akka.actor

ActorRef

abstract class ActorRef extends Comparable[ActorRef] with Serializable

Immutable and serializable handle to an actor, which may or may not reside on the local host or inside the same akka.actor.ActorSystem. An ActorRef can be obtained from an akka.actor.ActorRefFactory, an interface which is implemented by ActorSystem and akka.actor.ActorContext. This means actors can be created top-level in the ActorSystem or as children of an existing actor, but only from within that actor.

ActorRefs can be freely shared among actors by message passing. Message passing conversely is their only purpose, as demonstrated in the following examples:

Scala:

import akka.pattern.ask

class ExampleActor extends Actor {
  val other = context.actorOf(Props[OtherActor], "childName") // will be destroyed and re-created upon restart by default

  def receive {
    case Request1(msg) => other ! refine(msg)     // uses this actor as sender reference, reply goes to us
    case Request2(msg) => other.tell(msg, sender()) // forward sender reference, enabling direct reply
    case Request3(msg) =>
      implicit val timeout = Timeout(5.seconds)
      sender() ! (other ? msg)  // will reply with a Future for holding other's reply
  }
}

Java:

import static akka.pattern.Patterns.ask;

public class ExampleActor Extends UntypedActor {
  // this child will be destroyed and re-created upon restart by default
  final ActorRef other = getContext().actorOf(Props.create(OtherActor.class), "childName");

  @Override
  public void onReceive(Object o) {
    if (o instanceof Request1) {
      Msg msg = ((Request1) o).getMsg();
      other.tell(msg, getSelf()); // uses this actor as sender reference, reply goes to us

    } else if (o instanceof Request2) {
      Msg msg = ((Request2) o).getMsg();
      other.tell(msg, getSender()); // forward sender reference, enabling direct reply

    } else if (o instanceof Request3) {
      Msg msg = ((Request3) o).getMsg();
      getSender().tell(ask(other, msg, 5000)); // reply with Future for holding the other's reply (timeout 5 seconds)

    } else {
      unhandled(o);
    }
  }
}

ActorRef does not have a method for terminating the actor it points to, use akka.actor.ActorRefFactory.stop(ref), or send a akka.actor.PoisonPill, for this purpose.

Two actor references are compared equal when they have the same path and point to the same actor incarnation. A reference pointing to a terminated actor doesn't compare equal to a reference pointing to another (re-created) actor with the same path. Actor references acquired with actorFor do not always include the full information about the underlying actor identity and therefore such references do not always compare equal to references acquired with actorOf, sender, or context.self.

If you need to keep track of actor references in a collection and do not care about the exact actor incarnation you can use the ActorPath as key because the unique id of the actor is not taken into account when comparing actor paths.

Self Type
InternalActorRef
Source
ActorRef.scala
Linear Supertypes
Serializable, Serializable, Comparable[ActorRef], AnyRef, Any
Known Subclasses
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Inherited
  1. ActorRef
  2. Serializable
  3. Serializable
  4. Comparable
  5. AnyRef
  6. Any
Implicitly
  1. by actorRef2Scala
  2. by any2stringadd
  3. by any2stringfmt
  4. by any2ArrowAssoc
  5. by any2Ensuring
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  1. Public
  2. All

Instance Constructors

  1. new ActorRef()

Abstract Value Members

  1. abstract def path: ActorPath

    Returns the path for this actor (from this actor up to the root actor).

  2. abstract def isTerminated: Boolean

    Is the actor shut down? The contract is that if this method returns true, then it will never be false again.

    Is the actor shut down? The contract is that if this method returns true, then it will never be false again. But you cannot rely on that it is alive if it returns false, since this by nature is a racy method.

    Annotations
    @deprecated
    Deprecated

    (Since version 2.2) Use context.watch(actor) and receive Terminated(actor)

Concrete Value Members

  1. def !(message: Any)(implicit sender: ActorRef = Actor.noSender): Unit

    Sends a one-way asynchronous message.

    Sends a one-way asynchronous message. E.g. fire-and-forget semantics.

    If invoked from within an actor then the actor reference is implicitly passed on as the implicit 'sender' argument.

