001/*
002 * GWTEventService
003 * Copyright (c) 2011 and beyond, strawbill UG (haftungsbeschr?nkt)
004 *
005 * This is free software; you can redistribute it and/or modify it
006 * under the terms of the GNU Lesser General Public License as
007 * published by the Free Software Foundation; either version 3 of
008 * the License, or (at your option) any later version.
009 * Other licensing for GWTEventService may also be possible on request.
010 * Please view the license.txt of the project for more information.
011 *
012 * This software is distributed in the hope that it will be useful,
013 * but WITHOUT ANY WARRANTY; without even the implied warranty of
014 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
015 * Lesser General Public License for more details.
016 *
017 * You should have received a copy of the GNU Lesser General Public
018 * License along with this software; if not, write to the Free
019 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
020 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
021 */
022package de.novanic.eventservice.client.event.command.schedule;
023
024/**
025 * The ClientCommandSchedulerFactory is used to create the ClientCommandScheduler and to ensure that only one instance of
026 * ClientCommandSchedulerFactory and ClientCommandScheduler exists (singleton).
027 * @see de.novanic.eventservice.client.event.command.schedule.ClientCommandScheduler
028 *
029 * @author sstrohschein
030 *         <br>Date: 04.04.2009
031 *         <br>Time: 22:26:18
032 */
033public class ClientCommandSchedulerFactory
034{
035    private volatile ClientCommandScheduler myClientCommandScheduler;
036
037    /**
038     * The ClientCommandSchedulerFactory should be created via the getInstance method.
039     * @see ClientCommandSchedulerFactory#getInstance()
040     */
041    private ClientCommandSchedulerFactory() {}
042
043    /**
044     * Factory-Holder class to ensure thread-safe lazy-loading with IODH.
045     */
046    private static class ClientCommandSchedulerFactoryHolder {
047        private static ClientCommandSchedulerFactory INSTANCE = new ClientCommandSchedulerFactory();
048    }
049
050    /**
051     * This method should be used to create an instance of ClientCommandSchedulerFactory.
052     * ClientCommandSchedulerFactory is a singleton, so this method returns always the same instance of
053     * ClientCommandSchedulerFactory.
054     * @return ClientCommandSchedulerFactory (singleton)
055     */
056    public static ClientCommandSchedulerFactory getInstance() {
057        return ClientCommandSchedulerFactoryHolder.INSTANCE;
058    }
059
060    /**
061     * This method should be used to create an instance of RemoteEventService.
062     * RemoteEventService is a singleton, so this method returns always the same instance of RemoteEventService.
063     * The session is needed to generate the client/user id.
064     * @return RemoteEventService (singleton)
065     */
066    public ClientCommandScheduler getClientCommandScheduler() {
067        if(myClientCommandScheduler == null) {
068            synchronized(this) {
069                if(myClientCommandScheduler == null) {
070                    myClientCommandScheduler = new GWTCommandScheduler();
071                }
072            }
073        }
074        return myClientCommandScheduler;
075    }
076
077    /**
078     * Sets an instance of ClientCommandScheduler which is returned by {@link ClientCommandSchedulerFactory#getClientCommandScheduler()}.
079     * @param aClientCommandScheduler {@link ClientCommandScheduler}
080     */
081    public void setClientCommandSchedulerInstance(ClientCommandScheduler aClientCommandScheduler) {
082        myClientCommandScheduler = aClientCommandScheduler;
083    }
084
085    /**
086     * Resets the ClientCommandScheduler instance. 
087     */
088    public void reset() {
089        setClientCommandSchedulerInstance(null);
090    }
091}