multithreading - Scala:WAITING列表被填充

Question

假设有一个列表，其中存储了分布式计算的作业结果。

现在我有一个主线程正在等待所有作业完成。

我知道在所有工作完成之前需要有 List 的大小。
Scala 中让主线程(while(true) 循环)休眠并在作业完成时唤醒它的最优雅方式是什么？

谢谢你的回答

编辑:好的，在尝试了@Stefan-Kunze 的概念但没有成功(我猜我没有明白这一点......)我举了一个带有一些代码的例子:

第一个节点:

class PingPlugin extends SmasPlugin
{
  val messages = new ListBuffer[BaseMessage]()

  val sum = 5

  def onStop = true

  def onStart =
  {
    log.info("Ping Plugin created!")

    true
  }

  def handleInit(msg: Init)
  {
    log.info("Init received")

    for( a <- 1 to sum)
    {
      msg.pingTarget ! Ping() // Ping extends BaseMessage
    }

    // block here until all messages are received
    // wait for messages.length == sum

    log.info("handleInit - messages received: %d/%d ".format(messages.length, sum))


  }

  /**
   * This method handles incoming Pong messages
   * @param msg Pong extends BaseMessage
   */
  def handlePong(msg: Pong)
  {
    log.info("Pong received from: " + msg.sender)
    messages += msg

    log.info("handlePong - messages received: %d/%d ".format(messages.length, sum))
  }
}

第二个节点:

class PongPlugin extends SmasPlugin
{
  def onStop = true

  def onStart =
  {
    log.info("Pong Plugin created!")
    true
  }

  /**
   * This method receives Ping messages and send a Pong message back after a random time
   * @param msg Ping extends BaseMessage
   */
  def handlePing(msg: Ping)
  {
    log.info("Ping received from: " + msg.sender)
    val sleep: Int = math.round(5000 * Random.nextFloat())
    log.info("sleep: " + sleep)

    Thread.sleep(sleep)
    msg.sender ! Pong()
  }
}   

我想解决方案是可能的 future ......

Answer 1

选择@jilen 的方法:(此代码假设您的结果是结果类型)

//just like lists futures can be yielded
val tasks: Seq[Future[Result]] = for (i <- 1 to results.size) yield future {
                                                   //results.size is the number of                   //results you are expecting
  println("Executing task " + i)
  Thread.sleep(i * 1000L)
  val result = ??? //your code goes here
  result
}


//merge all future results into a future of a sequence of results
val aggregated: Future[Seq[Result]] = Future.sequence(tasks)


//awaits for your results to be computed
val squares: Seq[Int] = Await.result(aggregated, Duration.Inf)
println("Squares: " + squares)