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snapshot.go
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snapshot.go
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// (c) 2019-2020, Ava Labs, Inc.
//
// This file is a derived work, based on the go-ethereum library whose original
// notices appear below.
//
// It is distributed under a license compatible with the licensing terms of the
// original code from which it is derived.
//
// Much love to the original authors for their work.
// **********
// 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 <http://www.gnu.org/licenses/>.
// Package snapshot implements a journalled, dynamic state dump.
package snapshot
import (
"bytes"
"errors"
"fmt"
"sync"
"time"
"github.com/ava-labs/subnet-evm/core/rawdb"
"github.com/ava-labs/subnet-evm/ethdb"
"github.com/ava-labs/subnet-evm/metrics"
"github.com/ava-labs/subnet-evm/trie"
"github.com/ava-labs/subnet-evm/utils"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/log"
)
const (
// skipGenThreshold is the minimum time that must have elapsed since the
// creation of the previous disk layer to start snapshot generation on a new
// disk layer.
//
// If disk layers are being discarded at a frequency greater than this threshold,
// starting snapshot generation is not worth it (will be aborted before meaningful
// work can be done).
skipGenThreshold = 500 * time.Millisecond
)
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")
// ErrStaleParentLayer is returned when Flatten attempts to flatten a diff layer into
// a stale parent.
ErrStaleParentLayer = errors.New("parent disk layer is 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")
// ErrNotConstructed is returned if the callers want to iterate the snapshot
// while the generation is not finished yet.
ErrNotConstructed = errors.New("snapshot is not constructed")
)
// 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)
// AccountIterator creates an account iterator over the account trie given by the provided root hash.
AccountIterator(seek common.Hash) AccountIterator
// StorageIterator creates a storage iterator over the storage trie given by the provided root hash.
StorageIterator(account common.Hash, seek common.Hash) (StorageIterator, bool)
}
// snapshot is the internal version of the snapshot data layer that supports some
// additional methods compared to the public API.
type snapshot interface {
Snapshot
BlockHash() common.Hash
// 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(blockHash, blockRoot common.Hash, destructs map[common.Hash]struct{}, accounts map[common.Hash][]byte, storage map[common.Hash]map[common.Hash][]byte) *diffLayer
// Stale return whether this layer has become stale (was flattened across) or
// if it's still live.
Stale() bool
}
// Config includes the configurations for snapshots.
type Config struct {
CacheSize int // Megabytes permitted to use for read caches
NoBuild bool // Indicator that the snapshots generation is disallowed
AsyncBuild bool // The snapshot generation is allowed to be constructed asynchronously
SkipVerify bool // Indicator that all verification should be bypassed
}
// Tree 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 {
config Config // Snapshots configurations
diskdb ethdb.KeyValueStore // Persistent database to store the snapshot
triedb *trie.Database // In-memory cache to access the trie through
// Collection of all known layers
// blockHash -> snapshot
blockLayers map[common.Hash]snapshot
// stateRoot -> blockHash -> snapshot
// Update creates a new block layer with a parent taken from the blockHash -> snapshot map
// we can support grabbing a read only Snapshot by getting any one from the state root based map
stateLayers map[common.Hash]map[common.Hash]snapshot
verified bool // Indicates if snapshot integrity has been verified
lock sync.RWMutex
// Test hooks
onFlatten func() // Hook invoked when the bottom most diff layers are flattened
}
// 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 the disk layer is broken, the snapshot will be
// reconstructed using both the existing data and the state trie.
// The repair happens on a background thread.
func New(config Config, diskdb ethdb.KeyValueStore, triedb *trie.Database, blockHash, root common.Hash) (*Tree, error) {
// Create a new, empty snapshot tree
snap := &Tree{
config: config,
diskdb: diskdb,
triedb: triedb,
blockLayers: make(map[common.Hash]snapshot),
stateLayers: make(map[common.Hash]map[common.Hash]snapshot),
verified: config.SkipVerify, // if SkipVerify is true, all verification will be bypassed
}
// Attempt to load a previously persisted snapshot and rebuild one if failed
head, generated, err := loadSnapshot(diskdb, triedb, config.CacheSize, blockHash, root, config.NoBuild)
if err != nil {
log.Warn("Failed to load snapshot, regenerating", "err", err)
if !config.NoBuild {
snap.Rebuild(blockHash, root)
if !config.AsyncBuild {
if err := snap.verifyIntegrity(snap.disklayer(), true); err != nil {
return nil, err
}
}
return snap, nil
}
return nil, err // Bail out the error, don't rebuild automatically.
