akka 入门例子

来自akka官方文档。

import akka.actor._
import akka.routing.RoundRobinRouter
import akka.util._
import scala.concurrent.duration._
 

object Pi extends App {  
  
  def caculate (nrOfWorks:Int, nrOfMessage:Int, nrOfElement:Int){
    val system = ActorSystem("PiSystem")
    val listener = system.actorOf(Props[Listener], name="listener")
    val master = system.actorOf(Props(new Master(nrOfWorks,nrOfMessage,nrOfElement,listener)), name="master")
     master ! Caculate 
  }
  caculate (4, 10000, 10000)
}


sealed trait PiMessager
case object Caculate extends PiMessager
case class Work(start:Int, nrOfElements:Int) extends PiMessager
case class Result(value:Double) extends PiMessager
case class PiApproxomation(pi:Double, duration:Duration)

class Worker extends Actor{
  
  def receive = {
    case Work(start,nrOfElements) => sender ! Result(calculatePiFor(start, nrOfElements))
  }
  
  
  def calculatePiFor(start:Int, nrOfElements:Int):Double ={
    var acc = 0.0
    for(i <- start until (start + nrOfElements)){
      acc += 4.0 * (1- (i%2)*2)/(2*i+1)
    }
    acc    
  }
}

class Master (nrOfWorks:Int, nrOfMessage:Int, nrOfElement:Int, listener:ActorRef) extends Actor
{
  var pi: Double = _
  var nrOfResults: Int = _
  val start: Long = System.currentTimeMillis()
  
  val workerRouter = context.actorOf(
      Props[Worker].withRouter(RoundRobinRouter(nrOfWorks)), name = "workerRouter" )
  def receive = {
    case Caculate => {
      for (i <- 0 until nrOfMessage)
        workerRouter ! Work(i*nrOfElement, nrOfElement)
      }
    case Result(value) => {
      pi += value
      nrOfResults +=1
      if(nrOfResults == nrOfMessage){
        listener ! PiApproxomation(pi, (System.currentTimeMillis()-start).millis)
        context.stop(self)
      } 
    }                      
  } 
}


class Listener extends Actor{
  
  def receive = {
    case PiApproxomation(pi:Double, duration:Duration) => {
      println("
	Pi approximation: 		%s
	Calculation time: 	%s".format(pi, duration))
      context.system.shutdown()
    }
  }
}

流程图：