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

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// Copyright 2023 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 arm64 || amd64
// Package pebble implements the key-value database layer based on pebble.
package pebble
import (
"fmt"
"runtime"
"sync"
"sync/atomic"
"time"
"github.com/cockroachdb/pebble"
"github.com/cockroachdb/pebble/bloom"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/ethdb"
"github.com/ethereum/go-ethereum/log"
"github.com/ethereum/go-ethereum/metrics"
)
const (
// minCache is the minimum amount of memory in megabytes to allocate to pebble
// 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 pebble database
// compaction, io and pause stats to report to the user.
metricsGatheringInterval = 3 * time.Second
)
// Database is a persistent key-value store based on the pebble storage engine.
// 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 *pebble.DB // Underlying pebble storage engine
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 for tracking amount of non-managed memory currently allocated
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
activeComp int // Current number of active compactions
compStartTime time.Time // The start time of the earliest currently-active compaction
compTime int64 // Total time spent in compaction in ns
level0Comp uint32 // Total number of level-zero compactions
nonLevel0Comp uint32 // Total number of non level-zero compactions
writeDelayStartTime time.Time // The start time of the latest write stall
writeDelayCount int64 // Total number of write stall counts
writeDelayTime int64 // Total time spent in write stalls
}
func (d *Database) onCompactionBegin(info pebble.CompactionInfo) {
if d.activeComp == 0 {
d.compStartTime = time.Now()
}
l0 := info.Input[0]
if l0.Level == 0 {
atomic.AddUint32(&d.level0Comp, 1)
} else {
atomic.AddUint32(&d.nonLevel0Comp, 1)
}
d.activeComp++
}
func (d *Database) onCompactionEnd(info pebble.CompactionInfo) {
if d.activeComp == 1 {
atomic.AddInt64(&d.compTime, int64(time.Since(d.compStartTime)))
} else if d.activeComp == 0 {
panic("should not happen")
}
d.activeComp--
}
func (d *Database) onWriteStallBegin(b pebble.WriteStallBeginInfo) {
d.writeDelayStartTime = time.Now()
}
func (d *Database) onWriteStallEnd() {
atomic.AddInt64(&d.writeDelayTime, int64(time.Since(d.writeDelayStartTime)))
}
// New returns a wrapped pebble DB 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) {
// Ensure we have some minimal caching and file guarantees
if cache < minCache {
cache = minCache
}
if handles < minHandles {
handles = minHandles
}
logger := log.New("database", file)
logger.Info("Allocated cache and file handles", "cache", common.StorageSize(cache*1024*1024), "handles", handles)
// The max memtable size is limited by the uint32 offsets stored in
// internal/arenaskl.node, DeferredBatchOp, and flushableBatchEntry.
// Taken from https://github.com/cockroachdb/pebble/blob/master/open.go#L38
maxMemTableSize := 4 << 30 // 4 GB
// Two memory tables is configured which is identical to leveldb,
// including a frozen memory table and another live one.
memTableLimit := 2
memTableSize := cache * 1024 * 1024 / 2 / memTableLimit
if memTableSize > maxMemTableSize {
memTableSize = maxMemTableSize
}
db := &Database{
fn: file,
log: logger,
quitChan: make(chan chan error),
}
opt := &pebble.Options{
// Pebble has a single combined cache area and the write
// buffers are taken from this too. Assign all available
// memory allowance for cache.
Cache: pebble.NewCache(int64(cache * 1024 * 1024)),
MaxOpenFiles: handles,
// The size of memory table(as well as the write buffer).
// Note, there may have more than two memory tables in the system.
MemTableSize: memTableSize,
// MemTableStopWritesThreshold places a hard limit on the size
// of the existent MemTables(including the frozen one).
MemTableStopWritesThreshold: memTableLimit * memTableSize,
// The default compaction concurrency(1 thread),
// Here use all available CPUs for faster compaction.
MaxConcurrentCompactions: func() int { return runtime.NumCPU() },
// Per-level options. Options for at least one level must be specified. The
// options for the last level are used for all subsequent levels.
