AsyncRestart.scala

import akka.actor.{Actor, ActorSystem, Props, Stash}

import scala.concurrent._

object AsyncRestart extends App {

  val system = ActorSystem()

  val actor = system.actorOf(Props(new AsyncRestartActor))

  actor ! "1"
  actor ! "2"
  actor ! "fail"
  actor ! "3"

}


class AsyncRestartActor extends Actor with Stash {
  import context.dispatcher

  @scala.throws[Exception](classOf[Exception])
  override def preStart(): Unit = {
    init()
  }

  @scala.throws[Exception](classOf[Exception])
  override def postRestart(reason: Throwable): Unit = {} // to avoid init before PreviousStopped

  private def init(): Unit = {
    Future {
      blocking {
        Thread.sleep(1000)
        println("init done")
      }
    }.onComplete { _ =>
      self ! Initialized
    }
  }

  override def receive: Receive = {
    case PreviousStopped =>
      init()
    case Initialized =>
      unstashAll()
      context.become(initialized)
    case msg =>
      stash()
  }

  private val initialized: Receive = {
    case "fail" =>
      throw new Exception("failed")
    case msg =>
      println(msg)
  }

  override def postStop(): Unit = {
    Future {
      blocking {
        Thread.sleep(1000)
        println("stop done")
      }
    }.onComplete { _ =>
      self ! PreviousStopped
    }
    super.postStop()
  }
}

case object Initialized
case object PreviousStopped