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delete_range.go
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delete_range.go
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// Copyright 2017 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,
// See the License for the specific language governing permissions and
// limitations under the License.
package ddl
import (
"bytes"
"encoding/hex"
"fmt"
"math"
"github.com/juju/errors"
"github.com/ngaut/pools"
"github.com/pingcap/tidb/ddl/util"
"github.com/pingcap/tidb/kv"
"github.com/pingcap/tidb/model"
"github.com/pingcap/tidb/mysql"
"github.com/pingcap/tidb/sessionctx"
"github.com/pingcap/tidb/store/tikv/oracle"
"github.com/pingcap/tidb/tablecodec"
"github.com/pingcap/tidb/terror"
"github.com/pingcap/tidb/util/sqlexec"
log "github.com/sirupsen/logrus"
"golang.org/x/net/context"
)
const (
insertDeleteRangeSQL = `INSERT IGNORE INTO mysql.gc_delete_range VALUES ("%d", "%d", "%s", "%s", "%d")`
delBatchSize = 65536
delBackLog = 128
)
type delRangeManager interface {
// addDelRangeJob add a DDL job into gc_delete_range table.
addDelRangeJob(job *model.Job) error
start()
clear()
}
type delRange struct {
d *ddl
ctxPool *pools.ResourcePool
storeSupport bool
emulatorCh chan struct{}
keys []kv.Key
}
// newDelRangeManager returns a delRangeManager.
func newDelRangeManager(d *ddl, ctxPool *pools.ResourcePool, supportDelRange bool) delRangeManager {
dr := &delRange{
d: d,
ctxPool: ctxPool,
storeSupport: supportDelRange,
}
if !dr.storeSupport {
dr.emulatorCh = make(chan struct{}, delBackLog)
dr.keys = make([]kv.Key, 0, delBatchSize)
}
return dr
}
// addDelRangeJob implements delRangeManager interface.
func (dr *delRange) addDelRangeJob(job *model.Job) error {
resource, err := dr.ctxPool.Get()
if err != nil {
return errors.Trace(err)
}
defer dr.ctxPool.Put(resource)
ctx := resource.(sessionctx.Context)
ctx.GetSessionVars().SetStatusFlag(mysql.ServerStatusAutocommit, true)
ctx.GetSessionVars().InRestrictedSQL = true
err = insertJobIntoDeleteRangeTable(ctx, job)
if err != nil {
return errors.Trace(err)
}
if !dr.storeSupport {
dr.emulatorCh <- struct{}{}
}
log.Infof("[ddl] add job (%d,%s) into delete-range table", job.ID, job.Type.String())
return nil
}
// start implements delRangeManager interface.
func (dr *delRange) start() {
if !dr.storeSupport {
dr.d.wait.Add(1)
go dr.startEmulator()
}
}
// clear implements delRangeManager interface.
func (dr *delRange) clear() {
log.Infof("[ddl] closing delRange session pool")
dr.ctxPool.Close()
}
// startEmulator is only used for those storage engines which don't support
// delete-range. The emulator fetches records from gc_delete_range table and
// deletes all keys in each DelRangeTask.
