tidb write 源码
tidb write 代码
文件路径：/store/mockstore/unistore/tikv/write.go
// Copyright 2019-present PingCAP, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package tikv
import (
"bytes"
"math"
"sync"
"sync/atomic"
"github.com/pingcap/badger"
"github.com/pingcap/badger/y"
"github.com/pingcap/kvproto/pkg/kvrpcpb"
"github.com/pingcap/tidb/store/mockstore/unistore/lockstore"
"github.com/pingcap/tidb/store/mockstore/unistore/tikv/dbreader"
"github.com/pingcap/tidb/store/mockstore/unistore/tikv/mvcc"
"github.com/pingcap/tidb/util/mathutil"
)
const (
batchChanSize = 1024
)
type writeDBBatch struct {
entries []*badger.Entry
err error
wg sync.WaitGroup
}
func newWriteDBBatch() *writeDBBatch {
return &writeDBBatch{}
}
func (batch *writeDBBatch) set(key y.Key, val []byte, userMeta []byte) {
batch.entries = append(batch.entries, &badger.Entry{
Key: key,
Value: val,
UserMeta: userMeta,
})
}
// delete is a badger level operation, only used in DeleteRange, so we don't need to set UserMeta.
// Then we can tell the entry is delete if UserMeta is nil.
func (batch *writeDBBatch) delete(key y.Key) {
batch.entries = append(batch.entries, &badger.Entry{
Key: key,
})
}
type writeLockBatch struct {
entries []*badger.Entry
err error
wg sync.WaitGroup
}
func (batch *writeLockBatch) set(key, val []byte) {
batch.entries = append(batch.entries, &badger.Entry{
Key: y.KeyWithTs(key, 0),
Value: val,
UserMeta: mvcc.LockUserMetaNone,
})
}
func (batch *writeLockBatch) delete(key []byte) {
batch.entries = append(batch.entries, &badger.Entry{
Key: y.KeyWithTs(key, 0),
UserMeta: mvcc.LockUserMetaDelete,
})
}
type writeDBWorker struct {
batchCh chan *writeDBBatch
writer *dbWriter
}
func (w writeDBWorker) run() {
defer w.writer.wg.Done()
var batches []*writeDBBatch
for {
for i := range batches {
batches[i] = nil
}
batches = batches[:0]
select {
case <-w.writer.closeCh:
return
case batch := <-w.batchCh:
batches = append(batches, batch)
}
chLen := len(w.batchCh)
for i := 0; i < chLen; i++ {
batches = append(batches, <-w.batchCh)
}
if len(batches) > 0 {
w.updateBatchGroup(batches)
}
}
}
func (w writeDBWorker) updateBatchGroup(batchGroup []*writeDBBatch) {
e := w.writer.bundle.DB.Update(func(txn *badger.Txn) error {
for _, batch := range batchGroup {
for _, entry := range batch.entries {
var err error
if len(entry.UserMeta) == 0 {
entry.SetDelete()
}
err = txn.SetEntry(entry)
if err != nil {
return err
}
}
}
return nil
})
for _, batch := range batchGroup {
batch.err = e
batch.wg.Done()
}
}
type writeLockWorker struct {
batchCh chan *writeLockBatch
writer *dbWriter
}
func (w writeLockWorker) run() {
defer w.writer.wg.Done()
ls := w.writer.bundle.LockStore
var batches []*writeLockBatch
for {
for i := range batches {
batches[i] = nil
}
batches = batches[:0]
select {
case <-w.writer.closeCh:
return
case batch := <-w.batchCh:
batches = append(batches, batch)
}
chLen := len(w.batchCh)
for i := 0; i < chLen; i++ {
batches = append(batches, <-w.batchCh)
}
hint := new(lockstore.Hint)
var delCnt, insertCnt int
for _, batch := range batches {
for _, entry := range batch.entries {
switch entry.UserMeta[0] {
case mvcc.LockUserMetaDeleteByte:
delCnt++
// Ignore if the key doesn't exist
ls.DeleteWithHint(entry.Key.UserKey, hint)
default:
insertCnt++
ls.PutWithHint(entry.Key.UserKey, entry.Value, hint)
}
}
batch.wg.Done()
}
}
}
type dbWriter struct {
bundle *mvcc.DBBundle
dbCh chan<- *writeDBBatch
lockCh chan<- *writeLockBatch
wg sync.WaitGroup
closeCh chan struct{}
latestTS uint64
}
// NewDBWriter returns a new DBWriter.
