plugeth/core/state/snapshot/snapshot.go
2020-02-25 12:51:04 +02:00

245 lines
9.1 KiB
Go

// 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 (
"errors"
"fmt"
"os"
"sync"
"time"
"github.com/allegro/bigcache"
"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/rlp"
)
var (
snapshotCleanHitMeter = metrics.NewRegisteredMeter("state/snapshot/clean/hit", nil)
snapshotCleanMissMeter = metrics.NewRegisteredMeter("state/snapshot/clean/miss", nil)
snapshotCleanReadMeter = metrics.NewRegisteredMeter("state/snapshot/clean/read", nil)
snapshotCleanWriteMeter = metrics.NewRegisteredMeter("state/snapshot/clean/write", nil)
)
// Snapshot represents the functionality supported by a snapshot storage layer.
type Snapshot interface {
// Info returns the block number and root hash for which this snapshot was made.
Info() (uint64, common.Hash)
// Account directly retrieves the account associated with a particular hash in
// the snapshot slim data format.
Account(hash common.Hash) *Account
// AccountRLP directly retrieves the account RLP associated with a particular
// hash in the snapshot slim data format.
AccountRLP(hash common.Hash) []byte
// Storage directly retrieves the storage data associated with a particular hash,
// within a particular account.
Storage(accountHash, storageHash common.Hash) []byte
}
// snapshot is the internal version of the snapshot data layer that supports some
// additional methods compared to the public API.
type snapshot interface {
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
// Cap traverses downwards the diff tree until the number of allowed layers are
// crossed. All diffs beyond the permitted number are flattened downwards. The
// block numbers for the disk layer and first diff layer are returned for GC.
Cap(layers int, memory uint64) (uint64, uint64)
// Journal commits an entire diff hierarchy to disk into a single journal file.
// This is meant to be used during shutdown to persist the snapshot without
// flattening everything down (bad for reorgs).
Journal() error
}
// SnapshotTree is an Ethereum state snapshot tree. It consists of one persistent
// base layer backed by a key-value store, on top of which arbitrarilly 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 SnapshotTree struct {
layers map[common.Hash]snapshot // Collection of all known layers // TODO(karalabe): split Clique overlaps
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.
func New(db ethdb.KeyValueStore, journal string, headNumber uint64, headRoot common.Hash) (*SnapshotTree, error) {
// Attempt to load a previously persisted snapshot
head, err := loadSnapshot(db, journal, headNumber, headRoot)
if err != nil {
log.Warn("Failed to load snapshot, regenerating", "err", err)
if head, err = generateSnapshot(db, journal, headNumber, headRoot); err != nil {
return nil, err
}
}
// Existing snapshot loaded or one regenerated, seed all the layers
snap := &SnapshotTree{
layers: make(map[common.Hash]snapshot),
}
for head != nil {
_, root := head.Info()
snap.layers[root] = head
switch self := head.(type) {
case *diffLayer:
head = self.parent
case *diskLayer:
head = nil
default:
panic(fmt.Sprintf("unknown data layer: %T", self))
}
}
return snap, nil
}
// Snapshot retrieves a snapshot belonging to the given block root, or nil if no
// snapshot is maintained for that block.
func (st *SnapshotTree) Snapshot(blockRoot common.Hash) Snapshot {
st.lock.RLock()
defer st.lock.RUnlock()
return st.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 (st *SnapshotTree) Update(blockRoot common.Hash, parentRoot common.Hash, accounts map[common.Hash][]byte, storage map[common.Hash]map[common.Hash][]byte) error {
// Generate a new snapshot on top of the parent
parent := st.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
st.lock.Lock()
defer st.lock.Unlock()
st.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 (st *SnapshotTree) Cap(blockRoot common.Hash, layers int, memory uint64) error {
// Retrieve the head snapshot to cap from
snap := st.Snapshot(blockRoot).(snapshot)
if snap == nil {
return fmt.Errorf("snapshot [%#x] missing", blockRoot)
}
// Run the internal capping and discard all stale layers
st.lock.Lock()
defer st.lock.Unlock()
diskNumber, diffNumber := snap.Cap(layers, memory)
for root, snap := range st.layers {
if number, _ := snap.Info(); number != diskNumber && number < diffNumber {
delete(st.layers, root)
}
}
return nil
}
// Journal commits an entire diff hierarchy to disk into a single journal file.
// This is meant to be used during shutdown to persist the snapshot without
// flattening everything down (bad for reorgs).
func (st *SnapshotTree) Journal(blockRoot common.Hash) error {
// Retrieve the head snapshot to journal from
snap := st.Snapshot(blockRoot).(snapshot)
if snap == nil {
return fmt.Errorf("snapshot [%#x] missing", blockRoot)
}
// Run the journaling
st.lock.Lock()
defer st.lock.Unlock()
return snap.Journal()
}
// loadSnapshot loads a pre-existing state snapshot backed by a key-value store.
func loadSnapshot(db ethdb.KeyValueStore, journal string, headNumber uint64, headRoot common.Hash) (snapshot, error) {
// Retrieve the block number and hash of the snapshot, failing if no snapshot
// is present in the database (or crashed mid-update).
number, root := rawdb.ReadSnapshotBlock(db)
if root == (common.Hash{}) {
return nil, errors.New("missing or corrupted snapshot")
}
cache, _ := bigcache.NewBigCache(bigcache.Config{ // TODO(karalabe): dedup
Shards: 1024,
LifeWindow: time.Hour,
MaxEntriesInWindow: 512 * 1024,
MaxEntrySize: 512,
HardMaxCacheSize: 512,
})
base := &diskLayer{
journal: journal,
db: db,
cache: cache,
number: number,
root: root,
}
// Load all the snapshot diffs from the journal, failing if their chain is broken
// or does not lead from the disk snapshot to the specified head.
if _, err := os.Stat(journal); os.IsNotExist(err) {
// Journal doesn't exist, don't worry if it's not supposed to
if number != headNumber || root != headRoot {
return nil, fmt.Errorf("snapshot journal missing, head does't match snapshot: #%d [%#x] vs. #%d [%#x]",
headNumber, headRoot, number, root)
}
return base, nil
}
file, err := os.Open(journal)
if err != nil {
return nil, err
}
snapshot, err := loadDiffLayer(base, rlp.NewStream(file, 0))
if err != nil {
return nil, err
}
// Entire snapshot journal loaded, sanity check the head and return
// Journal doesn't exist, don't worry if it's not supposed to
number, root = snapshot.Info()
if number != headNumber || root != headRoot {
return nil, fmt.Errorf("head does't match snapshot: #%d [%#x] vs. #%d [%#x]",
headNumber, headRoot, number, root)
}
return snapshot, nil
}