executor: add the slow log for commit

executor/adapter.go

@@ -118,7 +118,7 @@ func (a *recordSet) NewChunk() *chunk.Chunk {
 
 func (a *recordSet) Close() error {
 	err := a.executor.Close()
-	a.stmt.logSlowQuery(a.txnStartTS, a.lastErr == nil)
+	a.stmt.LogSlowQuery(a.txnStartTS, a.lastErr == nil)
 	return errors.Trace(err)
 }
 
@@ -137,8 +137,9 @@ type ExecStmt struct {
 
 	StmtNode ast.StmtNode
 
-	Ctx            sessionctx.Context
-	startTime      time.Time
+	Ctx sessionctx.Context
+	// StartTime stands for the starting time when executing the statement.
+	StartTime      time.Time
 	isPreparedStmt bool
 }
 
@@ -184,7 +185,7 @@ func (a *ExecStmt) RebuildPlan() (int64, error) {
 // like the INSERT, UPDATE statements, it executes in this function, if the Executor returns
 // result, execution is done after this function returns, in the returned ast.RecordSet Next method.
 func (a *ExecStmt) Exec(ctx context.Context) (ast.RecordSet, error) {
-	a.startTime = time.Now()
+	a.StartTime = time.Now()
 	sctx := a.Ctx
 	if _, ok := a.Plan.(*plannercore.Analyze); ok && sctx.GetSessionVars().InRestrictedSQL {
 		oriStats, _ := sctx.GetSessionVars().GetSystemVar(variable.TiDBBuildStatsConcurrency)
@@ -264,7 +265,7 @@ func (a *ExecStmt) handleNoDelayExecutor(ctx context.Context, sctx sessionctx.Co
 		if sctx.Txn() != nil {
 			txnTS = sctx.Txn().StartTS()
 		}
-		a.logSlowQuery(txnTS, err == nil)
+		a.LogSlowQuery(txnTS, err == nil)
 	}()
 
 	err = e.Next(ctx, e.newFirstChunk())
@@ -329,13 +330,14 @@ func (a *ExecStmt) buildExecutor(ctx sessionctx.Context) (Executor, error) {
 // QueryReplacer replaces new line and tab for grep result including query string.
 var QueryReplacer = strings.NewReplacer("\r", " ", "\n", " ", "\t", " ")
 
-func (a *ExecStmt) logSlowQuery(txnTS uint64, succ bool) {
+// LogSlowQuery is used to print the slow query in the log files.
+func (a *ExecStmt) LogSlowQuery(txnTS uint64, succ bool) {
 	level := log.GetLevel()
 	if level < log.WarnLevel {
 		return
 	}
 	cfg := config.GetGlobalConfig()
-	costTime := time.Since(a.startTime)
+	costTime := time.Since(a.StartTime)
 	threshold := time.Duration(cfg.Log.SlowThreshold) * time.Millisecond
 	if costTime < threshold && level < log.DebugLevel {
 		return
@@ -385,7 +387,7 @@ func (a *ExecStmt) logSlowQuery(txnTS uint64, succ bool) {
 		}
 		domain.GetDomain(a.Ctx).LogSlowQuery(&domain.SlowQueryInfo{
 			SQL:      sql,
-			Start:    a.startTime,
+			Start:    a.StartTime,
 			Duration: costTime,
 			Detail:   sessVars.StmtCtx.GetExecDetails(),
 			Succ:     succ,

session/session.go

@@ -378,7 +378,13 @@ func (s *session) doCommitWithRetry(ctx context.Context) error {
 }
 
 func (s *session) CommitTxn(ctx context.Context) error {
+	stmt := executor.ExecStmt{
+		Text:      "commit",
+		Ctx:       s,
+		StartTime: time.Now(),
+	}
 	err := s.doCommitWithRetry(ctx)
+	stmt.LogSlowQuery(s.sessionVars.TxnCtx.StartTS, err == nil)
 	label := metrics.LblOK
 	if err != nil {
 		label = metrics.LblError