org.eclipse.swt.internal.Lock Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of org.eclipse.swt.gtk.linux.ppc64 Show documentation

SWT is an open source widget toolkit for Java designed to provide efficient, portable access to the user-interface facilities of the operating systems on which it is implemented.

The newest version!

/*******************************************************************************
 * Copyright (c) 2000, 2011 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.swt.internal;

/**
 * Instances of this represent a recursive monitor.
 */
public class Lock {
	int count, waitCount;
	Thread owner;

/**
 * Locks the monitor and returns the lock count. If
 * the lock is owned by another thread, wait until
 * the lock is released.
 * 
 * @return the lock count
 */
public int lock() {
	synchronized (this) {
		Thread current = Thread.currentThread();
		if (owner != current) {
			waitCount++;
			while (count > 0) {
				try {
					wait();
				} catch (InterruptedException e) {
					/* Wait forever, just like synchronized blocks */
				}
			}
			--waitCount;
			owner = current;
		}
		return ++count;
	}
}

/**
 * Unlocks the monitor. If the current thread is not
 * the monitor owner, do nothing.
 */
public void unlock() {
	synchronized (this) {
		Thread current = Thread.currentThread();
		if (owner == current) {
			if (--count == 0) {
				owner = null;
				if (waitCount > 0) notifyAll();
			}
		}
	}
}
}