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

This example Akka source code file (SimpleClusterListener.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, actorlogging, akka, cluster, initialstateasevents, member, memberevent, memberremoved, removed, unit, unreachablemember, up

The SimpleClusterListener.scala Akka example source code

package sample.cluster.simple

import akka.cluster.Cluster
import akka.cluster.ClusterEvent._
import akka.actor.ActorLogging
import akka.actor.Actor

class SimpleClusterListener extends Actor with ActorLogging {

  val cluster = Cluster(context.system)

  // subscribe to cluster changes, re-subscribe when restart 
  override def preStart(): Unit = {
    //#subscribe
    cluster.subscribe(self, initialStateMode = InitialStateAsEvents,
      classOf[MemberEvent], classOf[UnreachableMember])
    //#subscribe
  }
  override def postStop(): Unit = cluster.unsubscribe(self)

  def receive = {
    case MemberUp(member) =>
      log.info("Member is Up: {}", member.address)
    case UnreachableMember(member) =>
      log.info("Member detected as unreachable: {}", member)
    case MemberRemoved(member, previousStatus) =>
      log.info("Member is Removed: {} after {}",
        member.address, previousStatus)
    case _: MemberEvent => // ignore
  }
}