akka简单示例-2

手动敲了一遍计算pi的示例：http://www.gtan.com/akka_doc/intro/getting-started-first-scala.html

有个笔误，花了半个小时定位。

 [Torstani@sparkb5-i ~/akka_example/pi]$ cat src/Pi.scala
 package akka.tutorial.first.scala
 import akka.actor._
 import akka.routing.RoundRobinRouter
 import scala.concurrent.duration._

 object Pi extends App{
         calculate(nrOfWorkers=4, nrOfElements=1000, nrOfMessages=10000)
         sealed trait PiMessage
         case object Calculate extends PiMessage
         case class Work(stat:Int, nrOfElements: Int) extends PiMessage
         case class Result(value: Double) extends PiMessage
         case class PiApproximation(pi: Double, duration: Duration)

         class Worker extends Actor{
                 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
                 }
                 def receive = {
                         case Work(start, nrOfElements) =>
                                 //println("worker received "+start + ":"+nrOfElements)
                                 val res = calculatePiFor(start, nrOfElements)
                                 sender ! Result(res)
                                 //println("worker send result: "+res)
                 }
         }

         class Master(nrOfWorkers:Int, nrOfMessages:Int, nrOfElements: Int, listener: ActorRef) extends Actor {
                 var pi:Double = _
                 var nrOfResults:Int= _
                 val start:Long = System.currentTimeMillis

                 val workerRouter = context.actorOf(
                         Props[Worker].withRouter(RoundRobinRouter(nrOfWorkers)), name="workerRouter")
                 def receive = {
                         case Calculate =>
                                 //println("master receive Calculate")
                                 for(i <- 0 until nrOfMessages)
                                         workerRouter ! Work(i*nrOfElements, nrOfElements)
                         case Result(value) =>
                                 //println("master recieve result: "+value)
                                 pi += value
                                 nrOfResults += 1
                                 if(nrOfResults == nrOfMessages){
                                         listener ! PiApproximation(pi, duration=(System.currentTimeMillis - start).millis)
                                         context.stop(self)
                                 }
                 }
         }
         class Listener extends Actor{
                 def receive = {
                         case PiApproximation(pi, duration) =>
                                 println("\tpi approximation: \t\t%s\n\tCalculation time: \t%s".format(pi, duration))
                         context.system.shutdown()
                 }
         }
         def calculate(nrOfWorkers:Int, nrOfElements:Int, nrOfMessages:Int) = {
                 val system = ActorSystem("PiSystem")
                 val listener = system.actorOf(Props[Listener], name="listener")
                 val master = system.actorOf(Props(new Master(nrOfWorkers, nrOfMessages, nrOfElements, listener)), name="master")
                 master ! Calculate
         }
 }

 [Torstan@sparkb5-i ~/akka_example/pi]$ cat Makefile
 SRC_DIR := src
 SRC := $(shell find ${SRC_DIR} -name "*.scala")
 DIR=remote

 TARGET := HelloRemote.jar

 SCALAC := scalac
 SCFLAGS := /usr/local/scala-2.10.4/lib/akka-actors.jar  

 .PHONY: all clean

 all: ${TARGET}

 ${TARGET}: ${SRC}
         ${SCALAC} -cp ${SCFLAGS} $^

 clean:
         ${RM} -r ${TARGET} ${DIR}

 [Torstan@sparkb5-i ~/akka_example/pi]$ cat run.sh
 #!/bin/bash

 AKKA_LIB_PATH="/usr/local/akka-2.1.4/lib/akka/"

 java -cp \
  .:/usr/local/scala-2.10.4/lib/scala-library.jar:/usr/local/scala-2.10.4/lib/akka-actors.jar:/usr/local/scala-2.10.4/lib/typesafe-config.jar:${AKKA_LIB_PATH}/akka-remote_2.10-2.1.4.jar:${AKKA_LIB_PATH}/protobuf-java-2.4.1.jar:${AKKA_LIB_PATH}/netty-3.5.8.Final.jar \
 akka.tutorial.first.scala.Pi

执行结果：

[Torstan@sparkb5-i ~/akka_example/pi]$ ./run.sh
pi approximation: 3.1415925535897866
Calculation time: 383 milliseconds