From 5d86ddd4a381d59ef832a6f6740afc5056c83353 Mon Sep 17 00:00:00 2001
From: djshow832 <873581766@qq.com>
Date: Sun, 9 May 2021 19:31:36 +0800
Subject: [PATCH 1/2] add tests

---
 session/session_test.go | 43 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 43 insertions(+)

diff --git a/session/session_test.go b/session/session_test.go
index 4870215f33c9e..6d697d02d4ebe 100644
--- a/session/session_test.go
+++ b/session/session_test.go
@@ -789,6 +789,49 @@ func (s *testSessionSuite) TestRetryUnion(c *C) {
 	c.Assert(err, ErrorMatches, ".*can not retry select for update statement")
 }
 
+func (s *testSessionSuite) TestRetryGlobalTempTable(c *C) {
+	tk := testkit.NewTestKitWithInit(c, s.store)
+	tk.MustExec("drop table if exists normal_table")
+	tk.MustExec("create table normal_table(a int primary key, b int)")
+	defer tk.MustExec("drop table if exists normal_table")
+	tk.MustExec("drop table if exists temp_table")
+	tk.MustExec("create global temporary table temp_table(a int primary key, b int) on commit delete rows")
+	defer tk.MustExec("drop table if exists temp_table")
+
+	// insert select
+	tk.MustExec("set tidb_disable_txn_auto_retry = 0")
+	tk.MustExec("insert normal_table value(100, 100)")
+	tk.MustExec("set @@autocommit = 0")
+	// used to make conflicts
+	tk.MustExec("update normal_table set b=b+1 where a=100")
+	tk.MustExec("insert temp_table value(1, 1)")
+	tk.MustExec("insert normal_table select * from temp_table")
+	c.Assert(session.GetHistory(tk.Se).Count(), Equals, 3)
+
+	// try to conflict with tk
+	tk1 := testkit.NewTestKitWithInit(c, s.store)
+	tk1.MustExec("update normal_table set b=b+1 where a=100")
+
+	// It will retry internally.
+	tk.MustExec("commit")
+	tk.MustQuery("select a, b from normal_table order by a").Check(testkit.Rows("1 1", "100 102"))
+	tk.MustQuery("select a, b from temp_table order by a").Check(testkit.Rows())
+
+	// update multi-tables
+	tk.MustExec("update normal_table set b=b+1 where a=100")
+	tk.MustExec("insert temp_table value(1, 2)")
+	// before update: normal_table=(1 1) (100 102), temp_table=(1 2)
+	tk.MustExec("update normal_table, temp_table set normal_table.b=temp_table.b where normal_table.a=temp_table.a")
+	c.Assert(session.GetHistory(tk.Se).Count(), Equals, 3)
+
+	// try to conflict with tk
+	tk1.MustExec("update normal_table set b=b+1 where a=100")
+
+	// It will retry internally.
+	tk.MustExec("commit")
+	tk.MustQuery("select a, b from normal_table order by a").Check(testkit.Rows("1 2", "100 104"))
+}
+
 func (s *testSessionSuite) TestRetryShow(c *C) {
 	tk := testkit.NewTestKitWithInit(c, s.store)
 	tk.MustExec("set @@autocommit = 0")

From dad6d7a8b15c6d428f9cee132abf8b36ef5df3fb Mon Sep 17 00:00:00 2001
From: djshow832 <873581766@qq.com>
Date: Mon, 17 May 2021 19:57:09 +0800
Subject: [PATCH 2/2] fix data race

---
 session/session.go | 50 +++++++++++++++++++++++++++++-----------------
 1 file changed, 32 insertions(+), 18 deletions(-)

diff --git a/session/session.go b/session/session.go
index af3f41c863dc0..51030bc3134c1 100644
--- a/session/session.go
+++ b/session/session.go
@@ -473,6 +473,9 @@ func (s *session) doCommit(ctx context.Context) error {
 	if err != nil {
 		return err
 	}
+	if err = s.removeTempTableFromBuffer(); err != nil {
+		return err
+	}
 
 	// mockCommitError and mockGetTSErrorInRetry use to test PR #8743.
 	failpoint.Inject("mockCommitError", func(val failpoint.Value) {
@@ -526,29 +529,40 @@ func (s *session) doCommit(ctx context.Context) error {
 			s.GetSessionVars().TxnCtx.IsExplicit && s.GetSessionVars().GuaranteeLinearizability)
 	}
 
-	// Filter out the temporary table key-values.
-	if tables := s.sessionVars.TxnCtx.GlobalTemporaryTables; tables != nil {
-		memBuffer := s.txn.GetMemBuffer()
-		for tid := range tables {
-			seekKey := tablecodec.EncodeTablePrefix(tid)
-			endKey := tablecodec.EncodeTablePrefix(tid + 1)
-			iter, err := memBuffer.Iter(seekKey, endKey)
-			if err != nil {
+	return s.txn.Commit(tikvutil.SetSessionID(ctx, s.GetSessionVars().ConnectionID))
+}
+
+// removeTempTableFromBuffer filters out the temporary table key-values.
+func (s *session) removeTempTableFromBuffer() error {
+	tables := s.GetSessionVars().TxnCtx.GlobalTemporaryTables
+	if len(tables) == 0 {
+		return nil
+	}
+	memBuffer := s.txn.GetMemBuffer()
+	// Reset and new an empty stage buffer.
+	defer func() {
+		s.txn.cleanup()
+	}()
+	for tid := range tables {
+		seekKey := tablecodec.EncodeTablePrefix(tid)
+		endKey := tablecodec.EncodeTablePrefix(tid + 1)
+		iter, err := memBuffer.Iter(seekKey, endKey)
+		if err != nil {
+			return err
+		}
+		for iter.Valid() && iter.Key().HasPrefix(seekKey) {
+			if err = memBuffer.Delete(iter.Key()); err != nil {
 				return err
 			}
-			for iter.Valid() && iter.Key().HasPrefix(seekKey) {
-				if err = memBuffer.Delete(iter.Key()); err != nil {
-					return errors.Trace(err)
-				}
-				s.txn.UpdateEntriesCountAndSize()
-				if err = iter.Next(); err != nil {
-					return errors.Trace(err)
-				}
+			s.txn.UpdateEntriesCountAndSize()
+			if err = iter.Next(); err != nil {
+				return err
 			}
 		}
 	}
-
-	return s.txn.Commit(tikvutil.SetSessionID(ctx, s.GetSessionVars().ConnectionID))
+	// Flush to the root membuffer.
+	s.txn.flushStmtBuf()
+	return nil
 }
 
 // errIsNoisy is used to filter DUPLCATE KEY errors.