Levels: []pebble.LevelOptions{
{TargetFileSize: 2 * 1024 * 1024, FilterPolicy: bloom.FilterPolicy(10)},
{TargetFileSize: 2 * 1024 * 1024, FilterPolicy: bloom.FilterPolicy(10)},
{TargetFileSize: 2 * 1024 * 1024, FilterPolicy: bloom.FilterPolicy(10)},
{TargetFileSize: 2 * 1024 * 1024, FilterPolicy: bloom.FilterPolicy(10)},
{TargetFileSize: 2 * 1024 * 1024, FilterPolicy: bloom.FilterPolicy(10)},
{TargetFileSize: 2 * 1024 * 1024, FilterPolicy: bloom.FilterPolicy(10)},
{TargetFileSize: 2 * 1024 * 1024, FilterPolicy: bloom.FilterPolicy(10)},
},
ReadOnly: readonly,
EventListener: &pebble.EventListener{
CompactionBegin: db.onCompactionBegin,
CompactionEnd: db.onCompactionEnd,
WriteStallBegin: db.onWriteStallBegin,
WriteStallEnd: db.onWriteStallEnd,
},
}
// Disable seek compaction explicitly. Check https://github.com/ethereum/go-ethereum/pull/20130
// for more details.
opt.Experimental.ReadSamplingMultiplier = -1
// Open the db and recover any potential corruptions
innerDB, err := pebble.Open(file, opt)
if err != nil {
return nil, err
}
db.db = innerDB
db.compTimeMeter = metrics.NewRegisteredMeter(namespace+"compact/time", nil)
db.compReadMeter = metrics.NewRegisteredMeter(namespace+"compact/input", nil)
db.compWriteMeter = metrics.NewRegisteredMeter(namespace+"compact/output", nil)
db.diskSizeGauge = metrics.NewRegisteredGauge(namespace+"disk/size", nil)
db.diskReadMeter = metrics.NewRegisteredMeter(namespace+"disk/read", nil)
db.diskWriteMeter = metrics.NewRegisteredMeter(namespace+"disk/write", nil)
db.writeDelayMeter = metrics.NewRegisteredMeter(namespace+"compact/writedelay/duration", nil)
db.writeDelayNMeter = metrics.NewRegisteredMeter(namespace+"compact/writedelay/counter", nil)
db.memCompGauge = metrics.NewRegisteredGauge(namespace+"compact/memory", nil)
db.level0CompGauge = metrics.NewRegisteredGauge(namespace+"compact/level0", nil)
db.nonlevel0CompGauge = metrics.NewRegisteredGauge(namespace+"compact/nonlevel0", nil)
db.seekCompGauge = metrics.NewRegisteredGauge(namespace+"compact/seek", nil)
db.manualMemAllocGauge = metrics.NewRegisteredGauge(namespace+"memory/manualalloc", nil)
// Start up the metrics gathering and return
go db.meter(metricsGatheringInterval)
return db, nil
}
// Close stops the metrics collection, flushes any pending data to disk and closes
// all io accesses to the underlying key-value store.
func (d *Database) Close() error {
d.quitLock.Lock()
defer d.quitLock.Unlock()
if d.quitChan != nil {
errc := make(chan error)
d.quitChan <- errc
if err := <-errc; err != nil {
d.log.Error("Metrics collection failed", "err", err)
}
d.quitChan = nil
}
return d.db.Close()
}
// Has retrieves if a key is present in the key-value store.
func (d *Database) Has(key []byte) (bool, error) {
_, closer, err := d.db.Get(key)
if err == pebble.ErrNotFound {
return false, nil
} else if err != nil {
return false, err
}
closer.Close()
return true, nil
}
// Get retrieves the given key if it's present in the key-value store.
func (d *Database) Get(key []byte) ([]byte, error) {
dat, closer, err := d.db.Get(key)
if err != nil {
return nil, err
}
ret := make([]byte, len(dat))
copy(ret, dat)
closer.Close()
return ret, nil
}
// Put inserts the given value into the key-value store.
func (d *Database) Put(key []byte, value []byte) error {
return d.db.Set(key, value, pebble.NoSync)
}
// Delete removes the key from the key-value store.
func (d *Database) Delete(key []byte) error {
return d.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 (d *Database) NewBatch() ethdb.Batch {
return &batch{
b: d.db.NewBatch(),
}
}
// NewBatchWithSize creates a write-only database batch with pre-allocated buffer.
