ddl: watch the ddl ownerkey with the createRevision

pkg/owner/BUILD.bazel

@@ -37,7 +37,7 @@ go_test(
     ],
     embed = [":owner"],
     flaky = True,
-    shard_count = 5,
+    shard_count = 6,
     deps = [
         "//pkg/ddl",
         "//pkg/infoschema",

pkg/owner/manager.go

@@ -302,13 +302,13 @@ func (m *ownerManager) campaignLoop(etcdSession *concurrency.Session) {
 			continue
 		}
 
-		ownerKey, err := GetOwnerKey(campaignContext, logCtx, m.etcdCli, m.key, m.id)
+		ownerKey, createRevision, err := GetOwnerKeyWithCreateRevision(campaignContext, logCtx, m.etcdCli, m.key, m.id)
 		if err != nil {
 			continue
 		}
 
 		m.toBeOwner(elec)
-		m.watchOwner(campaignContext, etcdSession, ownerKey)
+		m.watchOwner(campaignContext, etcdSession, ownerKey, createRevision)
 		m.RetireOwner()
 
 		metrics.CampaignOwnerCounter.WithLabelValues(m.prompt, metrics.NoLongerOwner).Inc()
@@ -328,17 +328,17 @@ func (m *ownerManager) revokeSession(_ string, leaseID clientv3.LeaseID) {
 
 // GetOwnerID implements Manager.GetOwnerID interface.
 func (m *ownerManager) GetOwnerID(ctx context.Context) (string, error) {
-	_, ownerID, _, _, err := getOwnerInfo(ctx, m.logCtx, m.etcdCli, m.key)
+	_, ownerID, _, _, _, err := getOwnerInfo(ctx, m.logCtx, m.etcdCli, m.key)
 	return string(ownerID), errors.Trace(err)
 }
 
-func getOwnerInfo(ctx, logCtx context.Context, etcdCli *clientv3.Client, ownerPath string) (string, []byte, OpType, int64, error) {
+func getOwnerInfo(ctx, logCtx context.Context, etcdCli *clientv3.Client, ownerPath string) (string, []byte, OpType, int64, int64, error) {
 	var op OpType
 	var resp *clientv3.GetResponse
 	var err error
 	for i := 0; i < 3; i++ {
 		if err = ctx.Err(); err != nil {
-			return "", nil, op, 0, errors.Trace(err)
+			return "", nil, op, 0, 0, errors.Trace(err)
 		}
 
 		childCtx, cancel := context.WithTimeout(ctx, util.KeyOpDefaultTimeout)
@@ -352,31 +352,35 @@ func getOwnerInfo(ctx, logCtx context.Context, etcdCli *clientv3.Client, ownerPa
 	}
 	if err != nil {
 		logutil.Logger(logCtx).Warn("etcd-cli get owner info failed", zap.Error(err))
-		return "", nil, op, 0, errors.Trace(err)
+		return "", nil, op, 0, 0, errors.Trace(err)
 	}
 	if len(resp.Kvs) == 0 {
-		return "", nil, op, 0, concurrency.ErrElectionNoLeader
+		return "", nil, op, 0, 0, concurrency.ErrElectionNoLeader
 	}
 
 	var ownerID []byte
 	ownerID, op = splitOwnerValues(resp.Kvs[0].Value)
 	logutil.Logger(logCtx).Info("get owner", zap.ByteString("owner key", resp.Kvs[0].Key),
 		zap.ByteString("ownerID", ownerID), zap.Stringer("op", op))
-	return string(resp.Kvs[0].Key), ownerID, op, resp.Kvs[0].ModRevision, nil
+	return string(resp.Kvs[0].Key), ownerID, op, resp.Kvs[0].CreateRevision, resp.Kvs[0].ModRevision, nil
 }
 
-// GetOwnerKey gets the owner key information.
-func GetOwnerKey(ctx, logCtx context.Context, etcdCli *clientv3.Client, etcdKey, id string) (string, error) {
-	ownerKey, ownerID, _, _, err := getOwnerInfo(ctx, logCtx, etcdCli, etcdKey)
+// GetOwnerKeyWithCreateRevision gets the owner key and createRevision information.
+func GetOwnerKeyWithCreateRevision(
+	ctx, logCtx context.Context,
+	etcdCli *clientv3.Client,
+	etcdKey, id string,
+) (string, int64, error) {
+	ownerKey, ownerID, _, createRevision, _, err := getOwnerInfo(ctx, logCtx, etcdCli, etcdKey)
 	if err != nil {
-		return "", errors.Trace(err)
+		return "", 0, errors.Trace(err)
 	}
 	if string(ownerID) != id {
 		logutil.Logger(logCtx).Warn("is not the owner")
-		return "", errors.New("ownerInfoNotMatch")
+		return "", 0, errors.New("ownerInfoNotMatch")
 	}
 
