ScriptingLock.java

/**
 *  OpenKM, Open Document Management System (http://www.openkm.com)
 *  Copyright (c) 2006-2011  Paco Avila & Josep Llort
 *
 *  No bytes were intentionally harmed during the development of this application.
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *  
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License along
 *  with this program; if not, write to the Free Software Foundation, Inc.,
 *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

package com.openkm.util;

/**
 * Lock
 * 
 * @author jllort
 */
public class ScriptingLock {
	private static ScriptingLock instance = new ScriptingLock();
	
	boolean isLocked = false;
	Thread lockedBy = null;
	int lockedCount = 0;
	
	/**
	 * getInstance
	 */
	public static ScriptingLock getInstance() {
		return instance;
	}

	/**
	 * lock
	 */
	public synchronized void lock() throws InterruptedException {
		Thread callingThread = Thread.currentThread();
		
	    while(isLocked) {
	    	wait();
	    }
	    
	    isLocked = true;
	    lockedCount++;
	    lockedBy = callingThread;
	}

	/**
	 * unlock
	 */
	public synchronized void unlock() {
	    if(Thread.currentThread() == this.lockedBy) {
	    	lockedCount--;
	
	    	if(lockedCount == 0) {
	    		isLocked = false;
	    		notify();
	    	}
	    }
	}
}