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// Copyright (c) 2012, Suryandaru Triandana <syndtr@gmail.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"
"errors"
"github.com/syndtr/goleveldb/leveldb/memdb"
)
var (
errBatchTooShort = errors.New("leveldb: batch is too short")
errBatchBadRecord = errors.New("leveldb: bad record in batch")
)
const kBatchHdrLen = 8 + 4
type batchReplay interface {
put(key, value []byte, seq uint64)
delete(key []byte, seq uint64)
}
// Batch is a write batch.
type Batch struct {
buf []byte
rLen, bLen int
seq uint64
sync bool
}
func (b *Batch) grow(n int) {
off := len(b.buf)
if off == 0 {
// include headers
off = kBatchHdrLen
n += off
}
if cap(b.buf)-off >= n {
return
}
buf := make([]byte, 2*cap(b.buf)+n)
copy(buf, b.buf)
b.buf = buf[:off]
}
func (b *Batch) appendRec(t vType, key, value []byte) {
n := 1 + binary.MaxVarintLen32 + len(key)
if t == tVal {
n += binary.MaxVarintLen32 + len(value)
}
b.grow(n)
off := len(b.buf)
buf := b.buf[:off+n]
buf[off] = byte(t)
off += 1
off += binary.PutUvarint(buf[off:], uint64(len(key)))
copy(buf[off:], key)
off += len(key)
if t == tVal {
off += binary.PutUvarint(buf[off:], uint64(len(value)))
copy(buf[off:], value)
off += len(value)
}
b.buf = buf[:off]
b.rLen++
// Include 8-byte ikey header
b.bLen += len(key) + len(value) + 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.
func (b *Batch) Put(key, value []byte) {
b.appendRec(tVal, 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.
func (b *Batch) Delete(key []byte) {
b.appendRec(tDel, key, nil)
}
// Reset resets the batch.
func (b *Batch) Reset() {
b.buf = nil
b.seq = 0
b.rLen = 0
b.bLen = 0
b.sync = false
}
func (b *Batch) init(sync bool) {
b.sync = sync
}
func (b *Batch) put(key, value []byte, seq uint64) {
if b.rLen == 0 {
b.seq = seq
}
b.Put(key, value)
}
func (b *Batch) delete(key []byte, seq uint64) {
if b.rLen == 0 {
b.seq = seq
}
b.Delete(key)
}
func (b *Batch) append(p *Batch) {
if p.rLen > 0 {
b.grow(len(p.buf) - kBatchHdrLen)
b.buf = append(b.buf, p.buf[kBatchHdrLen:]...)
b.rLen += p.rLen
}
if p.sync {
b.sync = true
}
}
func (b *Batch) len() int {
return b.rLen
}
func (b *Batch) size() int {
return b.bLen
}
func (b *Batch) encode() []byte {
b.grow(0)
binary.LittleEndian.PutUint64(b.buf, b.seq)
binary.LittleEndian.PutUint32(b.buf[8:], uint32(b.rLen))
return b.buf
}
func (b *Batch) decode(buf []byte) error {
if len(buf) < kBatchHdrLen {
return errBatchTooShort
}
b.seq = binary.LittleEndian.Uint64(buf)
b.rLen = int(binary.LittleEndian.Uint32(buf[8:]))
// No need to be precise at this point, it won't be used anyway
b.bLen = len(buf) - kBatchHdrLen
b.buf = buf
return nil
}
func (b *Batch) decodeRec(f func(i int, t vType, key, value []byte)) error {
off := kBatchHdrLen
for i := 0; i < b.rLen; i++ {
if off >= len(b.buf) {
return errors.New("leveldb: invalid batch record length")
}
t := vType(b.buf[off])
if t > tVal {
return errors.New("leveldb: invalid batch record type in batch")
}
off += 1
x, n := binary.Uvarint(b.buf[off:])
off += n
if n <= 0 || off+int(x) > len(b.buf) {
return errBatchBadRecord
}
key := b.buf[off : off+int(x)]
off += int(x)
var value []byte
if t == tVal {
x, n := binary.Uvarint(b.buf[off:])
off += n
if n <= 0 || off+int(x) > len(b.buf) {
return errBatchBadRecord
}
value = b.buf[off : off+int(x)]
off += int(x)
}
f(i, t, key, value)
}
return nil
}
func (b *Batch) replay(to batchReplay) error {
return b.decodeRec(func(i int, t vType, key, value []byte) {
switch t {
case tVal:
to.put(key, value, b.seq+uint64(i))
case tDel:
to.delete(key, b.seq+uint64(i))
}
})
}
func (b *Batch) memReplay(to *memdb.DB) error {
return b.decodeRec(func(i int, t vType, key, value []byte) {
ikey := newIKey(key, b.seq+uint64(i), t)
to.Put(ikey, value)
})
}
func (b *Batch) revertMemReplay(to *memdb.DB) error {
return b.decodeRec(func(i int, t vType, key, value []byte) {
ikey := newIKey(key, b.seq+uint64(i), t)
to.Delete(ikey)
})
}
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