Package org.apache.pekko.actor.typed.javadsl

Interface ActorContext<T>

All Superinterfaces:
ClassicActorContextProvider, TypedActorContext<T>
All Known Subinterfaces:
ActorContextImpl<T>
public interface ActorContext<T> extends TypedActorContext<T>, ClassicActorContextProvider
An Actor is given by the combination of a Behavior and a context in which this behavior is executed. As per the Actor Model an Actor can perform the following actions when processing a message:

- send a finite number of messages to other Actors it knows - create a finite number of Actors - designate the behavior for the next message

In Pekko, the first capability is accessed by using the tell method on an ActorRef, the second is provided by spawn(org.apache.pekko.actor.typed.Behavior<U>, java.lang.String) and the third is implicit in the signature of Behavior in that the next behavior is always returned from the message processing logic.

An ActorContext in addition provides access to the Actor&rsquo;s own identity (&ldquo;getSelf&rdquo;), the ActorSystem it is part of, methods for querying the list of child Actors it created, access to Terminated and timed message scheduling.

Not for user extension.

  • Method Details

    • asScala

      ActorContext<T> asScala()
      Get the scaladsl of this ActorContext.

      This method is thread-safe and can be called from other threads than the ordinary actor message processing thread, such as CompletionStage callbacks.

      Specified by:
      asScala in interface TypedActorContext<T>

    • ask

      <Req, Res> void ask(Class<Res> resClass, RecipientRef<Req> target, Duration responseTimeout, Function<ActorRef<Res>,Req> createRequest, Function2<Res,Throwable,T> applyToResponse)
      Perform a single request-response message interaction with another actor, and transform the messages back to the protocol of this actor.

      The interaction has a timeout (to avoid a resource leak). If the timeout hits without any response it will be passed as an TimeoutException to the applyToResponse function.

      For other messaging patterns with other actors, see messageAdapter(java.lang.Class<U>, org.apache.pekko.japi.function.Function<U, T>).

      This method is thread-safe and can be called from other threads than the ordinary actor message processing thread, such as CompletionStage callbacks.

      Parameters:
      createRequest - A function that creates a message for the other actor, containing the provided ActorRef[Res] that the other actor can send a message back through.
      applyToResponse - Transforms the response from the target into a message this actor understands. Will be invoked with either the response message or an AskTimeoutException failed or potentially another exception if the remote actor is classic and sent a pekko.actor.Status.Failure as response. The returned message of type T is then fed into this actor as a message. Should be a pure function but is executed inside the actor when the response arrives so can safely touch the actor internals. If this function throws an exception it is just as if the normal message receiving logic would throw.

    • askWithStatus

      <Req, Res> void askWithStatus(Class<Res> resClass, RecipientRef<Req> target, Duration responseTimeout, Function<ActorRef<StatusReply<Res>>,Req> createRequest, Function2<Res,Throwable,T> applyToResponse)
      The same as <Req,Res>ask(java.lang.Class<Res>,org.apache.pekko.actor.typed.RecipientRef<Req>,java.time.Duration,org.apache.pekko.japi.function.Function<org.apache.pekko.actor.typed.ActorRef<Res>,Req>,org.apache.pekko.japi.function.Function2<Res,java.lang.Throwable,T>) but only for requests that result in a response of type pekko.pattern.StatusReply. If the response is a pekko.pattern.StatusReply#success the returned future is completed successfully with the wrapped response. If the status response is a pekko.pattern.StatusReply#error the returned future will be failed with the exception in the error (normally a pekko.pattern.StatusReply.ErrorMessage).

    • cancelReceiveTimeout

      void cancelReceiveTimeout()
      Cancel the sending of receive timeout notifications.

      *Warning*: This method is not thread-safe and must not be accessed from threads other than the ordinary actor message processing thread, such as CompletionStage callbacks.

    • delegate

      Behavior<T> delegate(Behavior<T> delegator, T msg)
      Delegate message and signal's execution by given pekko.actor.typed.Behavior using Behavior.interpretMessage or Behavior.interpretSignal

      note: if given pekko.actor.typed.Behavior resulting Behaviors.same that will cause context switching to the given behavior and if result is Behaviors.unhandled that will trigger the pekko.actor.typed.scaladsl.ActorContext.onUnhandled then switching to the given behavior.

