115 lines
3.5 KiB
Scala
115 lines
3.5 KiB
Scala
/**
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* Copyright (C) 2009-2011 Scalable Solutions AB <http://scalablesolutions.se>
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*/
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package akka.tutorial.second
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import akka.actor.Actor._
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import akka.routing.{Routing, CyclicIterator}
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import Routing._
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import akka.event.EventHandler
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import akka.actor.{Channel, Actor, PoisonPill}
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import akka.dispatch.Future
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import System.{currentTimeMillis => now}
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object Pi extends App {
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calculate(nrOfWorkers = 4, nrOfElements = 10000, nrOfMessages = 10000)
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// ====================
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// ===== Messages =====
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// ====================
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sealed trait PiMessage
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case object Calculate extends PiMessage
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case class Work(arg: Int, nrOfElements: Int) extends PiMessage
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case class Result(value: Double) extends PiMessage
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// ==================
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// ===== Worker =====
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// ==================
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class Worker() extends Actor {
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// define the work
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val calculatePiFor = (arg: Int, nrOfElements: Int) => {
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val range = (arg * nrOfElements) to ((arg + 1) * nrOfElements - 1)
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var acc = 0.0D
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range foreach (i => acc += 4 * math.pow(-1, i) / (2 * i + 1))
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acc
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//range map (j => 4 * math.pow(-1, j) / (2 * j + 1)) sum
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}
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def receive = {
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case Work(arg, nrOfElements) =>
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self reply Result(calculatePiFor(arg, nrOfElements)) // perform the work
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}
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}
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// ==================
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// ===== Master =====
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// ==================
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case class Master(nrOfWorkers: Int, nrOfElements: Int, nrOfMessages: Int) extends Actor {
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var pi: Double = _
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var nrOfResults: Int = _
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// create the workers
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val workers = Vector.fill(nrOfWorkers)(actorOf[Worker].start())
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// wrap them with a load-balancing router
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val router = Routing.loadBalancerActor(CyclicIterator(workers)).start()
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// phase 1, can accept a Calculate message
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def scatter: Receive = {
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case Calculate =>
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// schedule work
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for (arg <- 0 until nrOfMessages) router ! Work(arg, nrOfElements)
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//Assume the gathering behavior
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this become gather(self.channel)
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}
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// phase 2, aggregate the results of the Calculation
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def gather(recipient: Channel[Any]): Receive = {
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case Result(value) =>
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// handle result from the worker
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pi += value
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nrOfResults += 1
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if (nrOfResults == nrOfMessages) {
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// send the pi result back to the guy who started the calculation
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recipient ! pi
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// shut ourselves down, we're done
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self.stop()
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}
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}
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// message handler starts at the scattering behavior
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def receive = scatter
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// when we are stopped, stop our team of workers and our router
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override def postStop() {
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// send a PoisonPill to all workers telling them to shut down themselves
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router ! Broadcast(PoisonPill)
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// send a PoisonPill to the router, telling him to shut himself down
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router ! PoisonPill
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}
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}
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// ==================
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// ===== Run it =====
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// ==================
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def calculate(nrOfWorkers: Int, nrOfElements: Int, nrOfMessages: Int) {
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// create the master
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val master = actorOf(new Master(nrOfWorkers, nrOfElements, nrOfMessages)).start()
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//start the calculation
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val start = now
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//send calculate message
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master.!!.
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await.resultOrException match {//wait for the result, with a 60 seconds timeout
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case Some(pi) =>
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EventHandler.info(this, "\n\tPi estimate: \t\t%s\n\tCalculation time: \t%s millis".format(pi, (now - start)))
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case None =>
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EventHandler.error(this, "Pi calculation did not complete within the timeout.")
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}
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}
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}
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