func (dr *delRange) startEmulator() {
defer dr.d.wait.Done()
log.Infof("[ddl] start delRange emulator")
for {
select {
case <-dr.emulatorCh:
case <-dr.d.quitCh:
return
}
err := dr.doDelRangeWork()
terror.Log(errors.Trace(err))
}
}
func (dr *delRange) doDelRangeWork() error {
resource, err := dr.ctxPool.Get()
if err != nil {
log.Errorf("[ddl] delRange emulator get session fail: %s", err)
return errors.Trace(err)
}
defer dr.ctxPool.Put(resource)
ctx := resource.(sessionctx.Context)
ctx.GetSessionVars().SetStatusFlag(mysql.ServerStatusAutocommit, true)
ctx.GetSessionVars().InRestrictedSQL = true
ranges, err := util.LoadDeleteRanges(ctx, math.MaxInt64)
if err != nil {
log.Errorf("[dd] delRange emulator load tasks fail: %s", err)
return errors.Trace(err)
}
for _, r := range ranges {
if err := dr.doTask(ctx, r); err != nil {
log.Errorf("[ddl] delRange emulator do task fail: %s", err)
return errors.Trace(err)
}
}
return nil
}
func (dr *delRange) doTask(ctx sessionctx.Context, r util.DelRangeTask) error {
var oldStartKey, newStartKey kv.Key
oldStartKey = r.StartKey
for {
finish := true
dr.keys = dr.keys[:0]
err := kv.RunInNewTxn(dr.d.store, false, func(txn kv.Transaction) error {
iter, err := txn.Seek(oldStartKey)
if err != nil {
return errors.Trace(err)
}
defer iter.Close()
for i := 0; i < delBatchSize; i++ {
if !iter.Valid() {
break
}
finish = bytes.Compare(iter.Key(), r.EndKey) >= 0
if finish {
break
}
dr.keys = append(dr.keys, iter.Key().Clone())
newStartKey = iter.Key().Next()
if err := iter.Next(); err != nil {
return errors.Trace(err)
}
}
for _, key := range dr.keys {
err := txn.Delete(key)
if err != nil && !kv.ErrNotExist.Equal(err) {
return errors.Trace(err)
}
}
return nil
})
if err != nil {
return errors.Trace(err)
}
if finish {
if err := util.CompleteDeleteRange(ctx, r); err != nil {
log.Errorf("[ddl] delRange emulator complete task fail: %s", err)
return errors.Trace(err)
}
log.Infof("[ddl] delRange emulator complete task: (%d, %d)", r.JobID, r.ElementID)
break
} else {
if err := util.UpdateDeleteRange(ctx, r, newStartKey, oldStartKey); err != nil {
log.Errorf("[ddl] delRange emulator update task fail: %s", err)
}
oldStartKey = newStartKey
}
}
return nil
}
// insertJobIntoDeleteRangeTable parses the job into delete-range arguments,
// and inserts a new record into gc_delete_range table. The primary key is
// job ID, so we ignore key conflict error.
func insertJobIntoDeleteRangeTable(ctx sessionctx.Context, job *model.Job) error {
now, err := getNowTS(ctx)
if err != nil {
return errors.Trace(err)
}
s := ctx.(sqlexec.SQLExecutor)
switch job.Type {
case model.ActionDropSchema:
var tableIDs []int64
if err := job.DecodeArgs(&tableIDs); err != nil {
return errors.Trace(err)
}
for _, tableID := range tableIDs {
startKey := tablecodec.EncodeTablePrefix(tableID)
endKey := tablecodec.EncodeTablePrefix(tableID + 1)
if err := doInsert(s, job.ID, tableID, startKey, endKey, now); err != nil {
return errors.Trace(err)
}
}
case model.ActionDropTable, model.ActionTruncateTable:
tableID := job.TableID
startKey := tablecodec.EncodeTablePrefix(tableID)
endKey := tablecodec.EncodeTablePrefix(tableID + 1)
return doInsert(s, job.ID, tableID, startKey, endKey, now)
case model.ActionDropIndex:
tableID := job.TableID
var indexName interface{}
var indexID int64
if err := job.DecodeArgs(&indexName, &indexID); err != nil {
return errors.Trace(err)
}
startKey := tablecodec.EncodeTableIndexPrefix(tableID, indexID)
endKey := tablecodec.EncodeTableIndexPrefix(tableID, indexID+1)
return doInsert(s, job.ID, indexID, startKey, endKey, now)
}
return nil
}
func doInsert(s sqlexec.SQLExecutor, jobID int64, elementID int64, startKey, endKey kv.Key, ts int64) error {
log.Infof("[ddl] insert into delete-range table with key: (%d,%d)", jobID, elementID)
startKeyEncoded := hex.EncodeToString(startKey)
endKeyEncoded := hex.EncodeToString(endKey)
sql := fmt.Sprintf(insertDeleteRangeSQL, jobID, elementID, startKeyEncoded, endKeyEncoded, ts)
_, err := s.Execute(context.Background(), sql)
return errors.Trace(err)
}
// getNowTS gets the current timestamp, in second.
func getNowTS(ctx sessionctx.Context) (int64, error) {
currVer, err := ctx.GetStore().CurrentVersion()
if err != nil {
return 0, errors.Trace(err)
}
physical := oracle.ExtractPhysical(currVer.Ver)
return physical / 1e3, nil
}