    • getChild

      Optional<ActorRef<Void>> getChild(String name)
      The named child Actor if it is alive.

      *Warning*: This method is not thread-safe and must not be accessed from threads other than the ordinary actor message processing thread, such as CompletionStage callbacks.

    • getChildren

      List<ActorRef<Void>> getChildren()
      The list of child Actors created by this Actor during its lifetime that are still alive, in no particular order.

      *Warning*: This method is not thread-safe and must not be accessed from threads other than the ordinary actor message processing thread, such as CompletionStage callbacks.

    • getExecutionContext

      scala.concurrent.ExecutionContextExecutor getExecutionContext()
      This Actor&rsquo;s execution context. It can be used to run asynchronous tasks like Future combinators.

      This method is thread-safe and can be called from other threads than the ordinary actor message processing thread, such as CompletionStage callbacks.

    • getLog

      org.slf4j.Logger getLog()
      An actor specific logger.

      The logger name will be an estimated source class for the actor which is calculated when the logger is first used (the logger is lazily created upon first use). If this yields the wrong class or another class is preferred this can be changed with setLoggerName.

      *Warning*: This method is not thread-safe and must not be accessed from threads other than the ordinary actor message processing thread, such as CompletionStage callbacks.

    • getSelf

      ActorRef<T> getSelf()
      The identity of this Actor, bound to the lifecycle of this Actor instance. An Actor with the same name that lives before or after this instance will have a different ActorRef.

      This method is thread-safe and can be called from other threads than the ordinary actor message processing thread, such as CompletionStage callbacks.

    • getSystem

      ActorSystem<Void> getSystem()
      The ActorSystem to which this Actor belongs.

      This method is thread-safe and can be called from other threads than the ordinary actor message processing thread, such as CompletionStage callbacks.

    • messageAdapter

      <U> ActorRef<U> messageAdapter(Class<U> messageClass, Function<U,T> f)
      Create a message adapter that will convert or wrap messages such that other Actor&rsquo;s protocols can be ingested by this Actor.

      You can register several message adapters for different message classes. It's only possible to have one message adapter per message class to make sure that the number of adapters are not growing unbounded if registered repeatedly. That also means that a registered adapter will replace an existing adapter for the same message class.

      A message adapter will be used if the message class matches the given class or is a subclass thereof. The registered adapters are tried in reverse order of their registration order, i.e. the last registered first.

      A message adapter (and the returned ActorRef) has the same lifecycle as this actor. It's recommended to register the adapters in a top level Behaviors.setup or constructor of AbstractBehavior but it's possible to register them later also if needed. Message adapters don't have to be stopped since they consume no resources other than an entry in an internal Map and the number of adapters are bounded since it's only possible to have one per message class.

      The function is running in this actor and can safely access state of it.

      *Warning*: This method is not thread-safe and must not be accessed from threads other than the ordinary actor message processing thread, such as CompletionStage callbacks.

    • pipeToSelf

      <Value> void pipeToSelf(CompletionStage<Value> future, Function2<Value,Throwable,T> applyToResult)
      Sends the result of the given CompletionStage to this Actor (&ldquo;self&rdquo;), after adapted it with the given function.

      This method is thread-safe and can be called from other threads than the ordinary actor message processing thread, such as CompletionStage callbacks.

    • scheduleOnce

      <U> Cancellable scheduleOnce(Duration delay, ActorRef<U> target, U msg)
      Schedule the sending of the given message to the given target Actor after the given time period has elapsed. The scheduled action can be cancelled by invoking pekko.actor.Cancellable#cancel on the returned handle.

      For scheduling messages to the actor itself, use Behaviors.withTimers

      This method is thread-safe and can be called from other threads than the ordinary actor message processing thread, such as CompletionStage callbacks.

    • setLoggerName

      void setLoggerName(String name)
      Replace the current logger (or initialize a new logger if the logger was not touched before) with one that has ghe given name as logger name. Logger source MDC entry "pekkoSource" will be the actor path.

