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/*******************************************************************************
* 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();
}
}
}
}
}
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