func NewDBWriter(bundle *mvcc.DBBundle) mvcc.DBWriter {
return &dbWriter{
bundle: bundle,
closeCh: make(chan struct{}),
}
}
func (writer *dbWriter) Open() {
writer.wg.Add(2)
dbCh := make(chan *writeDBBatch, batchChanSize)
writer.dbCh = dbCh
go writeDBWorker{
batchCh: dbCh,
writer: writer,
}.run()
lockCh := make(chan *writeLockBatch, batchChanSize)
writer.lockCh = lockCh
go writeLockWorker{
batchCh: lockCh,
writer: writer,
}.run()
}
func (writer *dbWriter) Close() {
close(writer.closeCh)
writer.wg.Wait()
}
func (writer *dbWriter) Write(batch mvcc.WriteBatch) error {
wb := batch.(*writeBatch)
if len(wb.dbBatch.entries) > 0 {
wb.dbBatch.wg.Add(1)
writer.dbCh <- &wb.dbBatch
wb.dbBatch.wg.Wait()
err := wb.dbBatch.err
if err != nil {
return err
}
}
if len(wb.lockBatch.entries) > 0 {
// We must delete lock after commit succeed, or there will be inconsistency.
wb.lockBatch.wg.Add(1)
writer.lockCh <- &wb.lockBatch
wb.lockBatch.wg.Wait()
return wb.lockBatch.err
}
return nil
}
type writeBatch struct {
startTS uint64
commitTS uint64
dbBatch writeDBBatch
lockBatch writeLockBatch
}
func (wb *writeBatch) Prewrite(key []byte, lock *mvcc.Lock) {
wb.lockBatch.set(key, lock.MarshalBinary())
}
func (wb *writeBatch) Commit(key []byte, lock *mvcc.Lock) {
userMeta := mvcc.NewDBUserMeta(wb.startTS, wb.commitTS)
k := y.KeyWithTs(key, wb.commitTS)
if lock.Op != uint8(kvrpcpb.Op_Lock) {
wb.dbBatch.set(k, lock.Value, userMeta)
} else if bytes.Equal(key, lock.Primary) {
opLockKey := y.KeyWithTs(mvcc.EncodeExtraTxnStatusKey(key, wb.startTS), wb.startTS)
wb.dbBatch.set(opLockKey, nil, userMeta)
}
wb.lockBatch.delete(key)
}
func (wb *writeBatch) Rollback(key []byte, deleteLock bool) {
rollbackKey := y.KeyWithTs(mvcc.EncodeExtraTxnStatusKey(key, wb.startTS), wb.startTS)
userMeta := mvcc.NewDBUserMeta(wb.startTS, 0)
wb.dbBatch.set(rollbackKey, nil, userMeta)
if deleteLock {
wb.lockBatch.delete(key)
}
}
func (wb *writeBatch) PessimisticLock(key []byte, lock *mvcc.Lock) {
wb.lockBatch.set(key, lock.MarshalBinary())
}
func (wb *writeBatch) PessimisticRollback(key []byte) {
wb.lockBatch.delete(key)
}
func (writer *dbWriter) NewWriteBatch(startTS, commitTS uint64, ctx *kvrpcpb.Context) mvcc.WriteBatch {
if commitTS > 0 {
writer.updateLatestTS(commitTS)
} else {
writer.updateLatestTS(startTS)
}
return &writeBatch{
startTS: startTS,
commitTS: commitTS,
}
}
func (writer *dbWriter) getLatestTS() uint64 {
return atomic.LoadUint64(&writer.latestTS)
}
func (writer *dbWriter) updateLatestTS(ts uint64) {
latestTS := writer.getLatestTS()
if ts != math.MaxUint64 && ts > latestTS {
atomic.CompareAndSwapUint64(&writer.latestTS, latestTS, ts)
}
}
const delRangeBatchSize = 4096
func (writer *dbWriter) DeleteRange(startKey, endKey []byte, latchHandle mvcc.LatchHandle) error {
keys := make([]y.Key, 0, delRangeBatchSize)
txn := writer.bundle.DB.NewTransaction(false)
defer txn.Discard()
reader := dbreader.NewDBReader(startKey, endKey, txn)
keys = writer.collectRangeKeys(reader.GetIter(), startKey, endKey, keys)
reader.Close()
return writer.deleteKeysInBatch(latchHandle, keys, delRangeBatchSize)
}
func (writer *dbWriter) collectRangeKeys(it *badger.Iterator, startKey, endKey []byte, keys []y.Key) []y.Key {
if len(endKey) == 0 {
panic("invalid end key")
}
for it.Seek(startKey); it.Valid(); it.Next() {
item := it.Item()
key := item.KeyCopy(nil)
if exceedEndKey(key, endKey) {
break
}
keys = append(keys, y.KeyWithTs(key, item.Version()))
}
return keys
}
func (writer *dbWriter) deleteKeysInBatch(latchHandle mvcc.LatchHandle, keys []y.Key, batchSize int) error {
for len(keys) > 0 {
batchSize := mathutil.Min(len(keys), batchSize)
batchKeys := keys[:batchSize]
keys = keys[batchSize:]
hashVals := userKeysToHashVals(batchKeys...)
dbBatch := newWriteDBBatch()
for _, key := range batchKeys {
key.Version++
dbBatch.delete(key)
}
latchHandle.AcquireLatches(hashVals)
dbBatch.wg.Add(1)
writer.dbCh <- dbBatch
dbBatch.wg.Wait()
latchHandle.ReleaseLatches(hashVals)
if dbBatch.err != nil {
return dbBatch.err
}
}
return nil
}
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