Source.actorRefWithBackpressure

Materialize an ActorRef of the classic actors API; sending messages to it will emit them on the stream. The source acknowledges reception after emitting a message, to provide back pressure from the source.

Actor interop operators

Signature

Source.actorRefWithBackpressureSource.actorRefWithBackpressure

Description

Materialize an ActorRef, sending messages to it will emit them on the stream. The actor responds with the provided ack message once the element could be emitted allowing for backpressure from the source. Sending another message before the previous one has been acknowledged will fail the stream.

See also:

Examples

Scala

import akka.actor.Status.Success import akka.actor.ActorRef import akka.stream.CompletionStrategy import akka.stream.scaladsl._ val probe = TestProbe() val source: Source[String, ActorRef] = Source.actorRefWithBackpressure[String]( ackMessage = "ack", // complete when we send akka.actor.status.Success completionMatcher = { case _: Success => CompletionStrategy.immediately }, // do not fail on any message failureMatcher = PartialFunction.empty) val actorRef: ActorRef = source.to(Sink.foreach(println)).run() probe.send(actorRef, "hello") probe.expectMsg("ack") probe.send(actorRef, "hello") probe.expectMsg("ack") // The stream completes successfully with the following message actorRef ! Success(())
Java
import akka.actor.ActorRef;
import akka.actor.Status.Success;
import akka.stream.OverflowStrategy;
import akka.stream.CompletionStrategy;
import akka.stream.javadsl.Sink;
import akka.testkit.TestProbe;
Source<String, ActorRef> source =
    Source.<String>actorRefWithBackpressure(
        "ack",
        // complete when we send "complete"
        o -> {
          if (o == "complete") return Optional.of(CompletionStrategy.draining());
          else return Optional.empty();
        },
        // do not fail on any message
        o -> Optional.empty());

ActorRef actorRef = source.to(Sink.foreach(System.out::println)).run(system);
probe.send(actorRef, "hello");
probe.expectMsg("ack");
probe.send(actorRef, "hello");
probe.expectMsg("ack");

// The stream completes successfully with the following message
actorRef.tell("complete", ActorRef.noSender());

Reactive Streams semantics

emits when there is demand and there are messages in the buffer or a message is sent to the ActorRef

completes when the passed completion matcher returns a CompletionStrategy or fails if the passed failure matcher returns an exception

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