In disk_channel queues synchronously push to disk on shutdown (#18415) (#18788)

Partial Backport of #18415

Instead of using an asynchronous goroutine to push to disk on shutdown
just close the datachan and immediately push to the disk.

Prevents messages of incompletely flushed queues.

Signed-off-by: Andrew Thornton <art27@cantab.net>

Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>

modules/queue/queue_bytefifo.go

@@ -195,9 +195,11 @@ loop:
 	}
 }
 
-var errQueueEmpty = fmt.Errorf("empty queue")
-var errEmptyBytes = fmt.Errorf("empty bytes")
-var errUnmarshal = fmt.Errorf("failed to unmarshal")
+var (
+	errQueueEmpty = fmt.Errorf("empty queue")
+	errEmptyBytes = fmt.Errorf("empty bytes")
+	errUnmarshal  = fmt.Errorf("failed to unmarshal")
+)
 
 func (q *ByteFIFOQueue) doPop() error {
 	q.lock.Lock()

modules/queue/queue_disk_channel.go

@@ -251,8 +251,8 @@ func (q *PersistableChannelQueue) Shutdown() {
 	q.channelQueue.Wait()
 	q.internal.(*LevelQueue).Wait()
 	// Redirect all remaining data in the chan to the internal channel
-	close(q.channelQueue.dataChan)
 	log.Trace("PersistableChannelQueue: %s Redirecting remaining data", q.delayedStarter.name)
+	close(q.channelQueue.dataChan)
 	for data := range q.channelQueue.dataChan {
 		_ = q.internal.Push(data)
 		atomic.AddInt64(&q.channelQueue.numInQueue, -1)

modules/queue/queue_disk_channel_test.go

@@ -188,5 +188,4 @@ func TestPersistableChannelQueue(t *testing.T) {
 	for _, callback := range callbacks {
 		callback()
 	}
-
 }

modules/queue/unique_queue_disk_channel.go

@@ -238,13 +238,12 @@ func (q *PersistableChannelUniqueQueue) Shutdown() {
 	q.channelQueue.Wait()
 	q.internal.(*LevelUniqueQueue).Wait()
 	// Redirect all remaining data in the chan to the internal channel
-	go func() {
-		log.Trace("PersistableChannelUniqueQueue: %s Redirecting remaining data", q.delayedStarter.name)
-		for data := range q.channelQueue.dataChan {
-			_ = q.internal.Push(data)
-		}
-		log.Trace("PersistableChannelUniqueQueue: %s Done Redirecting remaining data", q.delayedStarter.name)
-	}()
+	close(q.channelQueue.dataChan)
+	log.Trace("PersistableChannelUniqueQueue: %s Redirecting remaining data", q.delayedStarter.name)
+	for data := range q.channelQueue.dataChan {
+		_ = q.internal.Push(data)
+	}
+	log.Trace("PersistableChannelUniqueQueue: %s Done Redirecting remaining data", q.delayedStarter.name)
 
 	log.Debug("PersistableChannelUniqueQueue: %s Shutdown", q.delayedStarter.name)
 }