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public interface AskSupport
This object contains implementation details of the “ask” pattern.
Nested Class Summary | |
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private static class |
AskSupport.AskableActorRef
Implementation detail of the “ask” pattern enrichment of ActorRef |
Method Summary | |
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AskSupport.AskableActorRef |
ask(ActorRef actorRef)
Import this implicit conversion to gain ? |
scala.concurrent.Future<java.lang.Object> |
ask(ActorRef actorRef,
java.lang.Object message,
Timeout timeout)
Sends a message asynchronously and returns a Future
holding the eventual reply message; this means that the target actor
needs to send the result to the sender reference provided. |
Method Detail |
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AskSupport.AskableActorRef ask(ActorRef actorRef)
?
and ask
methods on
ActorRef
, which will defer to the
ask(actorRef, message)(timeout)
method defined here.
import akka.pattern.ask
val future = actor ? message // => ask(actor, message)
val future = actor ask message // => ask(actor, message)
val future = actor.ask(message)(timeout) // => ask(actor, message)(timeout)
All of the above use an implicit akka.actor.Timeout
.
scala.concurrent.Future<java.lang.Object> ask(ActorRef actorRef, java.lang.Object message, Timeout timeout)
Future
holding the eventual reply message; this means that the target actor
needs to send the result to the sender
reference provided. The Future
will be completed with an AskTimeoutException
after the
given timeout has expired; this is independent from any timeout applied
while awaiting a result for this future (i.e. in
Await.result(..., timeout)
).
Warning: When using future callbacks, inside actors you need to carefully avoid closing over the containing actor’s object, i.e. do not call methods or access mutable state on the enclosing actor from within the callback. This would break the actor encapsulation and may introduce synchronization bugs and race conditions because the callback will be scheduled concurrently to the enclosing actor. Unfortunately there is not yet a way to detect these illegal accesses at compile time.
Recommended usage:
val f = ask(worker, request)(timeout)
flow {
EnrichedRequest(request, f())
} pipeTo nextActor
See Future
for a description of flow
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