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Scala example source code file (TerminationMonitor.scala)

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

Java - Scala tags/keywords

boolean, boolean, hashmap, ischeduler, none, none, some, terminationmonitor, trackedreactor, trackedreactor, unit, unit

The Scala TerminationMonitor.scala source code

/*                     __                                               *\
**     ________ ___   / /  ___     Scala API                            **
**    / __/ __// _ | / /  / _ |    (c) 2005-2011, LAMP/EPFL             **
**  __\ \/ /__/ __ |/ /__/ __ |    http://scala-lang.org/               **
** /____/\___/_/ |_/____/_/ | |                                         **
**                          |/                                          **
\*                                                                      */


package scala.actors
package scheduler

import scala.collection.mutable.HashMap

private[scheduler] trait TerminationMonitor {
  _: IScheduler =>

  protected var activeActors = 0
  protected val terminationHandlers = new HashMap[TrackedReactor, () => Unit]
  private var started = false

  /** newActor is invoked whenever a new actor is started. */
  def newActor(a: TrackedReactor) = synchronized {
    activeActors += 1
    if (!started)
      started = true
  }

  /** Registers a closure to be executed when the specified
   *  actor terminates.
   * 
   *  @param  a  the actor
   *  @param  f  the closure to be registered
   */
  def onTerminate(a: TrackedReactor)(f: => Unit): Unit = synchronized {
    terminationHandlers += (a -> (() => f))
  }

  /** Registers that the specified actor has terminated.
   *
   *  @param  a  the actor that has terminated
   */
  def terminated(a: TrackedReactor) = {
    // obtain termination handler (if any)
    val todo = synchronized {
      terminationHandlers.get(a) match {
        case Some(handler) =>
          terminationHandlers -= a
          handler
        case None =>
          () => { /* do nothing */ }
      }
    }

    // invoke termination handler (if any)
    todo()

    synchronized {
      activeActors -= 1
    }
  }

  /** Checks whether all actors have terminated. */
  private[actors] def allActorsTerminated: Boolean = synchronized {
    started && activeActors <= 0
  }
  
  /** Deprecated non-actor-private version */
  @deprecated("this method is going to be removed in a future release", "2.7.7")
  def allTerminated: Boolean = allActorsTerminated

  /** Checks for actors that have become garbage. */
  protected def gc() {}
}

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