domain: refine the runaway code and fix typos

pkg/domain/domain.go

@@ -1064,9 +1064,8 @@ func (do *Domain) Close() {
 	if do.etcdClient != nil {
 		terror.Log(errors.Trace(do.etcdClient.Close()))
 	}
-	if rm := do.RunawayManager(); rm != nil {
-		rm.Stop()
-	}
+
+	do.runawayManager.Stop()
 
 	if do.unprefixedEtcdCli != nil {
 		terror.Log(errors.Trace(do.unprefixedEtcdCli.Close()))

pkg/domain/resourcegroup/runaway.go

@@ -327,7 +327,7 @@ func (rm *RunawayManager) addWatchList(record *QuarantineRecord, ttl time.Durati
 	} else {
 		if item == nil {
 			rm.queryLock.Lock()
-			// When watchlist get record, it will check whether the record is stale, so add new record if returns nil.
+			// When watchList get record, it will check whether the record is stale, so add new record if returns nil.
 			if rm.watchList.Get(key) == nil {
 				rm.watchList.Set(key, record, ttl)
 			} else {
@@ -340,7 +340,7 @@ func (rm *RunawayManager) addWatchList(record *QuarantineRecord, ttl time.Durati
 			defer rm.queryLock.Unlock()
 			rm.watchList.Set(key, record, ttl)
 		} else if item.ID != record.ID {
-			// check the ID because of the eariler scan.
+			// check the ID because of the earlier scan.
 			rm.staleQuarantineRecord <- record
 		}
 	}
@@ -452,6 +452,9 @@ func (rm *RunawayManager) examineWatchList(resourceGroupName string, convict str
 
 // Stop stops the watchList which is a ttlcache.
 func (rm *RunawayManager) Stop() {
+	if rm == nil {
+		return
+	}
 	if rm.watchList != nil {
 		rm.watchList.Stop()
 	}

pkg/domain/runaway.go

@@ -242,21 +242,21 @@ func (do *Domain) runawayRecordFlushLoop() {
 
 	// this times is used to batch flushing records, with 1s duration,
 	// we can guarantee a watch record can be seen by the user within 1s.
-	runawayRecordFluashTimer := time.NewTimer(runawayRecordFlushInterval)
+	runawayRecordFlushTimer := time.NewTimer(runawayRecordFlushInterval)
 	runawayRecordGCTicker := time.NewTicker(runawayRecordGCInterval)
 	failpoint.Inject("FastRunawayGC", func() {
-		runawayRecordFluashTimer.Stop()
+		runawayRecordFlushTimer.Stop()
 		runawayRecordGCTicker.Stop()
-		runawayRecordFluashTimer = time.NewTimer(time.Millisecond * 50)
+		runawayRecordFlushTimer = time.NewTimer(time.Millisecond * 50)
 		runawayRecordGCTicker = time.NewTicker(time.Millisecond * 200)
 	})
 
 	fired := false
-	recordCh := do.RunawayManager().RunawayRecordChan()
-	quarantineRecordCh := do.RunawayManager().QuarantineRecordChan()
-	staleQuarantineRecordCh := do.RunawayManager().StaleQuarantineRecordChan()
-	flushThrehold := do.runawayManager.FlushThreshold()
-	records := make([]*resourcegroup.RunawayRecord, 0, flushThrehold)
+	recordCh := do.runawayManager.RunawayRecordChan()
+	quarantineRecordCh := do.runawayManager.QuarantineRecordChan()
+	staleQuarantineRecordCh := do.runawayManager.StaleQuarantineRecordChan()
+	flushThreshold := do.runawayManager.FlushThreshold()
+	records := make([]*resourcegroup.RunawayRecord, 0, flushThreshold)
 
 	flushRunawayRecords := func() {
 		if len(records) == 0 {
@@ -273,20 +273,20 @@ func (do *Domain) runawayRecordFlushLoop() {
 		select {
 		case <-do.exit:
 			return
-		case <-runawayRecordFluashTimer.C:
+		case <-runawayRecordFlushTimer.C:
 			flushRunawayRecords()
 			fired = true
 		case r := <-recordCh:
 			records = append(records, r)
 			failpoint.Inject("FastRunawayGC", func() {
 				flushRunawayRecords()
 			})
-			if len(records) >= flushThrehold {
+			if len(records) >= flushThreshold {
 				flushRunawayRecords()
 			} else if fired {
 				fired = false
 				// meet a new record, reset the timer.
-				runawayRecordFluashTimer.Reset(runawayRecordFlushInterval)
+				runawayRecordFlushTimer.Reset(runawayRecordFlushInterval)
 			}
 		case <-runawayRecordGCTicker.C:
 			go do.deleteExpiredRows("tidb_runaway_queries", "time", runawayRecordExpiredDuration)

pkg/executor/adapter.go

@@ -537,11 +537,11 @@ func (a *ExecStmt) Exec(ctx context.Context) (_ sqlexec.RecordSet, err error) {
 
 	// must set plan according to the `Execute` plan before getting planDigest
 	a.inheritContextFromExecuteStmt()
-	if variable.EnableResourceControl.Load() && domain.GetDomain(sctx).RunawayManager() != nil {
+	if rm := domain.GetDomain(sctx).RunawayManager(); variable.EnableResourceControl.Load() && rm != nil {
 		stmtCtx := sctx.GetSessionVars().StmtCtx
 		_, planDigest := GetPlanDigest(stmtCtx)
 		_, sqlDigest := stmtCtx.SQLDigest()
-		stmtCtx.RunawayChecker = domain.GetDomain(sctx).RunawayManager().DeriveChecker(sctx.GetSessionVars().StmtCtx.ResourceGroupName, stmtCtx.OriginalSQL, sqlDigest.String(), planDigest.String())
+		stmtCtx.RunawayChecker = rm.DeriveChecker(sctx.GetSessionVars().StmtCtx.ResourceGroupName, stmtCtx.OriginalSQL, sqlDigest.String(), planDigest.String())
 		if err := stmtCtx.RunawayChecker.BeforeExecutor(); err != nil {
 			return nil, err
 		}