tidb checksum 源码
tidb checksum 代码
文件路径：/br/pkg/lightning/restore/checksum.go
// Copyright 2021 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 restore
import (
"container/heap"
"context"
"database/sql"
"fmt"
"sync"
"time"
"github.com/google/uuid"
"github.com/pingcap/errors"
"github.com/pingcap/failpoint"
"github.com/pingcap/tidb/br/pkg/checksum"
"github.com/pingcap/tidb/br/pkg/lightning/checkpoints"
"github.com/pingcap/tidb/br/pkg/lightning/common"
"github.com/pingcap/tidb/br/pkg/lightning/config"
"github.com/pingcap/tidb/br/pkg/lightning/log"
"github.com/pingcap/tidb/br/pkg/lightning/metric"
"github.com/pingcap/tidb/br/pkg/pdutil"
"github.com/pingcap/tidb/kv"
"github.com/pingcap/tidb/util/mathutil"
"github.com/pingcap/tipb/go-tipb"
"github.com/tikv/client-go/v2/oracle"
pd "github.com/tikv/pd/client"
"go.uber.org/atomic"
"go.uber.org/zap"
)
const (
preUpdateServiceSafePointFactor = 3
maxErrorRetryCount = 3
)
var (
serviceSafePointTTL int64 = 10 * 60 // 10 min in seconds
minDistSQLScanConcurrency = 4
)
// RemoteChecksum represents a checksum result got from tidb.
type RemoteChecksum struct {
Schema string
Table string
Checksum uint64
TotalKVs uint64
TotalBytes uint64
}
type ChecksumManager interface {
Checksum(ctx context.Context, tableInfo *checkpoints.TidbTableInfo) (*RemoteChecksum, error)
}
func newChecksumManager(ctx context.Context, rc *Controller, store kv.Storage) (ChecksumManager, error) {
// if we don't need checksum, just return nil
if rc.cfg.TikvImporter.Backend == config.BackendTiDB || rc.cfg.PostRestore.Checksum == config.OpLevelOff {
return nil, nil
}
pdAddr := rc.cfg.TiDB.PdAddr
pdVersion, err := pdutil.FetchPDVersion(ctx, rc.tls, pdAddr)
if err != nil {
return nil, errors.Trace(err)
}
// for v4.0.0 or upper, we can use the gc ttl api
var manager ChecksumManager
if pdVersion.Major >= 4 {
tlsOpt := rc.tls.ToPDSecurityOption()
pdCli, err := pd.NewClientWithContext(ctx, []string{pdAddr}, tlsOpt)
if err != nil {
return nil, errors.Trace(err)
}
manager = newTiKVChecksumManager(store.GetClient(), pdCli, uint(rc.cfg.TiDB.DistSQLScanConcurrency))
} else {
db, err := rc.tidbGlue.GetDB()
if err != nil {
return nil, errors.Trace(err)
}
manager = newTiDBChecksumExecutor(db)
}
return manager, nil
}
// fetch checksum for tidb sql client
type tidbChecksumExecutor struct {
db *sql.DB
manager *gcLifeTimeManager
}
func newTiDBChecksumExecutor(db *sql.DB) *tidbChecksumExecutor {
return &tidbChecksumExecutor{
db: db,
manager: newGCLifeTimeManager(),
}
}
func (e *tidbChecksumExecutor) Checksum(ctx context.Context, tableInfo *checkpoints.TidbTableInfo) (*RemoteChecksum, error) {
var err error
if err = e.manager.addOneJob(ctx, e.db); err != nil {
return nil, err
}
// set it back finally
defer e.manager.removeOneJob(ctx, e.db)
tableName := common.UniqueTable(tableInfo.DB, tableInfo.Name)
task := log.FromContext(ctx).With(zap.String("table", tableName)).Begin(zap.InfoLevel, "remote checksum")
// ADMIN CHECKSUM TABLE <table>,<table> example.