}
// Existing snapshot loaded, seed all the layers
// It is unnecessary to grab the lock here, since it was created within this function
// call, but we grab it nevertheless to follow the spec for insertSnap.
snap.lock.Lock()
defer snap.lock.Unlock()
for head != nil {
snap.insertSnap(head)
head = head.Parent()
}
// Verify any synchronously generated or loaded snapshot from disk
if !config.AsyncBuild || generated {
if err := snap.verifyIntegrity(snap.disklayer(), !config.AsyncBuild && !generated); err != nil {
return nil, err
}
}
return snap, nil
}
// insertSnap inserts [snap] into the tree.
// Assumes the lock is held.
func (t *Tree) insertSnap(snap snapshot) {
t.blockLayers[snap.BlockHash()] = snap
blockSnaps, ok := t.stateLayers[snap.Root()]
if !ok {
blockSnaps = make(map[common.Hash]snapshot)
t.stateLayers[snap.Root()] = blockSnaps
}
blockSnaps[snap.BlockHash()] = snap
}
// Snapshot retrieves a snapshot belonging to the given state root, or nil if no
// snapshot is maintained for that state root.
func (t *Tree) Snapshot(stateRoot common.Hash) Snapshot {
return t.getSnapshot(stateRoot, false)
}
// getSnapshot retrieves a Snapshot by its state root. If the caller already holds the
// snapTree lock when callthing this function, [holdsTreeLock] should be set to true.
func (t *Tree) getSnapshot(stateRoot common.Hash, holdsTreeLock bool) snapshot {
if !holdsTreeLock {
t.lock.RLock()
defer t.lock.RUnlock()
}
layers := t.stateLayers[stateRoot]
for _, layer := range layers {
return layer
}
return nil
}
// Snapshots returns all visited layers from the topmost layer with specific
// root and traverses downward. The layer amount is limited by the given number.
// If nodisk is set, then disk layer is excluded.
func (t *Tree) Snapshots(blockHash common.Hash, limits int, nodisk bool) []Snapshot {
t.lock.RLock()
defer t.lock.RUnlock()
if limits == 0 {
return nil
}
layer, ok := t.blockLayers[blockHash]
if !ok {
return nil
}
var ret []Snapshot
for {
if _, isdisk := layer.(*diskLayer); isdisk && nodisk {
break
}
ret = append(ret, layer)
limits -= 1
if limits == 0 {
break
}
parent := layer.Parent()
if parent == nil {
break
}
layer = parent
}
return ret
}
// 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(blockHash, blockRoot, parentBlockHash common.Hash, destructs map[common.Hash]struct{}, accounts map[common.Hash][]byte, storage map[common.Hash]map[common.Hash][]byte) error {
t.lock.Lock()
defer t.lock.Unlock()
// Grab the parent snapshot based on the parent block hash, not the parent state root
parent := t.blockLayers[parentBlockHash]
if parent == nil {
return fmt.Errorf("parent [%#x] snapshot missing", parentBlockHash)
}
snap := t.blockLayers[blockHash]
if snap != nil {
log.Warn("Attempted to insert a snapshot layer for an existing block",
"blockHash", blockHash, "blockRoot", blockRoot, "parentHash", parentBlockHash,
"existingBlockRoot", snap.Root(),
)
}
snap = parent.Update(blockHash, blockRoot, destructs, accounts, storage)
t.insertSnap(snap)
return nil
}
// verifyIntegrity performs an integrity check on the current snapshot using
// verify. Most importantly, verifyIntegrity ensures verify is called at
// most once during the entire lifetime of [Tree], returning immediately if
// already invoked. If [waitBuild] is true, verifyIntegrity will wait for
// generation of the snapshot to finish before verifying.
