trait ActorPublisher[T] extends Actor

Extend/mixin this trait in your akka.actor.Actor to make it a stream publisher that keeps track of the subscription life cycle and requested elements.

Create a org.reactivestreams.Publisher backed by this actor with Scala API ActorPublisher#apply, or Java API UntypedActorPublisher#create or Java API compatible with lambda expressions AbstractActorPublisher#create.

It can be attached to a org.reactivestreams.Subscriber or be used as an input source for a akka.stream.scaladsl.Flow. You can only attach one subscriber to this publisher.

The life cycle state of the subscription is tracked with the following boolean members: #isActive, #isCompleted, #isErrorEmitted, and #isCanceled.

You send elements to the stream by calling #onNext. You are allowed to send as many elements as have been requested by the stream subscriber. This amount can be inquired with #totalDemand. It is only allowed to use onNext when isActive and totalDemand > 0, otherwise onNext will throw IllegalStateException.

When the stream subscriber requests more elements the ActorPublisher#Request message is delivered to this actor, and you can act on that event. The #totalDemand is updated automatically.

When the stream subscriber cancels the subscription the ActorPublisher#Cancel message is delivered to this actor. After that subsequent calls to onNext will be ignored.

You can complete the stream by calling #onComplete. After that you are not allowed to call #onNext, #onError and #onComplete.

You can terminate the stream with failure by calling #onError. After that you are not allowed to call #onNext, #onError and #onComplete.

If you suspect that this ActorPublisher may never get subscribed to, you can override the #subscriptionTimeout method to provide a timeout after which this Publisher should be considered canceled. The actor will be notified when the timeout triggers via an akka.stream.actor.ActorPublisherMessage.SubscriptionTimeoutExceeded message and MUST then perform cleanup and stop itself.

If the actor is stopped the stream will be completed, unless it was not already terminated with failure, completed or canceled.

Annotations
@deprecated
Deprecated

(Since version 2.5.0) Use akka.stream.stage.GraphStage instead, it allows for all operations an Actor would and is more type-safe as well as guaranteed to be ReactiveStreams compliant.

Source
ActorPublisher.scala
Linear Supertypes
Actor, AnyRef, Any
Known Subclasses
AbstractActorPublisher, AbstractActorPublisherWithStash, AbstractActorPublisherWithUnboundedStash, AbstractActorPublisherWithUnrestrictedStash, UntypedActorPublisher
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Type Members

  1. type Receive = PartialFunction[Any, Unit]
    Definition Classes
    Actor

Abstract Value Members

  1. abstract def receive: actor.Actor.Receive

    Scala API: This defines the initial actor behavior, it must return a partial function with the actor logic.

    Scala API: This defines the initial actor behavior, it must return a partial function with the actor logic.

    Definition Classes
    Actor

Concrete Value Members

  1. implicit val context: ActorContext

    Scala API: Stores the context for this actor, including self, and sender.

    Scala API: Stores the context for this actor, including self, and sender. It is implicit to support operations such as forward.

    WARNING: Only valid within the Actor itself, so do not close over it and publish it to other threads!

    akka.actor.ActorContext is the Scala API. getContext returns a akka.actor.AbstractActor.ActorContext, which is the Java API of the actor context.

    Definition Classes
    Actor
  2. final def isActive: Boolean

    The state when the publisher is active, i.e.

    The state when the publisher is active, i.e. before the subscriber is attached and when an subscriber is attached. It is allowed to call #onComplete and #onError in this state. It is allowed to call #onNext in this state when #totalDemand is greater than zero.

  3. final def isCanceled: Boolean

    The state after the stream subscriber has canceled the subscription.

    The state after the stream subscriber has canceled the subscription. It is allowed to call #onNext, #onError, and #onComplete in this state, but the calls will not perform anything.

  4. final def isCompleted: Boolean

    The terminal state after calling #onComplete.

    The terminal state after calling #onComplete. It is not allowed to call #onNext, #onError, and #onComplete in this state.

  5. final def isErrorEmitted: Boolean

    The terminal state after calling #onError.

    The terminal state after calling #onError. It is not allowed to call #onNext, #onError, and #onComplete in this state.

  6. def onComplete(): Unit

    Complete the stream.

    Complete the stream. After that you are not allowed to call #onNext, #onError and #onComplete.

  7. def onCompleteThenStop(): Unit

    Complete the stream.

    Complete the stream. After that you are not allowed to call #onNext, #onError and #onComplete.