-	return ownerKey, nil
+	return ownerKey, createRevision, nil
 }
 
 func splitOwnerValues(val []byte) ([]byte, OpType) {
@@ -395,7 +399,7 @@ func joinOwnerValues(vals ...[]byte) []byte {
 // SetOwnerOpValue implements Manager.SetOwnerOpValue interface.
 func (m *ownerManager) SetOwnerOpValue(ctx context.Context, op OpType) error {
 	// owner don't change.
-	ownerKey, ownerID, currOp, modRevision, err := getOwnerInfo(ctx, m.logCtx, m.etcdCli, m.key)
+	ownerKey, ownerID, currOp, _, modRevision, err := getOwnerInfo(ctx, m.logCtx, m.etcdCli, m.key)
 	if err != nil {
 		return errors.Trace(err)
 	}
@@ -438,15 +442,23 @@ func GetOwnerOpValue(ctx context.Context, etcdCli *clientv3.Client, ownerPath, l
 	}
 
 	logCtx := logutil.WithKeyValue(context.Background(), "owner info", logPrefix)
-	_, _, op, _, err := getOwnerInfo(ctx, logCtx, etcdCli, ownerPath)
+	_, _, op, _, _, err := getOwnerInfo(ctx, logCtx, etcdCli, ownerPath)
 	return op, errors.Trace(err)
 }
 
-func (m *ownerManager) watchOwner(ctx context.Context, etcdSession *concurrency.Session, key string) {
+// WatchOwnerForTest watches the ownerKey.
+// This function is used to test watchOwner().
+func WatchOwnerForTest(ctx context.Context, m Manager, etcdSession *concurrency.Session, key string, ownerRevision int64) {
+	if ownerManager, ok := m.(*ownerManager); ok {
+		ownerManager.watchOwner(ctx, etcdSession, key, ownerRevision)
+	}
+}
+
+func (m *ownerManager) watchOwner(ctx context.Context, etcdSession *concurrency.Session, key string, ownerRevision int64) {
 	logPrefix := fmt.Sprintf("[%s] ownerManager %s watch owner key %v", m.prompt, m.id, key)
 	logCtx := logutil.WithKeyValue(context.Background(), "owner info", logPrefix)
 	logutil.BgLogger().Debug(logPrefix)
-	watchCh := m.etcdCli.Watch(ctx, key)
+	watchCh := m.etcdCli.Watch(ctx, key, clientv3.WithRev(ownerRevision))
 	for {
 		select {
 		case resp, ok := <-watchCh:

pkg/owner/manager_test.go

@@ -293,13 +293,76 @@ func TestCluster(t *testing.T) {
 
 	logPrefix := fmt.Sprintf("[ddl] %s ownerManager %s", DDLOwnerKey, "useless id")
 	logCtx := logutil.WithKeyValue(context.Background(), "owner info", logPrefix)
-	_, err = owner.GetOwnerKey(context.Background(), logCtx, cliRW, DDLOwnerKey, "useless id")
+	_, _, err = owner.GetOwnerKeyWithCreateRevision(context.Background(), logCtx, cliRW, DDLOwnerKey, "useless id")
 	require.Truef(t, terror.ErrorEqual(err, concurrency.ErrElectionNoLeader), "get owner info result don't match, err %v", err)
 	op, err := owner.GetOwnerOpValue(context.Background(), cliRW, DDLOwnerKey, logPrefix)
 	require.Truef(t, terror.ErrorEqual(err, concurrency.ErrElectionNoLeader), "get owner info result don't match, err %v", err)
 	require.Equal(t, op, owner.OpNone)
 }
 
+func TestWatchOwner(t *testing.T) {
+	if runtime.GOOS == "windows" {
+		t.Skip("integration.NewClusterV3 will create file contains a colon which is not allowed on Windows")
+	}
+	integration.BeforeTestExternal(t)
+
+	tInfo := newTestInfo(t)
+	client, d := tInfo.client, tInfo.ddl
+	defer tInfo.Close(t)
+	ownerManager := d.OwnerManager()
+	lis := &listener{}
+	ownerManager.SetListener(lis)
+	require.NoError(t, ownerManager.CampaignOwner())
+	isOwner := checkOwner(d, true)
+	require.True(t, isOwner)
+
+	// get the owner id.
+	ctx := context.Background()
+	id, err := ownerManager.GetOwnerID(ctx)
+	require.NoError(t, err)
+
+	// create etcd session.
+	session, err := concurrency.NewSession(client)
+	require.NoError(t, err)
+
+	// test the GetOwnerKeyWithCreateRevision()
+	ownerKey, createRevision, err := owner.GetOwnerKeyWithCreateRevision(ctx, context.TODO(), client, DDLOwnerKey, id)
+	require.NoError(t, err)
+
+	// watch the ownerKey with the `DELETE` event.
+	ctx2, cancel2 := context.WithTimeout(ctx, time.Millisecond*300)
+	defer cancel2()
+	watchDone := make(chan bool)
+	watched := false
+	go func() {
+		owner.WatchOwnerForTest(ctx2, ownerManager, session, ownerKey, createRevision)
+		watchDone <- true
+	}()
+
+	select {
+	case watched = <-watchDone:
+	case <-ctx2.Done():
+	}
+	require.False(t, watched)
+
+	// delete the owner, and can watch the event.
+	deleteLeader(client, DDLOwnerKey)
+	require.NoError(t, err)
+	watched = <-watchDone
+	require.True(t, watched)
+
+	// the ownerKey has been deleted, watch ownerKey again, it can be watched.
+	ctx3, cancel3 := context.WithTimeout(ctx, time.Millisecond*300)
+	defer cancel3()
+	go func() {
+		owner.WatchOwnerForTest(ctx3, ownerManager, session, ownerKey, createRevision)
+		watchDone <- true
+	}()
+
+	watched = <-watchDone
+	require.True(t, watched)
+}
+
 func checkOwner(d DDL, fbVal bool) (isOwner bool) {
 	manager := d.OwnerManager()
 	// The longest to wait for 30 seconds to