Scala example source code file (BooleanLatch.scala)

This example Scala source code file (BooleanLatch.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.

Learn more about this Scala project at its project page.

Java - Scala tags/keywords

abstractqueuedsynchronizer, booleanlatch, int, released, threading, threads, unavailable, unit

The BooleanLatch.scala Scala example source code

package scalaz.concurrent

import java.util.concurrent._
import locks._

trait BooleanLatch {
  def release(): Boolean
  def await(): Unit
}

object BooleanLatch {
  def apply() = new BooleanLatch {
    val sync = new AbstractQueuedSynchronizer {
      val RELEASED = 0
      val UNAVAILABLE = -1

      setState(UNAVAILABLE)

      def released = getState == RELEASED
      def unavailable = getState == UNAVAILABLE

      override def tryAcquire(ignore: Int) =
        if (!released) false
        else compareAndSetState(RELEASED, UNAVAILABLE)

      override def tryRelease(ignore: Int) = {
        if (unavailable) setState(RELEASED)
        true
      }
    }

    override def release() = sync release 0
    override def await() = sync acquireInterruptibly 0
  }
}