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

This example Akka source code file (LoggingReceive.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, actorcontext, akka, any, boolean, event, loggingreceive, none, option, receive, some, string, unit

The LoggingReceive.scala Akka example source code

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

import language.existentials

import akka.actor.Actor.Receive
import akka.actor.ActorContext
import akka.actor.ActorCell
import akka.event.Logging.Debug

object LoggingReceive {

  /**
   * Wrap a Receive partial function in a logging enclosure, which sends a
   * debug message to the event bus each time before a message is matched.
   * This includes messages which are not handled.
   *
   * <pre><code>
   * def receive = LoggingReceive {
   *   case x => ...
   * }
   * </code></pre>
   *
   * This method does NOT modify the given Receive unless
   * `akka.actor.debug.receive` is set in configuration.
   */
  def apply(r: Receive)(implicit context: ActorContext): Receive = withLabel(null)(r)

  /**
   * Java API: compatible with lambda expressions
   * This is an EXPERIMENTAL feature and is subject to change until it has received more real world testing.
   */
  def create(r: Receive, context: ActorContext): Receive = apply(r)(context)

  /**
   * Create a decorated logger which will append `" in state " + label` to each message it logs.
   */
  def withLabel(label: String)(r: Receive)(implicit context: ActorContext): Receive = r match {
    case _: LoggingReceive ⇒ r
    case _                 ⇒ if (context.system.settings.AddLoggingReceive) new LoggingReceive(None, r, Option(label)) else r
  }
}

/**
 * This decorator adds invocation logging to a Receive function.
 * @param source the log source, if not defined the actor of the context will be used
 */
class LoggingReceive(source: Option[AnyRef], r: Receive, label: Option[String])(implicit context: ActorContext) extends Receive {
  def this(source: Option[AnyRef], r: Receive)(implicit context: ActorContext) = this(source, r, None)
  def isDefinedAt(o: Any): Boolean = {
    val handled = r.isDefinedAt(o)
    if (context.system.eventStream.logLevel >= Logging.DebugLevel) {
      val (str, clazz) = LogSource.fromAnyRef(source getOrElse context.asInstanceOf[ActorCell].actor)
      context.system.eventStream.publish(Debug(str, clazz, "received " + (if (handled) "handled" else "unhandled") + " message " + o
        + (label match {
          case Some(l) ⇒ " in state " + l
          case _       ⇒ ""
        })))
    }
    handled
  }
  def apply(o: Any): Unit = r(o)
}