//
// It is assumed that the caller holds the [snapTree] lock
// when calling this function.
func (t *Tree) verifyIntegrity(base *diskLayer, waitBuild bool) error {
// Find the rebuild termination channel and wait until
// the snapshot is generated
if done := base.genPending; waitBuild && done != nil {
log.Info("Waiting for snapshot generation", "root", base.root)
<-done
}
if t.verified {
return nil
}
if base.genMarker != nil {
return errors.New("cannot verify integrity of an unfinished snapshot")
}
start := time.Now()
log.Info("Verifying snapshot integrity", "root", base.root)
if err := t.verify(base.root, true); err != nil {
return fmt.Errorf("unable to verify snapshot integrity: %w", err)
}
log.Info("Verified snapshot integrity", "root", base.root, "elapsed", time.Since(start))
t.verified = true
return nil
}
// Flatten flattens the snapshot for [blockHash] into its parent. if its
// parent is not a disk layer, Flatten will return an error.
// Note: a blockHash is used instead of a state root so that the exact state
// transition between the two states is well defined. This is intended to
// prevent the following edge case
//
// A
// / \
// B C
// |
// D
//
// In this scenario, it's possible For (A, B) and (A, C, D) to be two
// different paths to the resulting state. We use block hashes and parent
// block hashes to ensure that the exact path through which we flatten
// diffLayers is well defined.
func (t *Tree) Flatten(blockHash common.Hash) error {
t.lock.Lock()
defer t.lock.Unlock()
start := time.Now()
snap, ok := t.blockLayers[blockHash]
if !ok {
return fmt.Errorf("cannot flatten missing snapshot: %s", blockHash)
}
diff, ok := snap.(*diffLayer)
if !ok {
return fmt.Errorf("cannot flatten disk layer: (%s, %s)", blockHash, snap.Root())
}
if diff.parent == nil {
return fmt.Errorf("cannot flatten snapshot with missing parent (%s, %s)", blockHash, diff.root)
}
if parentDiff, ok := diff.parent.(*diffLayer); ok {
return fmt.Errorf("cannot flatten snapshot (%s, %s) into diff layer parent (%s, %s)", blockHash, diff.root, parentDiff.blockHash, parentDiff.root)
}
parentLayer := t.blockLayers[diff.parent.BlockHash()]
if parentLayer == nil {
return fmt.Errorf("snapshot missing parent layer: %s", diff.parent.BlockHash())
}
diff.lock.Lock()
// Invoke the hook if it's registered. Ugly hack.
if t.onFlatten != nil {
t.onFlatten()
}
base, snapshotGenerated, err := diffToDisk(diff)
diff.lock.Unlock()
if err != nil {
return err
}
// Remove parent layer
if err := t.discard(diff.parent.BlockHash(), true); err != nil {
return fmt.Errorf("failed to discard parent layer while flattening (%s, %s): %w", blockHash, diff.root, err)
}
// We created a new diskLayer [base] to replace [diff], so we need to replace
// it in both maps and replace all pointers to it.
t.blockLayers[base.blockHash] = base
stateSnaps := t.stateLayers[base.root]
// stateSnaps must already be initialized here, since we are replacing
// an existing snapshot instead of adding a new one.
stateSnaps[base.blockHash] = base
// Replace the parent pointers for any snapshot that referenced
// the replaced diffLayer.
for _, snap := range t.blockLayers {
if diff, ok := snap.(*diffLayer); ok {
if base.blockHash == diff.parent.BlockHash() {
diff.lock.Lock()
diff.parent = base
diff.lock.Unlock()
}
}
}
// TODO add tracking of children to the snapshots to reduce overhead here.
children := make(map[common.Hash][]common.Hash)
for blockHash, snap := range t.blockLayers {
if diff, ok := snap.(*diffLayer); ok {
parent := diff.parent.BlockHash()
children[parent] = append(children[parent], blockHash)
}
}
var remove func(blockHash common.Hash)
remove = func(blockHash common.Hash) {
t.discard(blockHash, false)
for _, child := range children[blockHash] {
remove(child)
}
delete(children, blockHash)
}
for blockHash, snap := range t.blockLayers {
if snap.Stale() {
remove(blockHash)
}
}
// If the disk layer was modified, regenerate all the cumulative blooms
var rebloom func(blockHash common.Hash)
rebloom = func(blockHash common.Hash) {
if diff, ok := t.blockLayers[blockHash].(*diffLayer); ok {
diff.rebloom(base)
}
for _, child := range children[blockHash] {
rebloom(child)
}
}
rebloom(base.blockHash)
log.Debug("Flattened snapshot tree", "blockHash", blockHash, "root", base.root, "size", len(t.blockLayers), "elapsed", common.PrettyDuration(time.Since(start)))
if !snapshotGenerated {
return nil
}
return t.verifyIntegrity(base, false)
}
// Length returns the number of snapshot layers that is currently being maintained.
