Official Go implementation of the Ethereum protocol
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go-ethereum/ethdb/leveldb/leveldb.go

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// Copyright 2018 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/>.
//go:build !js
// +build !js
// Package leveldb implements the key-value database layer based on LevelDB.
package leveldb
import (
"fmt"
"sync"
"time"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/ethdb"
"github.com/ethereum/go-ethereum/log"
"github.com/ethereum/go-ethereum/metrics"
"github.com/syndtr/goleveldb/leveldb"
"github.com/syndtr/goleveldb/leveldb/errors"
"github.com/syndtr/goleveldb/leveldb/filter"
"github.com/syndtr/goleveldb/leveldb/opt"
"github.com/syndtr/goleveldb/leveldb/util"
)
const (
// degradationWarnInterval specifies how often warning should be printed if the
// leveldb database cannot keep up with requested writes.
degradationWarnInterval = time.Minute
// minCache is the minimum amount of memory in megabytes to allocate to leveldb
// read and write caching, split half and half.
minCache = 16
// minHandles is the minimum number of files handles to allocate to the open
// database files.
minHandles = 16
// metricsGatheringInterval specifies the interval to retrieve leveldb database
// compaction, io and pause stats to report to the user.
metricsGatheringInterval = 3 * time.Second
)
// Database is a persistent key-value store. Apart from basic data storage
// functionality it also supports batch writes and iterating over the keyspace in
// binary-alphabetical order.
type Database struct {
fn string // filename for reporting
db *leveldb.DB // LevelDB instance
compTimeMeter metrics.Meter // Meter for measuring the total time spent in database compaction
compReadMeter metrics.Meter // Meter for measuring the data read during compaction
compWriteMeter metrics.Meter // Meter for measuring the data written during compaction
writeDelayNMeter metrics.Meter // Meter for measuring the write delay number due to database compaction
writeDelayMeter metrics.Meter // Meter for measuring the write delay duration due to database compaction
diskSizeGauge metrics.Gauge // Gauge for tracking the size of all the levels in the database
diskReadMeter metrics.Meter // Meter for measuring the effective amount of data read
diskWriteMeter metrics.Meter // Meter for measuring the effective amount of data written
memCompGauge metrics.Gauge // Gauge for tracking the number of memory compaction
level0CompGauge metrics.Gauge // Gauge for tracking the number of table compaction in level0
nonlevel0CompGauge metrics.Gauge // Gauge for tracking the number of table compaction in non0 level
seekCompGauge metrics.Gauge // Gauge for tracking the number of table compaction caused by read opt
manualMemAllocGauge metrics.Gauge // Gauge to track the amount of memory that has been manually allocated (not a part of runtime/GC)
levelsGauge [7]metrics.Gauge // Gauge for tracking the number of tables in levels
quitLock sync.Mutex // Mutex protecting the quit channel access
quitChan chan chan error // Quit channel to stop the metrics collection before closing the database
log log.Logger // Contextual logger tracking the database path
}
// New returns a wrapped LevelDB object. The namespace is the prefix that the
// metrics reporting should use for surfacing internal stats.
func New(file string, cache int, handles int, namespace string, readonly bool) (*Database, error) {
return NewCustom(file, namespace, func(options *opt.Options) {
// Ensure we have some minimal caching and file guarantees
if cache < minCache {
cache = minCache
}
if handles < minHandles {
handles = minHandles
}
// Set default options
options.OpenFilesCacheCapacity = handles
options.BlockCacheCapacity = cache / 2 * opt.MiB
options.WriteBuffer = cache / 4 * opt.MiB // Two of these are used internally
if readonly {
options.ReadOnly = true
}
})
}
// NewCustom returns a wrapped LevelDB object. The namespace is the prefix that the
// metrics reporting should use for surfacing internal stats.
// The customize function allows the caller to modify the leveldb options.
func NewCustom(file string, namespace string, customize func(options *opt.Options)) (*Database, error) {
options := configureOptions(customize)
logger := log.New("database", file)
usedCache := options.GetBlockCacheCapacity() + options.GetWriteBuffer()*2
logCtx := []interface{}{"cache", common.StorageSize(usedCache), "handles", options.GetOpenFilesCacheCapacity()}
if options.ReadOnly {
logCtx = append(logCtx, "readonly", "true")
}
logger.Info("Allocated cache and file handles", logCtx...)
