Akka/Scala example source code file (DeadLetterListener.scala)

This example Akka source code file (DeadLetterListener.scala) is included in my "Source Code Warehouse" project. The intent of this project is to help you more easily find Akka and Scala source code examples by using tags.

All credit for the original source code belongs to akka.io; I'm just trying to make examples easier to find. (For my Scala work, see my Scala examples and tutorials.)

Akka tags/keywords

actor, akka, deadletter, deadletterlistener, event, message, option, this, throwable, unit

The DeadLetterListener.scala Akka example source code

/**
 * Copyright (C) 2009-2014 Typesafe Inc. <http://www.typesafe.com>
 */
package akka.event

import akka.actor.Actor
import akka.actor.DeadLetter
import akka.event.Logging.Info

class DeadLetterListener extends Actor {

  val eventStream = context.system.eventStream
  val maxCount = context.system.settings.LogDeadLetters
  var count = 0

  override def preStart(): Unit =
    eventStream.subscribe(self, classOf[DeadLetter])

  // don't re-subscribe, skip call to preStart
  override def postRestart(reason: Throwable): Unit = ()

  // don't remove subscription, skip call to postStop, no children to stop
  override def preRestart(reason: Throwable, message: Option[Any]): Unit = ()

  override def postStop(): Unit =
    eventStream.unsubscribe(self)

  def receive = {
    case DeadLetter(message, snd, rcp) ⇒
      count += 1
      val done = maxCount != Int.MaxValue && count >= maxCount
      val doneMsg = if (done) ", no more dead letters will be logged" else ""
      eventStream.publish(Info(rcp.path.toString, rcp.getClass,
        s"Message [${message.getClass.getName}] from $snd to $rcp was not delivered. [$count] dead letters encountered$doneMsg. " +
          "This logging can be turned off or adjusted with configuration settings 'akka.log-dead-letters' " +
          "and 'akka.log-dead-letters-during-shutdown'."))
      if (done) context.stop(self)
  }

}