Question

我在Scala中使用Akka Streams使用AWS SQS从AWS Java SDK队列进行投票。我创建了一个ActorPublisher，它以两秒的间隔使消息出列：

class SQSSubscriber(name: String) extends ActorPublisher[Message] {
  implicit val materializer = ActorMaterializer()

  val schedule = context.system.scheduler.schedule(0 seconds, 2 seconds, self, "dequeue")

  val client = new AmazonSQSClient()
  client.setRegion(RegionUtils.getRegion("us-east-1"))
  val url = client.getQueueUrl(name).getQueueUrl

  val MaxBufferSize = 100
  var buf = Vector.empty[Message]

  override def receive: Receive = {
    case "dequeue" =>
      val messages = iterableAsScalaIterable(client.receiveMessage(new ReceiveMessageRequest(url).getMessages).toList
      messages.foreach(self ! _)
    case message: Message if buf.size == MaxBufferSize =>
      log.error("The buffer is full")
    case message: Message =>
      if (buf.isEmpty && totalDemand > 0)
        onNext(message)
      else {
        buf :+= message
        deliverBuf()
      }
    case Request(_) =>
      deliverBuf()
    case Cancel =>
      context.stop(self)
  }

  @tailrec final def deliverBuf(): Unit =
    if (totalDemand > 0) {
      if (totalDemand <= Int.MaxValue) {
        val (use, keep) = buf.splitAt(totalDemand.toInt)
        buf = keep
        use foreach onNext
      } else {
        val (use, keep) = buf.splitAt(Int.MaxValue)
        buf = keep
        use foreach onNext
        deliverBuf()
      }
    }
}

在我的应用程序中，我也试图以2秒的间隔运行流程：

val system = ActorSystem("system")
val sqsSource = Source.actorPublisher[Message](SQSSubscriber.props("queue-name"))
val flow = Flow[Message]
  .map { elem => system.log.debug(s"${elem.getBody} (${elem.getMessageId})"); elem }
  .to(Sink.ignore)

system.scheduler.schedule(0 seconds, 2 seconds) {
  flow.runWith(sqsSource)(ActorMaterializer()(system))
}

但是，当我运行我的应用程序时，我会收到java.util.concurrent.TimeoutException: Futures timed out after [20000 milliseconds]以及由ActorMaterializer引起的死信通知。

是否有建议的方法来持续实现Akka Stream？

Akka流如何不断实现？

0 个答案: