path: root/src/library/scala/concurrent/SyncChannel.scala

/*                     __                                               *\
**     ________ ___   / /  ___     Scala API                            **
**    / __/ __// _ | / /  / _ |    (c) 2003-2006, LAMP/EPFL             **
**  __\ \/ /__/ __ |/ /__/ __ |                                         **
** /____/\___/_/ |_/____/_/ | |                                         **
**                          |/                                          **
\*                                                                      */

// $Id$


package scala.concurrent;


class SyncChannel[a] {
  private var data: a = _;
  private var reading = false;
  private var writing = false;

  def await(cond: => Boolean) = while (!cond) { wait() }

  def write(x: a) = synchronized {
    await(!writing);
    data = x;
    writing = true;
    if (reading) notifyAll();
    else await(reading)
  }

  def read: a = synchronized {
    await(!reading);
    reading = true;
    await(writing);
    val x = data;
    writing = false;
    reading = false;
    notifyAll();
    x
  }
}