctx.GlobalInt(CacheFlag.Name) * ctx.GlobalInt(CacheGCFlag.Name) / 100
 	}
 	if ctx.GlobalIsSet(MinerNotifyFlag.Name) {
 		cfg.MinerNotify = strings.Split(ctx.GlobalString(MinerNotifyFlag.Name), ",")
@ -1393,12 +1401,16 @@ func MakeChain(ctx *cli.Context, stack *node.Node) (chain *core.BlockChain, chai
 		Fatalf("--%s must be either 'full' or 'archive'", GCModeFlag.Name)
 	}
 	cache := &core.CacheConfig{
-		Disabled:      ctx.GlobalString(GCModeFlag.Name) == "archive",
-		TrieNodeLimit: eth.DefaultConfig.TrieCache,
-		TrieTimeLimit: eth.DefaultConfig.TrieTimeout,
+		Disabled:       ctx.GlobalString(GCModeFlag.Name) == "archive",
+		TrieCleanLimit: eth.DefaultConfig.TrieCleanCache,
+		TrieDirtyLimit: eth.DefaultConfig.TrieDirtyCache,
+		TrieTimeLimit:  eth.DefaultConfig.TrieTimeout,
+	}
+	if ctx.GlobalIsSet(CacheFlag.Name) || ctx.GlobalIsSet(CacheTrieFlag.Name) {
+		cache.TrieCleanLimit = ctx.GlobalInt(CacheFlag.Name) * ctx.GlobalInt(CacheTrieFlag.Name) / 100
 	}
 	if ctx.GlobalIsSet(CacheFlag.Name) || ctx.GlobalIsSet(CacheGCFlag.Name) {
-		cache.TrieNodeLimit = ctx.GlobalInt(CacheFlag.Name) * ctx.GlobalInt(CacheGCFlag.Name) / 100
+		cache.TrieDirtyLimit = ctx.GlobalInt(CacheFlag.Name) * ctx.GlobalInt(CacheGCFlag.Name) / 100
 	}
 	vmcfg := vm.Config{EnablePreimageRecording: ctx.GlobalBool(VMEnableDebugFlag.Name)}
 	chain, err = core.NewBlockChain(chainDb, cache, config, engine, vmcfg, nil)
--- a/core/blockchain.go
+++ b/core/blockchain.go
@ -68,9 +68,10 @@ const (
 // CacheConfig contains the configuration values for the trie caching/pruning
 // that's resident in a blockchain.
 type CacheConfig struct {
-	Disabled      bool          // Whether to disable trie write caching (archive node)
-	TrieNodeLimit int           // Memory limit (MB) at which to flush the current in-memory trie to disk
-	TrieTimeLimit time.Duration // Time limit after which to flush the current in-memory trie to disk
+	Disabled       bool          // Whether to disable trie write caching (archive node)
+	TrieCleanLimit int           // Memory allowance (MB) to use for caching trie nodes in memory
+	TrieDirtyLimit int           // Memory limit (MB) at which to start flushing dirty trie nodes to disk
+	TrieTimeLimit  time.Duration // Time limit after which to flush the current in-memory trie to disk
 }

 // BlockChain represents the canonical chain given a database with a genesis
@ -140,8 +141,9 @@ type BlockChain struct {
 func NewBlockChain(db ethdb.Database, cacheConfig *CacheConfig, chainConfig *params.ChainConfig, engine consensus.Engine, vmConfig vm.Config, shouldPreserve func(block *types.Block) bool) (*BlockChain, error) {
 	if cacheConfig == nil {
 		cacheConfig = &CacheConfig{
-			TrieNodeLimit: 256,
-			TrieTimeLimit: 5 * time.Minute,
+			TrieCleanLimit: 256,
+			TrieDirtyLimit: 256,
+			TrieTimeLimit:  5 * time.Minute,
 		}
 	}
 	bodyCache, _ := lru.New(bodyCacheLimit)
@ -156,7 +158,7 @@ func NewBlockChain(db ethdb.Database, cacheConfig *CacheConfig, chainConfig *par
 		cacheConfig:    cacheConfig,
 		db:             db,
 		triegc:         prque.New(nil),
-		stateCache:     state.NewDatabase(db),
+		stateCache:     state.NewDatabaseWithCache(db, cacheConfig.TrieCleanLimit),
 		quit:           make(chan struct{}),
 		shouldPreserve: shouldPreserve,
 		bodyCache:      bodyCache,
@ -393,6 +395,11 @@ func (bc *BlockChain) StateAt(root common.Hash) (*state.StateDB, error) {
 	return state.New(root, bc.stateCache)
 }

+// StateCache returns the caching database underpinning the blockchain instance.
+func (bc *BlockChain) StateCache() state.Database {
+	return bc.stateCache
+}
+
 // Reset purges the entire blockchain, restoring it to its genesis state.
 func (bc *BlockChain) Reset() error {
 	return bc.ResetWithGenesisBlock(bc.genesisBlock)
@ -938,7 +945,7 @@ func (bc *BlockChain) WriteBlockWithState(block *types.Block, receipts []*types.
 			// If we exceeded our memory allowance, flush matured singleton nodes to disk
 			var (
 				nodes, imgs = triedb.Size()
-				limit       = common.StorageSize(bc.cacheConfig.TrieNodeLimit) * 1024 * 1024
+				limit       = common.StorageSize(bc.cacheConfig.TrieDirtyLimit) * 1024 * 1024
 			)
 			if nodes > limit || imgs > 4*1024*1024 {
 				triedb.Cap(limit - ethdb.IdealBatchSize)
--- a/core/state/database.go
+++ b/core/state/database.go
@ -72,13 +72,19 @@ type Trie interface {
 }

 // NewDatabase creates a backing store for state. The returned database is safe for
-// concurrent use and retains cached trie nodes in memory. The pool is an optional
-// intermediate trie-node memory pool between the low level storage layer and the
-// high level trie abstraction.
+// concurrent use and retains a few recent expanded trie nodes in memory. To keep
+// more historical state in memory, use the NewDatabaseWithCache constructor.
 func NewDatabase(db ethdb.Database) Database {
+	return NewDatabaseWithCache(db, 0)
+}
+
+// NewDatabase creates a backing store for state. The returned database is safe for
+// concurrent use and retains both a few recent expanded trie nodes in memory, as
+// well as a lot of collapsed RLP trie nodes in a large memory cache.
+func NewDatabaseWithCache(db ethdb.Database, cache int) Database {
 	csc, _ := lru.New(codeSizeCacheSize)
 	return &cachingDB{
-		db:            trie.NewDatabase(db),
+		db:            trie.NewDatabaseWithCache(db, cache),
 		codeSizeCache: csc,
 	}
 }
--- a/eth/api.go
+++ b/eth/api.go
@ -444,16 +444,16 @@ func (api *PrivateDebugAPI) getModifiedAccounts(startBlock, endBlock *types.Bloc
 	if startBlock.Number().Uint64() >= endBlock.Number().Uint64() {
 		return nil, fmt.Errorf("start block height (%d) must be less than end block height (%d)", startBlock.Number().Uint64(), endBlock.Number().Uint64())
 	}
+	triedb := api.eth.BlockChain().StateCache().TrieDB()

-	oldTrie, err := trie.NewSecure(startBlock.Root(), trie.NewDatabase(api.eth.chainDb), 0)
+	oldTrie, err := trie.NewSecure(startBlock.Root(), triedb, 0)
 	if err != nil {
 		return nil, err
 	}
-	newTrie, err := trie.NewSecure(endBlock.Root(), trie.NewDatabase(api.eth.chainDb), 0)
+	newTrie, err := trie.NewSecure(endBlock.Root(), triedb, 0)
 	if err != nil {
 		return nil, err
 	}
-
 	diff, _ := trie.NewDifferenceIterator(oldTrie.NodeIterator([]byte{}), newTrie.NodeIterator([]byte{}))
 	iter := trie.NewIterator(diff)

--- a/eth/api_tracer.go
+++ b/eth/api_tracer.go
@ -138,7 +138,7 @@ func (api *PrivateDebugAPI) traceChain(ctx context.Context, start, end *types.Bl

 	// Ensure we have a valid starting state before doing any work
 	origin := start.NumberU64()
-	database := state.NewDatabase(api.eth.ChainDb())
+	database := state.NewDatabaseWithCache(api.eth.ChainDb(), 16) // Chain tracing will probably start at genesis

 	if number := start.NumberU64(); number > 0 {
 		start = api.eth.blockchain.GetBlock(start.ParentHash(), start.NumberU64()-1)
@ -492,7 +492,7 @@ func (api *PrivateDebugAPI) computeStateDB(block *types.Block, reexec uint64) (*
 	}
 	// Otherwise try to reexec blocks until we find a state or reach our limit
 	origin := block.NumberU64()
-	database := state.NewDatabase(api.eth.ChainDb())
+	database := state.NewDatabaseWithCache(api.eth.ChainDb(), 16)

 	for i := uint64(0); i < reexec; i++ {
 		block = api.eth.blockchain.GetBlock(block.ParentHash(), block.NumberU64()-1)
--- a/eth/backend.go
+++ b/eth/backend.go
@ -154,7 +154,7 @@ func New(ctx *node.ServiceContext, config *Config) (*Ethereum, error) {
 			EWASMInterpreter:        config.EWASMInterpreter,
 			EVMInterpreter:          config.EVMInterpreter,
 		}
-		cacheConfig = &core.CacheConfig{Disabled: config.NoPruning, TrieNodeLimit: config.TrieCache, TrieTimeLimit: config.TrieTimeout}
+		cacheConfig = &core.CacheConfig{Disabled: config.NoPruning, TrieCleanLimit: config.TrieCleanCache, TrieDirtyLimit: config.TrieDirtyCache, TrieTimeLimit: config.TrieTimeout}
 	)
 	eth.blockchain, err = core.NewBlockChain(chainDb, cacheConfig, eth.chainConfig, eth.engine, vmConfig, eth.shouldPreserve)
 	if err != nil {
--- a/eth/config.go
+++ b/eth/config.go
@ -43,15 +43,16 @@ var DefaultConfig = Config{
 		DatasetsInMem:  1,
 		DatasetsOnDisk: 2,
 	},
-	NetworkId:     1,
-	LightPeers:    100,
-	DatabaseCache: 768,
-	TrieCache:     256,
-	TrieTimeout:   60 * time.Minute,
-	MinerGasFloor: 8000000,
-	MinerGasCeil:  8000000,
-	MinerGasPrice: big.NewInt(params.GWei),
-	MinerRecommit: 3 * time.Second,
+	NetworkId:      1,
+	LightPeers:     100,
+	DatabaseCache:  512,
+	TrieCleanCache: 256,
+	TrieDirtyCache: 256,
+	TrieTimeout:    60 * time.Minute,
+	MinerGasFloor:  8000000,
+	MinerGasCeil:   8000000,
+	MinerGasPrice:  big.NewInt(params.GWei),
+	MinerRecommit:  3 * time.Second,

 	TxPool: core.DefaultTxPoolConfig,
 	GPO: gasprice.Config{
@ -94,7 +95,8 @@ type Config struct {
 	SkipBcVersionCheck bool `toml:"-"`
 	DatabaseHandles    int  `toml:"-"`
 	DatabaseCache      int
-	TrieCache          int
+	TrieCleanCache     int
+	TrieDirtyCache     int
 	TrieTimeout        time.Duration