// Open the db and recover any potential corruptions
db, err := leveldb.OpenFile(file, options)
if _, corrupted := err.(*errors.ErrCorrupted); corrupted {
db, err = leveldb.RecoverFile(file, nil)
}
if err != nil {
return nil, err
}
// Assemble the wrapper with all the registered metrics
ldb := &Database{
fn: file,
db: db,
log: logger,
quitChan: make(chan chan error),
}
ldb.compTimeMeter = metrics.NewRegisteredMeter(namespace+"compact/time", nil)
ldb.compReadMeter = metrics.NewRegisteredMeter(namespace+"compact/input", nil)
ldb.compWriteMeter = metrics.NewRegisteredMeter(namespace+"compact/output", nil)
ldb.diskSizeGauge = metrics.NewRegisteredGauge(namespace+"disk/size", nil)
ldb.diskReadMeter = metrics.NewRegisteredMeter(namespace+"disk/read", nil)
ldb.diskWriteMeter = metrics.NewRegisteredMeter(namespace+"disk/write", nil)
ldb.writeDelayMeter = metrics.NewRegisteredMeter(namespace+"compact/writedelay/duration", nil)
ldb.writeDelayNMeter = metrics.NewRegisteredMeter(namespace+"compact/writedelay/counter", nil)
ldb.memCompGauge = metrics.NewRegisteredGauge(namespace+"compact/memory", nil)
ldb.level0CompGauge = metrics.NewRegisteredGauge(namespace+"compact/level0", nil)
ldb.nonlevel0CompGauge = metrics.NewRegisteredGauge(namespace+"compact/nonlevel0", nil)
ldb.seekCompGauge = metrics.NewRegisteredGauge(namespace+"compact/seek", nil)
ldb.manualMemAllocGauge = metrics.NewRegisteredGauge(namespace+"memory/manualalloc", nil)
// leveldb has only up to 7 levels
for i := range ldb.levelsGauge {
ldb.levelsGauge[i] = metrics.NewRegisteredGauge(namespace+fmt.Sprintf("tables/level%v", i), nil)
}
// Start up the metrics gathering and return
go ldb.meter(metricsGatheringInterval)
return ldb, nil
}
// configureOptions sets some default options, then runs the provided setter.
func configureOptions(customizeFn func(*opt.Options)) *opt.Options {
// Set default options
options := &opt.Options{
Filter: filter.NewBloomFilter(10),
DisableSeeksCompaction: true,
}
// Allow caller to make custom modifications to the options
if customizeFn != nil {
customizeFn(options)
}
return options
}
// Close stops the metrics collection, flushes any pending data to disk and closes
// all io accesses to the underlying key-value store.
func (db *Database) Close() error {
db.quitLock.Lock()
defer db.quitLock.Unlock()
if db.quitChan != nil {
errc := make(chan error)
db.quitChan <- errc
if err := <-errc; err != nil {
db.log.Error("Metrics collection failed", "err", err)
}
db.quitChan = nil
}
return db.db.Close()
}
// Has retrieves if a key is present in the key-value store.
func (db *Database) Has(key []byte) (bool, error) {
return db.db.Has(key, nil)
}
// Get retrieves the given key if it's present in the key-value store.
func (db *Database) Get(key []byte) ([]byte, error) {
dat, err := db.db.Get(key, nil)
if err != nil {
return nil, err
}
return dat, nil
}
// Put inserts the given value into the key-value store.
func (db *Database) Put(key []byte, value []byte) error {
return db.db.Put(key, value, nil)
}
// Delete removes the key from the key-value store.
func (db *Database) Delete(key []byte) error {
return db.db.Delete(key, nil)
}
// NewBatch creates a write-only key-value store that buffers changes to its host
// database until a final write is called.