    After signaling completion the Actor will then stop itself as it has completed the protocol. When #onComplete is called before any Subscriber has had the chance to subscribe to this ActorPublisher the completion signal (and therefore stopping of the Actor as well) will be delayed until such Subscriber arrives.

  8. def onError(cause: Throwable): Unit

    Terminate the stream with failure.

    Terminate the stream with failure. After that you are not allowed to call #onNext, #onError and #onComplete.

  9. def onErrorThenStop(cause: Throwable): Unit

    Terminate the stream with failure.

    Terminate the stream with failure. After that you are not allowed to call #onNext, #onError and #onComplete.

    After signaling the Error the Actor will then stop itself as it has completed the protocol. When #onError is called before any Subscriber has had the chance to subscribe to this ActorPublisher the error signal (and therefore stopping of the Actor as well) will be delayed until such Subscriber arrives.

  10. def onNext(element: T): Unit

    Send an element to the stream subscriber.

    Send an element to the stream subscriber. You are allowed to send as many elements as have been requested by the stream subscriber. This amount can be inquired with #totalDemand. It is only allowed to use onNext when isActive and totalDemand > 0, otherwise onNext will throw IllegalStateException.

  11. def postRestart(reason: Throwable): Unit

    User overridable callback: By default it calls preStart().

    User overridable callback: By default it calls preStart().

    reason

    the Throwable that caused the restart to happen Is called right AFTER restart on the newly created Actor to allow reinitialization after an Actor crash.

    Definition Classes
    Actor
    Annotations
    @throws( classOf[Exception] )
  12. def postStop(): Unit

    User overridable callback.

    User overridable callback.

    Is called asynchronously after 'actor.stop()' is invoked. Empty default implementation.

    Definition Classes
    Actor
    Annotations
    @throws( classOf[Exception] )
  13. def preRestart(reason: Throwable, message: Option[Any]): Unit

    Scala API: User overridable callback: By default it disposes of all children and then calls postStop().

    Scala API: User overridable callback: By default it disposes of all children and then calls postStop().

    reason

    the Throwable that caused the restart to happen

    message

    optionally the current message the actor processed when failing, if applicable Is called on a crashed Actor right BEFORE it is restarted to allow clean up of resources before Actor is terminated.

    Definition Classes
    Actor
    Annotations
    @throws( classOf[Exception] )
  14. def preStart(): Unit

    User overridable callback.

    User overridable callback.

    Is called when an Actor is started. Actors are automatically started asynchronously when created. Empty default implementation.

    Definition Classes
    Actor
    Annotations
    @throws( classOf[Exception] )
  15. implicit final val self: ActorRef

    The 'self' field holds the ActorRef for this actor.

    The 'self' field holds the ActorRef for this actor.

    Can be used to send messages to itself: 

    self ! message

    Definition Classes
    Actor
  16. final def sender(): ActorRef

    The reference sender Actor of the last received message.

    The reference sender Actor of the last received message. Is defined if the message was sent from another Actor, else deadLetters in akka.actor.ActorSystem.

    WARNING: Only valid within the Actor itself, so do not close over it and publish it to other threads!

    Definition Classes
    Actor
  17. def subscriptionTimeout: Duration

    Subscription timeout after which this actor will become Canceled and reject any incoming "late" subscriber.

    Subscription timeout after which this actor will become Canceled and reject any incoming "late" subscriber.

    The actor will receive an SubscriptionTimeoutExceeded message upon which it MUST react by performing all necessary cleanup and stopping itself.

    Use this feature in order to avoid leaking actors when you suspect that this Publisher may never get subscribed to by some Subscriber.

  18. def supervisorStrategy: SupervisorStrategy

    User overridable definition the strategy to use for supervising child actors.

    User overridable definition the strategy to use for supervising child actors.

    Definition Classes
    Actor
  19. final def totalDemand: Long

    Total number of requested elements from the stream subscriber.

    Total number of requested elements from the stream subscriber. This actor automatically keeps tracks of this amount based on incoming request messages and outgoing onNext.

  20. def unhandled(message: Any): Unit

    User overridable callback.

    User overridable callback.

    Is called when a message isn't handled by the current behavior of the actor by default it fails with either a akka.actor.DeathPactException (in case of an unhandled akka.actor.Terminated message) or publishes an akka.actor.UnhandledMessage to the actor's system's akka.event.EventStream

    Definition Classes
    Actor