Package org.apache.pekko.actor.typed

Class BehaviorInterceptor<Outer,Inner>

java.lang.Object
org.apache.pekko.actor.typed.BehaviorInterceptor<Outer,Inner>
Type Parameters:
Outer - The outer message type – the type of messages the intercepting behavior will accept
Inner - The inner message type - the type of message the wrapped behavior accepts

Direct Known Subclasses:
AbstractSupervisor, BehaviorSignalInterceptor
public abstract class BehaviorInterceptor<Outer,Inner> extends Object
A behavior interceptor allows for intercepting message and signal reception and perform arbitrary logic - transform, filter, send to a side channel etc. It is the core API for decoration of behaviors.

The BehaviorInterceptor API is considered a low level tool for building other features and shouldn't be used for "normal" application logic. Several built-in intercepting behaviors are provided through factories in the respective Behaviors.

If the interceptor does keep mutable state care must be taken to create a new instance from the factory function of Behaviors.intercept so that a new instance is created per spawned actor rather than shared among actor instance.

param: interceptMessageClass Ensures that the interceptor will only receive O message types. If the message is not of this class or a subclass thereof (e.g. a private protocol) will bypass the interceptor and be continue to the inner behavior untouched.

See Also:

  • Constructor Details

    • BehaviorInterceptor

      public BehaviorInterceptor(Class<Outer> interceptMessageClass)

    • BehaviorInterceptor

      public BehaviorInterceptor(scala.reflect.ClassTag<Outer> interceptMessageClassTag)
      Scala API: The ClassTag for Outer ensures that only messages of this class or a subclass thereof will be intercepted. Other message types (e.g. a private protocol) will bypass the interceptor and be continue to the inner behavior untouched.

  • Method Details

    • interceptMessageClass

      public Class<Outer> interceptMessageClass()

    • aroundStart

      public Behavior<Inner> aroundStart(TypedActorContext<Outer> ctx, BehaviorInterceptor.PreStartTarget<Inner> target)
      Override to intercept actor startup. To trigger startup of the next behavior in the stack, call target.start().
      Returns:
      The returned behavior will be the "started" behavior of the actor used to accept the next message or signal.

    • aroundReceive

      public abstract Behavior<Inner> aroundReceive(TypedActorContext<Outer> ctx, Outer msg, BehaviorInterceptor.ReceiveTarget<Inner> target)
      Intercept a message sent to the running actor. Pass the message on to the next behavior in the stack by passing it to target.apply, return Behaviors.same without invoking target to filter out the message.

      Returns:
      The behavior for next message or signal

    • aroundSignal

      public Behavior<Inner> aroundSignal(TypedActorContext<Outer> ctx, Signal signal, BehaviorInterceptor.SignalTarget<Inner> target)
      Override to intercept a signal sent to the running actor. Pass the signal on to the next behavior in the stack by passing it to target.apply.

      Returns:
      The behavior for next message or signal

      See Also:

    • isSame

      public boolean isSame(BehaviorInterceptor<Object,Object> other)
      Returns:
      true if this behavior logically the same as another behavior interceptor and can therefore be eliminated (to avoid building infinitely growing stacks of behaviors)? Default implementation is based on instance equality. Override to provide use case specific logic.