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Scala example source code file (SyncVar.scala)
The Scala SyncVar.scala source code/* __ *\ ** ________ ___ / / ___ Scala API ** ** / __/ __// _ | / / / _ | (c) 2003-2011, LAMP/EPFL ** ** __\ \/ /__/ __ |/ /__/ __ | http://scala-lang.org/ ** ** /____/\___/_/ |_/____/_/ | | ** ** |/ ** \* */ package scala.concurrent /** A class to provide safe concurrent access to a mutable cell. * All methods are synchronized. * * @author Martin Odersky * @version 1.0, 10/03/2003 */ class SyncVar[A] { private var isDefined: Boolean = false private var value: A = _ def get = synchronized { while (!isDefined) wait() value } /** Waits `timeout` millis. If `timeout <= 0` just returns 0. If the system clock * went backward, it will return 0, so it never returns negative results. */ private def waitMeasuringElapsed(timeout: Long): Long = if (timeout <= 0) 0 else { val start = System.currentTimeMillis wait(timeout) val elapsed = System.currentTimeMillis - start if (elapsed < 0) 0 else elapsed } /** Waits for this SyncVar to become defined at least for * `timeout` milliseconds (possibly more), and gets its * value. * * @param timeout the amount of milliseconds to wait, 0 means forever * @return `None` if variable is undefined after `timeout`, `Some(value)` otherwise */ def get(timeout: Long): Option[A] = synchronized { /** Defending against the system clock going backward * by counting time elapsed directly. Loop required * to deal with spurious wakeups. */ var rest = timeout while (!isDefined && rest > 0) { val elapsed = waitMeasuringElapsed(rest) rest -= elapsed } if (isDefined) Some(value) else None } def take() = synchronized { try get finally unset() } def set(x: A) = synchronized { value = x isDefined = true notifyAll() } def put(x: A) = synchronized { while (isDefined) wait() set(x) } def isSet: Boolean = synchronized { isDefined } def unset(): Unit = synchronized { isDefined = false notifyAll() } } Other Scala examples (source code examples)Here is a short list of links related to this Scala SyncVar.scala source code file: |
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