Exponential Backoff for ByteFIFO

modules/queue/queue_bytefifo.go

@@ -114,43 +114,73 @@ func (q *ByteFIFOQueue) Run(atShutdown, atTerminate func(context.Context, func()
 }
 
 func (q *ByteFIFOQueue) readToChan() {
+	// handle quick cancels
+	select {
+	case <-q.closed:
+		// tell the pool to shutdown.
+		q.cancel()
+		return
+	default:
+	}
+
+	backOffTime := time.Millisecond * 100
+	maxBackOffTime := time.Second * 3
 	for {
-		select {
-		case <-q.closed:
-			// tell the pool to shutdown.
-			q.cancel()
-			return
-		default:
-			q.lock.Lock()
-			bs, err := q.byteFIFO.Pop()
-			if err != nil {
-				q.lock.Unlock()
-				log.Error("%s: %s Error on Pop: %v", q.typ, q.name, err)
-				time.Sleep(time.Millisecond * 100)
-				continue
-			}
+		success, resetBackoff := q.doPop()
+		if resetBackoff {
+			backOffTime = 100 * time.Millisecond
+		}
 
-			if len(bs) == 0 {
-				q.lock.Unlock()
-				time.Sleep(time.Millisecond * 100)
-				continue
+		if success {
+			select {
+			case <-q.closed:
+				// tell the pool to shutdown.
+				q.cancel()
+				return
+			default:
 			}
-
-			data, err := unmarshalAs(bs, q.exemplar)
-			if err != nil {
-				log.Error("%s: %s Failed to unmarshal with error: %v", q.typ, q.name, err)
-				q.lock.Unlock()
-				time.Sleep(time.Millisecond * 100)
-				continue
+		} else {
+			select {
+			case <-q.closed:
+				// tell the pool to shutdown.
+				q.cancel()
+				return
+			case <-time.After(backOffTime):
+			}
+			backOffTime += backOffTime / 2
+			if backOffTime > maxBackOffTime {
+				backOffTime = maxBackOffTime
 			}
-
-			log.Trace("%s %s: Task found: %#v", q.typ, q.name, data)
-			q.WorkerPool.Push(data)
-			q.lock.Unlock()
 		}
 	}
 }
 
+func (q *ByteFIFOQueue) doPop() (success, resetBackoff bool) {
+	q.lock.Lock()
+	defer q.lock.Unlock()
+	bs, err := q.byteFIFO.Pop()
+	if err != nil {
+		log.Error("%s: %s Error on Pop: %v", q.typ, q.name, err)
+		return
+	}
+	if len(bs) == 0 {
+		return
+	}
+
+	resetBackoff = true
+
+	data, err := unmarshalAs(bs, q.exemplar)
+	if err != nil {
+		log.Error("%s: %s Failed to unmarshal with error: %v", q.typ, q.name, err)
+		return
+	}
+
+	log.Trace("%s %s: Task found: %#v", q.typ, q.name, data)
+	q.WorkerPool.Push(data)
+	success = true
+	return
+}
+
 // Shutdown processing from this queue
 func (q *ByteFIFOQueue) Shutdown() {
 	log.Trace("%s: %s Shutting down", q.typ, q.name)