 	// Mining-related options
--- a/eth/gen_config.go
+++ b/eth/gen_config.go
@ -28,7 +28,8 @@ func (c Config) MarshalTOML() (interface{}, error) {
 		SkipBcVersionCheck      bool `toml:"-"`
 		DatabaseHandles         int  `toml:"-"`
 		DatabaseCache           int
-		TrieCache               int
+		TrieCleanCache          int
+		TrieDirtyCache          int
 		TrieTimeout             time.Duration
 		Etherbase               common.Address `toml:",omitempty"`
 		MinerNotify             []string       `toml:",omitempty"`
@ -43,6 +44,8 @@ func (c Config) MarshalTOML() (interface{}, error) {
 		GPO                     gasprice.Config
 		EnablePreimageRecording bool
 		DocRoot                 string `toml:"-"`
+		EWASMInterpreter        string
+		EVMInterpreter          string
 	}
 	var enc Config
 	enc.Genesis = c.Genesis
@ -54,7 +57,8 @@ func (c Config) MarshalTOML() (interface{}, error) {
 	enc.SkipBcVersionCheck = c.SkipBcVersionCheck
 	enc.DatabaseHandles = c.DatabaseHandles
 	enc.DatabaseCache = c.DatabaseCache
-	enc.TrieCache = c.TrieCache
+	enc.TrieCleanCache = c.TrieCleanCache
+	enc.TrieDirtyCache = c.TrieDirtyCache
 	enc.TrieTimeout = c.TrieTimeout
 	enc.Etherbase = c.Etherbase
 	enc.MinerNotify = c.MinerNotify
@ -69,6 +73,8 @@ func (c Config) MarshalTOML() (interface{}, error) {
 	enc.GPO = c.GPO
 	enc.EnablePreimageRecording = c.EnablePreimageRecording
 	enc.DocRoot = c.DocRoot
+	enc.EWASMInterpreter = c.EWASMInterpreter
+	enc.EVMInterpreter = c.EVMInterpreter
 	return &enc, nil
 }

@ -84,7 +90,8 @@ func (c *Config) UnmarshalTOML(unmarshal func(interface{}) error) error {
 		SkipBcVersionCheck      *bool `toml:"-"`
 		DatabaseHandles         *int  `toml:"-"`
 		DatabaseCache           *int
-		TrieCache               *int
+		TrieCleanCache          *int
+		TrieDirtyCache          *int
 		TrieTimeout             *time.Duration
 		Etherbase               *common.Address `toml:",omitempty"`
 		MinerNotify             []string        `toml:",omitempty"`
@ -99,6 +106,8 @@ func (c *Config) UnmarshalTOML(unmarshal func(interface{}) error) error {
 		GPO                     *gasprice.Config
 		EnablePreimageRecording *bool
 		DocRoot                 *string `toml:"-"`
+		EWASMInterpreter        *string
+		EVMInterpreter          *string
 	}
 	var dec Config
 	if err := unmarshal(&dec); err != nil {
@ -131,8 +140,11 @@ func (c *Config) UnmarshalTOML(unmarshal func(interface{}) error) error {
 	if dec.DatabaseCache != nil {
 		c.DatabaseCache = *dec.DatabaseCache
 	}
-	if dec.TrieCache != nil {
-		c.TrieCache = *dec.TrieCache
+	if dec.TrieCleanCache != nil {
+		c.TrieCleanCache = *dec.TrieCleanCache
+	}
+	if dec.TrieDirtyCache != nil {
+		c.TrieDirtyCache = *dec.TrieDirtyCache
 	}
 	if dec.TrieTimeout != nil {
 		c.TrieTimeout = *dec.TrieTimeout
@ -176,5 +188,11 @@ func (c *Config) UnmarshalTOML(unmarshal func(interface{}) error) error {
 	if dec.DocRoot != nil {
 		c.DocRoot = *dec.DocRoot
 	}
+	if dec.EWASMInterpreter != nil {
+		c.EWASMInterpreter = *dec.EWASMInterpreter
+	}
+	if dec.EVMInterpreter != nil {
+		c.EVMInterpreter = *dec.EVMInterpreter
+	}
 	return nil
 }
--- a/light/postprocess.go
+++ b/light/postprocess.go
@ -159,7 +159,7 @@ func NewChtIndexer(db ethdb.Database, odr OdrBackend, size, confirms uint64) *co
 		diskdb:      db,
 		odr:         odr,
 		trieTable:   trieTable,
-		triedb:      trie.NewDatabase(trieTable),
+		triedb:      trie.NewDatabaseWithCache(trieTable, 1), // Use a tiny cache only to keep memory down
 		sectionSize: size,
 	}
 	return core.NewChainIndexer(db, ethdb.NewTable(db, "chtIndex-"), backend, size, confirms, time.Millisecond*100, "cht")
@ -281,7 +281,7 @@ func NewBloomTrieIndexer(db ethdb.Database, odr OdrBackend, parentSize, size uin
 		diskdb:     db,
 		odr:        odr,
 		trieTable:  trieTable,
-		triedb:     trie.NewDatabase(trieTable),
+		triedb:     trie.NewDatabaseWithCache(trieTable, 1), // Use a tiny cache only to keep memory down
 		parentSize: parentSize,
 		size:       size,
 	}
--- a/tests/block_test_util.go
+++ b/tests/block_test_util.go
@ -118,7 +118,7 @@ func (t *BlockTest) Run() error {
 	} else {
 		engine = ethash.NewShared()
 	}
-	chain, err := core.NewBlockChain(db, nil, config, engine, vm.Config{}, nil)
+	chain, err := core.NewBlockChain(db, &core.CacheConfig{TrieCleanLimit: 0}, config, engine, vm.Config{}, nil)
 	if err != nil {
 		return err
 	}
--- a/trie/database.go
+++ b/trie/database.go
@ -22,6 +22,7 @@ import (
 	"sync"
 	"time"

+	"github.com/allegro/bigcache"
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/ethdb"
 	"github.com/ethereum/go-ethereum/log"
@ -30,6 +31,11 @@ import (
 )

 var (
+	memcacheCleanHitMeter   = metrics.NewRegisteredMeter("trie/memcache/clean/hit", nil)
+	memcacheCleanMissMeter  = metrics.NewRegisteredMeter("trie/memcache/clean/miss", nil)
+	memcacheCleanReadMeter  = metrics.NewRegisteredMeter("trie/memcache/clean/read", nil)
+	memcacheCleanWriteMeter = metrics.NewRegisteredMeter("trie/memcache/clean/write", nil)
+
 	memcacheFlushTimeTimer  = metrics.NewRegisteredResettingTimer("trie/memcache/flush/time", nil)
 	memcacheFlushNodesMeter = metrics.NewRegisteredMeter("trie/memcache/flush/nodes", nil)
 	memcacheFlushSizeMeter  = metrics.NewRegisteredMeter("trie/memcache/flush/size", nil)
@ -64,9 +70,10 @@ type DatabaseReader interface {
 type Database struct {
 	diskdb ethdb.Database // Persistent storage for matured trie nodes

-	nodes  map[common.Hash]*cachedNode // Data and references relationships of a node
-	oldest common.Hash                 // Oldest tracked node, flush-list head
-	newest common.Hash                 // Newest tracked node, flush-list tail
+	cleans  *bigcache.BigCache          // GC friendly memory cache of clean node RLPs
+	dirties map[common.Hash]*cachedNode // Data and references relationships of dirty nodes
+	oldest  common.Hash                 // Oldest tracked node, flush-list head
+	newest  common.Hash                 // Newest tracked node, flush-list tail

 	preimages map[common.Hash][]byte // Preimages of nodes from the secure trie
 	seckeybuf [secureKeyLength]byte  // Ephemeral buffer for calculating preimage keys
@ -79,7 +86,7 @@ type Database struct {
 	flushnodes uint64             // Nodes flushed since last commit
 	flushsize  common.StorageSize // Data storage flushed since last commit

-	nodesSize     common.StorageSize // Storage size of the nodes cache (exc. flushlist)
+	dirtiesSize   common.StorageSize // Storage size of the dirty node cache (exc. flushlist)
 	preimagesSize common.StorageSize // Storage size of the preimages cache

 	lock sync.RWMutex
@ -262,11 +269,30 @@ func expandNode(hash hashNode, n node, cachegen uint16) node {
 }

 // NewDatabase creates a new trie database to store ephemeral trie content before
-// its written out to disk or garbage collected.
+// its written out to disk or garbage collected. No read cache is created, so all
+// data retrievals will hit the underlying disk database.
 func NewDatabase(diskdb ethdb.Database) *Database {
+	return NewDatabaseWithCache(diskdb, 0)
+}
+
+// NewDatabaseWithCache creates a new trie database to store ephemeral trie content
+// before its written out to disk or garbage collected. It also acts as a read cache
+// for nodes loaded from disk.
+func NewDatabaseWithCache(diskdb ethdb.Database, cache int) *Database {
+	var cleans *bigcache.BigCache
+	if cache > 0 {
+		cleans, _ = bigcache.NewBigCache(bigcache.Config{
+			Shards:             1024,
+			LifeWindow:         time.Hour,
+			MaxEntriesInWindow: cache * 1024,
+			MaxEntrySize:       512,
+			HardMaxCacheSize:   cache,
+		})
+	}
 	return &Database{
 		diskdb:    diskdb,
-		nodes:     map[common.Hash]*cachedNode{{}: {}},
+		cleans:    cleans,
+		dirties:   map[common.Hash]*cachedNode{{}: {}},
 		preimages: make(map[common.Hash][]byte),
 	}
 }
@ -293,7 +319,7 @@ func (db *Database) InsertBlob(hash common.Hash, blob []byte) {
 // size tracking.
 func (db *Database) insert(hash common.Hash, blob []byte, node node) {
 	// If the node's already cached, skip
-	if _, ok := db.nodes[hash]; ok {
+	if _, ok := db.dirties[hash]; ok {
 		return
 	}
 	// Create the cached entry for this node
@ -303,19 +329,19 @@ func (db *Database) insert(hash common.Hash, blob []byte, node node) {
 		flushPrev: db.newest,
 	}
 	for _, child := range entry.childs() {
-		if c := db.nodes[child]; c != nil {
+		if c := db.dirties[child]; c != nil {
 			c.parents++
 		}
 	}
-	db.nodes[hash] = entry
+	db.dirties[hash] = entry

 	// Update the flush-list endpoints
 	if db.oldest == (common.Hash{}) {
 		db.oldest, db.newest = hash, hash
 	} else {
-		db.nodes[db.newest].flushNext, db.newest = hash, hash
+		db.dirties[db.newest].flushNext, db.newest = hash, hash
 	}
-	db.nodesSize += common.StorageSize(common.HashLength + entry.size)
+	db.dirtiesSize += common.StorageSize(common.HashLength + entry.size)
 }

 // insertPreimage writes a new trie node pre-image to the memory database if it's
@ -333,35 +359,64 @@ func (db *Database) insertPreimage(hash common.Hash, preimage []byte) {
 // node retrieves a cached trie node from memory, or returns nil if none can be
 // found in the memory cache.
 func (db *Database) node(hash common.Hash, cachegen uint16) node {
-	// Retrieve the node from cache if available
+	// Retrieve the node from the clean cache if available
+	if db.cleans != nil {
+		if enc, err := db.cleans.Get(string(hash[:])); err == nil && enc != nil {
+			memcacheCleanHitMeter.Mark(1)
+			memcacheCleanReadMeter.Mark(int64(len(enc)))
+			return mustDecodeNode(hash[:], enc, cachegen)
+		}
+	}
+	// Retrieve the node from the dirty cache if available
 	db.lock.RLock()
-	node := db.nodes[hash]
+	dirty := db.dirties[hash]
 	db.lock.RUnlock()

