55 lines
1.4 KiB
Scala
55 lines
1.4 KiB
Scala
/*
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* Copyright (C) 2018-2020 Lightbend Inc. <https://www.lightbend.com>
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*/
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package scala.docs.cluster
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import scala.annotation.tailrec
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import scala.concurrent.Future
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import com.typesafe.config.ConfigFactory
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import akka.actor.Actor
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import akka.actor.ActorLogging
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import akka.actor.ActorSystem
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import akka.actor.Props
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import akka.pattern.pipe
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//#backend
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class FactorialBackend extends Actor with ActorLogging {
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import context.dispatcher
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def receive = {
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case (n: Int) =>
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Future(factorial(n))
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.map { result =>
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(n, result)
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}
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.pipeTo(sender())
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}
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def factorial(n: Int): BigInt = {
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@tailrec def factorialAcc(acc: BigInt, n: Int): BigInt = {
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if (n <= 1) acc
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else factorialAcc(acc * n, n - 1)
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}
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factorialAcc(BigInt(1), n)
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}
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}
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//#backend
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object FactorialBackend {
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def main(args: Array[String]): Unit = {
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// Override the configuration of the port when specified as program argument
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val port = if (args.isEmpty) "0" else args(0)
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val config = ConfigFactory
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.parseString(s"akka.remote.classic.netty.tcp.port=$port")
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.withFallback(ConfigFactory.parseString("akka.cluster.roles = [backend]"))
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.withFallback(ConfigFactory.load("factorial"))
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val system = ActorSystem("ClusterSystem", config)
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system.actorOf(Props[FactorialBackend](), name = "factorialBackend")
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system.actorOf(Props[MetricsListener](), name = "metricsListener")
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}
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}
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