/*
* @(#)Lock.java 1.10 95/09/06
*
* Copyright (c) 1994 Sun Microsystems, Inc. All Rights Reserved.
*
* Permission to use, copy, modify, and distribute this software
* and its documentation for NON-COMMERCIAL purposes and without
* fee is hereby granted provided that this copyright notice
* appears in all copies. Please refer to the file "copyright.html"
* for further important copyright and licensing information.
*
* SUN MAKES NO REPRESENTATIONS OR WARRANTIES ABOUT THE SUITABILITY OF
* THE SOFTWARE, EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
* TO THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
* PARTICULAR PURPOSE, OR NON-INFRINGEMENT. SUN SHALL NOT BE LIABLE FOR
* ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING OR
* DISTRIBUTING THIS SOFTWARE OR ITS DERIVATIVES.
*/
package sun.misc;
/**
* The Lock class provides a simple, useful interface to a lock.
* Unlike monitors which synchronize access to an object, locks
* synchronize access to an arbitrary set of resources (objects,
* methods, variables, etc.). <p>
*
* The programmer using locks must be responsible for clearly defining
* the semantics of their use and should handle deadlock avoidance in
* the face of exceptions. <p>
*
* For example, if you want to protect a set of method invocations with
* a lock, and one of the methods may throw an exception, you must be
* prepared to release the lock similarly to the following example:
* <pre>
* class SomeClass {
* Lock myLock = new Lock();
* void someMethod() {
* myLock.lock();
* try {
* StartOperation();
* ContinueOperation();
* EndOperation();
* } finally {
* myLock.unlock();
* }
* }
* }
* </pre>
*
* @version 1.10, 06 Sep 1995
* @author Peter King
*/
public
class Lock {
private boolean locked = false;
/**
* Create a lock, which is initially not locked.
*/
public Lock () {
}
/**
* Acquire the lock. If someone else has the lock, wait until it
* has been freed, and then try to acquire it again. This method
* will not return until the lock has been acquired.
*/
public final synchronized void lock() throws InterruptedException {
while (locked) {
wait();
}
locked = true;
}
/**
* Release the lock. If someone else is waiting for the lock, the
* will be notitified so they can try to acquire the lock again.
*/
public final synchronized void unlock() {
locked = false;
notifyAll();
}
}