-	if node != nil {
-		return node.obj(hash, cachegen)
+	if dirty != nil {
+		return dirty.obj(hash, cachegen)
 	}
 	// Content unavailable in memory, attempt to retrieve from disk
 	enc, err := db.diskdb.Get(hash[:])
 	if err != nil || enc == nil {
 		return nil
 	}
+	if db.cleans != nil {
+		db.cleans.Set(string(hash[:]), enc)
+		memcacheCleanMissMeter.Mark(1)
+		memcacheCleanWriteMeter.Mark(int64(len(enc)))
+	}
 	return mustDecodeNode(hash[:], enc, cachegen)
 }

 // Node retrieves an encoded cached trie node from memory. If it cannot be found
 // cached, the method queries the persistent database for the content.
 func (db *Database) Node(hash common.Hash) ([]byte, error) {
-	// Retrieve the node from cache if available
+	// Retrieve the node from the clean cache if available
+	if db.cleans != nil {
+		if enc, err := db.cleans.Get(string(hash[:])); err == nil && enc != nil {
+			memcacheCleanHitMeter.Mark(1)
+			memcacheCleanReadMeter.Mark(int64(len(enc)))
+			return enc, nil
+		}
+	}
+	// Retrieve the node from the dirty cache if available
 	db.lock.RLock()
-	node := db.nodes[hash]
+	dirty := db.dirties[hash]
 	db.lock.RUnlock()

-	if node != nil {
-		return node.rlp(), nil
+	if dirty != nil {
+		return dirty.rlp(), nil
 	}
 	// Content unavailable in memory, attempt to retrieve from disk
-	return db.diskdb.Get(hash[:])
+	enc, err := db.diskdb.Get(hash[:])
+	if err == nil && enc != nil {
+		if db.cleans != nil {
+			db.cleans.Set(string(hash[:]), enc)
+			memcacheCleanMissMeter.Mark(1)
+			memcacheCleanWriteMeter.Mark(int64(len(enc)))
+		}
+	}
+	return enc, err
 }

 // preimage retrieves a cached trie node pre-image from memory. If it cannot be
@ -395,8 +450,8 @@ func (db *Database) Nodes() []common.Hash {
 	db.lock.RLock()
 	defer db.lock.RUnlock()

-	var hashes = make([]common.Hash, 0, len(db.nodes))
-	for hash := range db.nodes {
+	var hashes = make([]common.Hash, 0, len(db.dirties))
+	for hash := range db.dirties {
 		if hash != (common.Hash{}) { // Special case for "root" references/nodes
 			hashes = append(hashes, hash)
 		}
@ -415,18 +470,18 @@ func (db *Database) Reference(child common.Hash, parent common.Hash) {
 // reference is the private locked version of Reference.
 func (db *Database) reference(child common.Hash, parent common.Hash) {
 	// If the node does not exist, it's a node pulled from disk, skip
-	node, ok := db.nodes[child]
+	node, ok := db.dirties[child]
 	if !ok {
 		return
 	}
 	// If the reference already exists, only duplicate for roots
-	if db.nodes[parent].children == nil {
-		db.nodes[parent].children = make(map[common.Hash]uint16)
-	} else if _, ok = db.nodes[parent].children[child]; ok && parent != (common.Hash{}) {
+	if db.dirties[parent].children == nil {
+		db.dirties[parent].children = make(map[common.Hash]uint16)
+	} else if _, ok = db.dirties[parent].children[child]; ok && parent != (common.Hash{}) {
 		return
 	}
 	node.parents++
-	db.nodes[parent].children[child]++
+	db.dirties[parent].children[child]++
 }

 // Dereference removes an existing reference from a root node.
@ -439,25 +494,25 @@ func (db *Database) Dereference(root common.Hash) {
 	db.lock.Lock()
 	defer db.lock.Unlock()

-	nodes, storage, start := len(db.nodes), db.nodesSize, time.Now()
+	nodes, storage, start := len(db.dirties), db.dirtiesSize, time.Now()
 	db.dereference(root, common.Hash{})

-	db.gcnodes += uint64(nodes - len(db.nodes))
-	db.gcsize += storage - db.nodesSize
+	db.gcnodes += uint64(nodes - len(db.dirties))
+	db.gcsize += storage - db.dirtiesSize
 	db.gctime += time.Since(start)

 	memcacheGCTimeTimer.Update(time.Since(start))
-	memcacheGCSizeMeter.Mark(int64(storage - db.nodesSize))
-	memcacheGCNodesMeter.Mark(int64(nodes - len(db.nodes)))
+	memcacheGCSizeMeter.Mark(int64(storage - db.dirtiesSize))
+	memcacheGCNodesMeter.Mark(int64(nodes - len(db.dirties)))

-	log.Debug("Dereferenced trie from memory database", "nodes", nodes-len(db.nodes), "size", storage-db.nodesSize, "time", time.Since(start),
-		"gcnodes", db.gcnodes, "gcsize", db.gcsize, "gctime", db.gctime, "livenodes", len(db.nodes), "livesize", db.nodesSize)
+	log.Debug("Dereferenced trie from memory database", "nodes", nodes-len(db.dirties), "size", storage-db.dirtiesSize, "time", time.Since(start),
+		"gcnodes", db.gcnodes, "gcsize", db.gcsize, "gctime", db.gctime, "livenodes", len(db.dirties), "livesize", db.dirtiesSize)
 }

 // dereference is the private locked version of Dereference.
 func (db *Database) dereference(child common.Hash, parent common.Hash) {
 	// Dereference the parent-child
-	node := db.nodes[parent]
+	node := db.dirties[parent]

 	if node.children != nil && node.children[child] > 0 {
 		node.children[child]--
@ -466,7 +521,7 @@ func (db *Database) dereference(child common.Hash, parent common.Hash) {
 		}
 	}
 	// If the child does not exist, it's a previously committed node.
-	node, ok := db.nodes[child]
+	node, ok := db.dirties[child]
 	if !ok {
 		return
 	}
@ -483,20 +538,20 @@ func (db *Database) dereference(child common.Hash, parent common.Hash) {
 		switch child {
 		case db.oldest:
 			db.oldest = node.flushNext
-			db.nodes[node.flushNext].flushPrev = common.Hash{}
+			db.dirties[node.flushNext].flushPrev = common.Hash{}
 		case db.newest:
 			db.newest = node.flushPrev
-			db.nodes[node.flushPrev].flushNext = common.Hash{}
+			db.dirties[node.flushPrev].flushNext = common.Hash{}
 		default:
-			db.nodes[node.flushPrev].flushNext = node.flushNext
-			db.nodes[node.flushNext].flushPrev = node.flushPrev
+			db.dirties[node.flushPrev].flushNext = node.flushNext
+			db.dirties[node.flushNext].flushPrev = node.flushPrev
 		}
 		// Dereference all children and delete the node
 		for _, hash := range node.childs() {
 			db.dereference(hash, child)
 		}
-		delete(db.nodes, child)
-		db.nodesSize -= common.StorageSize(common.HashLength + int(node.size))
+		delete(db.dirties, child)
+		db.dirtiesSize -= common.StorageSize(common.HashLength + int(node.size))
 	}
 }

@ -509,13 +564,13 @@ func (db *Database) Cap(limit common.StorageSize) error {
 	// by only uncaching existing data when the database write finalizes.
 	db.lock.RLock()

-	nodes, storage, start := len(db.nodes), db.nodesSize, time.Now()
+	nodes, storage, start := len(db.dirties), db.dirtiesSize, time.Now()
 	batch := db.diskdb.NewBatch()

-	// db.nodesSize only contains the useful data in the cache, but when reporting
+	// db.dirtiesSize only contains the useful data in the cache, but when reporting
 	// the total memory consumption, the maintenance metadata is also needed to be
 	// counted. For every useful node, we track 2 extra hashes as the flushlist.
-	size := db.nodesSize + common.StorageSize((len(db.nodes)-1)*2*common.HashLength)
+	size := db.dirtiesSize + common.StorageSize((len(db.dirties)-1)*2*common.HashLength)

 	// If the preimage cache got large enough, push to disk. If it's still small
 	// leave for later to deduplicate writes.
@ -540,7 +595,7 @@ func (db *Database) Cap(limit common.StorageSize) error {
 	oldest := db.oldest
 	for size > limit && oldest != (common.Hash{}) {
 		// Fetch the oldest referenced node and push into the batch
-		node := db.nodes[oldest]
+		node := db.dirties[oldest]
 		if err := batch.Put(oldest[:], node.rlp()); err != nil {
 			db.lock.RUnlock()
 			return err
@ -578,25 +633,25 @@ func (db *Database) Cap(limit common.StorageSize) error {
 		db.preimagesSize = 0
 	}
 	for db.oldest != oldest {
-		node := db.nodes[db.oldest]
-		delete(db.nodes, db.oldest)
+		node := db.dirties[db.oldest]
+		delete(db.dirties, db.oldest)
 		db.oldest = node.flushNext

-		db.nodesSize -= common.StorageSize(common.HashLength + int(node.size))
+		db.dirtiesSize -= common.StorageSize(common.HashLength + int(node.size))
 	}
 	if db.oldest != (common.Hash{}) {
-		db.nodes[db.oldest].flushPrev = common.Hash{}
+		db.dirties[db.oldest].flushPrev = common.Hash{}
 	}
-	db.flushnodes += uint64(nodes - len(db.nodes))
-	db.flushsize += storage - db.nodesSize
+	db.flushnodes += uint64(nodes - len(db.dirties))
+	db.flushsize += storage - db.dirtiesSize
 	db.flushtime += time.Since(start)

 	memcacheFlushTimeTimer.Update(time.Since(start))
-	memcacheFlushSizeMeter.Mark(int64(storage - db.nodesSize))
-	memcacheFlushNodesMeter.Mark(int64(nodes - len(db.nodes)))
+	memcacheFlushSizeMeter.Mark(int64(storage - db.dirtiesSize))
+	memcacheFlushNodesMeter.Mark(int64(nodes - len(db.dirties)))

-	log.Debug("Persisted nodes from memory database", "nodes", nodes-len(db.nodes), "size", storage-db.nodesSize, "time", time.Since(start),
-		"flushnodes", db.flushnodes, "flushsize", db.flushsize, "flushtime", db.flushtime, "livenodes", len(db.nodes), "livesize", db.nodesSize)
+	log.Debug("Persisted nodes from memory database", "nodes", nodes-len(db.dirties), "size", storage-db.dirtiesSize, "time", time.Since(start),
+		"flushnodes", db.flushnodes, "flushsize", db.flushsize, "flushtime", db.flushtime, "livenodes", len(db.dirties), "livesize", db.dirtiesSize)

 	return nil
 }
@ -630,7 +685,7 @@ func (db *Database) Commit(node common.Hash, report bool) error {
 		}
 	}
 	// Move the trie itself into the batch, flushing if enough data is accumulated
-	nodes, storage := len(db.nodes), db.nodesSize
+	nodes, storage := len(db.dirties), db.dirtiesSize
 	if err := db.commit(node, batch); err != nil {
 		log.Error("Failed to commit trie from trie database", "err", err)
 		db.lock.RUnlock()
@ -654,15 +709,15 @@ func (db *Database) Commit(node common.Hash, report bool) error {
 	db.uncache(node)

 	memcacheCommitTimeTimer.Update(time.Since(start))
-	memcacheCommitSizeMeter.Mark(int64(storage - db.nodesSize))
-	memcacheCommitNodesMeter.Mark(int64(nodes - len(db.nodes)))
+	memcacheCommitSizeMeter.Mark(int64(storage - db.dirtiesSize))
+	memcacheCommitNodesMeter.Mark(int64(nodes - len(db.dirties)))

 	logger := log.Info
 	if !report {
 		logger = log.Debug
 	}
-	logger("Persisted trie from memory database", "nodes", nodes-len(db.nodes)+int(db.flushnodes), "size", storage-db.nodesSize+db.flushsize, "time", time.Since(start)+db.flushtime,
-		"gcnodes", db.gcnodes, "gcsize", db.gcsize, "gctime", db.gctime, "livenodes", len(db.nodes), "livesize", db.nodesSize)
+	logger("Persisted trie from memory database", "nodes", nodes-len(db.dirties)+int(db.flushnodes), "size", storage-db.dirtiesSize+db.flushsize, "time", time.Since(start)+db.flushtime,
+		"gcnodes", db.gcnodes, "gcsize", db.gcsize, "gctime", db.gctime, "livenodes", len(db.dirties), "livesize", db.dirtiesSize)

