leveldb/batch.go
// Copyright © 2012, Suryandaru Triandana <syndtr@gmail.com>
// Copyright © 2021, Jeffrey H. Johnson <trnsz@pobox.com>
//
// All rights reserved.
//
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
package leveldb
import (
"encoding/binary"
"fmt"
"io"
"github.com/johnsonjh/jleveldb/leveldb/errors"
"github.com/johnsonjh/jleveldb/leveldb/memdb"
"github.com/johnsonjh/jleveldb/leveldb/storage"
)
// ErrBatchCorrupted records reason of batch corruption. This error will be
// wrapped with errors.ErrCorrupted.
type ErrBatchCorrupted struct {
Reason string
}
func (e *ErrBatchCorrupted) Error() string {
return fmt.Sprintf("leveldb: batch corrupted: %s", e.Reason)
}
func newErrBatchCorrupted(reason string) error {
return errors.NewErrCorrupted(storage.FileDesc{}, &ErrBatchCorrupted{reason})
}
const (
batchHeaderLen = 8 + 4
batchGrowRec = 3000
)
// BatchReplay wraps basic batch operations.
type BatchReplay interface {
Put(key, value []byte)
Delete(key []byte)
}
type batchIndex struct {
keyType keyType
keyPos, keyLen int
valuePos, valueLen int
}
func (index batchIndex) k(data []byte) []byte {
return data[index.keyPos : index.keyPos+index.keyLen]
}
func (index batchIndex) v(data []byte) []byte {
if index.valueLen != 0 {
return data[index.valuePos : index.valuePos+index.valueLen]
}
return nil
}
// Batch is a write batch.
type Batch struct {
data []byte
index []batchIndex
// internalLen is sums of key/value pair length plus 8-bytes internal key.
internalLen int
}
func (b *Batch) grow(n int) {
o := len(b.data)
if cap(b.data)-o < n {
div := 1
if len(b.index) > batchGrowRec {
div = len(b.index) / batchGrowRec
}
ndata := make([]byte, o, o+n+o/div)
copy(ndata, b.data)
b.data = ndata
}
}
func (b *Batch) appendRec(kt keyType, key, value []byte) {
n := 1 + binary.MaxVarintLen32 + len(key)
if kt == keyTypeVal {
n += binary.MaxVarintLen32 + len(value)
}
b.grow(n)
index := batchIndex{keyType: kt}
o := len(b.data)
data := b.data[:o+n]
data[o] = byte(kt)
o++
o += binary.PutUvarint(data[o:], uint64(len(key)))
index.keyPos = o
index.keyLen = len(key)
o += copy(data[o:], key)
if kt == keyTypeVal {
o += binary.PutUvarint(data[o:], uint64(len(value)))
index.valuePos = o
index.valueLen = len(value)
o += copy(data[o:], value)
}
b.data = data[:o]
b.index = append(b.index, index)
b.internalLen += index.keyLen + index.valueLen + 8
}
// Put appends 'put operation' of the given key/value pair to the batch.
// It is safe to modify the contents of the argument after Put returns but not
// before.
func (b *Batch) Put(key, value []byte) {
b.appendRec(keyTypeVal, key, value)
}
// Delete appends 'delete operation' of the given key to the batch.
// It is safe to modify the contents of the argument after Delete returns but
// not before.
func (b *Batch) Delete(key []byte) {
b.appendRec(keyTypeDel, key, nil)
}
// Dump dumps batch contents. The returned slice can be loaded into the
// batch using Load method.
// The returned slice is not its own copy, so the contents should not be
// modified.
func (b *Batch) Dump() []byte {
return b.data
}
// Load loads given slice into the batch. Previous contents of the batch
// will be discarded.
// The given slice will not be copied and will be used as batch buffer, so
// it is not safe to modify the contents of the slice.
func (b *Batch) Load(data []byte) error {
return b.decode(data, -1)
}
// Replay replays batch contents.
func (b *Batch) Replay(r BatchReplay) error {
for _, index := range b.index {
switch index.keyType {
case keyTypeVal:
r.Put(index.k(b.data), index.v(b.data))
case keyTypeDel:
r.Delete(index.k(b.data))
}
}
return nil
}
// Len returns number of records in the batch.
func (b *Batch) Len() int {
return len(b.index)
}
// Reset resets the batch.
func (b *Batch) Reset() {
b.data = b.data[:0]
b.index = b.index[:0]
b.internalLen = 0
}
func (b *Batch) replayInternal(fn func(i int, kt keyType, k, v []byte) error) error {
for i, index := range b.index {
if err := fn(i, index.keyType, index.k(b.data), index.v(b.data)); err != nil {
return err
}
}
return nil
}
func (b *Batch) append(p *Batch) {
ob := len(b.data)
oi := len(b.index)
b.data = append(b.data, p.data...)
