Copyright (c) 2003, 2012 IBM Corporation and others.
This program and the accompanying materials
are made available under the terms of the Eclipse Public License 2.0
which accompanies this distribution, and is available at
https://www.eclipse.org/legal/epl-2.0/
SPDX-License-Identifier: EPL-2.0
Contributors:
    IBM Corporation - initial API and implementation
    James Blackburn (Broadcom Corp.) - Bug 311863 Ordered Lock lost after interrupt
/*******************************************************************************
 * Copyright (c) 2003, 2012 IBM Corporation and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *     James Blackburn (Broadcom Corp.) - Bug 311863 Ordered Lock lost after interrupt
 *******************************************************************************/
package org.eclipse.core.internal.jobs;

import java.util.Objects;

public class Semaphore {
	protected long notifications;
	protected Runnable runnable;

	public Semaphore(Runnable runnable) {
		this.runnable = runnable;
		notifications = 0;
	}

	
Attempts to acquire this semaphore.  Returns true if it was successfully acquired,
and false otherwise.
/**
	 * Attempts to acquire this semaphore.  Returns true if it was successfully acquired,
	 * and false otherwise.
	 */
	public synchronized boolean acquire(long delay) throws InterruptedException {
		if (Thread.interrupted())
			throw new InterruptedException();
		long start = System.currentTimeMillis();
		long timeLeft = delay;
		while (true) {
			if (notifications > 0) {
				notifications--;
				return true;
			}
			if (timeLeft <= 0)
				return false;
			wait(timeLeft);
			timeLeft = start + delay - System.currentTimeMillis();
		}
	}

	
Attempt to acquire the semaphore without waiting.
Returns true if successfully acquired, false otherwise.
/**
	 * Attempt to acquire the semaphore without waiting.
	 * Returns true if successfully acquired, false otherwise.
	 */
	public synchronized boolean attempt() {
		if (notifications > 0) {
			notifications--;
			return true;
		}
		return false;
	}

	@Override
	public boolean equals(Object obj) {
		if (obj == null) {
			return false;
		}
		if (!(obj instanceof Semaphore)) {
			return false;
		}
		return (runnable == ((Semaphore) obj).runnable);
	}

	@Override
	public int hashCode() {
		return Objects.hashCode(runnable);
	}

	public synchronized void release() {
		notifications++;
		notifyAll();
	}

	// for debug only
	@Override
	public String toString() {
		return "Semaphore(" + runnable + ")"; //$NON-NLS-1$ //$NON-NLS-2$
	}
}