 	// Reset the garbage collection statistics
 	db.gcnodes, db.gcsize, db.gctime = 0, 0, 0
@ -674,7 +729,7 @@ func (db *Database) Commit(node common.Hash, report bool) error {
 // commit is the private locked version of Commit.
 func (db *Database) commit(hash common.Hash, batch ethdb.Batch) error {
 	// If the node does not exist, it's a previously committed node
-	node, ok := db.nodes[hash]
+	node, ok := db.dirties[hash]
 	if !ok {
 		return nil
 	}
@ -702,7 +757,7 @@ func (db *Database) commit(hash common.Hash, batch ethdb.Batch) error {
 // to disk.
 func (db *Database) uncache(hash common.Hash) {
 	// If the node does not exist, we're done on this path
-	node, ok := db.nodes[hash]
+	node, ok := db.dirties[hash]
 	if !ok {
 		return
 	}
@ -710,20 +765,20 @@ func (db *Database) uncache(hash common.Hash) {
 	switch hash {
 	case db.oldest:
 		db.oldest = node.flushNext
-		db.nodes[node.flushNext].flushPrev = common.Hash{}
+		db.dirties[node.flushNext].flushPrev = common.Hash{}
 	case db.newest:
 		db.newest = node.flushPrev
-		db.nodes[node.flushPrev].flushNext = common.Hash{}
+		db.dirties[node.flushPrev].flushNext = common.Hash{}
 	default:
-		db.nodes[node.flushPrev].flushNext = node.flushNext
-		db.nodes[node.flushNext].flushPrev = node.flushPrev
+		db.dirties[node.flushPrev].flushNext = node.flushNext
+		db.dirties[node.flushNext].flushPrev = node.flushPrev
 	}
 	// Uncache the node's subtries and remove the node itself too
 	for _, child := range node.childs() {
 		db.uncache(child)
 	}
-	delete(db.nodes, hash)
-	db.nodesSize -= common.StorageSize(common.HashLength + int(node.size))
+	delete(db.dirties, hash)
+	db.dirtiesSize -= common.StorageSize(common.HashLength + int(node.size))
 }

 // Size returns the current storage size of the memory cache in front of the
@ -732,11 +787,11 @@ func (db *Database) Size() (common.StorageSize, common.StorageSize) {
 	db.lock.RLock()
 	defer db.lock.RUnlock()

-	// db.nodesSize only contains the useful data in the cache, but when reporting
+	// db.dirtiesSize only contains the useful data in the cache, but when reporting
 	// the total memory consumption, the maintenance metadata is also needed to be
 	// counted. For every useful node, we track 2 extra hashes as the flushlist.
-	var flushlistSize = common.StorageSize((len(db.nodes) - 1) * 2 * common.HashLength)
-	return db.nodesSize + flushlistSize, db.preimagesSize
+	var flushlistSize = common.StorageSize((len(db.dirties) - 1) * 2 * common.HashLength)
+	return db.dirtiesSize + flushlistSize, db.preimagesSize
 }

 // verifyIntegrity is a debug method to iterate over the entire trie stored in
@ -749,12 +804,12 @@ func (db *Database) verifyIntegrity() {
 	// Iterate over all the cached nodes and accumulate them into a set
 	reachable := map[common.Hash]struct{}{{}: {}}

-	for child := range db.nodes[common.Hash{}].children {
+	for child := range db.dirties[common.Hash{}].children {
 		db.accumulate(child, reachable)
 	}
 	// Find any unreachable but cached nodes
 	unreachable := []string{}
-	for hash, node := range db.nodes {
+	for hash, node := range db.dirties {
 		if _, ok := reachable[hash]; !ok {
 			unreachable = append(unreachable, fmt.Sprintf("%x: {Node: %v, Parents: %d, Prev: %x, Next: %x}",
 				hash, node.node, node.parents, node.flushPrev, node.flushNext))
@ -769,7 +824,7 @@ func (db *Database) verifyIntegrity() {
 // cached children found in memory.
 func (db *Database) accumulate(hash common.Hash, reachable map[common.Hash]struct{}) {
 	// Mark the node reachable if present in the memory cache
-	node, ok := db.nodes[hash]
+	node, ok := db.dirties[hash]
 	if !ok {
 		return
 	}
--- a/trie/iterator_test.go
+++ b/trie/iterator_test.go
@ -113,7 +113,7 @@ func TestNodeIteratorCoverage(t *testing.T) {
 			t.Errorf("failed to retrieve reported node %x: %v", hash, err)
 		}
 	}
-	for hash, obj := range db.nodes {
+	for hash, obj := range db.dirties {
 		if obj != nil && hash != (common.Hash{}) {
 			if _, ok := hashes[hash]; !ok {
 				t.Errorf("state entry not reported %x", hash)
@ -333,8 +333,8 @@ func testIteratorContinueAfterError(t *testing.T, memonly bool) {
 			}
 		}
 		if memonly {
-			robj = triedb.nodes[rkey]
-			delete(triedb.nodes, rkey)
+			robj = triedb.dirties[rkey]
+			delete(triedb.dirties, rkey)
 		} else {
 			rval, _ = diskdb.Get(rkey[:])
 			diskdb.Delete(rkey[:])
@ -350,7 +350,7 @@ func testIteratorContinueAfterError(t *testing.T, memonly bool) {

 		// Add the node back and continue iteration.
 		if memonly {
-			triedb.nodes[rkey] = robj
+			triedb.dirties[rkey] = robj
 		} else {
 			diskdb.Put(rkey[:], rval)
 		}
@ -393,8 +393,8 @@ func testIteratorContinueAfterSeekError(t *testing.T, memonly bool) {
 		barNodeObj  *cachedNode
 	)
 	if memonly {
-		barNodeObj = triedb.nodes[barNodeHash]
-		delete(triedb.nodes, barNodeHash)
+		barNodeObj = triedb.dirties[barNodeHash]
+		delete(triedb.dirties, barNodeHash)
 	} else {
 		barNodeBlob, _ = diskdb.Get(barNodeHash[:])
 		diskdb.Delete(barNodeHash[:])
@ -411,7 +411,7 @@ func testIteratorContinueAfterSeekError(t *testing.T, memonly bool) {
 	}
 	// Reinsert the missing node.
 	if memonly {
-		triedb.nodes[barNodeHash] = barNodeObj
+		triedb.dirties[barNodeHash] = barNodeObj
 	} else {
 		diskdb.Put(barNodeHash[:], barNodeBlob)
 	}
--- a/trie/trie_test.go
+++ b/trie/trie_test.go
@ -119,7 +119,7 @@ func testMissingNode(t *testing.T, memonly bool) {