// mysql> admin checksum table test.t;
// +---------+------------+---------------------+-----------+-------------+
// | Db_name | Table_name | Checksum_crc64_xor | Total_kvs | Total_bytes |
// +---------+------------+---------------------+-----------+-------------+
// | test | t | 8520875019404689597 | 7296873 | 357601387 |
// +---------+------------+---------------------+-----------+-------------+
cs := RemoteChecksum{}
err = common.SQLWithRetry{DB: e.db, Logger: task.Logger}.QueryRow(ctx, "compute remote checksum",
"ADMIN CHECKSUM TABLE "+tableName, &cs.Schema, &cs.Table, &cs.Checksum, &cs.TotalKVs, &cs.TotalBytes,
)
dur := task.End(zap.ErrorLevel, err)
if m, ok := metric.FromContext(ctx); ok {
m.ChecksumSecondsHistogram.Observe(dur.Seconds())
}
if err != nil {
return nil, errors.Trace(err)
}
return &cs, nil
}
// DoChecksum do checksum for tables.
// table should be in <db>.<table>, format. e.g. foo.bar
func DoChecksum(ctx context.Context, table *checkpoints.TidbTableInfo) (*RemoteChecksum, error) {
var err error
manager, ok := ctx.Value(&checksumManagerKey).(ChecksumManager)
if !ok {
return nil, errors.New("No gcLifeTimeManager found in context, check context initialization")
}
task := log.FromContext(ctx).With(zap.String("table", table.Name)).Begin(zap.InfoLevel, "remote checksum")
cs, err := manager.Checksum(ctx, table)
dur := task.End(zap.ErrorLevel, err)
if m, ok := metric.FromContext(ctx); ok {
m.ChecksumSecondsHistogram.Observe(dur.Seconds())
}
return cs, err
}
type gcLifeTimeManager struct {
runningJobsLock sync.Mutex
runningJobs int
oriGCLifeTime string
}
func newGCLifeTimeManager() *gcLifeTimeManager {
// Default values of three member are enough to initialize this struct
return &gcLifeTimeManager{}
}
// Pre- and post-condition:
// if m.runningJobs == 0, GC life time has not been increased.
// if m.runningJobs > 0, GC life time has been increased.
// m.runningJobs won't be negative(overflow) since index concurrency is relatively small
func (m *gcLifeTimeManager) addOneJob(ctx context.Context, db *sql.DB) error {
m.runningJobsLock.Lock()
defer m.runningJobsLock.Unlock()
if m.runningJobs == 0 {
oriGCLifeTime, err := ObtainGCLifeTime(ctx, db)
if err != nil {
return err
}
m.oriGCLifeTime = oriGCLifeTime
err = increaseGCLifeTime(ctx, m, db)
if err != nil {
return err
}
}
m.runningJobs++
return nil
}
// Pre- and post-condition:
// if m.runningJobs == 0, GC life time has been tried to recovered. If this try fails, a warning will be printed.
// if m.runningJobs > 0, GC life time has not been recovered.
// m.runningJobs won't minus to negative since removeOneJob follows a successful addOneJob.
func (m *gcLifeTimeManager) removeOneJob(ctx context.Context, db *sql.DB) {
m.runningJobsLock.Lock()
defer m.runningJobsLock.Unlock()
m.runningJobs--
if m.runningJobs == 0 {
err := UpdateGCLifeTime(ctx, db, m.oriGCLifeTime)
if err != nil {
query := fmt.Sprintf(
"UPDATE mysql.tidb SET VARIABLE_VALUE = '%s' WHERE VARIABLE_NAME = 'tikv_gc_life_time'",
m.oriGCLifeTime,
)
log.FromContext(ctx).Warn("revert GC lifetime failed, please reset the GC lifetime manually after Lightning completed",
zap.String("query", query),
log.ShortError(err),
)
}
}
}
func increaseGCLifeTime(ctx context.Context, manager *gcLifeTimeManager, db *sql.DB) (err error) {
// checksum command usually takes a long time to execute,
// so here need to increase the gcLifeTime for single transaction.