func (db *Database) NewBatch() ethdb.Batch {
return &batch{
db: db.db,
b: new(leveldb.Batch),
}
}
// NewBatchWithSize creates a write-only database batch with pre-allocated buffer.
func (db *Database) NewBatchWithSize(size int) ethdb.Batch {
return &batch{
db: db.db,
b: leveldb.MakeBatch(size),
}
}
// NewIterator creates a binary-alphabetical iterator over a subset
// of database content with a particular key prefix, starting at a particular
// initial key (or after, if it does not exist).
func (db *Database) NewIterator(prefix []byte, start []byte) ethdb.Iterator {
return db.db.NewIterator(bytesPrefixRange(prefix, start), nil)
}
// NewSnapshot creates a database snapshot based on the current state.
// The created snapshot will not be affected by all following mutations
// happened on the database.
// Note don't forget to release the snapshot once it's used up, otherwise
// the stale data will never be cleaned up by the underlying compactor.
func (db *Database) NewSnapshot() (ethdb.Snapshot, error) {
snap, err := db.db.GetSnapshot()
if err != nil {
return nil, err
}
return &snapshot{db: snap}, nil
}
// Stat returns a particular internal stat of the database.
func (db *Database) Stat(property string) (string, error) {
return db.db.GetProperty(property)
}
// Compact flattens the underlying data store for the given key range. In essence,
// deleted and overwritten versions are discarded, and the data is rearranged to
// reduce the cost of operations needed to access them.
//
// A nil start is treated as a key before all keys in the data store; a nil limit
// is treated as a key after all keys in the data store. If both is nil then it
// will compact entire data store.
func (db *Database) Compact(start []byte, limit []byte) error {
return db.db.CompactRange(util.Range{Start: start, Limit: limit})
}
// Path returns the path to the database directory.
func (db *Database) Path() string {
return db.fn
}
// meter periodically retrieves internal leveldb counters and reports them to
// the metrics subsystem.
func (db *Database) meter(refresh time.Duration) {
// Create the counters to store current and previous compaction values
compactions := make([][]int64, 2)
for i := 0; i < 2; i++ {
compactions[i] = make([]int64, 4)
}
// Create storages for states and warning log tracer.
var (
errc chan error
merr error
stats leveldb.DBStats
iostats [2]int64
delaystats [2]int64
lastWritePaused time.Time
)
timer := time.NewTimer(refresh)
defer timer.Stop()
// Iterate ad infinitum and collect the stats
for i := 1; errc == nil && merr == nil; i++ {
// Retrieve the database stats
// Stats method resets buffers inside therefore it's okay to just pass the struct.
err := db.db.Stats(&stats)
if err != nil {
db.log.Error("Failed to read database stats", "err", err)
merr = err
continue
}
// Iterate over all the leveldbTable rows, and accumulate the entries
for j := 0; j < len(compactions[i%2]); j++ {
compactions[i%2][j] = 0
}
compactions[i%2][0] = stats.LevelSizes.Sum()
for _, t := range stats.LevelDurations {
compactions[i%2][1] += t.Nanoseconds()
}
compactions[i%2][2] = stats.LevelRead.Sum()
compactions[i%2][3] = stats.LevelWrite.Sum()
// Update all the requested meters
if db.diskSizeGauge != nil {
db.diskSizeGauge.Update(compactions[i%2][0])
}
if db.compTimeMeter != nil {
db.compTimeMeter.Mark(compactions[i%2][1] - compactions[(i-1)%2][1])
}
if db.compReadMeter != nil {
db.compReadMeter.Mark(compactions[i%2][2] - compactions[(i-1)%2][2])
}
if db.compWriteMeter != nil {
db.compWriteMeter.Mark(compactions[i%2][3] - compactions[(i-1)%2][3])
}
var (
delayN = int64(stats.WriteDelayCount)
duration = stats.WriteDelayDuration
paused = stats.WritePaused
)
if db.writeDelayNMeter != nil {
db.writeDelayNMeter.Mark(delayN - delaystats[0])
}
if db.writeDelayMeter != nil {
db.writeDelayMeter.Mark(duration.Nanoseconds() - delaystats[1])
}
// If a warning that db is performing compaction has been displayed, any subsequent
// warnings will be withheld for one minute not to overwhelm the user.