 	hash := common.HexToHash("0xe1d943cc8f061a0c0b98162830b970395ac9315654824bf21b73b891365262f9")
 	if memonly {
-		delete(triedb.nodes, hash)
+		delete(triedb.dirties, hash)
 	} else {
 		diskdb.Delete(hash[:])
 	}
@ -342,15 +342,16 @@ func TestCacheUnload(t *testing.T) {
 	// Commit the trie repeatedly and access key1.
 	// The branch containing it is loaded from DB exactly two times:
 	// in the 0th and 6th iteration.
-	db := &countingDB{Database: trie.db.diskdb, gets: make(map[string]int)}
-	trie, _ = New(root, NewDatabase(db))
+	diskdb := &countingDB{Database: trie.db.diskdb, gets: make(map[string]int)}
+	triedb := NewDatabase(diskdb)
+	trie, _ = New(root, triedb)
 	trie.SetCacheLimit(5)
 	for i := 0; i < 12; i++ {
 		getString(trie, key1)
 		trie.Commit(nil)
 	}
 	// Check that it got loaded two times.
-	for dbkey, count := range db.gets {
+	for dbkey, count := range diskdb.gets {
 		if count != 2 {
 			t.Errorf("db key %x loaded %d times, want %d times", []byte(dbkey), count, 2)
 		}
--- a/vendor/github.com/allegro/bigcache/LICENSE
+++ b/vendor/github.com/allegro/bigcache/LICENSE
@ -0,0 +1,201 @@
+                                 Apache License
+                           Version 2.0, January 2004
+                        http://www.apache.org/licenses/
+
+   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
+
+   1. Definitions.
+
+      "License" shall mean the terms and conditions for use, reproduction,
+      and distribution as defined by Sections 1 through 9 of this document.
+
+      "Licensor" shall mean the copyright owner or entity authorized by
+      the copyright owner that is granting the License.
+
+      "Legal Entity" shall mean the union of the acting entity and all
+      other entities that control, are controlled by, or are under common
+      control with that entity. For the purposes of this definition,
+      "control" means (i) the power, direct or indirect, to cause the
+      direction or management of such entity, whether by contract or
+      otherwise, or (ii) ownership of fifty percent (50%) or more of the
+      outstanding shares, or (iii) beneficial ownership of such entity.
+
+      "You" (or "Your") shall mean an individual or Legal Entity
+      exercising permissions granted by this License.
+
+      "Source" form shall mean the preferred form for making modifications,
+      including but not limited to software source code, documentation
+      source, and configuration files.
+
+      "Object" form shall mean any form resulting from mechanical
+      transformation or translation of a Source form, including but
+      not limited to compiled object code, generated documentation,
+      and conversions to other media types.
+
+      "Work" shall mean the work of authorship, whether in Source or
+      Object form, made available under the License, as indicated by a
+      copyright notice that is included in or attached to the work
+      (an example is provided in the Appendix below).
+
+      "Derivative Works" shall mean any work, whether in Source or Object
+      form, that is based on (or derived from) the Work and for which the
+      editorial revisions, annotations, elaborations, or other modifications
+      represent, as a whole, an original work of authorship. For the purposes
+      of this License, Derivative Works shall not include works that remain
+      separable from, or merely link (or bind by name) to the interfaces of,
+      the Work and Derivative Works thereof.
+
+      "Contribution" shall mean any work of authorship, including
+      the original version of the Work and any modifications or additions
+      to that Work or Derivative Works thereof, that is intentionally
+      submitted to Licensor for inclusion in the Work by the copyright owner
+      or by an individual or Legal Entity authorized to submit on behalf of
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+      to the Licensor or its representatives, including but not limited to
+      communication on electronic mailing lists, source code control systems,
+      and issue tracking systems that are managed by, or on behalf of, the
+      Licensor for the purpose of discussing and improving the Work, but
+      excluding communication that is conspicuously marked or otherwise
+      designated in writing by the copyright owner as "Not a Contribution."
+
+      "Contributor" shall mean Licensor and any individual or Legal Entity
+      on behalf of whom a Contribution has been received by Licensor and
+      subsequently incorporated within the Work.
+
+   2. Grant of Copyright License. Subject to the terms and conditions of
+      this License, each Contributor hereby grants to You a perpetual,
+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      copyright license to reproduce, prepare Derivative Works of,
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+      Work and such Derivative Works in Source or Object form.
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+      (except as stated in this section) patent license to make, have made,
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+      meet the following conditions:
+
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+          Derivative Works a copy of this License; and
+
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+
+      (c) You must retain, in the Source form of any Derivative Works
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+   6. Trademarks. This License does not grant permission to use the trade
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+
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+      risks associated with Your exercise of permissions under this License.
+
+   8. Limitation of Liability. In no event and under no legal theory,
+      whether in tort (including negligence), contract, or otherwise,
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+      negligent acts) or agreed to in writing, shall any Contributor be
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+      of your accepting any such warranty or additional liability.
+
+   END OF TERMS AND CONDITIONS
+
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+
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+      boilerplate notice, with the fields enclosed by brackets "{}"
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+
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+
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+
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--- a/vendor/github.com/allegro/bigcache/README.md
+++ b/vendor/github.com/allegro/bigcache/README.md
@ -0,0 +1,150 @@
+# BigCache [![Build Status](https://travis-ci.org/allegro/bigcache.svg?branch=master)](https://travis-ci.org/allegro/bigcache)&nbsp;[![Coverage Status](https://coveralls.io/repos/github/allegro/bigcache/badge.svg?branch=master)](https://coveralls.io/github/allegro/bigcache?branch=master)&nbsp;[![GoDoc](https://godoc.org/github.com/allegro/bigcache?status.svg)](https://godoc.org/github.com/allegro/bigcache)&nbsp;[![Go Report Card](https://goreportcard.com/badge/github.com/allegro/bigcache)](https://goreportcard.com/report/github.com/allegro/bigcache)
+
+Fast, concurrent, evicting in-memory cache written to keep big number of entries without impact on performance.
+BigCache keeps entries on heap but omits GC for them. To achieve that operations on bytes arrays take place,
+therefore entries (de)serialization in front of the cache will be needed in most use cases.
+
+## Usage
+
+### Simple initialization
+
+```go
+import "github.com/allegro/bigcache"
+
+cache, _ := bigcache.NewBigCache(bigcache.DefaultConfig(10 * time.Minute))
+
+cache.Set("my-unique-key", []byte("value"))
+
+entry, _ := cache.Get("my-unique-key")
+fmt.Println(string(entry))
+```
+
+### Custom initialization
+
+When cache load can be predicted in advance then it is better to use custom initialization because additional memory
+allocation can be avoided in that way.
+
+```go
+import (
+	"log"
+
+	"github.com/allegro/bigcache"
+)
+
+config := bigcache.Config {
+		// number of shards (must be a power of 2)
+		Shards: 1024,
+		// time after which entry can be evicted
+		LifeWindow: 10 * time.Minute,
+		// rps * lifeWindow, used only in initial memory allocation
+		MaxEntriesInWindow: 1000 * 10 * 60,
+		// max entry size in bytes, used only in initial memory allocation
+		MaxEntrySize: 500,
+		// prints information about additional memory allocation
+		Verbose: true,
+		// cache will not allocate more memory than this limit, value in MB
+		// if value is reached then the oldest entries can be overridden for the new ones
+		// 0 value means no size limit
+		HardMaxCacheSize: 8192,
+		// callback fired when the oldest entry is removed because of its expiration time or no space left
+		// for the new entry, or because delete was called. A bitmask representing the reason will be returned.
+		// Default value is nil which means no callback and it prevents from unwrapping the oldest entry.
+		OnRemove: nil,
+		// OnRemoveWithReason is a callback fired when the oldest entry is removed because of its expiration time or no space left
+		// for the new entry, or because delete was called. A constant representing the reason will be passed through.
+		// Default value is nil which means no callback and it prevents from unwrapping the oldest entry.
+		// Ignored if OnRemove is specified.
+		OnRemoveWithReason: nil,
+	}
+
+cache, initErr := bigcache.NewBigCache(config)
+if initErr != nil {
+	log.Fatal(initErr)
+}
+
+cache.Set("my-unique-key", []byte("value"))
+
+if entry, err := cache.Get("my-unique-key"); err == nil {
+	fmt.Println(string(entry))
+}
+```
+
+## Benchmarks
+
+Three caches were compared: bigcache, [freecache](https://github.com/coocood/freecache) and map.
+Benchmark tests were made using an i7-6700K with 32GB of RAM on Windows 10.
+
+### Writes and reads
+
+```bash
+cd caches_bench; go test -bench=. -benchtime=10s ./... -timeout 30m
+
+BenchmarkMapSet-8                        3000000               569 ns/op             202 B/op          3 allocs/op
+BenchmarkConcurrentMapSet-8              1000000              1592 ns/op             347 B/op          8 allocs/op
+BenchmarkFreeCacheSet-8                  3000000               775 ns/op             355 B/op          2 allocs/op
+BenchmarkBigCacheSet-8                   3000000               640 ns/op             303 B/op          2 allocs/op
+BenchmarkMapGet-8                        5000000               407 ns/op              24 B/op          1 allocs/op
+BenchmarkConcurrentMapGet-8              3000000               558 ns/op              24 B/op          2 allocs/op
+BenchmarkFreeCacheGet-8                  2000000               682 ns/op             136 B/op          2 allocs/op
+BenchmarkBigCacheGet-8                   3000000               512 ns/op             152 B/op          4 allocs/op
+BenchmarkBigCacheSetParallel-8          10000000               225 ns/op             313 B/op          3 allocs/op
+BenchmarkFreeCacheSetParallel-8         10000000               218 ns/op             341 B/op          3 allocs/op
+BenchmarkConcurrentMapSetParallel-8      5000000               318 ns/op             200 B/op          6 allocs/op
