pekko/akka-docs/scala/code/docs/extension/ExtensionDocSpec.scala

/**
 * Copyright (C) 2009-2012 Typesafe Inc. <http://www.typesafe.com>
 */
package docs.extension

import java.util.concurrent.atomic.AtomicLong
import akka.actor.Actor
import akka.testkit.AkkaSpec

//#extension
import akka.actor.Extension

class CountExtensionImpl extends Extension {
  //Since this Extension is a shared instance
  // per ActorSystem we need to be threadsafe
  private val counter = new AtomicLong(0)

  //This is the operation this Extension provides
  def increment() = counter.incrementAndGet()
}
//#extension

//#extensionid
import akka.actor.ExtensionId
import akka.actor.ExtensionIdProvider
import akka.actor.ExtendedActorSystem

object CountExtension
  extends ExtensionId[CountExtensionImpl]
  with ExtensionIdProvider {
  //The lookup method is required by ExtensionIdProvider,
  // so we return ourselves here, this allows us
  // to configure our extension to be loaded when
  // the ActorSystem starts up
  override def lookup = CountExtension

  //This method will be called by Akka
  // to instantiate our Extension
  override def createExtension(system: ExtendedActorSystem) = new CountExtensionImpl
}
//#extensionid

object ExtensionDocSpec {

  val config = """
    //#config
    akka {
      extensions = ["docs.extension.CountExtension$"]
    }
    //#config
    """

  //#extension-usage-actor

  class MyActor extends Actor {
    def receive = {
      case someMessage ⇒
        CountExtension(context.system).increment()
    }
  }
  //#extension-usage-actor

  //#extension-usage-actor-trait

  trait Counting { self: Actor ⇒
    def increment() = CountExtension(context.system).increment()
  }
  class MyCounterActor extends Actor with Counting {
    def receive = {
      case someMessage ⇒ increment()
    }
  }
  //#extension-usage-actor-trait
}

class ExtensionDocSpec extends AkkaSpec(ExtensionDocSpec.config) {
  import ExtensionDocSpec._

  "demonstrate how to create an extension in Scala" in {
    //#extension-usage
    CountExtension(system).increment
    //#extension-usage
  }

  "demonstrate how to lookup a configured extension in Scala" in {
    //#extension-lookup
    system.extension(CountExtension)
    //#extension-lookup
  }

}