    This actor 'sender' reference is then available in the receiving actor in the 'sender()' member variable, if invoked from within an Actor. If not then no sender is available.

      actor ! message
    

    Implicit information
    This member is added by an implicit conversion from ActorRef to ScalaActorRef performed by method actorRef2Scala in akka.actor.
    Definition Classes
    ScalaActorRef
  2. final def !=(arg0: AnyRef): Boolean

    Definition Classes
    AnyRef
  3. final def !=(arg0: Any): Boolean

    Definition Classes
    Any
  4. final def ##(): Int

    Definition Classes
    AnyRef → Any
  5. def +(other: String): String

    Implicit information
    This member is added by an implicit conversion from ActorRef to StringAdd performed by method any2stringadd in scala.Predef.
    Definition Classes
    StringAdd
  6. def ->[B](y: B): (ActorRef, B)

    Implicit information
    This member is added by an implicit conversion from ActorRef to ArrowAssoc[ActorRef] performed by method any2ArrowAssoc in scala.Predef.
    Definition Classes
    ArrowAssoc
    Annotations
    @inline()
  7. final def ==(arg0: AnyRef): Boolean

    Definition Classes
    AnyRef
  8. final def ==(arg0: Any): Boolean

    Definition Classes
    Any
  9. final def asInstanceOf[T0]: T0

    Definition Classes
    Any
  10. def clone(): AnyRef

    Attributes
    protected[java.lang]
    Definition Classes
    AnyRef
    Annotations
    @throws( ... )
  11. final def compareTo(other: ActorRef): Int

    Comparison takes path and the unique id of the actor cell into account.

    Comparison takes path and the unique id of the actor cell into account.

    Definition Classes
    ActorRef → Comparable
  12. def ensuring(cond: (ActorRef) ⇒ Boolean, msg: ⇒ Any): ActorRef

    Implicit information
    This member is added by an implicit conversion from ActorRef to Ensuring[ActorRef] performed by method any2Ensuring in scala.Predef.
    Definition Classes
    Ensuring
  13. def ensuring(cond: (ActorRef) ⇒ Boolean): ActorRef

    Implicit information
    This member is added by an implicit conversion from ActorRef to Ensuring[ActorRef] performed by method any2Ensuring in scala.Predef.
    Definition Classes
    Ensuring
  14. def ensuring(cond: Boolean, msg: ⇒ Any): ActorRef

    Implicit information
    This member is added by an implicit conversion from ActorRef to Ensuring[ActorRef] performed by method any2Ensuring in scala.Predef.
    Definition Classes
    Ensuring
  15. def ensuring(cond: Boolean): ActorRef

    Implicit information
    This member is added by an implicit conversion from ActorRef to Ensuring[ActorRef] performed by method any2Ensuring in scala.Predef.
    Definition Classes
    Ensuring
  16. final def eq(arg0: AnyRef): Boolean

    Definition Classes
    AnyRef
  17. final def equals(that: Any): Boolean

    Equals takes path and the unique id of the actor cell into account.

    Equals takes path and the unique id of the actor cell into account.

    Definition Classes
    ActorRef → AnyRef → Any
  18. def finalize(): Unit

    Attributes
    protected[java.lang]
    Definition Classes
    AnyRef
    Annotations
    @throws( classOf[java.lang.Throwable] )
  19. def formatted(fmtstr: String): String

    Implicit information
    This member is added by an implicit conversion from ActorRef to StringFormat performed by method any2stringfmt in scala.Predef.
    Definition Classes
    StringFormat
    Annotations
    @inline()
  20. def forward(message: Any)(implicit context: ActorContext): Unit

    Forwards the message and passes the original sender actor as the sender.

    Forwards the message and passes the original sender actor as the sender.

    Works, no matter whether originally sent with tell/'!' or ask/'?'.