      *Warning*: This method is not thread-safe and must not be accessed from threads other than the ordinary actor message processing thread, such as CompletionStage callbacks.

    • setLoggerName

      void setLoggerName(Class<?> clazz)
      Replace the current logger (or initialize a new logger if the logger was not touched before) with one that has ghe given class name as logger name. Logger source MDC entry "pekkoSource" will be the actor path.

      *Warning*: This method is not thread-safe and must not be accessed from threads other than the ordinary actor message processing thread, such as CompletionStage callbacks.

    • setReceiveTimeout

      void setReceiveTimeout(Duration timeout, T msg)
      Schedule the sending of a notification in case no other message is received during the given period of time. The timeout starts anew with each received message. Use cancelReceiveTimeout to switch off this mechanism.

      *Warning*: This method is not thread-safe and must not be accessed from threads other than the ordinary actor message processing thread, such as CompletionStage callbacks.

    • spawn

      <U> ActorRef<U> spawn(Behavior<U> behavior, String name)
      Create a child Actor from the given pekko.actor.typed.Behavior and with the given name.

      *Warning*: This method is not thread-safe and must not be accessed from threads other than the ordinary actor message processing thread, such as CompletionStage callbacks.

    • spawn

      <U> ActorRef<U> spawn(Behavior<U> behavior, String name, Props props)
      Create a child Actor from the given pekko.actor.typed.Behavior and with the given name.

      *Warning*: This method is not thread-safe and must not be accessed from threads other than the ordinary actor message processing thread, such as CompletionStage callbacks.

    • spawnAnonymous

      <U> ActorRef<U> spawnAnonymous(Behavior<U> behavior)
      Create a child Actor from the given pekko.actor.typed.Behavior under a randomly chosen name. It is good practice to name Actors wherever practical.

      *Warning*: This method is not thread-safe and must not be accessed from threads other than the ordinary actor message processing thread, such as CompletionStage callbacks.

    • spawnAnonymous

      <U> ActorRef<U> spawnAnonymous(Behavior<U> behavior, Props props)
      Create a child Actor from the given pekko.actor.typed.Behavior under a randomly chosen name. It is good practice to name Actors wherever practical.

      *Warning*: This method is not thread-safe and must not be accessed from threads other than the ordinary actor message processing thread, such as CompletionStage callbacks.

    • stop

      <U> void stop(ActorRef<U> child)
      Force the child Actor under the given name to terminate after it finishes processing its current message. Nothing happens if the ActorRef is a child that is already stopped.

      *Warning*: This method is not thread-safe and must not be accessed from threads other than the ordinary actor message processing thread, such as CompletionStage callbacks.

      Throws:
      IllegalArgumentException - if the given actor ref is not a direct child of this actorc

    • unwatch

      <U> void unwatch(ActorRef<U> other)
      Revoke the registration established by watch. A Terminated notification will not subsequently be received for the referenced Actor.

      *Warning*: This method is not thread-safe and must not be accessed from threads other than the ordinary actor message processing thread, such as CompletionStage callbacks.

    • watch

      <U> void watch(ActorRef<U> other)
      Register for Terminated notification once the Actor identified by the given ActorRef terminates. This message is also sent when the watched actor is on a node that has been removed from the cluster when using Pekko Cluster.

      watch is idempotent if it is not mixed with watchWith.

      It will fail with an IllegalStateException if the same subject was watched before using watchWith. To clear the termination message, unwatch first.

      *Warning*: This method is not thread-safe and must not be accessed from threads other than the ordinary actor message processing thread, such as CompletionStage callbacks.

    • watchWith

      <U> void watchWith(ActorRef<U> other, T msg)
      Register for termination notification with a custom message once the Actor identified by the given ActorRef terminates. This message is also sent when the watched actor is on a node that has been removed from the cluster when using Pekko Cluster.

      watchWith is idempotent if it is called with the same msg and not mixed with watch.

      It will fail with an IllegalStateException if the same subject was watched before using watch or watchWith with another termination message. To change the termination message, unwatch first.

      *Warning*: This method is not thread-safe and must not be accessed from threads other than the ordinary actor message processing thread, such as CompletionStage callbacks.