Fix races in memory topo and watcher

go/vt/srvtopo/watch.go

@@ -219,7 +219,8 @@ func (entry *watchEntry) onErrorLocked(callerCtx context.Context, err error, ini
 
 	entry.watchState = watchStateIdle
 
-	if len(entry.listeners) > 0 {
+	// only retry the watch if we haven't been explicitly interrupted
+	if len(entry.listeners) > 0 && !topo.IsErrType(err, topo.Interrupted) {
 		go func() {
 			time.Sleep(entry.rw.cacheRefreshInterval)
 

go/vt/topo/memorytopo/election.go

@@ -76,30 +76,29 @@ func (mp *cLeaderParticipation) WaitForLeadership() (context.Context, error) {
 	}
 
 	electionPath := path.Join(electionsPath, mp.name)
-	var ld topo.LockDescriptor
 
 	// We use a cancelable context here. If stop is closed,
 	// we just cancel that context.
 	lockCtx, lockCancel := context.WithCancel(context.Background())
-	go func() {
-		<-mp.stop
-		if ld != nil {
-			if err := ld.Unlock(context.Background()); err != nil {
-				log.Errorf("failed to unlock LockDescriptor %v: %v", electionPath, err)
-			}
-		}
-		lockCancel()
-		close(mp.done)
-	}()
 
 	// Try to get the primaryship, by getting a lock.
-	var err error
-	ld, err = mp.c.Lock(lockCtx, electionPath, mp.id)
+	ld, err := mp.c.Lock(lockCtx, electionPath, mp.id)
 	if err != nil {
+		lockCancel()
+		close(mp.done)
 		// It can be that we were interrupted.
 		return nil, err
 	}
 
+	go func() {
+		<-mp.stop
+		if err := ld.Unlock(context.Background()); err != nil {
+			log.Errorf("failed to unlock LockDescriptor %v: %v", electionPath, err)
+		}
+		lockCancel()
+		close(mp.done)
+	}()
+
 	// We got the lock. Return the lockContext. If Stop() is called,
 	// it will cancel the lockCtx, and cancel the returned context.
 	return lockCtx, nil