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Akka Typed Add example of how to java getSelf for persistence typed #27061 (#27196)

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Helena Edelson 2019-06-21 07:30:33 -07:00 • committed by GitHub
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27
akka-docs/src/main/paradox/typed/actor-lifecycle.md
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@ -21,6 +21,33 @@ forming an actor hierarchy. @apidoc[akka.actor.typed.ActorSystem] hosts the hier
actor at the top of the hierarchy of the `ActorSystem`. The lifecycle of a child actor is tied to the parent -- a child
can stop itself or be stopped at any time but it can never outlive its parent.
### The ActorContext
The ActorContext can be accessed for many purposes such as:
* Spawning child actors and supervision
* Watching other actors (`DeathWatch`) to receive a `Terminated(otherActor)` event should the watched actor stop permanently
* Logging
* Creating message adapters
* Request-response interactions (ask) with another actor
* Access to the `self` ActorRef
If a behavior needs to use the `ActorContext`, for example to spawn child actors, or use
@scala[`context.self`]@java[`context.getSelf()`], it can be obtained by wrapping construction with `Behaviors.setup`:
Scala
: @@snip [BasicPersistentBehaviorCompileOnly.scala](/akka-persistence-typed/src/test/scala/docs/akka/persistence/typed/BasicPersistentBehaviorCompileOnly.scala) { #actor-context }
Java
: @@snip [BasicPersistentBehaviorTest.java](/akka-persistence-typed/src/test/java/jdocs/akka/persistence/typed/BasicPersistentBehaviorTest.java) { #actor-context }
#### ActorContext Thread Safety
Many of the methods in `ActorContext` are not thread-safe and
* Must not be accessed by threads from @scala[`scala.concurrent.Future`]@java[`java.util.concurrent.CompletionStage`] callbacks
* Must not be shared between several actor instances
* Should only be used in the ordinary actor message processing thread
### The Guardian Actor

5
akka-persistence-typed/src/test/java/jdocs/akka/persistence/typed/BasicPersistentBehaviorTest.java
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@ -4,6 +4,7 @@
package jdocs.akka.persistence.typed;
import akka.actor.typed.ActorRef;
import akka.actor.typed.Behavior;
import akka.actor.typed.SupervisorStrategy;
import akka.actor.typed.javadsl.ActorContext;
@ -341,9 +342,13 @@ public class BasicPersistentBehaviorTest {
// this makes the context available to the command handler etc.
private final ActorContext<Command> ctx;
// optionally if you only need `ActorContext.getSelf()`
private final ActorRef<Command> self;
public MyPersistentBehavior(PersistenceId persistenceId, ActorContext<Command> ctx) {
super(persistenceId);
this.ctx = ctx;
this.self = ctx.getSelf();
}
// #actor-context