250 lines
9.3 KiB
Go
250 lines
9.3 KiB
Go
// Copyright 2019 The go-ethereum Authors
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// This file is part of the go-ethereum library.
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//
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// The go-ethereum library is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// The go-ethereum library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
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// Package snapshot implements a journalled, dynamic state dump.
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package snapshot
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import (
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"errors"
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"fmt"
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"os"
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"sync"
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"time"
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"github.com/allegro/bigcache"
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"github.com/ethereum/go-ethereum/common"
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"github.com/ethereum/go-ethereum/core/rawdb"
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"github.com/ethereum/go-ethereum/ethdb"
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"github.com/ethereum/go-ethereum/log"
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"github.com/ethereum/go-ethereum/metrics"
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"github.com/ethereum/go-ethereum/rlp"
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)
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var (
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snapshotCleanHitMeter = metrics.NewRegisteredMeter("state/snapshot/clean/hit", nil)
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snapshotCleanMissMeter = metrics.NewRegisteredMeter("state/snapshot/clean/miss", nil)
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snapshotCleanReadMeter = metrics.NewRegisteredMeter("state/snapshot/clean/read", nil)
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snapshotCleanWriteMeter = metrics.NewRegisteredMeter("state/snapshot/clean/write", nil)
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// ErrSnapshotStale is returned from data accessors if the underlying snapshot
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// layer had been invalidated due to the chain progressing forward far enough
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// to not maintain the layer's original state.
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ErrSnapshotStale = errors.New("snapshot stale")
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)
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// Snapshot represents the functionality supported by a snapshot storage layer.
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type Snapshot interface {
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// Info returns the block number and root hash for which this snapshot was made.
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Info() (uint64, common.Hash)
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// Account directly retrieves the account associated with a particular hash in
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// the snapshot slim data format.
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Account(hash common.Hash) (*Account, error)
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// AccountRLP directly retrieves the account RLP associated with a particular
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// hash in the snapshot slim data format.
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AccountRLP(hash common.Hash) ([]byte, error)
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// Storage directly retrieves the storage data associated with a particular hash,
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// within a particular account.
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Storage(accountHash, storageHash common.Hash) ([]byte, error)
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}
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// snapshot is the internal version of the snapshot data layer that supports some
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// additional methods compared to the public API.
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type snapshot interface {
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Snapshot
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// Update creates a new layer on top of the existing snapshot diff tree with
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// the specified data items. Note, the maps are retained by the method to avoid
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// copying everything.
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Update(blockRoot common.Hash, accounts map[common.Hash][]byte, storage map[common.Hash]map[common.Hash][]byte) *diffLayer
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// Cap traverses downwards the diff tree until the number of allowed layers are
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// crossed. All diffs beyond the permitted number are flattened downwards. The
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// block numbers for the disk layer and first diff layer are returned for GC.
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Cap(layers int, memory uint64) (uint64, uint64)
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// Journal commits an entire diff hierarchy to disk into a single journal file.
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// This is meant to be used during shutdown to persist the snapshot without
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// flattening everything down (bad for reorgs).
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Journal() error
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}
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// SnapshotTree is an Ethereum state snapshot tree. It consists of one persistent
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// base layer backed by a key-value store, on top of which arbitrarily many in-
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// memory diff layers are topped. The memory diffs can form a tree with branching,
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// but the disk layer is singleton and common to all. If a reorg goes deeper than
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// the disk layer, everything needs to be deleted.
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//
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// The goal of a state snapshot is twofold: to allow direct access to account and
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// storage data to avoid expensive multi-level trie lookups; and to allow sorted,
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// cheap iteration of the account/storage tries for sync aid.
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type SnapshotTree struct {
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layers map[common.Hash]snapshot // Collection of all known layers // TODO(karalabe): split Clique overlaps
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lock sync.RWMutex
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}
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// New attempts to load an already existing snapshot from a persistent key-value
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// store (with a number of memory layers from a journal), ensuring that the head
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// of the snapshot matches the expected one.
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//
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// If the snapshot is missing or inconsistent, the entirety is deleted and will
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// be reconstructed from scratch based on the tries in the key-value store.
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func New(db ethdb.KeyValueStore, journal string, headNumber uint64, headRoot common.Hash) (*SnapshotTree, error) {
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// Attempt to load a previously persisted snapshot
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head, err := loadSnapshot(db, journal, headNumber, headRoot)
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if err != nil {
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log.Warn("Failed to load snapshot, regenerating", "err", err)
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if head, err = generateSnapshot(db, journal, headNumber, headRoot); err != nil {
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return nil, err
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}
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}
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// Existing snapshot loaded or one regenerated, seed all the layers
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snap := &SnapshotTree{
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layers: make(map[common.Hash]snapshot),
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}
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for head != nil {
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_, root := head.Info()
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snap.layers[root] = head
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switch self := head.(type) {
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case *diffLayer:
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head = self.parent
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case *diskLayer:
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head = nil
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default:
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panic(fmt.Sprintf("unknown data layer: %T", self))
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}
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}
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return snap, nil
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}
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// Snapshot retrieves a snapshot belonging to the given block root, or nil if no
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// snapshot is maintained for that block.