func (t *Tree) NumStateLayers() int {
t.lock.RLock()
defer t.lock.RUnlock()
return len(t.stateLayers)
}
func (t *Tree) NumBlockLayers() int {
t.lock.RLock()
defer t.lock.RUnlock()
return len(t.blockLayers)
}
// Discard removes layers that we no longer need
func (t *Tree) Discard(blockHash common.Hash) error {
t.lock.Lock()
defer t.lock.Unlock()
return t.discard(blockHash, false)
}
// discard removes the snapshot associated with [blockHash] from the
// snapshot tree.
// If [force] is true, discard may delete the disk layer. This should
// only be called within Flatten, when a new disk layer is being created.
// Assumes the lock is held.
func (t *Tree) discard(blockHash common.Hash, force bool) error {
snap := t.blockLayers[blockHash]
if snap == nil {
return fmt.Errorf("cannot discard missing snapshot: %s", blockHash)
}
_, ok := snap.(*diffLayer)
// Never discard the disk layer
if !ok && !force {
return fmt.Errorf("cannot discard the disk layer: %s", blockHash)
}
snaps, ok := t.stateLayers[snap.Root()]
if !ok {
return fmt.Errorf("cannot discard snapshot %s missing from state: %s", blockHash, snap.Root())
}
// Discard the block from the map. If there are no more blocks
// mapping to the same state remove it from [stateLayers] as well.
delete(snaps, blockHash)
if len(snaps) == 0 {
delete(t.stateLayers, snap.Root())
}
delete(t.blockLayers, blockHash)
return nil
}
// AbortGeneration aborts an ongoing snapshot generation process (if it hasn't
// stopped already).
//
// It is not required to manually abort snapshot generation. If generation has not
// been manually aborted prior to invoking [diffToDisk], it will be aborted anyways.
//
// It is safe to call this method multiple times and when there is no snapshot
// generation currently underway.
func (t *Tree) AbortGeneration() {
t.lock.Lock()
defer t.lock.Unlock()
dl := t.disklayer()
dl.abortGeneration()
}
// abortGeneration sends an abort message to the generate goroutine and waits
// for it to shutdown before returning (if it is running). This call should not
// be made concurrently.
func (dl *diskLayer) abortGeneration() bool {
// Store ideal time for abort to get better estimate of load
//
// Note that we set this time regardless if abortion was skipped otherwise we
// will never restart generation (age will always be negative).
if dl.abortStarted.IsZero() {
dl.abortStarted = time.Now()
}
// If the disk layer is running a snapshot generator, abort it
if dl.genAbort != nil && dl.genStats == nil {
abort := make(chan struct{})
dl.genAbort <- abort
<-abort
return true
}
return false
}
// 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.
//
// The disk layer persistence should be operated in an atomic way. All updates should
// be discarded if the whole transition if not finished.
func diffToDisk(bottom *diffLayer) (*diskLayer, bool, error) {
var (
base = bottom.parent.(*diskLayer)
batch = base.diskdb.NewBatch()
)
// Attempt to abort generation (if not already aborted)
base.abortGeneration()
// Put the deletion in the batch writer, flush all updates in the final step.
rawdb.DeleteSnapshotBlockHash(batch)
rawdb.DeleteSnapshotRoot(batch)
// Mark the original base as stale as we're going to create a new wrapper
base.lock.Lock()
if base.stale {
base.lock.Unlock()
return nil, false, ErrStaleParentLayer // we've committed into the same base from two children, boo
}
base.stale = true
base.lock.Unlock()
// Destroy all the destructed accounts from the database
for hash := range bottom.destructSet {
// Skip any account not covered yet by the snapshot
if base.genMarker != nil && bytes.Compare(hash[:], base.genMarker) > 0 {
continue
}
// Remove all storage slots
rawdb.DeleteAccountSnapshot(batch, hash)
base.cache.Set(hash[:], nil)
it := rawdb.IterateStorageSnapshots(base.diskdb, hash)
for it.Next() {
key := it.Key()
batch.Delete(key)
base.cache.Del(key[1:])
snapshotFlushStorageItemMeter.Mark(1)
// Ensure we don't delete too much data blindly (contract can be
// huge). It's ok to flush, the root will go missing in case of a
// crash and we'll detect and regenerate the snapshot.