b.index = append(b.index, p.index...)
b.internalLen += p.internalLen
// Updating index offset.
if ob != 0 {
for ; oi < len(b.index); oi++ {
index := &b.index[oi]
index.keyPos += ob
if index.valueLen != 0 {
index.valuePos += ob
}
}
}
}
func (b *Batch) decode(data []byte, expectedLen int) error {
b.data = data
b.index = b.index[:0]
b.internalLen = 0
err := decodeBatch(data, func(i int, index batchIndex) error {
b.index = append(b.index, index)
b.internalLen += index.keyLen + index.valueLen + 8
return nil
})
if err != nil {
return err
}
if expectedLen >= 0 && len(b.index) != expectedLen {
return newErrBatchCorrupted(fmt.Sprintf("invalid records length: %d vs %d", expectedLen, len(b.index)))
}
return nil
}
func (b *Batch) putMem(seq uint64, mdb *memdb.DB) error {
var ik []byte
for i, index := range b.index {
ik = makeInternalKey(ik, index.k(b.data), seq+uint64(i), index.keyType)
if err := mdb.Put(ik, index.v(b.data)); err != nil {
return err
}
}
return nil
}
func newBatch() interface{} {
return &Batch{}
}
// MakeBatch returns empty batch with preallocated buffer.
func MakeBatch(n int) *Batch {
return &Batch{data: make([]byte, 0, n)}
}
func decodeBatch(data []byte, fn func(i int, index batchIndex) error) error {
var index batchIndex
for i, o := 0, 0; o < len(data); i++ {
// Key type.
index.keyType = keyType(data[o])
if index.keyType > keyTypeVal {
return newErrBatchCorrupted(fmt.Sprintf("bad record: invalid type %#x", uint(index.keyType)))
}
o++
// Key.
x, n := binary.Uvarint(data[o:])
o += n
if n <= 0 || o+int(x) > len(data) {
return newErrBatchCorrupted("bad record: invalid key length")
}
index.keyPos = o
index.keyLen = int(x)
o += index.keyLen
// Value.
if index.keyType == keyTypeVal {
x, n = binary.Uvarint(data[o:])
o += n
if n <= 0 || o+int(x) > len(data) {
return newErrBatchCorrupted("bad record: invalid value length")
}
index.valuePos = o
index.valueLen = int(x)
o += index.valueLen
} else {
index.valuePos = 0
index.valueLen = 0
}
if err := fn(i, index); err != nil {
return err
}
}
return nil
}
func decodeBatchToMem(data []byte, expectSeq uint64, mdb *memdb.DB) (seq uint64, batchLen int, err error) {
seq, batchLen, err = decodeBatchHeader(data)
if err != nil {
return 0, 0, err
}
if seq < expectSeq {
return 0, 0, newErrBatchCorrupted("invalid sequence number")
}
data = data[batchHeaderLen:]
var ik []byte
var decodedLen int
err = decodeBatch(data, func(i int, index batchIndex) error {
if i >= batchLen {
return newErrBatchCorrupted("invalid records length")
}
ik = makeInternalKey(ik, index.k(data), seq+uint64(i), index.keyType)
if err := mdb.Put(ik, index.v(data)); err != nil {
return err
}
decodedLen++
return nil
})
if err == nil && decodedLen != batchLen {
err = newErrBatchCorrupted(fmt.Sprintf("invalid records length: %d vs %d", batchLen, decodedLen))
}
return
}
func encodeBatchHeader(dst []byte, seq uint64, batchLen int) []byte {
dst = ensureBuffer(dst, batchHeaderLen)
binary.LittleEndian.PutUint64(dst, seq)
binary.LittleEndian.PutUint32(dst[8:], uint32(batchLen))
return dst
}
func decodeBatchHeader(data []byte) (seq uint64, batchLen int, err error) {
if len(data) < batchHeaderLen {
return 0, 0, newErrBatchCorrupted("too short")
}
seq = binary.LittleEndian.Uint64(data)
batchLen = int(binary.LittleEndian.Uint32(data[8:]))
if batchLen < 0 {
return 0, 0, newErrBatchCorrupted("invalid records length")
}
return
}
func batchesLen(batches []*Batch) int {
batchLen := 0
for _, batch := range batches {
batchLen += batch.Len()
}
return batchLen
}
func writeBatchesWithHeader(wr io.Writer, batches []*Batch, seq uint64) error {
if _, err := wr.Write(encodeBatchHeader(nil, seq, batchesLen(batches))); err != nil {
return err
}
for _, batch := range batches {
if _, err := wr.Write(batch.data); err != nil {
return err
}
}
return nil
}