在 Scala 中实现不使用 Akka 的 Actor 模型

Question

我正在做我的小研究，在没有 Akka 的情况下实现 Actor 我在 Scala 中找到了 Actor 的一种实现。 (How to implement actor model without Akka?)

很简单。因为我没有足够的声誉来添加评论，所以我创建了这个问题。我想知道我是否像下面这样使用 Actor。

1/ 如何从主线程中关闭该 actor？

2/ 如何添加类似Akka的功能，如parent actor、kill request、become method？

import scala.concurrent._

trait Actor[T] {
      implicit val context = ExecutionContext.fromExecutor(java.util.concurrent.Executors.newFixedThreadPool(1))
      def receive: T => Unit
      def !(m: T) = Future { receive(m) }
}

这是我自己尝试改编上述代码片段时的示例

import scala.concurrent._

/**
  * Created by hminle on 10/21/2016.
  */
trait Message
case class HelloMessage(hello: String) extends Message
case class GoodByeMessage(goodBye: String) extends Message

object State extends Enumeration {
  type State = Value
  val Waiting, Running, Terminating = Value
}

trait Actor[T] {
  implicit val context = ExecutionContext.fromExecutor(java.util.concurrent.Executors.newFixedThreadPool(1))
  private var state: State.State = State.Waiting
  def handleMessage: T => Unit ={
    if(state == State.Waiting) handleMessageWhenWaiting
    else if(state == State.Running) handleMessageWhenRunning
    else handleMessageWhenTerminating
  }
  def !(m: T) = Future {handleMessage(m)}
  def handleMessageWhenWaiting: T => Unit
  def handleMessageWhenRunning: T => Unit
  def handleMessageWhenTerminating: T => Unit
  def transitionTo(destinationState: State.State): Unit = {
    this.state = destinationState
  }
}

class Component1 extends Actor[Message]{
  def handleMessageWhenRunning = {
    case HelloMessage(hello) => {
      println(Thread.currentThread().getName + hello)
    }
    case GoodByeMessage(goodBye) => {
      println(Thread.currentThread().getName + goodBye)
      transitionTo(State.Terminating)
    }
  }

  def handleMessageWhenWaiting = {
    case m => {
      println(Thread.currentThread().getName + " I am waiting, I am not ready to run")
      transitionTo(State.Running)
    }
  }

  def handleMessageWhenTerminating = {
    case m => {
      println(Thread.currentThread().getName + " I am terminating, I cannot handle any message")
      //need to shutdown here
    }
  }

}
class Component2(component1: Actor[Message]) extends Actor[Message]{
  def handleMessageWhenRunning = {
    case HelloMessage(hello) => {
      println(Thread.currentThread().getName + hello)
      component1 ! HelloMessage("hello 1")
    }
    case GoodByeMessage(goodBye) => {
      println(Thread.currentThread().getName + goodBye)
      component1 ! GoodByeMessage("goodbye 1")
      transitionTo(State.Terminating)
    }
  }

  def handleMessageWhenWaiting = {
    case m => {
      println(Thread.currentThread().getName + " I am waiting, I am not ready to run")
      transitionTo(State.Running)
    }
  }

  def handleMessageWhenTerminating = {
    case m => {
      println(Thread.currentThread().getName + " I am terminating, I cannot handle any message")
      //need to shutdown here
    }
  }
}
object ActorExample extends App {
  val a = new Component1
  val b = new Component2(a)
  b ! HelloMessage("hello World 2")
  b ! HelloMessage("hello World 2, 2nd")
  b ! GoodByeMessage("Good bye 2")
  println(Thread.currentThread().getName)
}

Answer 1

您可以查看 scalaz 中的 Actor model 实现并从中汲取灵感，scalaz actor 中的源代码比 akka 中的源代码更容易理解。您可以自由选择架构：您可以像在 Akka 中一样使用基于 ConcurrentLinkedQueue 的邮箱，像在 scalaz 中一样对 AtomicReffernce 使用 CAS，在您的情况下您使用 Future 机制。 IMO，你必须写一个你的演员系统的上下文，所以解决你问题中的第一和第二项它是 ActorContext 的变体：

val contextStack = new ThreadLocal[List[ActorContext]]

关机看起来像这样：

1.

case Kill                       ⇒ throw new ActorKilledException("Kill")
case PoisonPill                 ⇒ self.stop()

2。为了存储父 actor 和类似任务，您必须在它们上存储引用：

def parent: ActorRef

很难说每种技术（CAS、邮箱）的优势，它可能是您研究的变体。

在 Scala 中实现不使用 Akka 的 Actor 模型

Implement Actor model without Akka in Scala

scala

actor

akka