+BenchmarkBigCacheGetParallel-8          20000000               178 ns/op             152 B/op          4 allocs/op
+BenchmarkFreeCacheGetParallel-8         20000000               295 ns/op             136 B/op          3 allocs/op
+BenchmarkConcurrentMapGetParallel-8     10000000               237 ns/op              24 B/op          2 allocs/op
+```
+
+Writes and reads in bigcache are faster than in freecache.
+Writes to map are the slowest.
+
+### GC pause time
+
+```bash
+cd caches_bench; go run caches_gc_overhead_comparison.go
+
+Number of entries:  20000000
+GC pause for bigcache:  5.8658ms
+GC pause for freecache:  32.4341ms
+GC pause for map:  52.9661ms
+```
+
+Test shows how long are the GC pauses for caches filled with 20mln of entries.
+Bigcache and freecache have very similar GC pause time.
+It is clear that both reduce GC overhead in contrast to map
+which GC pause time took more than 10 seconds.
+
+## How it works
+
+BigCache relies on optimization presented in 1.5 version of Go ([issue-9477](https://github.com/golang/go/issues/9477)).
+This optimization states that if map without pointers in keys and values is used then GC will omit its content.
+Therefore BigCache uses `map[uint64]uint32` where keys are hashed and values are offsets of entries.
+
+Entries are kept in bytes array, to omit GC again.
+Bytes array size can grow to gigabytes without impact on performance
+because GC will only see single pointer to it.
+
+## Bigcache vs Freecache
+
+Both caches provide the same core features but they reduce GC overhead in different ways.
+Bigcache relies on `map[uint64]uint32`, freecache implements its own mapping built on
+slices to reduce number of pointers.
+
+Results from benchmark tests are presented above.
+One of the advantage of bigcache over freecache is that you don’t need to know
+the size of the cache in advance, because when bigcache is full,
+it can allocate additional memory for new entries instead of
+overwriting existing ones as freecache does currently.
+However hard max size in bigcache also can be set, check [HardMaxCacheSize](https://godoc.org/github.com/allegro/bigcache#Config).
+
+## HTTP Server
+
+This package also includes an easily deployable HTTP implementation of BigCache, which can be found in the [server](/server) package.
+
+## More
+
+Bigcache genesis is described in allegro.tech blog post: [writing a very fast cache service in Go](http://allegro.tech/2016/03/writing-fast-cache-service-in-go.html)
+
+## License
+
+BigCache is released under the Apache 2.0 license (see [LICENSE](LICENSE))
--- a/vendor/github.com/allegro/bigcache/bigcache.go
+++ b/vendor/github.com/allegro/bigcache/bigcache.go
@ -0,0 +1,202 @@
+package bigcache
+
+import (
+	"fmt"
+	"time"
+)
+
+const (
+	minimumEntriesInShard = 10 // Minimum number of entries in single shard
+)
+
+// BigCache is fast, concurrent, evicting cache created to keep big number of entries without impact on performance.
+// It keeps entries on heap but omits GC for them. To achieve that, operations take place on byte arrays,
+// therefore entries (de)serialization in front of the cache will be needed in most use cases.
+type BigCache struct {
+	shards       []*cacheShard
+	lifeWindow   uint64
+	clock        clock
+	hash         Hasher
+	config       Config
+	shardMask    uint64
+	maxShardSize uint32
+	close        chan struct{}
+}
+
+// RemoveReason is a value used to signal to the user why a particular key was removed in the OnRemove callback.
+type RemoveReason uint32
+
+const (
+	// Expired means the key is past its LifeWindow.
+	Expired RemoveReason = iota
+	// NoSpace means the key is the oldest and the cache size was at its maximum when Set was called, or the
+	// entry exceeded the maximum shard size.
+	NoSpace
+	// Deleted means Delete was called and this key was removed as a result.
+	Deleted
+)
+
+// NewBigCache initialize new instance of BigCache
+func NewBigCache(config Config) (*BigCache, error) {
+	return newBigCache(config, &systemClock{})
+}
+
+func newBigCache(config Config, clock clock) (*BigCache, error) {
+
+	if !isPowerOfTwo(config.Shards) {
+		return nil, fmt.Errorf("Shards number must be power of two")
+	}
+
+	if config.Hasher == nil {
+		config.Hasher = newDefaultHasher()
+	}
+
+	cache := &BigCache{
+		shards:       make([]*cacheShard, config.Shards),
+		lifeWindow:   uint64(config.LifeWindow.Seconds()),
+		clock:        clock,
+		hash:         config.Hasher,
+		config:       config,
+		shardMask:    uint64(config.Shards - 1),
+		maxShardSize: uint32(config.maximumShardSize()),
+		close:        make(chan struct{}),
+	}
+
+	var onRemove func(wrappedEntry []byte, reason RemoveReason)
+	if config.OnRemove != nil {
+		onRemove = cache.providedOnRemove
+	} else if config.OnRemoveWithReason != nil {
+		onRemove = cache.providedOnRemoveWithReason
+	} else {
+		onRemove = cache.notProvidedOnRemove
+	}
+
+	for i := 0; i < config.Shards; i++ {
+		cache.shards[i] = initNewShard(config, onRemove, clock)
+	}
+
+	if config.CleanWindow > 0 {
+		go func() {
+			ticker := time.NewTicker(config.CleanWindow)
+			defer ticker.Stop()
+			for {
+				select {
+				case t := <-ticker.C:
+					cache.cleanUp(uint64(t.Unix()))
+				case <-cache.close:
+					return
+				}
+			}
+		}()
+	}
+
+	return cache, nil
+}
+
+// Close is used to signal a shutdown of the cache when you are done with it.
+// This allows the cleaning goroutines to exit and ensures references are not
+// kept to the cache preventing GC of the entire cache.
+func (c *BigCache) Close() error {
+	close(c.close)
+	return nil
+}
+
+// Get reads entry for the key.
+// It returns an EntryNotFoundError when
+// no entry exists for the given key.
+func (c *BigCache) Get(key string) ([]byte, error) {
+	hashedKey := c.hash.Sum64(key)
+	shard := c.getShard(hashedKey)
+	return shard.get(key, hashedKey)
+}
+
+// Set saves entry under the key
+func (c *BigCache) Set(key string, entry []byte) error {
+	hashedKey := c.hash.Sum64(key)
+	shard := c.getShard(hashedKey)
+	return shard.set(key, hashedKey, entry)
+}
+
+// Delete removes the key
+func (c *BigCache) Delete(key string) error {
+	hashedKey := c.hash.Sum64(key)
+	shard := c.getShard(hashedKey)
+	return shard.del(key, hashedKey)
+}
+
+// Reset empties all cache shards
+func (c *BigCache) Reset() error {
+	for _, shard := range c.shards {
+		shard.reset(c.config)
+	}
+	return nil
+}
+
+// Len computes number of entries in cache
+func (c *BigCache) Len() int {
+	var len int
+	for _, shard := range c.shards {
+		len += shard.len()
+	}
+	return len
+}
+
+// Capacity returns amount of bytes store in the cache.
+func (c *BigCache) Capacity() int {
+	var len int
+	for _, shard := range c.shards {
+		len += shard.capacity()
+	}
+	return len
+}
+
+// Stats returns cache's statistics
+func (c *BigCache) Stats() Stats {
+	var s Stats
+	for _, shard := range c.shards {
+		tmp := shard.getStats()
+		s.Hits += tmp.Hits
+		s.Misses += tmp.Misses
+		s.DelHits += tmp.DelHits
+		s.DelMisses += tmp.DelMisses
+		s.Collisions += tmp.Collisions
+	}
+	return s
+}
+
+// Iterator returns iterator function to iterate over EntryInfo's from whole cache.
+func (c *BigCache) Iterator() *EntryInfoIterator {
+	return newIterator(c)
+}
+
+func (c *BigCache) onEvict(oldestEntry []byte, currentTimestamp uint64, evict func(reason RemoveReason) error) bool {
+	oldestTimestamp := readTimestampFromEntry(oldestEntry)
+	if currentTimestamp-oldestTimestamp > c.lifeWindow {
+		evict(Expired)
+		return true
+	}
+	return false
+}
+
+func (c *BigCache) cleanUp(currentTimestamp uint64) {
+	for _, shard := range c.shards {
+		shard.cleanUp(currentTimestamp)
+	}
+}
+
+func (c *BigCache) getShard(hashedKey uint64) (shard *cacheShard) {
+	return c.shards[hashedKey&c.shardMask]
+}
+
+func (c *BigCache) providedOnRemove(wrappedEntry []byte, reason RemoveReason) {
+	c.config.OnRemove(readKeyFromEntry(wrappedEntry), readEntry(wrappedEntry))
+}
+
+func (c *BigCache) providedOnRemoveWithReason(wrappedEntry []byte, reason RemoveReason) {
+	if c.config.onRemoveFilter == 0 || (1<<uint(reason))&c.config.onRemoveFilter > 0 {
+		c.config.OnRemoveWithReason(readKeyFromEntry(wrappedEntry), readEntry(wrappedEntry), reason)
+	}
+}
+
+func (c *BigCache) notProvidedOnRemove(wrappedEntry []byte, reason RemoveReason) {
+}
--- a/vendor/github.com/allegro/bigcache/bytes.go
+++ b/vendor/github.com/allegro/bigcache/bytes.go
@ -0,0 +1,14 @@
+// +build !appengine
+
+package bigcache
+
+import (
+	"reflect"
+	"unsafe"
+)
+
+func bytesToString(b []byte) string {
+	bytesHeader := (*reflect.SliceHeader)(unsafe.Pointer(&b))
+	strHeader := reflect.StringHeader{Data: bytesHeader.Data, Len: bytesHeader.Len}
+	return *(*string)(unsafe.Pointer(&strHeader))
+}
--- a/vendor/github.com/allegro/bigcache/bytes_appengine.go
+++ b/vendor/github.com/allegro/bigcache/bytes_appengine.go
@ -0,0 +1,7 @@
+// +build appengine
+
+package bigcache
+
+func bytesToString(b []byte) string {
+	return string(b)
+}
--- a/vendor/github.com/allegro/bigcache/clock.go
+++ b/vendor/github.com/allegro/bigcache/clock.go
@ -0,0 +1,14 @@
+package bigcache
+
+import "time"
+
+type clock interface {
+	epoch() int64
+}
+
+type systemClock struct {
+}
+
+func (c systemClock) epoch() int64 {
+	return time.Now().Unix()
+}
--- a/vendor/github.com/allegro/bigcache/config.go
+++ b/vendor/github.com/allegro/bigcache/config.go
@ -0,0 +1,86 @@
+package bigcache
+
+import "time"
+
+// Config for BigCache
+type Config struct {
+	// Number of cache shards, value must be a power of two
+	Shards int
+	// Time after which entry can be evicted
+	LifeWindow time.Duration
+	// Interval between removing expired entries (clean up).
+	// If set to <= 0 then no action is performed. Setting to < 1 second is counterproductive — bigcache has a one second resolution.
+	CleanWindow time.Duration
+	// Max number of entries in life window. Used only to calculate initial size for cache shards.
+	// When proper value is set then additional memory allocation does not occur.
+	MaxEntriesInWindow int
+	// Max size of entry in bytes. Used only to calculate initial size for cache shards.
+	MaxEntrySize int
+	// Verbose mode prints information about new memory allocation
+	Verbose bool
+	// Hasher used to map between string keys and unsigned 64bit integers, by default fnv64 hashing is used.
+	Hasher Hasher
+	// HardMaxCacheSize is a limit for cache size in MB. Cache will not allocate more memory than this limit.
+	// It can protect application from consuming all available memory on machine, therefore from running OOM Killer.
+	// Default value is 0 which means unlimited size. When the limit is higher than 0 and reached then
+	// the oldest entries are overridden for the new ones.
+	HardMaxCacheSize int
+	// OnRemove is a callback fired when the oldest entry is removed because of its expiration time or no space left
+	// for the new entry, or because delete was called.
+	// Default value is nil which means no callback and it prevents from unwrapping the oldest entry.
+	OnRemove func(key string, entry []byte)
+	// OnRemoveWithReason is a callback fired when the oldest entry is removed because of its expiration time or no space left
+	// for the new entry, or because delete was called. A constant representing the reason will be passed through.
+	// Default value is nil which means no callback and it prevents from unwrapping the oldest entry.
+	// Ignored if OnRemove is specified.
+	OnRemoveWithReason func(key string, entry []byte, reason RemoveReason)
+
+	onRemoveFilter int
+
+	// Logger is a logging interface and used in combination with `Verbose`
+	// Defaults to `DefaultLogger()`
+	Logger Logger
+}
+
+// DefaultConfig initializes config with default values.
+// When load for BigCache can be predicted in advance then it is better to use custom config.
+func DefaultConfig(eviction time.Duration) Config {
+	return Config{
+		Shards:             1024,
+		LifeWindow:         eviction,
+		CleanWindow:        0,
+		MaxEntriesInWindow: 1000 * 10 * 60,
+		MaxEntrySize:       500,
+		Verbose:            true,
+		Hasher:             newDefaultHasher(),
+		HardMaxCacheSize:   0,
+		Logger:             DefaultLogger(),
+	}
+}
+
+// initialShardSize computes initial shard size
+func (c Config) initialShardSize() int {
+	return max(c.MaxEntriesInWindow/c.Shards, minimumEntriesInShard)
+}
+
+// maximumShardSize computes maximum shard size
+func (c Config) maximumShardSize() int {
+	maxShardSize := 0
+
+	if c.HardMaxCacheSize > 0 {
+		maxShardSize = convertMBToBytes(c.HardMaxCacheSize) / c.Shards
+	}
+
+	return maxShardSize
+}
+
+// OnRemoveFilterSet sets which remove reasons will trigger a call to OnRemoveWithReason.
+// Filtering out reasons prevents bigcache from unwrapping them, which saves cpu.
+func (c Config) OnRemoveFilterSet(reasons ...RemoveReason) Config {
+	c.onRemoveFilter = 0
+	for i := range reasons {
+		c.onRemoveFilter |= 1 << uint(reasons[i])
+	}
+
+	return c
+}
--- a/vendor/github.com/allegro/bigcache/encoding.go
+++ b/vendor/github.com/allegro/bigcache/encoding.go
@ -0,0 +1,62 @@
+package bigcache
+
+import (
+	"encoding/binary"
+)
+
+const (
+	timestampSizeInBytes = 8                                                       // Number of bytes used for timestamp
+	hashSizeInBytes      = 8                                                       // Number of bytes used for hash
+	keySizeInBytes       = 2                                                       // Number of bytes used for size of entry key
+	headersSizeInBytes   = timestampSizeInBytes + hashSizeInBytes + keySizeInBytes // Number of bytes used for all headers
+)
+
+func wrapEntry(timestamp uint64, hash uint64, key string, entry []byte, buffer *[]byte) []byte {
+	keyLength := len(key)
+	blobLength := len(entry) + headersSizeInBytes + keyLength
+
+	if blobLength > len(*buffer) {
+		*buffer = make([]byte, blobLength)
+	}
+	blob := *buffer
+
+	binary.LittleEndian.PutUint64(blob, timestamp)
+	binary.LittleEndian.PutUint64(blob[timestampSizeInBytes:], hash)
+	binary.LittleEndian.PutUint16(blob[timestampSizeInBytes+hashSizeInBytes:], uint16(keyLength))
+	copy(blob[headersSizeInBytes:], key)
+	copy(blob[headersSizeInBytes+keyLength:], entry)
+
+	return blob[:blobLength]
+}
+
+func readEntry(data []byte) []byte {
+	length := binary.LittleEndian.Uint16(data[timestampSizeInBytes+hashSizeInBytes:])
+
+	// copy on read
+	dst := make([]byte, len(data)-int(headersSizeInBytes+length))
+	copy(dst, data[headersSizeInBytes+length:])
+
+	return dst
+}
+
+func readTimestampFromEntry(data []byte) uint64 {
+	return binary.LittleEndian.Uint64(data)
+}
+
+func readKeyFromEntry(data []byte) string {
+	length := binary.LittleEndian.Uint16(data[timestampSizeInBytes+hashSizeInBytes:])
+
+	// copy on read
+	dst := make([]byte, length)
+	copy(dst, data[headersSizeInBytes:headersSizeInBytes+length])
+
+	return bytesToString(dst)
+}
+
+func readHashFromEntry(data []byte) uint64 {
+	return binary.LittleEndian.Uint64(data[timestampSizeInBytes:])
+}
+
+func resetKeyFromEntry(data []byte) {
+	binary.LittleEndian.PutUint64(data[timestampSizeInBytes:], 0)
+}
--- a/vendor/github.com/allegro/bigcache/entry_not_found_error.go
+++ b/vendor/github.com/allegro/bigcache/entry_not_found_error.go
@ -0,0 +1,17 @@
+package bigcache
+
+import "fmt"
+
+// EntryNotFoundError is an error type struct which is returned when entry was not found for provided key
+type EntryNotFoundError struct {
+	key string
+}
+
+func notFound(key string) error {
+	return &EntryNotFoundError{key}
+}
+
+// Error returned when entry does not exist.
+func (e EntryNotFoundError) Error() string {
+	return fmt.Sprintf("Entry %q not found", e.key)
+}
--- a/vendor/github.com/allegro/bigcache/fnv.go
+++ b/vendor/github.com/allegro/bigcache/fnv.go
@ -0,0 +1,28 @@
+package bigcache
+
+// newDefaultHasher returns a new 64-bit FNV-1a Hasher which makes no memory allocations.
+// Its Sum64 method will lay the value out in big-endian byte order.
+// See https://en.wikipedia.org/wiki/Fowler–Noll–Vo_hash_function
+func newDefaultHasher() Hasher {
+	return fnv64a{}
+}
+
+type fnv64a struct{}
+
+const (
+	// offset64 FNVa offset basis. See https://en.wikipedia.org/wiki/Fowler–Noll–Vo_hash_function#FNV-1a_hash
+	offset64 = 14695981039346656037
+	// prime64 FNVa prime value. See https://en.wikipedia.org/wiki/Fowler–Noll–Vo_hash_function#FNV-1a_hash
+	prime64 = 1099511628211
+)
+
+// Sum64 gets the string and returns its uint64 hash value.
+func (f fnv64a) Sum64(key string) uint64 {
+	var hash uint64 = offset64
+	for i := 0; i < len(key); i++ {
+		hash ^= uint64(key[i])
+		hash *= prime64
+	}
+
+	return hash
+}
--- a/vendor/github.com/allegro/bigcache/hash.go
+++ b/vendor/github.com/allegro/bigcache/hash.go
@ -0,0 +1,8 @@
+package bigcache
+
+// Hasher is responsible for generating unsigned, 64 bit hash of provided string. Hasher should minimize collisions
+// (generating same hash for different strings) and while performance is also important fast functions are preferable (i.e.
+// you can use FarmHash family).
+type Hasher interface {
+	Sum64(string) uint64
+}
--- a/vendor/github.com/allegro/bigcache/iterator.go
+++ b/vendor/github.com/allegro/bigcache/iterator.go
@ -0,0 +1,122 @@
+package bigcache
+
+import "sync"
+
+type iteratorError string
+
+func (e iteratorError) Error() string {
+	return string(e)
+}
+
+// ErrInvalidIteratorState is reported when iterator is in invalid state
+const ErrInvalidIteratorState = iteratorError("Iterator is in invalid state. Use SetNext() to move to next position")
+
+// ErrCannotRetrieveEntry is reported when entry cannot be retrieved from underlying
+const ErrCannotRetrieveEntry = iteratorError("Could not retrieve entry from cache")
+
+var emptyEntryInfo = EntryInfo{}
+
+// EntryInfo holds informations about entry in the cache
+type EntryInfo struct {
+	timestamp uint64
+	hash      uint64
+	key       string
+	value     []byte
+}
+
+// Key returns entry's underlying key
+func (e EntryInfo) Key() string {
+	return e.key
+}
+
+// Hash returns entry's hash value
+func (e EntryInfo) Hash() uint64 {
+	return e.hash
+}
+
+// Timestamp returns entry's timestamp (time of insertion)
+func (e EntryInfo) Timestamp() uint64 {
+	return e.timestamp
+}
+
+// Value returns entry's underlying value
+func (e EntryInfo) Value() []byte {
+	return e.value
+}
+
+// EntryInfoIterator allows to iterate over entries in the cache
+type EntryInfoIterator struct {
+	mutex         sync.Mutex
+	cache         *BigCache
+	currentShard  int
+	currentIndex  int
+	elements      []uint32
+	elementsCount int
+	valid         bool
+}
+
+// SetNext moves to next element and returns true if it exists.
+func (it *EntryInfoIterator) SetNext() bool {
+	it.mutex.Lock()
+
+	it.valid = false
+	it.currentIndex++
+
+	if it.elementsCount > it.currentIndex {
+		it.valid = true
+		it.mutex.Unlock()
+		return true
+	}
+
+	for i := it.currentShard + 1; i < it.cache.config.Shards; i++ {
+		it.elements, it.elementsCount = it.cache.shards[i].copyKeys()
+
+		// Non empty shard - stick with it
+		if it.elementsCount > 0 {
+			it.currentIndex = 0
+			it.currentShard = i
+			it.valid = true
+			it.mutex.Unlock()
+			return true
+		}
+	}
+	it.mutex.Unlock()
+	return false
+}
+
+func newIterator(cache *BigCache) *EntryInfoIterator {
+	elements, count := cache.shards[0].copyKeys()
+
+	return &EntryInfoIterator{
+		cache:         cache,
+		currentShard:  0,
+		currentIndex:  -1,
+		elements:      elements,
+		elementsCount: count,
+	}
+}
+
+// Value returns current value from the iterator
+func (it *EntryInfoIterator) Value() (EntryInfo, error) {
+	it.mutex.Lock()
+
+	if !it.valid {
+		it.mutex.Unlock()
+		return emptyEntryInfo, ErrInvalidIteratorState
+	}
+
+	entry, err := it.cache.shards[it.currentShard].getEntry(int(it.elements[it.currentIndex]))
+
+	if err != nil {
+		it.mutex.Unlock()
+		return emptyEntryInfo, ErrCannotRetrieveEntry
+	}
+	it.mutex.Unlock()
+
+	return EntryInfo{
+		timestamp: readTimestampFromEntry(entry),
+		hash:      readHashFromEntry(entry),
+		key:       readKeyFromEntry(entry),
+		value:     readEntry(entry),
+	}, nil
+}
--- a/vendor/github.com/allegro/bigcache/logger.go
+++ b/vendor/github.com/allegro/bigcache/logger.go
@ -0,0 +1,30 @@
+package bigcache
+
+import (
+	"log"
+	"os"
+)
+
+// Logger is invoked when `Config.Verbose=true`
+type Logger interface {
+	Printf(format string, v ...interface{})
+}
+
+// this is a safeguard, breaking on compile time in case
+// `log.Logger` does not adhere to our `Logger` interface.
+// see https://golang.org/doc/faq#guarantee_satisfies_interface
+var _ Logger = &log.Logger{}
+
+// DefaultLogger returns a `Logger` implementation
+// backed by stdlib's log
+func DefaultLogger() *log.Logger {
+	return log.New(os.Stdout, "", log.LstdFlags)
+}
+
+func newLogger(custom Logger) Logger {
+	if custom != nil {
+		return custom
+	}
+
+	return DefaultLogger()
+}
--- a/vendor/github.com/allegro/bigcache/queue/bytes_queue.go
+++ b/vendor/github.com/allegro/bigcache/queue/bytes_queue.go
@ -0,0 +1,210 @@
+package queue
+
+import (
+	"encoding/binary"
+	"log"
+	"time"
+)
+
+const (
+	// Number of bytes used to keep information about entry size
+	headerEntrySize = 4
+	// Bytes before left margin are not used. Zero index means element does not exist in queue, useful while reading slice from index
+	leftMarginIndex = 1
+	// Minimum empty blob size in bytes. Empty blob fills space between tail and head in additional memory allocation.
+	// It keeps entries indexes unchanged
+	minimumEmptyBlobSize = 32 + headerEntrySize
+)
+
+// BytesQueue is a non-thread safe queue type of fifo based on bytes array.
+// For every push operation index of entry is returned. It can be used to read the entry later
+type BytesQueue struct {
+	array           []byte
+	capacity        int
+	maxCapacity     int
+	head            int
+	tail            int
+	count           int
+	rightMargin     int
+	headerBuffer    []byte
+	verbose         bool
+	initialCapacity int
+}
+
+type queueError struct {
+	message string
+}
+
+// NewBytesQueue initialize new bytes queue.
+// Initial capacity is used in bytes array allocation
+// When verbose flag is set then information about memory allocation are printed
+func NewBytesQueue(initialCapacity int, maxCapacity int, verbose bool) *BytesQueue {
+	return &BytesQueue{
+		array:           make([]byte, initialCapacity),
+		capacity:        initialCapacity,
+		maxCapacity:     maxCapacity,
+		headerBuffer:    make([]byte, headerEntrySize),
+		tail:            leftMarginIndex,
+		head:            leftMarginIndex,
+		rightMargin:     leftMarginIndex,
+		verbose:         verbose,
