pekko/akka-docs/src/test/java/jdocs/event/LoggingDocTest.java

/*
 * Copyright (C) 2009-2021 Lightbend Inc. <https://www.lightbend.com>
 */

package jdocs.event;

// #imports
import akka.actor.*;
import akka.event.Logging;
import akka.event.LoggingAdapter;

// #imports

// #imports-listener
import akka.event.Logging.InitializeLogger;
import akka.event.Logging.Error;
import akka.event.Logging.Warning;
import akka.event.Logging.Info;
import akka.event.Logging.Debug;

// #imports-listener

import jdocs.AbstractJavaTest;
import akka.testkit.javadsl.TestKit;
import org.junit.Test;
import java.util.Optional;

// #imports-mdc
import akka.event.DiagnosticLoggingAdapter;
import java.util.HashMap;
import java.util.Map;
// #imports-mdc

// #imports-deadletter
import akka.actor.ActorRef;
import akka.actor.ActorSystem;
// #imports-deadletter

public class LoggingDocTest extends AbstractJavaTest {

  @Test
  public void useLoggingActor() {
    ActorSystem system = ActorSystem.create("MySystem");
    ActorRef myActor = system.actorOf(Props.create(MyActor.class, this));
    myActor.tell("test", ActorRef.noSender());
    TestKit.shutdownActorSystem(system);
  }

  @Test
  public void useLoggingActorWithMDC() {
    ActorSystem system = ActorSystem.create("MyDiagnosticSystem");
    ActorRef mdcActor = system.actorOf(Props.create(MdcActor.class, this));
    mdcActor.tell("some request", ActorRef.noSender());
    TestKit.shutdownActorSystem(system);
  }

  @Test
  public void subscribeToDeadLetters() {
    // #deadletters
    final ActorSystem system = ActorSystem.create("DeadLetters");
    final ActorRef actor = system.actorOf(Props.create(DeadLetterActor.class));
    system.getEventStream().subscribe(actor, DeadLetter.class);
    // #deadletters
    TestKit.shutdownActorSystem(system);
  }

  // #superclass-subscription-eventstream
  interface AllKindsOfMusic {}

  class Jazz implements AllKindsOfMusic {
    public final String artist;

    public Jazz(String artist) {
      this.artist = artist;
    }
  }

  class Electronic implements AllKindsOfMusic {
    public final String artist;

    public Electronic(String artist) {
      this.artist = artist;
    }
  }

  static class Listener extends AbstractActor {
    @Override
    public Receive createReceive() {
      return receiveBuilder()
          .match(
              Jazz.class,
              msg -> System.out.printf("%s is listening to: %s%n", getSelf().path().name(), msg))
          .match(
              Electronic.class,
              msg -> System.out.printf("%s is listening to: %s%n", getSelf().path().name(), msg))
          .build();
    }
  }
  // #superclass-subscription-eventstream

  @Test
  public void subscribeBySubclassification() {
    final ActorSystem system = ActorSystem.create("DeadLetters");
    // #superclass-subscription-eventstream
    final ActorRef actor = system.actorOf(Props.create(DeadLetterActor.class));
    system.getEventStream().subscribe(actor, DeadLetter.class);

    final ActorRef jazzListener = system.actorOf(Props.create(Listener.class));
    final ActorRef musicListener = system.actorOf(Props.create(Listener.class));
    system.getEventStream().subscribe(jazzListener, Jazz.class);
    system.getEventStream().subscribe(musicListener, AllKindsOfMusic.class);

    // only musicListener gets this message, since it listens to *all* kinds of music:
    system.getEventStream().publish(new Electronic("Parov Stelar"));

    // jazzListener and musicListener will be notified about Jazz:
    system.getEventStream().publish(new Jazz("Sonny Rollins"));

    // #superclass-subscription-eventstream
    TestKit.shutdownActorSystem(system);
  }

  @Test
  public void subscribeToSuppressedDeadLetters() {
    final ActorSystem system = ActorSystem.create("SuppressedDeadLetters");
    final ActorRef actor = system.actorOf(Props.create(DeadLetterActor.class));

    // #suppressed-deadletters
    system.getEventStream().subscribe(actor, SuppressedDeadLetter.class);
    // #suppressed-deadletters

    TestKit.shutdownActorSystem(system);
  }

  @Test
  public void subscribeToAllDeadLetters() {
    final ActorSystem system = ActorSystem.create("AllDeadLetters");
    final ActorRef actor = system.actorOf(Props.create(DeadLetterActor.class));

    // #all-deadletters
    system.getEventStream().subscribe(actor, AllDeadLetters.class);
    // #all-deadletters

    TestKit.shutdownActorSystem(system);
  }

  @Test
  public void demonstrateMultipleArgs() {
    final ActorSystem system = ActorSystem.create("multiArg");
    // #array
    final Object[] args = new Object[] {"The", "brown", "fox", "jumps", 42};
    system.log().debug("five parameters: {}, {}, {}, {}, {}", args);
    // #array
    TestKit.shutdownActorSystem(system);
  }

  // #my-actor
  class MyActor extends AbstractActor {
    LoggingAdapter log = Logging.getLogger(getContext().getSystem(), this);

    @Override
    public void preStart() {
      log.debug("Starting");
    }

    @Override
    public void preRestart(Throwable reason, Optional<Object> message) {
      log.error(
          reason,
          "Restarting due to [{}] when processing [{}]",
          reason.getMessage(),
          message.isPresent() ? message.get() : "");
    }

    @Override
    public Receive createReceive() {
      return receiveBuilder()
          .matchEquals("test", msg -> log.info("Received test"))
          .matchAny(msg -> log.warning("Received unknown message: {}", msg))
          .build();
    }
  }

  // #my-actor

  // #mdc-actor
  class MdcActor extends AbstractActor {

    final DiagnosticLoggingAdapter log = Logging.getLogger(this);

    @Override
    public Receive createReceive() {
      return receiveBuilder()
          .matchAny(
              msg -> {
                Map<String, Object> mdc;
                mdc = new HashMap<String, Object>();
                mdc.put("requestId", 1234);
                mdc.put("visitorId", 5678);
                log.setMDC(mdc);

                log.info("Starting new request");

                log.clearMDC();
              })
          .build();
    }
  }

  // #mdc-actor

  // #my-event-listener
  class MyEventListener extends AbstractActor {
    @Override
    public Receive createReceive() {
      return receiveBuilder()
          .match(
              InitializeLogger.class,
              msg -> {
                getSender().tell(Logging.loggerInitialized(), getSelf());
              })
          .match(
              Error.class,
              msg -> {
                // ...
              })
          .match(
              Warning.class,
              msg -> {
                // ...
              })
          .match(
              Info.class,
              msg -> {
                // ...
              })
          .match(
              Debug.class,
              msg -> {
                // ...
              })
          .build();
    }
  }
  // #my-event-listener

  public
  // #deadletter-actor
  static class DeadLetterActor extends AbstractActor {
    @Override
    public Receive createReceive() {
      return receiveBuilder()
          .match(
              DeadLetter.class,
              msg -> {
                System.out.println(msg);
              })
          .build();
    }
  }
  // #deadletter-actor
}