session: add gofail test for (pingcap#8743) (pingcap#8771)

session/session.go

@@ -282,6 +282,9 @@ func (s *schemaLeaseChecker) Check(txnTS uint64) error {
 	return domain.ErrInfoSchemaExpired
 }
 
+// mockCommitErrorOnce use to make sure gofail mockCommitError only mock commit error once.
+var mockCommitErrorOnce = true
+
 func (s *session) doCommit(ctx context.Context) error {
 	if !s.txn.Valid() {
 		return nil
@@ -290,6 +293,14 @@ func (s *session) doCommit(ctx context.Context) error {
 		s.txn.changeToInvalid()
 		s.sessionVars.SetStatusFlag(mysql.ServerStatusInTrans, false)
 	}()
+
+	// mockCommitError and mockGetTSErrorInRetry use to test PR #8743.
+	// gofail: var mockCommitError bool
+	//if mockCommitError && mockCommitErrorOnce {
+	//	mockCommitErrorOnce = false
+	//	return kv.ErrRetryable
+	//}
+
 	if s.sessionVars.BinlogClient != nil {
 		prewriteValue := binloginfo.GetPrewriteValue(s, false)
 		if prewriteValue != nil {

session/session_fail_test.go

@@ -47,3 +47,16 @@ func (s *testSessionSuite) TestGetTSFailDirtyState(c *C) {
 	tk.MustExec("insert into t values (1)")
 	tk.MustQuery(`select * from t`).Check(testkit.Rows("1"))
 }
+
+func (s *testSessionSuite) TestGetTSFailDirtyStateInretry(c *C) {
+	defer gofail.Disable("github.com/pingcap/tidb/session/mockCommitError")
+	defer gofail.Disable("github.com/pingcap/tidb/session/mockGetTSErrorInRetry")
+
+	tk := testkit.NewTestKitWithInit(c, s.store)
+	tk.MustExec("create table t (id int)")
+
+	gofail.Enable("github.com/pingcap/tidb/session/mockCommitError", `return(true)`)
+	gofail.Enable("github.com/pingcap/tidb/session/mockGetTSErrorInRetry", `return(true)`)
+	tk.MustExec("insert into t values (2)")
+	tk.MustQuery(`select * from t`).Check(testkit.Rows("2"))
+}

session/txn.go

@@ -277,11 +277,22 @@ type txnFuture struct {
 	mockFail bool
 }
 
+var mockGetTSErrorInRetryOnce = true
+
 func (tf *txnFuture) wait() (kv.Transaction, error) {
 	if tf.mockFail {
 		return nil, errors.New("mock get timestamp fail")
 	}
 
+	// mockGetTSErrorInRetry should wait mockCommitErrorOnce first, then will run into retry() logic.
+	// Then mockGetTSErrorInRetry will return retryable error when first retry.
+	// Before PR #8743, we don't cleanup txn after meet error such as error like: PD server timeout[try again later]
+	// This may cause duplicate data to be written.
+	// gofail: var mockGetTSErrorInRetry bool
+	//if mockGetTSErrorInRetry && mockGetTSErrorInRetryOnce && !mockCommitErrorOnce {
+	//	 mockGetTSErrorInRetryOnce = false
+	//	 return nil, errors.Errorf("PD server timeout[try again later]")
+	//}
 	startTS, err := tf.future.Wait()
 	tf.span.Finish()
 	if err == nil {