Spotlight for Cluster Death Watch

ClusterWatch.scala

case object BackendRegistration
case class Job(text: String)

class Frontend extends Actor {
 
  var backends = IndexedSeq.empty[ActorRef]
  var jobCounter = 0
 
  def receive = {
    case job: Job if backends.isEmpty =>
      sender ! "Service unavailable, try again later"
 
    case job: Job =>
      jobCounter += 1
      backends(jobCounter % backends.size) forward job
 
    case BackendRegistration if !backends.contains(sender) =>
      context watch sender
      backends = backends :+ sender
 
    case Terminated(a) ⇒ 
      backends = backends.filterNot(_ == a)
  }
}

backends = backends.filterNot(_ == a)