// Copyright 2019 The go-ethereum Authors // This file is part of the go-ethereum library. // // The go-ethereum library is free software: you can redistribute it and/or modify // it under the terms of the GNU Lesser General Public License as published by // the Free Software Foundation, either version 3 of the License, or // (at your option) any later version. // // The go-ethereum library is distributed in the hope that it will be useful, // but WITHOUT ANY WARRANTY; without even the implied warranty of // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the // GNU Lesser General Public License for more details. // // You should have received a copy of the GNU Lesser General Public License // along with the go-ethereum library. If not, see . // Package snapshot implements a journalled, dynamic state dump. package snapshot import ( "bytes" "errors" "fmt" "sync" "github.com/ethereum/go-ethereum/common" "github.com/ethereum/go-ethereum/core/rawdb" "github.com/ethereum/go-ethereum/ethdb" "github.com/ethereum/go-ethereum/log" "github.com/ethereum/go-ethereum/metrics" "github.com/ethereum/go-ethereum/trie" ) var ( snapshotCleanAccountHitMeter = metrics.NewRegisteredMeter("state/snapshot/clean/account/hit", nil) snapshotCleanAccountMissMeter = metrics.NewRegisteredMeter("state/snapshot/clean/account/miss", nil) snapshotCleanAccountInexMeter = metrics.NewRegisteredMeter("state/snapshot/clean/account/inex", nil) snapshotCleanAccountReadMeter = metrics.NewRegisteredMeter("state/snapshot/clean/account/read", nil) snapshotCleanAccountWriteMeter = metrics.NewRegisteredMeter("state/snapshot/clean/account/write", nil) snapshotCleanStorageHitMeter = metrics.NewRegisteredMeter("state/snapshot/clean/storage/hit", nil) snapshotCleanStorageMissMeter = metrics.NewRegisteredMeter("state/snapshot/clean/storage/miss", nil) snapshotCleanStorageInexMeter = metrics.NewRegisteredMeter("state/snapshot/clean/storage/inex", nil) snapshotCleanStorageReadMeter = metrics.NewRegisteredMeter("state/snapshot/clean/storage/read", nil) snapshotCleanStorageWriteMeter = metrics.NewRegisteredMeter("state/snapshot/clean/storage/write", nil) snapshotDirtyAccountHitMeter = metrics.NewRegisteredMeter("state/snapshot/dirty/account/hit", nil) snapshotDirtyAccountMissMeter = metrics.NewRegisteredMeter("state/snapshot/dirty/account/miss", nil) snapshotDirtyAccountInexMeter = metrics.NewRegisteredMeter("state/snapshot/dirty/account/inex", nil) snapshotDirtyAccountReadMeter = metrics.NewRegisteredMeter("state/snapshot/dirty/account/read", nil) snapshotDirtyAccountWriteMeter = metrics.NewRegisteredMeter("state/snapshot/dirty/account/write", nil) snapshotDirtyStorageHitMeter = metrics.NewRegisteredMeter("state/snapshot/dirty/storage/hit", nil) snapshotDirtyStorageMissMeter = metrics.NewRegisteredMeter("state/snapshot/dirty/storage/miss", nil) snapshotDirtyStorageInexMeter = metrics.NewRegisteredMeter("state/snapshot/dirty/storage/inex", nil) snapshotDirtyStorageReadMeter = metrics.NewRegisteredMeter("state/snapshot/dirty/storage/read", nil) snapshotDirtyStorageWriteMeter = metrics.NewRegisteredMeter("state/snapshot/dirty/storage/write", nil) snapshotDirtyAccountHitDepthHist = metrics.NewRegisteredHistogram("state/snapshot/dirty/account/hit/depth", nil, metrics.NewExpDecaySample(1028, 0.015)) snapshotDirtyStorageHitDepthHist = metrics.NewRegisteredHistogram("state/snapshot/dirty/storage/hit/depth", nil, metrics.NewExpDecaySample(1028, 0.015)) snapshotFlushAccountItemMeter = metrics.NewRegisteredMeter("state/snapshot/flush/account/item", nil) snapshotFlushAccountSizeMeter = metrics.NewRegisteredMeter("state/snapshot/flush/account/size", nil) snapshotFlushStorageItemMeter = metrics.NewRegisteredMeter("state/snapshot/flush/storage/item", nil) snapshotFlushStorageSizeMeter = metrics.NewRegisteredMeter("state/snapshot/flush/storage/size", nil) snapshotBloomIndexTimer = metrics.NewRegisteredResettingTimer("state/snapshot/bloom/index", nil) snapshotBloomErrorGauge = metrics.NewRegisteredGaugeFloat64("state/snapshot/bloom/error", nil) snapshotBloomAccountTrueHitMeter = metrics.NewRegisteredMeter("state/snapshot/bloom/account/truehit", nil) snapshotBloomAccountFalseHitMeter = metrics.NewRegisteredMeter("state/snapshot/bloom/account/falsehit", nil) snapshotBloomAccountMissMeter = metrics.NewRegisteredMeter("state/snapshot/bloom/account/miss", nil) snapshotBloomStorageTrueHitMeter = metrics.NewRegisteredMeter("state/snapshot/bloom/storage/truehit", nil) snapshotBloomStorageFalseHitMeter = metrics.NewRegisteredMeter("state/snapshot/bloom/storage/falsehit", nil) snapshotBloomStorageMissMeter = metrics.NewRegisteredMeter("state/snapshot/bloom/storage/miss", nil) // ErrSnapshotStale is returned from data accessors if the underlying snapshot // layer had been invalidated due to the chain progressing forward far enough // to not maintain the layer's original state. ErrSnapshotStale = errors.New("snapshot stale") // ErrNotCoveredYet is returned from data accessors if the underlying snapshot // is being generated currently and the requested data item is not yet in the // range of accounts covered. ErrNotCoveredYet = errors.New("not covered yet") // errSnapshotCycle is returned if a snapshot is attempted to be inserted // that forms a cycle in the snapshot tree. errSnapshotCycle = errors.New("snapshot cycle") ) // Snapshot represents the functionality supported by a snapshot storage layer. type Snapshot interface { // Root returns the root hash for which this snapshot was made. Root() common.Hash // Account directly retrieves the account associated with a particular hash in // the snapshot slim data format. Account(hash common.Hash) (*Account, error) // AccountRLP directly retrieves the account RLP associated with a particular // hash in the snapshot slim data format. AccountRLP(hash common.Hash) ([]byte, error) // Storage directly retrieves the storage data associated with a particular hash, // within a particular account. Storage(accountHash, storageHash common.Hash) ([]byte, error) } // snapshot is the internal version of the snapshot data layer that supports some // additional methods compared to the public API. type snapshot interface { Snapshot // Parent returns the subsequent layer of a snapshot, or nil if the base was // reached. // // Note, the method is an internal helper to avoid type switching between the // disk and diff layers. There is no locking involved. Parent() snapshot // Update creates a new layer on top of the existing snapshot diff tree with // the specified data items. // // Note, the maps are retained by the method to avoid copying everything. Update(blockRoot common.Hash, accounts map[common.Hash][]byte, storage map[common.Hash]map[common.Hash][]byte) *diffLayer // Journal commits an entire diff hierarchy to disk into a single journal entry. // This is meant to be used during shutdown to persist the snapshot without // flattening everything down (bad for reorgs). Journal(buffer *bytes.Buffer) (common.Hash, error) // Stale return whether this layer has become stale (was flattened across) or // if it's still live. Stale() bool // AccountIterator creates an account iterator over an arbitrary layer. AccountIterator(seek common.Hash) AccountIterator } // SnapshotTree is an Ethereum state snapshot tree. It consists of one persistent // base layer backed by a key-value store, on top of which arbitrarily many in- // memory diff layers are topped. The memory diffs can form a tree with branching, // but the disk layer is singleton and common to all. If a reorg goes deeper than // the disk layer, everything needs to be deleted. // // The goal of a state snapshot is twofold: to allow direct access to account and // storage data to avoid expensive multi-level trie lookups; and to allow sorted, // cheap iteration of the account/storage tries for sync aid. type Tree struct { diskdb ethdb.KeyValueStore // Persistent database to store the snapshot triedb *trie.Database // In-memory cache to access the trie through cache int // Megabytes permitted to use for read caches layers map[common.Hash]snapshot // Collection of all known layers lock sync.RWMutex } // New attempts to load an already existing snapshot from a persistent key-value // store (with a number of memory layers from a journal), ensuring that the head // of the snapshot matches the expected one. // // If the snapshot is missing or inconsistent, the entirety is deleted and will // be reconstructed from scratch based on the tries in the key-value store, on a // background thread. func New(diskdb ethdb.KeyValueStore, triedb *trie.Database, cache int, root common.Hash) *Tree { // Create a new, empty snapshot tree snap := &Tree{ diskdb: diskdb, triedb: triedb, cache: cache, layers: make(map[common.Hash]snapshot), } // Attempt to load a previously persisted snapshot and rebuild one if failed head, err := loadSnapshot(diskdb, triedb, cache, root) if err != nil { log.Warn("Failed to load snapshot, regenerating", "err", err) snap.Rebuild(root) return snap } // Existing snapshot loaded, seed all the layers for head != nil { snap.layers[head.Root()] = head head = head.Parent() } return snap } // Snapshot retrieves a snapshot belonging to the given block root, or nil if no // snapshot is maintained for that block. func (t *Tree) Snapshot(blockRoot common.Hash) Snapshot { t.lock.RLock() defer t.lock.RUnlock() return t.layers[blockRoot] } // Update adds a new snapshot into the tree, if that can be linked to an existing // old parent. It is disallowed to insert a disk layer (the origin of all). func (t *Tree) Update(blockRoot common.Hash, parentRoot common.Hash, accounts map[common.Hash][]byte, storage map[common.Hash]map[common.Hash][]byte) error { // Reject noop updates to avoid self-loops in the snapshot tree. This is a // special case that can only happen for Clique networks where empty blocks // don't modify the state (0 block subsidy). // // Although we could silently ignore this internally, it should be the caller's // responsibility to avoid even attempting to insert such a snapshot. if blockRoot == parentRoot { return errSnapshotCycle } // Generate a new snapshot on top of the parent parent := t.Snapshot(parentRoot).(snapshot) if parent == nil { return fmt.Errorf("parent [%#x] snapshot missing", parentRoot) } snap := parent.Update(blockRoot, accounts, storage) // Save the new snapshot for later t.lock.Lock() defer t.lock.Unlock() t.layers[snap.root] = snap return nil } // Cap traverses downwards the snapshot tree from a head block hash until the // number of allowed layers are crossed. All layers beyond the permitted number // are flattened downwards. func (t *Tree) Cap(root common.Hash, layers int) error { // Retrieve the head snapshot to cap from snap := t.Snapshot(root) if snap == nil { return fmt.Errorf("snapshot [%#x] missing", root) } diff, ok := snap.(*diffLayer) if !ok { return fmt.Errorf("snapshot [%#x] is disk layer", root) } // Run the internal capping and discard all stale layers t.lock.Lock() defer t.lock.Unlock() // Flattening the bottom-most diff layer requires special casing since there's // no child to rewire to the grandparent. In that case we can fake a temporary // child for the capping and then remove it. var persisted *diskLayer switch layers { case 0: // If full commit was requested, flatten the diffs and merge onto disk diff.lock.RLock() base := diffToDisk(diff.flatten().(*diffLayer)) diff.lock.RUnlock() // Replace the entire snapshot tree with the flat base t.layers = map[common.Hash]snapshot{base.root: base} return nil case 1: // If full flattening was requested, flatten the diffs but only merge if the // memory limit was reached var ( bottom *diffLayer base *diskLayer ) diff.lock.RLock() bottom = diff.flatten().(*diffLayer) if bottom.memory >= aggregatorMemoryLimit { base = diffToDisk(bottom) } diff.lock.RUnlock() // If all diff layers were removed, replace the entire snapshot tree if base != nil { t.layers = map[common.Hash]snapshot{base.root: base} return nil } // Merge the new aggregated layer into the snapshot tree, clean stales below t.layers[bottom.root] = bottom default: // Many layers requested to be retained, cap normally persisted = t.cap(diff, layers) } // Remove any layer that is stale or links into a stale layer children := make(map[common.Hash][]common.Hash) for root, snap := range t.layers { if diff, ok := snap.(*diffLayer); ok { parent := diff.parent.Root() children[parent] = append(children[parent], root) } } var remove func(root common.Hash) remove = func(root common.Hash) { delete(t.layers, root) for _, child := range children[root] { remove(child) } delete(children, root) } for root, snap := range t.layers { if snap.Stale() { remove(root) } } // If the disk layer was modified, regenerate all the cummulative blooms if persisted != nil { var rebloom func(root common.Hash) rebloom = func(root common.Hash) { if diff, ok := t.layers[root].