if batch.ValueSize() > 64*1024*1024 {
if err := batch.Write(); err != nil {
log.Crit("Failed to write storage deletions", "err", err)
}
batch.Reset()
}
}
it.Release()
}
// Push all updated 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
}
// Push the account to disk
rawdb.WriteAccountSnapshot(batch, hash, data)
base.cache.Set(hash[:], data)
snapshotCleanAccountWriteMeter.Mark(int64(len(data)))
snapshotFlushAccountItemMeter.Mark(1)
snapshotFlushAccountSizeMeter.Mark(int64(len(data)))
// Ensure we don't write too much data blindly. It's ok to flush, the
// root will go missing in case of a crash and we'll detect and regen
// the snapshot.
if batch.ValueSize() > 64*1024*1024 {
if err := batch.Write(); err != nil {
log.Crit("Failed to write storage deletions", "err", err)
}
batch.Reset()
}
}
// 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)))
}
}
// Update the snapshot block marker and write any remainder data
rawdb.WriteSnapshotBlockHash(batch, bottom.blockHash)
rawdb.WriteSnapshotRoot(batch, bottom.root)
// Write out the generator progress marker and report
journalProgress(batch, base.genMarker, base.genStats)
// Flush all the updates in the single db operation. Ensure the
// disk layer transition is atomic.
if err := batch.Write(); err != nil {
log.Crit("Failed to write leftover snapshot", "err", err)
}
log.Debug("Journalled disk layer", "root", bottom.root, "complete", base.genMarker == nil)
res := &diskLayer{
root: bottom.root,
blockHash: bottom.blockHash,
cache: base.cache,
diskdb: base.diskdb,
triedb: base.triedb,
genMarker: base.genMarker,
genPending: base.genPending,
created: time.Now(),
}
// 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 struct{})
// If the diskLayer we are about to discard is not very old, we skip
// generation on the next layer (assuming generation will just get canceled
// before doing meaningful work anyways).
diskLayerAge := base.abortStarted.Sub(base.created)
if diskLayerAge < skipGenThreshold {
log.Debug("Skipping snapshot generation", "previous disk layer age", diskLayerAge)
res.genStats = base.genStats
} else {
go res.generate(base.genStats)
}
}
return res, base.genMarker == nil, 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(blockHash, 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.blockLayers {
switch layer := layer.(type) {
case *diskLayer:
// If the base layer is generating, abort it and save
if layer.genAbort != nil {
abort := make(chan struct{})
layer.genAbort <- abort
<-abort
if stats := layer.genStats; 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.Store(true)
layer.lock.Unlock()
default:
panic(fmt.Sprintf("unknown layer type: %T", layer))
}
}
// Start generating a new snapshot from scratch on a background thread. The
// generator will run a wiper first if there's not one running right now.
log.Info("Rebuilding state snapshot")
base := generateSnapshot(t.diskdb, t.triedb, t.config.CacheSize, blockHash, root, wiper)
t.blockLayers = map[common.Hash]snapshot{
blockHash: base,
}
t.stateLayers = map[common.Hash]map[common.Hash]snapshot{
root: {
blockHash: base,
},
}
}
// AccountIterator creates a new account iterator for the specified root hash and
// seeks to a starting account hash. When [force] is true, a new account
// iterator is created without acquiring the [snapTree] lock and without
// confirming that the snapshot on the disk layer is fully generated.
func (t *Tree) AccountIterator(root common.Hash, seek common.Hash, force bool) (AccountIterator, error) {
if !force {
ok, err := t.generating()
if err != nil {
return nil, err
}
if ok {
return nil, ErrNotConstructed
}
}
return newFastAccountIterator(t, root, seek, force)
}
// StorageIterator creates a new storage iterator for the specified root hash and
// account. The iterator will be move to the specific start position. When [force]
// is true, a new account iterator is created without acquiring the [snapTree]
// lock and without confirming that the snapshot on the disk layer is fully generated.
func (t *Tree) StorageIterator(root common.Hash, account common.Hash, seek common.Hash, force bool) (StorageIterator, error) {
if !force {
ok, err := t.generating()
if err != nil {
return nil, err
}
if ok {
return nil, ErrNotConstructed
}
}
return newFastStorageIterator(t, root, account, seek, force)
}
// Verify iterates the whole state(all the accounts as well as the corresponding storages)
// with the specific root and compares the re-computed hash with the original one.
func (t *Tree) Verify(root common.Hash) error {
return t.verify(root, false)
}
// verify iterates the whole state(all the accounts as well as the corresponding storages)
// with the specific root and compares the re-computed hash with the original one.