// TODO can't do this with pebble. Batches are allocated in a pool so maybe this doesn't matter?
func (d *Database) NewBatchWithSize(_ int) ethdb.Batch {
return &batch{
b: d.db.NewBatch(),
}
}
// snapshot wraps a pebble snapshot for implementing the Snapshot interface.
type snapshot struct {
db *pebble.Snapshot
}
// 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 (d *Database) NewSnapshot() (ethdb.Snapshot, error) {
snap := d.db.NewSnapshot()
return &snapshot{db: snap}, nil
}
// 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) {
_, closer, err := snap.db.Get(key)
if err != nil {
if err != pebble.ErrNotFound {
return false, err
} else {
return false, nil
}
}
closer.Close()
return true, 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) {
dat, closer, err := snap.db.Get(key)
if err != nil {
return nil, err
}
ret := make([]byte, len(dat))
copy(ret, dat)
closer.Close()
return ret, nil
}
// Release releases associated resources. Release should always succeed and can
// be called multiple times without causing error.
func (snap *snapshot) Release() {
snap.db.Close()
}
// upperBound returns the upper bound for the given prefix
func upperBound(prefix []byte) (limit []byte) {
for i := len(prefix) - 1; i >= 0; i-- {
c := prefix[i]
if c == 0xff {
continue
}
limit = make([]byte, i+1)
copy(limit, prefix)
limit[i] = c + 1
break
}
return limit
}
// Stat returns a particular internal stat of the database.
func (d *Database) Stat(property string) (string, error) {
return "", nil
}
// 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 (d *Database) Compact(start []byte, limit []byte) error {
return d.db.Compact(start, limit, true) // Parallelization is preferred
}
// Path returns the path to the database directory.
func (d *Database) Path() string {
return d.fn
}
// meter periodically retrieves internal pebble counters and reports them to
// the metrics subsystem.
func (d *Database) meter(refresh time.Duration) {
var errc chan error
timer := time.NewTimer(refresh)
defer timer.Stop()
// Create storage and warning log tracer for write delay.
var (
compTimes [2]int64
writeDelayTimes [2]int64
writeDelayCounts [2]int64
compWrites [2]int64
compReads [2]int64
nWrites [2]int64
)
// Iterate ad infinitum and collect the stats
for i := 1; errc == nil; i++ {
var (
compWrite int64
compRead int64
nWrite int64
metrics = d.db.Metrics()
compTime = atomic.LoadInt64(&d.compTime)
writeDelayCount = atomic.LoadInt64(&d.writeDelayCount)
writeDelayTime = atomic.LoadInt64(&d.writeDelayTime)
nonLevel0CompCount = int64(atomic.LoadUint32(&d.nonLevel0Comp))
level0CompCount = int64(atomic.LoadUint32(&d.level0Comp))
)
writeDelayTimes[i%2] = writeDelayTime
writeDelayCounts[i%2] = writeDelayCount
compTimes[i%2] = compTime
for _, levelMetrics := range metrics.Levels {
nWrite += int64(levelMetrics.BytesCompacted)
nWrite += int64(levelMetrics.BytesFlushed)
compWrite += int64(levelMetrics.BytesCompacted)
compRead += int64(levelMetrics.BytesRead)
}
nWrite += int64(metrics.WAL.BytesWritten)
compWrites[i%2] = compWrite
compReads[i%2] = compRead
nWrites[i%2] = nWrite
if d.writeDelayNMeter != nil {
d.writeDelayNMeter.Mark(writeDelayCounts[i%2] - writeDelayCounts[(i-1)%2])
}
if d.writeDelayMeter != nil {
d.writeDelayMeter.Mark(writeDelayTimes[i%2] - writeDelayTimes[(i-1)%2])
}
if d.compTimeMeter != nil {
d.compTimeMeter.Mark(compTimes[i%2] - compTimes[(i-1)%2])
}
if d.compReadMeter != nil {
d.compReadMeter.Mark(compReads[i%2] - compReads[(i-1)%2])
}
if d.compWriteMeter != nil {
d.compWriteMeter.Mark(compWrites[i%2] - compWrites[(i-1)%2])
