访问由 Source.actorRef 创建的 akka 流 Source 的底层 ActorRef

Question

我正在尝试使用Source.actorRef 方法来创建akka.stream.scaladsl.Source 对象。某种形式的东西

import akka.stream.OverflowStrategy.fail
import akka.stream.scaladsl.Source

case class Weather(zip : String, temp : Double, raining : Boolean)

val weatherSource = Source.actorRef[Weather](Int.MaxValue, fail)

val sunnySource = weatherSource.filter(!_.raining)
...

我的问题是：如何将数据发送到基于 ActorRef 的 Source 对象？

我认为向源发送消息是某种形式

//does not compile
weatherSource ! Weather("90210", 72.0, false)
weatherSource ! Weather("02139", 32.0, true)

但是weatherSource 没有! 运算符或tell 方法。

documentation 没有过多描述如何使用 Source.actorRef，它只是说您可以...

提前感谢您的评论和回复。

Answer 1

你需要一个Flow:

  import akka.stream.OverflowStrategy.fail
  import akka.stream.scaladsl.Source
  import akka.stream.scaladsl.{Sink, Flow}

  case class Weather(zip : String, temp : Double, raining : Boolean)

  val weatherSource = Source.actorRef[Weather](Int.MaxValue, fail)

  val sunnySource = weatherSource.filter(!_.raining)

  val ref = Flow[Weather]
    .to(Sink.ignore)
    .runWith(sunnySource)

  ref ! Weather("02139", 32.0, true)

请记住，这都是实验性的，可能会改变！

Answer 2

@Noah 指出 akka-streams 的实验性质，他的回答可能不适用于 1.0 版本。我不得不按照this example给出的例子：

implicit val materializer = ActorMaterializer()
val (actorRef: ActorRef, publisher: Publisher[TweetInfo]) = Source.actorRef[TweetInfo](1000, OverflowStrategy.fail).toMat(Sink.publisher)(Keep.both).run()
actorRef ! TweetInfo(...)
val source: Source[TweetInfo, Unit] = Source[TweetInfo](publisher)

Answer 3

ActorRef 的实例与所有“物化值”一样，只有在整个流被物化后才能访问，换句话说，当 RunnableGraph 正在运行时。

// RunnableGraph[ActorRef] means that you get ActorRef when you run the graph
val rg1: RunnableGraph[ActorRef] = sunnySource.to(Sink.foreach(println))

// You get ActorRef instance as a materialized value
val actorRef1: ActorRef = rg1.run()

// Or even more correct way: to materialize both ActorRef and future to completion 
// of the stream, so that we know when we are done:

// RunnableGraph[(ActorRef, Future[Done])] means that you get tuple
// (ActorRef, Future[Done]) when you run the graph
val rg2: RunnableGraph[(ActorRef, Future[Done])] =
  sunnySource.toMat(Sink.foreach(println))(Keep.both)

// You get both ActorRef and Future[Done] instances as materialized values
val (actorRef2, future) = rg2.run()

actorRef2 ! Weather("90210", 72.0, false)
actorRef2 ! Weather("02139", 32.0, true)
actorRef2 ! akka.actor.Status.Success("Done!") // Complete the stream
future onComplete { /* ... */ }