(*diffLayer); ok { diff.rebloom(persisted) } for _, child := range children[root] { rebloom(child) } } rebloom(persisted.root) } return nil } // cap traverses downwards the diff tree until the number of allowed layers are // crossed. All diffs beyond the permitted number are flattened downwards. If the // layer limit is reached, memory cap is also enforced (but not before). // // The method returns the new disk layer if diffs were persistend into it. func (t *Tree) cap(diff *diffLayer, layers int) *diskLayer { // Dive until we run out of layers or reach the persistent database for ; layers > 2; layers-- { // If we still have diff layers below, continue down if parent, ok := diff.parent.(*diffLayer); ok { diff = parent } else { // Diff stack too shallow, return without modifications return nil } } // We're out of layers, flatten anything below, stopping if it's the disk or if // the memory limit is not yet exceeded. switch parent := diff.parent.(type) { case *diskLayer: return nil case *diffLayer: // Flatten the parent into the grandparent. The flattening internally obtains a // write lock on grandparent. flattened := parent.flatten().(*diffLayer) t.layers[flattened.root] = flattened diff.lock.Lock() defer diff.lock.Unlock() diff.parent = flattened if flattened.memory < aggregatorMemoryLimit { // Accumulator layer is smaller than the limit, so we can abort, unless // there's a snapshot being generated currently. In that case, the trie // will move fron underneath the generator so we **must** merge all the // partial data down into the snapshot and restart the generation. if flattened.parent.(*diskLayer).genAbort == nil { return nil } } default: panic(fmt.Sprintf("unknown data layer: %T", parent)) } // If the bottom-most layer is larger than our memory cap, persist to disk bottom := diff.parent.(*diffLayer) bottom.lock.RLock() base := diffToDisk(bottom) bottom.lock.RUnlock() t.layers[base.root] = base diff.parent = base return base } // diffToDisk merges a bottom-most diff into the persistent disk layer underneath // it. The method will panic if called onto a non-bottom-most diff layer. func diffToDisk(bottom *diffLayer) *diskLayer { var ( base = bottom.parent.(*diskLayer) batch = base.diskdb.NewBatch() stats *generatorStats ) // If the disk layer is running a snapshot generator, abort it if base.genAbort != nil { abort := make(chan *generatorStats) base.genAbort <- abort stats = <-abort } // Start by temporarily deleting the current snapshot block marker. This // ensures that in the case of a crash, the entire snapshot is invalidated. rawdb.DeleteSnapshotRoot(batch) // Mark the original base as stale as we're going to create a new wrapper base.lock.Lock() if base.stale { panic("parent disk layer is stale") // we've committed into the same base from two children, boo } base.stale = true base.lock.Unlock() // Push all the accounts into the database for hash, data := range bottom.accountData { // Skip any account not covered yet by the snapshot if base.genMarker != nil && bytes.Compare(hash[:], base.genMarker) > 0 { continue } if len(data) > 0 { // Account was updated, push to disk rawdb.WriteAccountSnapshot(batch, hash, data) base.cache.Set(hash[:], data) snapshotCleanAccountWriteMeter.Mark(int64(len(data))) if batch.ValueSize() > ethdb.IdealBatchSize { if err := batch.Write(); err != nil { log.Crit("Failed to write account snapshot", "err", err) } batch.Reset() } } else { // Account was deleted, remove all storage slots too rawdb.DeleteAccountSnapshot(batch, hash) base.cache.Set(hash[:], nil) it := rawdb.IterateStorageSnapshots(base.diskdb, hash) for it.Next() { if key := it.Key(); len(key) == 65 { // TODO(karalabe): Yuck, we should move this into the iterator batch.Delete(key) base.cache.Del(key[1:]) snapshotFlushStorageItemMeter.Mark(1) snapshotFlushStorageSizeMeter.Mark(int64(len(data))) } } it.Release() } snapshotFlushAccountItemMeter.Mark(1) snapshotFlushAccountSizeMeter.Mark(int64(len(data))) } // Push all the storage slots into the database for accountHash, storage := range bottom.storageData { // Skip any account not covered yet by the snapshot