问当存在单例时，如何在akka集群中配置关闭

EN

class ClusterListener extends Actor with ActorLogging {

  val cluster = Cluster(context.system)
  var unreachableMember: Set[Member] = Set()

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

  def receive = {
    case UnreachableMember(member) =>
      log.info("Member detected as unreachable: {}", member)
      val state = cluster.state
      if (isMajority(state.members.size, state.unreachable.size)) {
        scheduletakeDown(member)
      }
    case ReachableMember(member) =>
      unreachableMember = unreachableMember - member
    case _: MemberEvent => // ignore
    case "die" =>
      unreachableMember.foreach { member =>
        cluster.down(member.address)
      }
  }

  // find out majority number of the group
  private def majority(n: Int): Int = (n+1)/2 + (n+1)%2

  private def isMajority(total: Int, dead: Int): Boolean = {
    require(total > 0)
    require(dead >= 0)
    (total - dead) >= majority(total)
  }

  private def scheduletakeDown(member: Member) = {
    implicit val dispatcher = context.system.dispatcher
    unreachableMember = unreachableMember + member
    // make 5s config able!!!
    context.system.scheduler.scheduleOnce(5 seconds, self, "die")
  }

}