/**
 * Copyright (C) 2007 - 2016 52°North Initiative for Geospatial Open Source
 * Software GmbH
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published
 * by the Free Software Foundation.
 *
 * If the program is linked with libraries which are licensed under one of
 * the following licenses, the combination of the program with the linked
 * library is not considered a "derivative work" of the program:
 *
 *       • Apache License, version 2.0
 *       • Apache Software License, version 1.0
 *       • GNU Lesser General Public License, version 3
 *       • Mozilla Public License, versions 1.0, 1.1 and 2.0
 *       • Common Development and Distribution License (CDDL), version 1.0
 *
 * Therefore the distribution of the program linked with libraries licensed
 * under the aforementioned licenses, is permitted by the copyright holders
 * if the distribution is compliant with both the GNU General Public
 * License version 2 and the aforementioned licenses.
 *
 * 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.
 */
package org.n52.wps.server;

import java.util.ArrayList;


/**
 * @author Matthias Mueller, TU Dresden
 *
 */
public class ProcessIDRegistry {
	
	private static ProcessIDRegistry instance = new ProcessIDRegistry();
	private volatile boolean lock = false;
	private static ArrayList<String> idList = new ArrayList<String>();
	
	private ProcessIDRegistry(){
		//empty private constructor
	}
	
	public static ProcessIDRegistry getInstance(){
		return instance;
	}
	
	public boolean addID(String id){
		while (lock){
			//spin
		}
		try{
			lock = true;
			boolean retval = idList.add(id);
			lock = false;
			return retval;
		}
		finally{
			lock = false;
		}
	}
	
	public synchronized boolean removeID(String id){
		while (lock){
			//spin
		}
		try{
			lock = true;
			boolean retval = idList.remove(id);
			lock = false;
			return retval;
		}
		finally{
			lock = false;
		}
	}
	
	public boolean containsID(String id){
		return idList.contains(id);
	}
	
	public String[] getIDs(){
		return idList.toArray(new String[idList.size()]);
	}
	
	protected void clearRegistry(){
		while (lock){
			//spin
		}
		try{
			lock = true;
			idList.clear();
			lock = false;
		}
		finally{
			lock = false;
		}
	}
}