Package org.apache.pekko.pattern

Interface ExplicitAskSupport

public interface ExplicitAskSupport

This object contains implementation details of the “ask” pattern, which can be combined with "replyTo" pattern.

Method Summary

Modifier and Type	Method	Description
ExplicitlyAskableActorRef	ask(ActorRef actorRef)	Import this implicit conversion to gain ? and ask methods on pekko.actor.ActorRef, which will defer to the ask(actorRef, askSender => message)(timeout) method defined here.
scala.concurrent.Future<java.lang.Object>	ask(ActorRef actorRef, scala.Function1<ActorRef,java.lang.Object> messageFactory, ActorRef sender, Timeout timeout)
scala.concurrent.Future<java.lang.Object>	ask(ActorRef actorRef, scala.Function1<ActorRef,java.lang.Object> messageFactory, 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.
ExplicitlyAskableActorSelection	ask(ActorSelection actorSelection)	Import this implicit conversion to gain ? and ask methods on pekko.actor.ActorSelection, which will defer to the ask(actorSelection, message)(timeout) method defined here.
scala.concurrent.Future<java.lang.Object>	ask(ActorSelection actorSelection, scala.Function1<ActorRef,java.lang.Object> messageFactory, ActorRef sender, Timeout timeout)
scala.concurrent.Future<java.lang.Object>	ask(ActorSelection actorSelection, scala.Function1<ActorRef,java.lang.Object> messageFactory, 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

ask

ExplicitlyAskableActorRef ask(ActorRef actorRef)

Import this implicit conversion to gain ? and ask methods on pekko.actor.ActorRef, which will defer to the ask(actorRef, askSender => message)(timeout) method defined here.

 import org.apache.pekko.pattern.ask

 // same as `ask(actor, askSender => Request(askSender))`
 val future = actor ? { askSender => Request(askSender) }

 // same as `ask(actor, Request(_))`
 val future = actor ? (Request(_))

 // same as `ask(actor, Request(_))(timeout)`
 val future = actor ? (Request(_))(timeout)
 

All of the above use a required implicit pekko.util.Timeout and optional implicit sender pekko.actor.ActorRef.

ask

scala.concurrent.Future<java.lang.Object> ask(ActorRef actorRef,
                                              scala.Function1<ActorRef,java.lang.Object> messageFactory,
                                              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.

The Future will be completed with an pekko.pattern.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)). A typical reason for AskTimeoutException is that the recipient actor didn't send a reply.

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, replyTo => Request(replyTo))(timeout)
 f.map { response =>
   EnrichedMessage(response)
 } pipeTo nextActor
 

ask

scala.concurrent.Future<java.lang.Object> ask(ActorRef actorRef,
                                              scala.Function1<ActorRef,java.lang.Object> messageFactory,
                                              ActorRef sender,
                                              Timeout timeout)

ask

ExplicitlyAskableActorSelection ask(ActorSelection actorSelection)

Import this implicit conversion to gain ? and ask methods on pekko.actor.ActorSelection, which will defer to the ask(actorSelection, message)(timeout) method defined here.

 import org.apache.pekko.pattern.ask

 // same as `ask(selection, askSender => Request(askSender))`
 val future = selection ? { askSender => Request(askSender) }

 // same as `ask(selection, Request(_))`
 val future = selection ? (Request(_))

 // same as `ask(selection, Request(_))(timeout)`
 val future = selection ? (Request(_))(timeout)
 

All of the above use a required implicit pekko.util.Timeout and optional implicit sender pekko.actor.ActorRef.

ask

scala.concurrent.Future<java.lang.Object> ask(ActorSelection actorSelection,
                                              scala.Function1<ActorRef,java.lang.Object> messageFactory,
                                              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.

The Future will be completed with an pekko.pattern.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)). A typical reason for AskTimeoutException is that the recipient actor didn't send a reply.

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, replyTo => Request(replyTo))(timeout)
 f.map { response =>
   EnrichedMessage(response)
 } pipeTo nextActor
 

ask

scala.concurrent.Future<java.lang.Object> ask(ActorSelection actorSelection,
                                              scala.Function1<ActorRef,java.lang.Object> messageFactory,
                                              ActorRef sender,
                                              Timeout timeout)