// When [force] is true, it is assumed that the caller has confirmed that the
// snapshot is generated and that they hold the snapTree lock.
func (t *Tree) verify(root common.Hash, force bool) error {
acctIt, err := t.AccountIterator(root, common.Hash{}, force)
if err != nil {
return err
}
defer acctIt.Release()
got, err := generateTrieRoot(nil, "", acctIt, common.Hash{}, stackTrieGenerate, func(db ethdb.KeyValueWriter, accountHash, codeHash common.Hash, stat *generateStats) (common.Hash, error) {
storageIt, err := t.StorageIterator(root, accountHash, common.Hash{}, force)
if err != nil {
return common.Hash{}, err
}
defer storageIt.Release()
hash, err := generateTrieRoot(nil, "", storageIt, accountHash, stackTrieGenerate, nil, stat, false)
if err != nil {
return common.Hash{}, err
}
return hash, nil
}, newGenerateStats(), true)
if err != nil {
return err
}
if got != root {
return fmt.Errorf("state root hash mismatch: got %x, want %x", got, root)
}
return nil
}
// disklayer is an internal helper function to return the disk layer.
// The lock of snapTree is assumed to be held already.
func (t *Tree) disklayer() *diskLayer {
var snap snapshot
for _, s := range t.blockLayers {
snap = s
break
}
if snap == nil {
return nil
}
switch layer := snap.(type) {
case *diskLayer:
return layer
case *diffLayer:
return layer.origin
default:
panic(fmt.Sprintf("%T: undefined layer", snap))
}
}
// diskRoot is a internal helper function to return the disk layer root.
// The lock of snapTree is assumed to be held already.
func (t *Tree) diskRoot() common.Hash {
disklayer := t.disklayer()
if disklayer == nil {
return common.Hash{}
}
return disklayer.Root()
}
// generating is an internal helper function which reports whether the snapshot
// is still under the construction.
func (t *Tree) generating() (bool, error) {
t.lock.Lock()
defer t.lock.Unlock()
layer := t.disklayer()
if layer == nil {
return false, errors.New("disk layer is missing")
}
layer.lock.RLock()
defer layer.lock.RUnlock()
return layer.genMarker != nil, nil
}
// DiskRoot is a external helper function to return the disk layer root.
func (t *Tree) DiskRoot() common.Hash {
t.lock.Lock()
defer t.lock.Unlock()
return t.diskRoot()
}
func (t *Tree) DiskAccountIterator(seek common.Hash) AccountIterator {
t.lock.Lock()
defer t.lock.Unlock()
return t.disklayer().AccountIterator(seek)
}
func (t *Tree) DiskStorageIterator(account common.Hash, seek common.Hash) StorageIterator {
t.lock.Lock()
defer t.lock.Unlock()
it, _ := t.disklayer().StorageIterator(account, seek)
return it
}
// NewDiskLayer creates a diskLayer for direct access to the contents of the on-disk
// snapshot. Does not perform any validation.
func NewDiskLayer(diskdb ethdb.KeyValueStore) Snapshot {
return &diskLayer{
diskdb: diskdb,
created: time.Now(),
// state sync uses iterators to access data, so this cache is not used.
// initializing it out of caution.
cache: utils.NewMeteredCache(32*1024, "", "", 0),
}
}
// NewTestTree creates a *Tree with a pre-populated diskLayer
func NewTestTree(diskdb ethdb.KeyValueStore, blockHash, root common.Hash) *Tree {
base := &diskLayer{
diskdb: diskdb,
root: root,
blockHash: blockHash,
cache: utils.NewMeteredCache(128*256, "", "", 0),
created: time.Now(),
}
return &Tree{
blockLayers: map[common.Hash]snapshot{
blockHash: base,
},
stateLayers: map[common.Hash]map[common.Hash]snapshot{
root: {
blockHash: base,
},
},
}
}