From 43b1c61a6811b2583d8e524046d9b255780e7b1c Mon Sep 17 00:00:00 2001
From: wjHuang <huangwenjun1997@gmail.com>
Date: Mon, 28 Nov 2022 22:15:59 +0800
Subject: [PATCH] ddl, domain: handle the corner case that putting the MDL key
 to etcd failed (#39418)

close pingcap/tidb#39416
---
 ddl/db_test.go   | 12 ++++++++++++
 ddl/mock.go      |  6 ++++++
 domain/domain.go |  1 +
 3 files changed, 19 insertions(+)

diff --git a/ddl/db_test.go b/ddl/db_test.go
index ce2ea307e97af..e1347276637e4 100644
--- a/ddl/db_test.go
+++ b/ddl/db_test.go
@@ -1763,3 +1763,15 @@ func TestDDLBlockedCreateView(t *testing.T) {
 	dom.DDL().SetHook(hook)
 	tk.MustExec("alter table t modify column a char(10)")
 }
+
+func TestMDLPutETCDFail(t *testing.T) {
+	store := testkit.CreateMockStore(t)
+
+	tk := testkit.NewTestKit(t, store)
+	tk.MustExec("use test")
+	tk.MustExec("create table t(a int)")
+
+	require.NoError(t, failpoint.Enable("github.com/pingcap/tidb/ddl/putEtcdFailed", `return(true)`))
+	defer require.NoError(t, failpoint.Disable("github.com/pingcap/tidb/ddl/putEtcdFailed"))
+	tk.MustExec("alter table t add column b int")
+}
diff --git a/ddl/mock.go b/ddl/mock.go
index 57a60794f514a..9475a5c34ee2e 100644
--- a/ddl/mock.go
+++ b/ddl/mock.go
@@ -66,6 +66,12 @@ func (s *MockSchemaSyncer) WatchGlobalSchemaVer(context.Context) {}
 
 // UpdateSelfVersion implements SchemaSyncer.UpdateSelfVersion interface.
 func (s *MockSchemaSyncer) UpdateSelfVersion(ctx context.Context, jobID int64, version int64) error {
+	failpoint.Inject("putEtcdFailed", func() {
+		if mockDDLErrOnce < 3 {
+			mockDDLErrOnce++
+			failpoint.Return(errors.New("mock putEtcdFailed"))
+		}
+	})
 	if variable.EnableMDL.Load() {
 		s.mdlSchemaVersions.Store(jobID, version)
 	} else {
diff --git a/domain/domain.go b/domain/domain.go
index 66fcf3ca0e3b3..899ad458d78eb 100644
--- a/domain/domain.go
+++ b/domain/domain.go
@@ -724,6 +724,7 @@ func (do *Domain) mdlCheckLoop() {
 				err := do.ddl.SchemaSyncer().UpdateSelfVersion(context.Background(), jobID, ver)
 				if err != nil {
 					logutil.BgLogger().Warn("update self version failed", zap.Error(err))
+					jobNeedToSync = true
 				} else {
 					jobCache[jobID] = ver
 				}