var increaseGCLifeTime bool
if manager.oriGCLifeTime != "" {
ori, err := time.ParseDuration(manager.oriGCLifeTime)
if err != nil {
return errors.Trace(err)
}
if ori < defaultGCLifeTime {
increaseGCLifeTime = true
}
} else {
increaseGCLifeTime = true
}
if increaseGCLifeTime {
err = UpdateGCLifeTime(ctx, db, defaultGCLifeTime.String())
if err != nil {
return err
}
}
failpoint.Inject("IncreaseGCUpdateDuration", nil)
return nil
}
type tikvChecksumManager struct {
client kv.Client
manager gcTTLManager
distSQLScanConcurrency uint
}
// newTiKVChecksumManager return a new tikv checksum manager
func newTiKVChecksumManager(client kv.Client, pdClient pd.Client, distSQLScanConcurrency uint) *tikvChecksumManager {
return &tikvChecksumManager{
client: client,
manager: newGCTTLManager(pdClient),
distSQLScanConcurrency: distSQLScanConcurrency,
}
}
func (e *tikvChecksumManager) checksumDB(ctx context.Context, tableInfo *checkpoints.TidbTableInfo, ts uint64) (*RemoteChecksum, error) {
executor, err := checksum.NewExecutorBuilder(tableInfo.Core, ts).
SetConcurrency(e.distSQLScanConcurrency).
Build()
if err != nil {
return nil, errors.Trace(err)
}
distSQLScanConcurrency := int(e.distSQLScanConcurrency)
for i := 0; i < maxErrorRetryCount; i++ {
_ = executor.Each(func(request *kv.Request) error {
request.Concurrency = distSQLScanConcurrency
return nil
})
var execRes *tipb.ChecksumResponse
execRes, err = executor.Execute(ctx, e.client, func() {})
if err == nil {
return &RemoteChecksum{
Schema: tableInfo.DB,
Table: tableInfo.Name,
Checksum: execRes.Checksum,
TotalBytes: execRes.TotalBytes,
TotalKVs: execRes.TotalKvs,
}, nil
}
log.FromContext(ctx).Warn("remote checksum failed", zap.String("db", tableInfo.DB),
zap.String("table", tableInfo.Name), zap.Error(err),
zap.Int("concurrency", distSQLScanConcurrency), zap.Int("retry", i))
// do not retry context.Canceled error
if !common.IsRetryableError(err) {
break
}
if distSQLScanConcurrency > minDistSQLScanConcurrency {
distSQLScanConcurrency = mathutil.Max(distSQLScanConcurrency/2, minDistSQLScanConcurrency)
}
}
return nil, err
}
func (e *tikvChecksumManager) Checksum(ctx context.Context, tableInfo *checkpoints.TidbTableInfo) (*RemoteChecksum, error) {
tbl := common.UniqueTable(tableInfo.DB, tableInfo.Name)
physicalTS, logicalTS, err := e.manager.pdClient.GetTS(ctx)
if err != nil {
return nil, errors.Annotate(err, "fetch tso from pd failed")
}
ts := oracle.ComposeTS(physicalTS, logicalTS)
if err := e.manager.addOneJob(ctx, tbl, ts); err != nil {
return nil, errors.Trace(err)
}
defer e.manager.removeOneJob(tbl)
return e.checksumDB(ctx, tableInfo, ts)
}
type tableChecksumTS struct {
table string
gcSafeTS uint64
}
// following function are for implement `heap.Interface`
func (m *gcTTLManager) Len() int {
return len(m.tableGCSafeTS)
}
func (m *gcTTLManager) Less(i, j int) bool {
return m.tableGCSafeTS[i].gcSafeTS < m.tableGCSafeTS[j].gcSafeTS
}
func (m *gcTTLManager) Swap(i, j int) {
m.tableGCSafeTS[i], m.tableGCSafeTS[j] = m.tableGCSafeTS[j], m.tableGCSafeTS[i]
}
func (m *gcTTLManager) Push(x interface{}) {
m.tableGCSafeTS = append(m.tableGCSafeTS, x.(*tableChecksumTS))
}
func (m *gcTTLManager) Pop() interface{} {
i := m.tableGCSafeTS[len(m.tableGCSafeTS)-1]
m.tableGCSafeTS = m.tableGCSafeTS[:len(m.tableGCSafeTS)-1]
return i
}
type gcTTLManager struct {
lock sync.Mutex
pdClient pd.Client
// tableGCSafeTS is a binary heap that stored active checksum jobs GC safe point ts
tableGCSafeTS []*tableChecksumTS
currentTS uint64
serviceID string
// 0 for not start, otherwise started
started atomic.Bool
}
func newGCTTLManager(pdClient pd.Client) gcTTLManager {
return gcTTLManager{
pdClient: pdClient,
serviceID: fmt.Sprintf("lightning-%s", uuid.New()),
}
}
func (m *gcTTLManager) addOneJob(ctx context.Context, table string, ts uint64) error {
// start gc ttl loop if not started yet.
if m.started.CAS(false, true) {
m.start(ctx)
}
m.lock.Lock()
defer m.lock.Unlock()
var curTS uint64
if len(m.tableGCSafeTS) > 0 {
curTS = m.tableGCSafeTS[0].gcSafeTS
}
m.Push(&tableChecksumTS{table: table, gcSafeTS: ts})
heap.Fix(m, len(m.tableGCSafeTS)-1)
m.currentTS = m.tableGCSafeTS[0].gcSafeTS
if curTS == 0 || m.currentTS < curTS {
return m.doUpdateGCTTL(ctx, m.currentTS)
}
return nil
}
func (m *gcTTLManager) removeOneJob(table string) {
m.lock.Lock()
defer m.lock.Unlock()
idx := -1
for i := 0; i < len(m.tableGCSafeTS); i++ {
if m.tableGCSafeTS[i].table == table {
idx = i
break
}
}
if idx >= 0 {
l := len(m.tableGCSafeTS)
m.tableGCSafeTS[idx] = m.tableGCSafeTS[l-1]
m.tableGCSafeTS = m.tableGCSafeTS[:l-1]
if l > 1 && idx < l-1 {
heap.Fix(m, idx)
}
}
var newTS uint64
if len(m.tableGCSafeTS) > 0 {
newTS = m.tableGCSafeTS[0].gcSafeTS
}
m.currentTS = newTS
}
func (m *gcTTLManager) updateGCTTL(ctx context.Context) error {
m.lock.Lock()
currentTS := m.currentTS
m.lock.Unlock()
return m.doUpdateGCTTL(ctx, currentTS)
}
func (m *gcTTLManager) doUpdateGCTTL(ctx context.Context, ts uint64) error {
log.FromContext(ctx).Debug("update PD safePoint limit with TTL",
zap.Uint64("currnet_ts", ts))
var err error
if ts > 0 {
_, err = m.pdClient.UpdateServiceGCSafePoint(ctx,
m.serviceID, serviceSafePointTTL, ts)
}
return err
}
func (m *gcTTLManager) start(ctx context.Context) {
// It would be OK since TTL won't be zero, so gapTime should > `0.
updateGapTime := time.Duration(serviceSafePointTTL) * time.Second / preUpdateServiceSafePointFactor
updateTick := time.NewTicker(updateGapTime)
updateGCTTL := func() {
if err := m.updateGCTTL(ctx); err != nil {
log.FromContext(ctx).Warn("failed to update service safe point, checksum may fail if gc triggered", zap.Error(err))
}
}
// trigger a service gc ttl at start
updateGCTTL()
go func() {
defer updateTick.Stop()
for {
select {
case <-ctx.Done():
log.FromContext(ctx).Info("service safe point keeper exited")
return
case <-updateTick.C:
updateGCTTL()
}
}
}()
}
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