if base.genMarker != nil && bytes.Compare(accountHash[:], base.genMarker) > 0 { continue } // Generation might be mid-account, track that case too midAccount := base.genMarker != nil && bytes.Equal(accountHash[:], base.genMarker[:common.HashLength]) for storageHash, data := range storage { // Skip any slot not covered yet by the snapshot if midAccount && bytes.Compare(storageHash[:], base.genMarker[common.HashLength:]) > 0 { continue } if len(data) > 0 { rawdb.WriteStorageSnapshot(batch, accountHash, storageHash, data) base.cache.Set(append(accountHash[:], storageHash[:]...), data) snapshotCleanStorageWriteMeter.Mark(int64(len(data))) } else { rawdb.DeleteStorageSnapshot(batch, accountHash, storageHash) base.cache.Set(append(accountHash[:], storageHash[:]...), nil) } snapshotFlushStorageItemMeter.Mark(1) snapshotFlushStorageSizeMeter.Mark(int64(len(data))) } if batch.ValueSize() > ethdb.IdealBatchSize { if err := batch.Write(); err != nil { log.Crit("Failed to write storage snapshot", "err", err) } batch.Reset() } } // Update the snapshot block marker and write any remainder data rawdb.WriteSnapshotRoot(batch, bottom.root) if err := batch.Write(); err != nil { log.Crit("Failed to write leftover snapshot", "err", err) } res := &diskLayer{ root: bottom.root, cache: base.cache, diskdb: base.diskdb, triedb: base.triedb, genMarker: base.genMarker, } // If snapshot generation hasn't finished yet, port over all the starts and // continue where the previous round left off. // // Note, the `base.genAbort` comparison is not used normally, it's checked // to allow the tests to play with the marker without triggering this path. if base.genMarker != nil && base.genAbort != nil { res.genMarker = base.genMarker res.genAbort = make(chan chan *generatorStats) go res.generate(stats) } return res } // Journal commits an entire diff hierarchy to disk into a single journal entry. // This is meant to be used during shutdown to persist the snapshot without // flattening everything down (bad for reorgs). // // The method returns the root hash of the base layer that needs to be persisted // to disk as a trie too to allow continuing any pending generation op. func (t *Tree) Journal(root common.Hash) (common.Hash, error) { // Retrieve the head snapshot to journal from var snap snapshot snap := t.Snapshot(root) if snap == nil { return common.Hash{}, fmt.Errorf("snapshot [%#x] missing", root) } // Run the journaling t.lock.Lock() defer t.lock.Unlock() journal := new(bytes.Buffer) base, err := snap.(snapshot).Journal(journal) if err != nil { return common.Hash{}, err } // Store the journal into the database and return rawdb.WriteSnapshotJournal(t.diskdb, journal.Bytes()) return base, nil } // Rebuild wipes all available snapshot data from the persistent database and // discard all caches and diff layers. Afterwards, it starts a new snapshot // generator with the given root hash. func (t *Tree) Rebuild(root common.Hash) { t.lock.Lock() defer t.lock.Unlock() // Track whether there's a wipe currently running and keep it alive if so var wiper chan struct{} // Iterate over and mark all layers stale for _, layer := range t.layers { switch layer := layer.(type) { case *diskLayer: // If the base layer is generating, abort it and save if layer.genAbort != nil { abort := make(chan *generatorStats) layer.genAbort <- abort if stats := <-abort; stats != nil { wiper = stats.wiping } } // Layer should be inactive now, mark it as stale layer.lock.Lock() layer.stale = true layer.lock.Unlock() case *diffLayer: // If the layer is a simple diff, simply mark as stale layer.lock.Lock() layer.stale = true layer.lock.Unlock() default: panic(fmt.Sprintf("unknown layer type: %T", layer)) } } // Start generating a new snapshot from scratch on a backgroung thread. The // generator will run a wiper first if there's not one running right now. log.Info("Rebuilding state snapshot") t.layers = map[common.Hash]snapshot{ root: generateSnapshot(t.diskdb, t.triedb, t.cache, root, wiper), } } // AccountIterator creates a new account iterator for the specified root hash and // seeks to a starting account hash. func (t *Tree) AccountIterator(root common.Hash, seek common.Hash) (AccountIterator, error) { return newFastAccountIterator(t, root, seek) }