log_backup: Fix owner transfer panic (pingcap#47537) (pingcap#47558)

close pingcap#47533

Author: ti-chi-bot

br/pkg/streamhelper/BUILD.bazel

@@ -68,7 +68,7 @@ go_test(
     ],
     flaky = True,
     race = "on",
-    shard_count = 19,
+    shard_count = 20,
     deps = [
         ":streamhelper",
         "//br/pkg/errors",

br/pkg/streamhelper/advancer.go

@@ -443,7 +443,7 @@ func (c *CheckpointAdvancer) stopSubscriber() {
 	c.subscriber = nil
 }
 
-func (c *CheckpointAdvancer) spawnSubscriptionHandler(ctx context.Context) {
+func (c *CheckpointAdvancer) SpawnSubscriptionHandler(ctx context.Context) {
 	c.subscriberMu.Lock()
 	defer c.subscriberMu.Unlock()
 	c.subscriber = NewSubscriber(c.env, c.env, WithMasterContext(ctx))
@@ -470,9 +470,12 @@ func (c *CheckpointAdvancer) spawnSubscriptionHandler(ctx context.Context) {
 }
 
 func (c *CheckpointAdvancer) subscribeTick(ctx context.Context) error {
+	c.subscriberMu.Lock()
+	defer c.subscriberMu.Unlock()
 	if c.subscriber == nil {
 		return nil
 	}
+	failpoint.Inject("get_subscriber", nil)
 	if err := c.subscriber.UpdateStoreTopology(ctx); err != nil {
 		log.Warn("[log backup advancer] Error when updating store topology.", logutil.ShortError(err))
 	}

br/pkg/streamhelper/advancer_daemon.go

@@ -34,10 +34,10 @@ func (c *CheckpointAdvancer) OnStart(ctx context.Context) {
 // OnBecomeOwner implements daemon.Interface. If the tidb-server become owner, this function will be called.
 func (c *CheckpointAdvancer) OnBecomeOwner(ctx context.Context) {
 	metrics.AdvancerOwner.Set(1.0)
-	c.spawnSubscriptionHandler(ctx)
+	c.SpawnSubscriptionHandler(ctx)
 	go func() {
 		<-ctx.Done()
-		c.onStop()
+		c.OnStop()
 	}()
 }
 
@@ -46,7 +46,7 @@ func (c *CheckpointAdvancer) Name() string {
 	return "LogBackup::Advancer"
 }
 
-func (c *CheckpointAdvancer) onStop() {
+func (c *CheckpointAdvancer) OnStop() {
 	metrics.AdvancerOwner.Set(0.0)
 	c.stopSubscriber()
 }

br/pkg/streamhelper/advancer_test.go

@@ -361,3 +361,38 @@ func TestResolveLock(t *testing.T) {
 	require.Len(t, r.FailureSubRanges, 0)
 	require.Equal(t, r.Checkpoint, minCheckpoint, "%d %d", r.Checkpoint, minCheckpoint)
 }
+
+func TestOwnerDropped(t *testing.T) {
+	ctx := context.Background()
+	c := createFakeCluster(t, 4, false)
+	c.splitAndScatter("01", "02", "022", "023", "033", "04", "043")
+	installSubscribeSupport(c)
+	env := &testEnv{testCtx: t, fakeCluster: c}
+	fp := "github.com/pingcap/tidb/br/pkg/streamhelper/get_subscriber"
+	defer func() {
+		if t.Failed() {
+			fmt.Println(c)
+		}
+	}()
+
+	adv := streamhelper.NewCheckpointAdvancer(env)
+	adv.OnStart(ctx)
+	adv.SpawnSubscriptionHandler(ctx)
+	require.NoError(t, adv.OnTick(ctx))
+	failpoint.Enable(fp, "pause")
+	ch := make(chan struct{})
+	go func() {
+		defer close(ch)
+		require.NoError(t, adv.OnTick(ctx))
+	}()
+	adv.OnStop()
+	failpoint.Disable(fp)
+
+	cp := c.advanceCheckpoints()
+	c.flushAll()
+	<-ch
+	adv.WithCheckpoints(func(vsf *spans.ValueSortedFull) {
+		// Advancer will manually poll the checkpoint...
+		require.Equal(t, vsf.MinValue(), cp)
+	})
+}

br/pkg/streamhelper/flush_subscriber.go

@@ -230,8 +230,10 @@ func (s *subscription) doConnect(ctx context.Context, dialer LogBackupService) e
 		cancel()
 		return errors.Annotate(err, "failed to subscribe events")
 	}
+	lcx := logutil.ContextWithField(cx, zap.Uint64("store-id", s.storeID),
+		zap.String("category", "log backup flush subscriber"))
 	s.cancel = cancel
-	s.background = spawnJoinable(func() { s.listenOver(cli) })
+	s.background = spawnJoinable(func() { s.listenOver(lcx, cli) })
 	return nil
 }
 
@@ -244,15 +246,16 @@ func (s *subscription) close() {
 	// because it is a ever-sharing channel.
 }
 
-func (s *subscription) listenOver(cli eventStream) {
+func (s *subscription) listenOver(ctx context.Context, cli eventStream) {
 	storeID := s.storeID
-	log.Info("[log backup flush subscriber] Listen starting.", zap.Uint64("store", storeID))
+	logutil.CL(ctx).Info("Listen starting.", zap.Uint64("store", storeID))
 	for {
 		// Shall we use RecvMsg for better performance?
 		// Note that the spans.Full requires the input slice be immutable.
 		msg, err := cli.Recv()
 		if err != nil {
-			log.Info("[log backup flush subscriber] Listen stopped.", zap.Uint64("store", storeID), logutil.ShortError(err))
+			logutil.CL(ctx).Info("Listen stopped.",
+				zap.Uint64("store", storeID), logutil.ShortError(err))
 			if err == io.EOF || err == context.Canceled || status.Code(err) == codes.Canceled {
 				return
 			}
@@ -263,13 +266,13 @@ func (s *subscription) listenOver(cli eventStream) {
 		for _, m := range msg.Events {
 			start, err := decodeKey(m.StartKey)
 			if err != nil {
-				log.Warn("start key not encoded, skipping",
+				logutil.CL(ctx).Warn("start key not encoded, skipping",
 					logutil.Key("event", m.StartKey), logutil.ShortError(err))
 				continue
 			}
 			end, err := decodeKey(m.EndKey)
 			if err != nil {
-				log.Warn("end key not encoded, skipping",
+				logutil.CL(ctx).Warn("end key not encoded, skipping",
 					logutil.Key("event", m.EndKey), logutil.ShortError(err))
 				continue
 			}