  21. final def getClass(): Class[_]

    Definition Classes
    AnyRef → Any
  22. final def hashCode(): Int

    Definition Classes
    ActorRef → AnyRef → Any
  23. final def isInstanceOf[T0]: Boolean

    Definition Classes
    Any
  24. final def ne(arg0: AnyRef): Boolean

    Definition Classes
    AnyRef
  25. final def notify(): Unit

    Definition Classes
    AnyRef
  26. final def notifyAll(): Unit

    Definition Classes
    AnyRef
  27. final def synchronized[T0](arg0: ⇒ T0): T0

    Definition Classes
    AnyRef
  28. final def tell(msg: Any, sender: ActorRef): Unit

    Sends the specified message to the sender, i.

    Sends the specified message to the sender, i.e. fire-and-forget semantics, including the sender reference if possible.

    Pass akka.actor.ActorRef$.noSender or null as sender if there is nobody to reply to

  29. def toString(): String

    Definition Classes
    ActorRef → AnyRef → Any
  30. final def wait(): Unit

    Definition Classes
    AnyRef
    Annotations
    @throws( ... )
  31. final def wait(arg0: Long, arg1: Int): Unit

    Definition Classes
    AnyRef
    Annotations
    @throws( ... )
  32. final def wait(arg0: Long): Unit

    Definition Classes
    AnyRef
    Annotations
    @throws( ... )
  33. def [B](y: B): (ActorRef, B)

    Implicit information
    This member is added by an implicit conversion from ActorRef to ArrowAssoc[ActorRef] performed by method any2ArrowAssoc in scala.Predef.
    Definition Classes
    ArrowAssoc

Shadowed Implicit Value Members

  1. val self: Any

    Implicit information
    This member is added by an implicit conversion from ActorRef to StringAdd performed by method any2stringadd in scala.Predef.
    Shadowing
    This implicitly inherited member is ambiguous. One or more implicitly inherited members have similar signatures, so calling this member may produce an ambiguous implicit conversion compiler error.
    To access this member you can use a type ascription:
    (actorRef: StringAdd).self
    Definition Classes
    StringAdd
  2. val self: Any

    Implicit information
    This member is added by an implicit conversion from ActorRef to StringFormat performed by method any2stringfmt in scala.Predef.
    Shadowing
    This implicitly inherited member is ambiguous. One or more implicitly inherited members have similar signatures, so calling this member may produce an ambiguous implicit conversion compiler error.
    To access this member you can use a type ascription:
    (actorRef: StringFormat).self
    Definition Classes
    StringFormat

Deprecated Value Members

  1. def x: ActorRef

    Implicit information
    This member is added by an implicit conversion from ActorRef to ArrowAssoc[ActorRef] performed by method any2ArrowAssoc in scala.Predef.
    Shadowing
    This implicitly inherited member is ambiguous. One or more implicitly inherited members have similar signatures, so calling this member may produce an ambiguous implicit conversion compiler error.
    To access this member you can use a type ascription:
    (actorRef: ArrowAssoc[ActorRef]).x
    Definition Classes
    ArrowAssoc
    Annotations
    @deprecated
    Deprecated

    (Since version 2.10.0) Use leftOfArrow instead

  2. def x: ActorRef

    Implicit information
    This member is added by an implicit conversion from ActorRef to Ensuring[ActorRef] performed by method any2Ensuring in scala.Predef.
    Shadowing
    This implicitly inherited member is ambiguous. One or more implicitly inherited members have similar signatures, so calling this member may produce an ambiguous implicit conversion compiler error.
    To access this member you can use a type ascription:
    (actorRef: Ensuring[ActorRef]).x
    Definition Classes
    Ensuring
    Annotations
    @deprecated
    Deprecated

    (Since version 2.10.0) Use resultOfEnsuring instead

Inherited from Serializable

Inherited from Serializable

Inherited from Comparable[ActorRef]

Inherited from AnyRef

Inherited from Any

Inherited by implicit conversion actorRef2Scala from ActorRef to ScalaActorRef

Inherited by implicit conversion any2stringadd from ActorRef to StringAdd

Inherited by implicit conversion any2stringfmt from ActorRef to StringFormat

Inherited by implicit conversion any2ArrowAssoc from ActorRef to ArrowAssoc[ActorRef]

Inherited by implicit conversion any2Ensuring from ActorRef to Ensuring[ActorRef]

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