if paused && delayN-delaystats[0] == 0 && duration.Nanoseconds()-delaystats[1] == 0 &&
time.Now().After(lastWritePaused.Add(degradationWarnInterval)) {
db.log.Warn("Database compacting, degraded performance")
lastWritePaused = time.Now()
}
delaystats[0], delaystats[1] = delayN, duration.Nanoseconds()
var (
nRead = int64(stats.IORead)
nWrite = int64(stats.IOWrite)
)
if db.diskReadMeter != nil {
db.diskReadMeter.Mark(nRead - iostats[0])
}
if db.diskWriteMeter != nil {
db.diskWriteMeter.Mark(nWrite - iostats[1])
}
iostats[0], iostats[1] = nRead, nWrite
db.memCompGauge.Update(int64(stats.MemComp))
db.level0CompGauge.Update(int64(stats.Level0Comp))
db.nonlevel0CompGauge.Update(int64(stats.NonLevel0Comp))
db.seekCompGauge.Update(int64(stats.SeekComp))
// update tables amount
for i, tables := range stats.LevelTablesCounts {
db.levelsGauge[i].Update(int64(tables))
}
// Sleep a bit, then repeat the stats collection
select {
case errc = <-db.quitChan:
// Quit requesting, stop hammering the database
case <-timer.C:
timer.Reset(refresh)
// Timeout, gather a new set of stats
}
}
if errc == nil {
errc = <-db.quitChan
}
errc <- merr
}
// batch is a write-only leveldb batch that commits changes to its host database
// when Write is called. A batch cannot be used concurrently.
type batch struct {
db *leveldb.DB
b *leveldb.Batch
size int
}
// Put inserts the given value into the batch for later committing.
func (b *batch) Put(key, value []byte) error {
b.b.Put(key, value)
b.size += len(key) + len(value)
return nil
}
// Delete inserts the a key removal into the batch for later committing.
func (b *batch) Delete(key []byte) error {
b.b.Delete(key)
b.size += len(key)
return nil
}
// ValueSize retrieves the amount of data queued up for writing.
func (b *batch) ValueSize() int {
return b.size
}
// Write flushes any accumulated data to disk.
func (b *batch) Write() error {
return b.db.Write(b.b, nil)
}
// Reset resets the batch for reuse.
func (b *batch) Reset() {
b.b.Reset()
b.size = 0
}
// Replay replays the batch contents.
func (b *batch) Replay(w ethdb.KeyValueWriter) error {
return b.b.Replay(&replayer{writer: w})
}
// replayer is a small wrapper to implement the correct replay methods.
type replayer struct {
writer ethdb.KeyValueWriter
failure error
}
// Put inserts the given value into the key-value data store.
func (r *replayer) Put(key, value []byte) {
// If the replay already failed, stop executing ops
if r.failure != nil {
return
}
r.failure = r.writer.Put(key, value)
}
// Delete removes the key from the key-value data store.
func (r *replayer) Delete(key []byte) {
// If the replay already failed, stop executing ops
if r.failure != nil {
return
}
r.failure = r.writer.Delete(key)
}
// bytesPrefixRange returns key range that satisfy
// - the given prefix, and
// - the given seek position
func bytesPrefixRange(prefix, start []byte) *util.Range {
r := util.BytesPrefix(prefix)
r.Start = append(r.Start, start...)
return r
}
// snapshot wraps a leveldb snapshot for implementing the Snapshot interface.
type snapshot struct {
db *leveldb.Snapshot
}
// Has retrieves if a key is present in the snapshot backing by a key-value
// data store.
func (snap *snapshot) Has(key []byte) (bool, error) {
return snap.db.Has(key, nil)
}
// Get retrieves the given key if it's present in the snapshot backing by
// key-value data store.
func (snap *snapshot) Get(key []byte) ([]byte, error) {
return snap.db.Get(key, nil)
}
// Release releases associated resources. Release should always succeed and can
// be called multiple times without causing error.
func (snap *snapshot) Release() {
snap.db.Release()
}