+		initialCapacity: initialCapacity,
+	}
+}
+
+// Reset removes all entries from queue
+func (q *BytesQueue) Reset() {
+	// Just reset indexes
+	q.tail = leftMarginIndex
+	q.head = leftMarginIndex
+	q.rightMargin = leftMarginIndex
+	q.count = 0
+}
+
+// Push copies entry at the end of queue and moves tail pointer. Allocates more space if needed.
+// Returns index for pushed data or error if maximum size queue limit is reached.
+func (q *BytesQueue) Push(data []byte) (int, error) {
+	dataLen := len(data)
+
+	if q.availableSpaceAfterTail() < dataLen+headerEntrySize {
+		if q.availableSpaceBeforeHead() >= dataLen+headerEntrySize {
+			q.tail = leftMarginIndex
+		} else if q.capacity+headerEntrySize+dataLen >= q.maxCapacity && q.maxCapacity > 0 {
+			return -1, &queueError{"Full queue. Maximum size limit reached."}
+		} else {
+			q.allocateAdditionalMemory(dataLen + headerEntrySize)
+		}
+	}
+
+	index := q.tail
+
+	q.push(data, dataLen)
+
+	return index, nil
+}
+
+func (q *BytesQueue) allocateAdditionalMemory(minimum int) {
+	start := time.Now()
+	if q.capacity < minimum {
+		q.capacity += minimum
+	}
+	q.capacity = q.capacity * 2
+	if q.capacity > q.maxCapacity && q.maxCapacity > 0 {
+		q.capacity = q.maxCapacity
+	}
+
+	oldArray := q.array
+	q.array = make([]byte, q.capacity)
+
+	if leftMarginIndex != q.rightMargin {
+		copy(q.array, oldArray[:q.rightMargin])
+
+		if q.tail < q.head {
+			emptyBlobLen := q.head - q.tail - headerEntrySize
+			q.push(make([]byte, emptyBlobLen), emptyBlobLen)
+			q.head = leftMarginIndex
+			q.tail = q.rightMargin
+		}
+	}
+
+	if q.verbose {
+		log.Printf("Allocated new queue in %s; Capacity: %d \n", time.Since(start), q.capacity)
+	}
+}
+
+func (q *BytesQueue) push(data []byte, len int) {
+	binary.LittleEndian.PutUint32(q.headerBuffer, uint32(len))
+	q.copy(q.headerBuffer, headerEntrySize)
+
+	q.copy(data, len)
+
+	if q.tail > q.head {
+		q.rightMargin = q.tail
+	}
+
+	q.count++
+}
+
+func (q *BytesQueue) copy(data []byte, len int) {
+	q.tail += copy(q.array[q.tail:], data[:len])
+}
+
+// Pop reads the oldest entry from queue and moves head pointer to the next one
+func (q *BytesQueue) Pop() ([]byte, error) {
+	data, size, err := q.peek(q.head)
+	if err != nil {
+		return nil, err
+	}
+
+	q.head += headerEntrySize + size
+	q.count--
+
+	if q.head == q.rightMargin {
+		q.head = leftMarginIndex
+		if q.tail == q.rightMargin {
+			q.tail = leftMarginIndex
+		}
+		q.rightMargin = q.tail
+	}
+
+	return data, nil
+}
+
+// Peek reads the oldest entry from list without moving head pointer
+func (q *BytesQueue) Peek() ([]byte, error) {
+	data, _, err := q.peek(q.head)
+	return data, err
+}
+
+// Get reads entry from index
+func (q *BytesQueue) Get(index int) ([]byte, error) {
+	data, _, err := q.peek(index)
+	return data, err
+}
+
+// Capacity returns number of allocated bytes for queue
+func (q *BytesQueue) Capacity() int {
+	return q.capacity
+}
+
+// Len returns number of entries kept in queue
+func (q *BytesQueue) Len() int {
+	return q.count
+}
+
+// Error returns error message
+func (e *queueError) Error() string {
+	return e.message
+}
+
+func (q *BytesQueue) peek(index int) ([]byte, int, error) {
+
+	if q.count == 0 {
+		return nil, 0, &queueError{"Empty queue"}
+	}
+
+	if index <= 0 {
+		return nil, 0, &queueError{"Index must be grater than zero. Invalid index."}
+	}
+
+	if index+headerEntrySize >= len(q.array) {
+		return nil, 0, &queueError{"Index out of range"}
+	}
+
+	blockSize := int(binary.LittleEndian.Uint32(q.array[index : index+headerEntrySize]))
+	return q.array[index+headerEntrySize : index+headerEntrySize+blockSize], blockSize, nil
+}
+
+func (q *BytesQueue) availableSpaceAfterTail() int {
+	if q.tail >= q.head {
+		return q.capacity - q.tail
+	}
+	return q.head - q.tail - minimumEmptyBlobSize
+}
+
+func (q *BytesQueue) availableSpaceBeforeHead() int {
+	if q.tail >= q.head {
+		return q.head - leftMarginIndex - minimumEmptyBlobSize
+	}
+	return q.head - q.tail - minimumEmptyBlobSize
+}
--- a/vendor/github.com/allegro/bigcache/shard.go
+++ b/vendor/github.com/allegro/bigcache/shard.go
@ -0,0 +1,236 @@
+package bigcache
+
+import (
+	"fmt"
+	"sync"
+	"sync/atomic"
+
+	"github.com/allegro/bigcache/queue"
+)
+
+type onRemoveCallback func(wrappedEntry []byte, reason RemoveReason)
+
+type cacheShard struct {
+	hashmap     map[uint64]uint32
+	entries     queue.BytesQueue
+	lock        sync.RWMutex
+	entryBuffer []byte
+	onRemove    onRemoveCallback
+
+	isVerbose  bool
+	logger     Logger
+	clock      clock
+	lifeWindow uint64
+
+	stats Stats
+}
+
+func (s *cacheShard) get(key string, hashedKey uint64) ([]byte, error) {
+	s.lock.RLock()
+	itemIndex := s.hashmap[hashedKey]
+
+	if itemIndex == 0 {
+		s.lock.RUnlock()
+		s.miss()
+		return nil, notFound(key)
+	}
+
+	wrappedEntry, err := s.entries.Get(int(itemIndex))
+	if err != nil {
+		s.lock.RUnlock()
+		s.miss()
+		return nil, err
+	}
+	if entryKey := readKeyFromEntry(wrappedEntry); key != entryKey {
+		if s.isVerbose {
+			s.logger.Printf("Collision detected. Both %q and %q have the same hash %x", key, entryKey, hashedKey)
+		}
+		s.lock.RUnlock()
+		s.collision()
+		return nil, notFound(key)
+	}
+	s.lock.RUnlock()
+	s.hit()
+	return readEntry(wrappedEntry), nil
+}
+
+func (s *cacheShard) set(key string, hashedKey uint64, entry []byte) error {
+	currentTimestamp := uint64(s.clock.epoch())
+
+	s.lock.Lock()
+
+	if previousIndex := s.hashmap[hashedKey]; previousIndex != 0 {
+		if previousEntry, err := s.entries.Get(int(previousIndex)); err == nil {
+			resetKeyFromEntry(previousEntry)
+		}
+	}
+
+	if oldestEntry, err := s.entries.Peek(); err == nil {
+		s.onEvict(oldestEntry, currentTimestamp, s.removeOldestEntry)
+	}
+
+	w := wrapEntry(currentTimestamp, hashedKey, key, entry, &s.entryBuffer)
+
+	for {
+		if index, err := s.entries.Push(w); err == nil {
+			s.hashmap[hashedKey] = uint32(index)
+			s.lock.Unlock()
+			return nil
+		}
+		if s.removeOldestEntry(NoSpace) != nil {
+			s.lock.Unlock()
+			return fmt.Errorf("entry is bigger than max shard size")
+		}
+	}
+}
+
+func (s *cacheShard) del(key string, hashedKey uint64) error {
+	s.lock.RLock()
+	itemIndex := s.hashmap[hashedKey]
+
+	if itemIndex == 0 {
+		s.lock.RUnlock()
+		s.delmiss()
+		return notFound(key)
+	}
+
+	wrappedEntry, err := s.entries.Get(int(itemIndex))
+	if err != nil {
+		s.lock.RUnlock()
+		s.delmiss()
+		return err
+	}
+	s.lock.RUnlock()
+
+	s.lock.Lock()
+	{
+		delete(s.hashmap, hashedKey)
+		s.onRemove(wrappedEntry, Deleted)
+		resetKeyFromEntry(wrappedEntry)
+	}
+	s.lock.Unlock()
+
+	s.delhit()
+	return nil
+}
+
+func (s *cacheShard) onEvict(oldestEntry []byte, currentTimestamp uint64, evict func(reason RemoveReason) error) bool {
+	oldestTimestamp := readTimestampFromEntry(oldestEntry)
+	if currentTimestamp-oldestTimestamp > s.lifeWindow {
+		evict(Expired)
+		return true
+	}
+	return false
+}
+
+func (s *cacheShard) cleanUp(currentTimestamp uint64) {
+	s.lock.Lock()
+	for {
+		if oldestEntry, err := s.entries.Peek(); err != nil {
+			break
+		} else if evicted := s.onEvict(oldestEntry, currentTimestamp, s.removeOldestEntry); !evicted {
+			break
+		}
+	}
+	s.lock.Unlock()
+}
+
+func (s *cacheShard) getOldestEntry() ([]byte, error) {
+	return s.entries.Peek()
+}
+
+func (s *cacheShard) getEntry(index int) ([]byte, error) {
+	return s.entries.Get(index)
+}
+
+func (s *cacheShard) copyKeys() (keys []uint32, next int) {
+	keys = make([]uint32, len(s.hashmap))
+
+	s.lock.RLock()
+
+	for _, index := range s.hashmap {
+		keys[next] = index
+		next++
+	}
+
+	s.lock.RUnlock()
+	return keys, next
+}
+
+func (s *cacheShard) removeOldestEntry(reason RemoveReason) error {
+	oldest, err := s.entries.Pop()
+	if err == nil {
+		hash := readHashFromEntry(oldest)
+		delete(s.hashmap, hash)
+		s.onRemove(oldest, reason)
+		return nil
+	}
+	return err
+}
+
+func (s *cacheShard) reset(config Config) {
+	s.lock.Lock()
+	s.hashmap = make(map[uint64]uint32, config.initialShardSize())
+	s.entryBuffer = make([]byte, config.MaxEntrySize+headersSizeInBytes)
+	s.entries.Reset()
+	s.lock.Unlock()
+}
+
+func (s *cacheShard) len() int {
+	s.lock.RLock()
+	res := len(s.hashmap)
+	s.lock.RUnlock()
+	return res
+}
+
+func (s *cacheShard) capacity() int {
+	s.lock.RLock()
+	res := s.entries.Capacity()
+	s.lock.RUnlock()
+	return res
+}
+
+func (s *cacheShard) getStats() Stats {
+	var stats = Stats{
+		Hits:       atomic.LoadInt64(&s.stats.Hits),
+		Misses:     atomic.LoadInt64(&s.stats.Misses),
+		DelHits:    atomic.LoadInt64(&s.stats.DelHits),
+		DelMisses:  atomic.LoadInt64(&s.stats.DelMisses),
+		Collisions: atomic.LoadInt64(&s.stats.Collisions),
+	}
+	return stats
+}
+
+func (s *cacheShard) hit() {
+	atomic.AddInt64(&s.stats.Hits, 1)
+}
+
+func (s *cacheShard) miss() {
+	atomic.AddInt64(&s.stats.Misses, 1)
+}
+
+func (s *cacheShard) delhit() {
+	atomic.AddInt64(&s.stats.DelHits, 1)
+}
+
+func (s *cacheShard) delmiss() {
+	atomic.AddInt64(&s.stats.DelMisses, 1)
+}
+
+func (s *cacheShard) collision() {
+	atomic.AddInt64(&s.stats.Collisions, 1)
+}
+
+func initNewShard(config Config, callback onRemoveCallback, clock clock) *cacheShard {
+	return &cacheShard{
+		hashmap:     make(map[uint64]uint32, config.initialShardSize()),
+		entries:     *queue.NewBytesQueue(config.initialShardSize()*config.MaxEntrySize, config.maximumShardSize(), config.Verbose),
+		entryBuffer: make([]byte, config.MaxEntrySize+headersSizeInBytes),
+		onRemove:    callback,
+
+		isVerbose:  config.Verbose,
+		logger:     newLogger(config.Logger),
+		clock:      clock,
+		lifeWindow: uint64(config.LifeWindow.Seconds()),
+	}
+}
--- a/vendor/github.com/allegro/bigcache/stats.go
+++ b/vendor/github.com/allegro/bigcache/stats.go
@ -0,0 +1,15 @@
+package bigcache
+
+// Stats stores cache statistics
+type Stats struct {
+	// Hits is a number of successfully found keys
+	Hits int64 `json:"hits"`
+	// Misses is a number of not found keys
+	Misses int64 `json:"misses"`
+	// DelHits is a number of successfully deleted keys
+	DelHits int64 `json:"delete_hits"`
+	// DelMisses is a number of not deleted keys
+	DelMisses int64 `json:"delete_misses"`
+	// Collisions is a number of happened key-collisions
+	Collisions int64 `json:"collisions"`
+}
--- a/vendor/github.com/allegro/bigcache/utils.go
+++ b/vendor/github.com/allegro/bigcache/utils.go
@ -0,0 +1,16 @@
+package bigcache
+
+func max(a, b int) int {
+	if a > b {
+		return a
+	}
+	return b
+}
+
+func convertMBToBytes(value int) int {
+	return value * 1024 * 1024
+}
+
+func isPowerOfTwo(number int) bool {
+	return (number & (number - 1)) == 0
+}
--- a/vendor/vendor.json
+++ b/vendor/vendor.json
@ -38,6 +38,18 @@
 			"revision": "5d049714c4a64225c3c79a7cf7d02f7fb5b96338",
 			"revisionTime": "2018-01-16T20:38:02Z"
 		},
+		{
+			"checksumSHA1": "9Niiu1GNhWUrXnGZrl8AU4EzbVE=",
+			"path": "github.com/allegro/bigcache",
+			"revision": "bff00e20c68d9f136477d62d182a7dc917bae0ca",
+			"revisionTime": "2018-10-22T20:06:25Z"
+		},
+		{
+			"checksumSHA1": "zqToN+R6KybEskp1D4G/lAOKXU4=",
+			"path": "github.com/allegro/bigcache/queue",
+			"revision": "bff00e20c68d9f136477d62d182a7dc917bae0ca",
+			"revisionTime": "2018-10-22T20:06:25Z"
+		},
 		{
 			"checksumSHA1": "USkefO0g1U9mr+8hagv3fpSkrxg=",
 			"path": "github.com/aristanetworks/goarista/monotime",