Scala example source code file (ConcurrentTaskTest.scala)

This example Scala source code file (ConcurrentTaskTest.scala) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Scala by Example" ^TM.

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Java - Scala tags/keywords

concurrenttasktest, int, list, queue, runnable, some, speclite, string, syncvar, thread, threadfactory, threading, threads

The ConcurrentTaskTest.scala Scala example source code

package scalaz.concurrent

import scalaz.{\/, SpecLite}
import scalaz.concurrent.Task._
import java.util.concurrent.{ThreadFactory, Executors}
import scala.collection.immutable.Queue
import scala.concurrent.SyncVar
import scalaz.\/._

/**
 *
 * User: pach
 * Date: 7/9/13
 * Time: 6:53 PM
 * (c) 2011-2013 Spinoco Czech Republic, a.s.
 */
object ConcurrentTaskTest extends SpecLite {

  "Task" should {

    "correctly use threads when forked and flatmapped" in {
      @volatile var q = Queue[(Int, String)]()

      val forked = "forked-thread"
      val current =  Thread.currentThread().getName

      def enqueue(taskId: Int) =
        q = q.enqueue((taskId, Thread.currentThread().getName))

      val es = Executors.newFixedThreadPool(1, new ThreadFactory {
        def newThread(p1: Runnable) = new Thread(p1, forked)
      })

      val sync = new SyncVar[Boolean]

      (for {
        _ <- now(enqueue(1))
        _ <- delay(enqueue(2))
        _ <- fork(now(enqueue(3)))(es)
        _ <- delay(enqueue(4))
        _ <- fork(now(enqueue(5)))(es)
        _ <- now(enqueue(6))
        _ <- fork(delay(enqueue(7)))(es)

      } yield ()).unsafePerformAsync(_ => {
        enqueue(8)
        sync.put(true)
      })
      enqueue(9)

      sync.get(5000) must_== Some(true)

      val runned = q.toList

      //trampoline should be evaluated at the head before anything else gets evaluated
      runned(0) must_== (1,current)
      runned(1) must_== (2,current)

      //the after async must not be the last ever
      (runned.last._1 != 9) must_==(true)

      //the rest of tasks must be run off the forked thread
      runned.filter(_._2 == forked).map(_._1) must_== List(3,4,5,6,7,8)

    }

    "complete even when interrupted" in {
      val t = Task.fork(Task.delay(Thread.sleep(3000)))
      val sync = new SyncVar[Throwable\/Unit]
      val interrupt = t.unsafePerformAsyncInterruptibly(sync.put)
      Thread.sleep(1000)
      interrupt()
      sync.get(3000) == Some(left(Task.TaskInterrupted))
    }

  }
}