Alpakka s3 `multipartUpload`不上传文件

Question

我有一个关于alpakka_kafka+alpakka_s3集成的问题。当我使用Alpakka kafka源码时，alpakka s3 multipartUpload似乎不会上传文件。

kafkaSource ~> kafkaSubscriber.serializer.deserializeFlow ~> bcast.in
    bcast.out(0) ~> kafkaMsgToByteStringFlow ~> s3Sink
    bcast.out(1) ~> kafkaMsgToOffsetFlow ~> commitFlow ~> Sink.ignore

然而，一旦我在kafkaSource之后添加了.take(100)。一切都很好。

kafkaSource.take(100) ~> kafkaSubscriber.serializer.deserializeFlow ~>     bcast.in
    bcast.out(0) ~> kafkaMsgToByteStringFlow ~> s3Sink
    bcast.out(1) ~> kafkaMsgToOffsetFlow ~> commitFlow ~> Sink.ignore

任何帮助都将不胜感激。提前感谢！

下面是完整的代码片段：

// Source
val kafkaSource: Source[(CommittableOffset, Array[Byte]), Consumer.Control] = {
    Consumer
      .committableSource(consumerSettings, Subscriptions.topics(prefixedTopics))
      .map(committableMessage => (committableMessage.committableOffset, committableMessage.record.value))
      .watchTermination() { (mat, f: Future[Done]) =>
        f.foreach { _ =>
          log.debug("consumer source shutdown, consumerId={}, group={}, topics={}", consumerId, group,     prefixedTopics.mkString(", "))
        }

        mat
      }
  }

// Flow
val commitFlow: Flow[CommittableOffset, Done, NotUsed] = {
    Flow[CommittableOffset]
      .groupedWithin(batchingSize, batchingInterval)
      .map(group => group.foldLeft(CommittableOffsetBatch.empty) { (batch, elem) => batch.updated(elem) })
      .mapAsync(parallelism = 3) { msg =>
        log.debug("committing offset, msg={}", msg)

        msg.commitScaladsl().map { result =>
          log.debug("committed offset, msg={}", msg)
          result
        }
      }
  }

private val kafkaMsgToByteStringFlow = Flow[KafkaMessage[Any]].map(x => ByteString(x.msg + "\n"))

private val kafkaMsgToOffsetFlow = {
    implicit val askTimeout: Timeout = Timeout(5.seconds)
    Flow[KafkaMessage[Any]].mapAsync(parallelism = 5) { elem =>
      Future(elem.offset)
    }
  }


// Sink

val s3Sink = {
      val BUCKET = "test-data"
      s3Client.multipartUpload(BUCKET, s"tmp/data.txt")



// Doesnt' work..... ( no files are showing up on the S3)
kafkaSource ~> kafkaSubscriber.serializer.deserializeFlow ~> bcast.in
        bcast.out(0) ~> kafkaMsgToByteStringFlow ~> s3Sink
        bcast.out(1) ~> kafkaMsgToOffsetFlow ~> commitFlow ~> Sink.ignore

// This one works...
kafkaSource.take(100) ~> kafkaSubscriber.serializer.deserializeFlow ~> bcast.in
        bcast.out(0) ~> kafkaMsgToByteStringFlow ~> s3Sink
        bcast.out(1) ~> kafkaMsgToOffsetFlow ~> commitFlow ~> Sink.ignore

Answer 1

实际上，它确实可以上传。问题是，你需要向s3发送一个完成请求，以完成上传，然后你的文件就可以在存储桶中使用了。我敢打赌，因为没有take(n)的kafka source不会停止向下游产生数据，所以接收器永远不会向s3发送完成请求，因为流实际上永远不会完成，所以接收器总是在完成请求之前等待更多的数据上传。

只将所有内容上传到一个文件中是无法做到的，所以，我的建议是:将kafkaSource消息分组，然后将压缩的ArrayByte发送到接收器。诀窍部分是你必须为每个文件创建一个接收器，而不是只使用一个接收器。

Answer 2

 private def running: Receive = {
    case Subscribe(subscriberId) =>

      val kafkaSubscriber = new KafkaSubscriber(
        serviceName = "akka_kafka_subscriber",
        group = kafkaConfig.group,
        topics = kafkaConfig.subscriberTopics,
        system = system,
        configurationProperties = Seq(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG -> "earliest")
      )

      RunnableGraph.fromGraph(GraphDSL.create() { implicit builder =>
        import GraphDSL.Implicits._
        val bcast = builder.add(Broadcast[KafkaMessage[Any]](2))

        kafkaSource ~> kafkaSubscriber.serializer.deserializeFlow ~> kafkaSubscriber.filterTypeFlow[Any] ~> bcast.in
        bcast.out(0) ~> kafkaMsgToStringFlow
          .groupedWithin(BATCH_SIZE, BATCH_DURATION)
          .map(group => group.foldLeft(new StringBuilder()) { (batch, elem) => batch.append(elem) })
          .mapAsync(parallelism = 3) { data =>
            self ? ReadyForUpload(ByteString(data.toString()),UUID.randomUUID().toString,subscriberId)
          } ~> Sink.ignore
        bcast.out(1) ~> kafkaMsgToOffsetFlow ~> kafkaSubscriber.commitFlow ~> Sink.ignore
        ClosedShape
      }).withAttributes(ActorAttributes.supervisionStrategy(decider)).run()
      sender ! "subscription started"

    case ready: ReadyForUpload=>
      println("==========================Got ReadyForUpload: " + ready.fileName)
      val BUCKET = "S3_BUCKET"
      Source.single(ready.data).runWith(s3Client.multipartUpload(BUCKET, s"tmp/${ready.fileName}_${ready.subscriberId}.txt"))
      sender() ! "Done"