Revert "restore: update and restore GCLifeTime once when parallel (#220…

…)"

This reverts commit 9f36067.

lightning/restore/restore.go

@@ -74,6 +74,7 @@ var (
 	requiredTiKVVersion = *semver.New("2.1.0")
 )
 
+var gcLifeTimeKey struct{}
 
 func init() {
 	cfg := tidbcfg.GetGlobalConfig()
@@ -448,59 +449,6 @@ func (rc *RestoreController) runPeriodicActions(ctx context.Context, stop <-chan
 	}
 }
 
-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, db)
-		if err != nil {
-			return err
-		}
-	}
-	m.runningJobs += 1
-	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, table string) {
-	m.runningJobsLock.Lock()
-	defer m.runningJobsLock.Unlock()
-
-	m.runningJobs -= 1
-	if m.runningJobs == 0 {
-		err := UpdateGCLifeTime(ctx, db, m.oriGCLifeTime)
-		if err != nil && common.ShouldLogError(err) {
-			common.AppLogger.Errorf("[%s] update tikv_gc_life_time error %v", table, errors.ErrorStack(err))
-		}
-	}
-}
-
-var gcLifeTimeKey struct{}
-
 func (rc *RestoreController) restoreTables(ctx context.Context) error {
 	timer := time.Now()
 	var wg sync.WaitGroup
@@ -516,9 +464,11 @@ func (rc *RestoreController) restoreTables(ctx context.Context) error {
 	}
 	taskCh := make(chan task, rc.cfg.App.IndexConcurrency)
 	defer close(taskCh)
-
-	manager := newGCLifeTimeManager()
-	ctx2 := context.WithValue(ctx, &gcLifeTimeKey, manager)
+	oriGCLifeTime, err := ObtainGCLifeTime(ctx, rc.tidbMgr.db)
+	if err != nil {
+		return err
+	}
+	ctx2 := context.WithValue(ctx, &gcLifeTimeKey, oriGCLifeTime)
 	for i := 0; i < rc.cfg.App.IndexConcurrency; i++ {
 		go func() {
 			for task := range taskCh {
@@ -1365,18 +1315,17 @@ func setSessionConcurrencyVars(ctx context.Context, db *sql.DB, dsn config.DBSto
 func DoChecksum(ctx context.Context, db *sql.DB, table string) (*RemoteChecksum, error) {
 	timer := time.Now()
 
-	var err error
-	manager, ok := ctx.Value(&gcLifeTimeKey).(*gcLifeTimeManager)
-	if !ok {
-		return nil, errors.New("No gcLifeTimeManager found in context, check context initialization")
-	}
-
-	if err = manager.addOneJob(ctx, db); err != nil {
-		return nil, err
+	ori, err := increaseGCLifeTime(ctx, db)
+	if err != nil {
+		return nil, errors.Trace(err)
 	}
-
 	// set it back finally
-	defer manager.removeOneJob(ctx, db, table)
+	defer func() {
+		err = UpdateGCLifeTime(ctx, db, ori)
+		if err != nil && common.ShouldLogError(err) {
+			common.AppLogger.Errorf("[%s] update tikv_gc_life_time error %v", table, errors.ErrorStack(err))
+		}
+	}()
 
 	// ADMIN CHECKSUM TABLE <table>,<table>  example.
 	// 	mysql> admin checksum table test.t;
@@ -1398,19 +1347,25 @@ func DoChecksum(ctx context.Context, db *sql.DB, table string) (*RemoteChecksum,
 	return &cs, nil
 }
 
-func increaseGCLifeTime(ctx context.Context, db *sql.DB) (err error) {
+func increaseGCLifeTime(ctx context.Context, db *sql.DB) (oriGCLifeTime string, err error) {
 	// checksum command usually takes a long time to execute,
 	// so here need to increase the gcLifeTime for single transaction.
-
-	// try to get gcLifeTimeManager from context first.
-	// DoChecksum has assure this getting action success.
-	manager, _ := ctx.Value(&gcLifeTimeKey).(*gcLifeTimeManager)
+	// try to get gcLifeTime from context first.
+	gcLifeTime, ok := ctx.Value(&gcLifeTimeKey).(string)
+	if !ok {
+		oriGCLifeTime, err = ObtainGCLifeTime(ctx, db)
+		if err != nil {
+			return "", err
+		}
+	} else {
+		oriGCLifeTime = gcLifeTime
+	}
 
 	var increaseGCLifeTime bool
-	if manager.oriGCLifeTime != "" {
-		ori, err := time.ParseDuration(manager.oriGCLifeTime)
+	if oriGCLifeTime != "" {
+		ori, err := time.ParseDuration(oriGCLifeTime)
 		if err != nil {
-			return errors.Trace(err)
+			return "", errors.Trace(err)
 		}
 		if ori < defaultGCLifeTime {
 			increaseGCLifeTime = true
@@ -1422,13 +1377,13 @@ func increaseGCLifeTime(ctx context.Context, db *sql.DB) (err error) {
 	if increaseGCLifeTime {
 		err = UpdateGCLifeTime(ctx, db, defaultGCLifeTime.String())
 		if err != nil {
-			return err
+			return "", errors.Trace(err)
 		}
 	}
 
 	failpoint.Inject("IncreaseGCUpdateDuration", func() {})
 
-	return nil
+	return oriGCLifeTime, nil
 }
 
 ////////////////////////////////////////////////////////////////