}
if d.diskSizeGauge != nil {
d.diskSizeGauge.Update(int64(metrics.DiskSpaceUsage()))
}
if d.diskReadMeter != nil {
d.diskReadMeter.Mark(0) // pebble doesn't track non-compaction reads
}
if d.diskWriteMeter != nil {
d.diskWriteMeter.Mark(nWrites[i%2] - nWrites[(i-1)%2])
}
// See https://github.com/cockroachdb/pebble/pull/1628#pullrequestreview-1026664054
manuallyAllocated := metrics.BlockCache.Size + int64(metrics.MemTable.Size) + int64(metrics.MemTable.ZombieSize)
d.manualMemAllocGauge.Update(manuallyAllocated)
d.memCompGauge.Update(metrics.Flush.Count)
d.nonlevel0CompGauge.Update(nonLevel0CompCount)
d.level0CompGauge.Update(level0CompCount)
d.seekCompGauge.Update(metrics.Compact.ReadCount)
// Sleep a bit, then repeat the stats collection
select {
case errc = <-d.quitChan:
// Quit requesting, stop hammering the database
case <-timer.C:
timer.Reset(refresh)
// Timeout, gather a new set of stats
}
}
errc <- nil
}
// batch is a write-only batch that commits changes to its host database
// when Write is called. A batch cannot be used concurrently.
type batch struct {
b *pebble.Batch
size int
}
// Put inserts the given value into the batch for later committing.
func (b *batch) Put(key, value []byte) error {
b.b.Set(key, value, nil)
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, nil)
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.b.Commit(pebble.NoSync)
}
// 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 {
reader := b.b.Reader()
for {
kind, k, v, ok := reader.Next()
if !ok {
break
}
// The (k,v) slices might be overwritten if the batch is reset/reused,
// and the receiver should copy them if they are to be retained long-term.
if kind == pebble.InternalKeyKindSet {
w.Put(k, v)
} else if kind == pebble.InternalKeyKindDelete {
w.Delete(k)
} else {
return fmt.Errorf("unhandled operation, keytype: %v", kind)
}
}
return nil
}
// pebbleIterator is a wrapper of underlying iterator in storage engine.
// The purpose of this structure is to implement the missing APIs.
type pebbleIterator struct {
iter *pebble.Iterator
moved bool
}
// 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 (d *Database) NewIterator(prefix []byte, start []byte) ethdb.Iterator {
iter := d.db.NewIter(&pebble.IterOptions{
LowerBound: append(prefix, start...),
UpperBound: upperBound(prefix),
})
iter.First()
return &pebbleIterator{iter: iter, moved: true}
}
// Next moves the iterator to the next key/value pair. It returns whether the
// iterator is exhausted.
func (iter *pebbleIterator) Next() bool {
if iter.moved {
iter.moved = false
return iter.iter.Valid()
}
return iter.iter.Next()
}
// Error returns any accumulated error. Exhausting all the key/value pairs
// is not considered to be an error.
func (iter *pebbleIterator) Error() error {
return iter.iter.Error()
}
// Key returns the key of the current key/value pair, or nil if done. The caller
// should not modify the contents of the returned slice, and its contents may
// change on the next call to Next.
func (iter *pebbleIterator) Key() []byte {
return iter.iter.Key()
}
// Value returns the value of the current key/value pair, or nil if done. The
// caller should not modify the contents of the returned slice, and its contents
// may change on the next call to Next.
func (iter *pebbleIterator) Value() []byte {
return iter.iter.Value()
}
// Release releases associated resources. Release should always succeed and can
// be called multiple times without causing error.
func (iter *pebbleIterator) Release() { iter.iter.Close() }