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func (st *SnapshotTree) Snapshot(blockRoot common.Hash) Snapshot {
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st.lock.RLock()
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defer st.lock.RUnlock()
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return st.layers[blockRoot]
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}
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// Update adds a new snapshot into the tree, if that can be linked to an existing
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// old parent. It is disallowed to insert a disk layer (the origin of all).
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func (st *SnapshotTree) Update(blockRoot common.Hash, parentRoot common.Hash, accounts map[common.Hash][]byte, storage map[common.Hash]map[common.Hash][]byte) error {
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// Generate a new snapshot on top of the parent
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parent := st.Snapshot(parentRoot).(snapshot)
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if parent == nil {
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return fmt.Errorf("parent [%#x] snapshot missing", parentRoot)
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}
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snap := parent.Update(blockRoot, accounts, storage)
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// Save the new snapshot for later
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st.lock.Lock()
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defer st.lock.Unlock()
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st.layers[snap.root] = snap
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return nil
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}
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// Cap traverses downwards the snapshot tree from a head block hash until the
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// number of allowed layers are crossed. All layers beyond the permitted number
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// are flattened downwards.
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func (st *SnapshotTree) Cap(blockRoot common.Hash, layers int, memory uint64) error {
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// Retrieve the head snapshot to cap from
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snap := st.Snapshot(blockRoot).(snapshot)
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if snap == nil {
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return fmt.Errorf("snapshot [%#x] missing", blockRoot)
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}
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// Run the internal capping and discard all stale layers
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st.lock.Lock()
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defer st.lock.Unlock()
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diskNumber, diffNumber := snap.Cap(layers, memory)
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for root, snap := range st.layers {
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if number, _ := snap.Info(); number != diskNumber && number < diffNumber {
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delete(st.layers, root)
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}
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}
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return nil
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}
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// Journal commits an entire diff hierarchy to disk into a single journal file.
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// This is meant to be used during shutdown to persist the snapshot without
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// flattening everything down (bad for reorgs).
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func (st *SnapshotTree) Journal(blockRoot common.Hash) error {
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// Retrieve the head snapshot to journal from
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snap := st.Snapshot(blockRoot).(snapshot)
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if snap == nil {
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return fmt.Errorf("snapshot [%#x] missing", blockRoot)
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}
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// Run the journaling
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st.lock.Lock()
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defer st.lock.Unlock()
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return snap.Journal()
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}
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// loadSnapshot loads a pre-existing state snapshot backed by a key-value store.
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func loadSnapshot(db ethdb.KeyValueStore, journal string, headNumber uint64, headRoot common.Hash) (snapshot, error) {
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// Retrieve the block number and hash of the snapshot, failing if no snapshot
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// is present in the database (or crashed mid-update).
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number, root := rawdb.ReadSnapshotBlock(db)
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if root == (common.Hash{}) {
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return nil, errors.New("missing or corrupted snapshot")
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}
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cache, _ := bigcache.NewBigCache(bigcache.Config{ // TODO(karalabe): dedup
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Shards: 1024,
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LifeWindow: time.Hour,
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MaxEntriesInWindow: 512 * 1024,
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MaxEntrySize: 512,
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HardMaxCacheSize: 512,
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})
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base := &diskLayer{
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journal: journal,
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db: db,
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cache: cache,
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number: number,
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root: root,
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}
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// Load all the snapshot diffs from the journal, failing if their chain is broken
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// or does not lead from the disk snapshot to the specified head.
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if _, err := os.Stat(journal); os.IsNotExist(err) {
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// Journal doesn't exist, don't worry if it's not supposed to
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if number != headNumber || root != headRoot {
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return nil, fmt.Errorf("snapshot journal missing, head doesn't match snapshot: #%d [%#x] vs. #%d [%#x]",
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headNumber, headRoot, number, root)
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}
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return base, nil
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}
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file, err := os.Open(journal)
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if err != nil {
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return nil, err
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}
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snapshot, err := loadDiffLayer(base, rlp.NewStream(file, 0))
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if err != nil {
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return nil, err
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}
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// Entire snapshot journal loaded, sanity check the head and return
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// Journal doesn't exist, don't worry if it's not supposed to
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number, root = snapshot.Info()
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if number != headNumber || root != headRoot {
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return nil, fmt.Errorf("head doesn't match snapshot: #%d [%#x] vs. #%d [%#x]",
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headNumber, headRoot, number, root)
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}
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return snapshot, nil
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}
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