001/*
002 * jPOS Project [http://jpos.org]
003 * Copyright (C) 2000-2026 jPOS Software SRL
004 *
005 * This program is free software: you can redistribute it and/or modify
006 * it under the terms of the GNU Affero General Public License as
007 * published by the Free Software Foundation, either version 3 of the
008 * License, or (at your option) any later version.
009 *
010 * This program is distributed in the hope that it will be useful,
011 * but WITHOUT ANY WARRANTY; without even the implied warranty of
012 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
013 * GNU Affero General Public License for more details.
014 *
015 * You should have received a copy of the GNU Affero General Public License
016 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
017 */
018
019package org.jpos.q2.qbean;
020
021import java.io.IOException;
022import java.net.ServerSocket;
023
024import org.jpos.core.Configuration;
025import org.jpos.core.ConfigurationException;
026import org.jpos.q2.QBeanSupport;
027
028/**
029 * QBean that enforces a single live Q2 instance by binding a configured TCP
030 * port at startup; a second instance fails to start when the port is taken.
031 */
032public class QSingleInstancePortBasedManager extends QBeanSupport {
033    /** Default constructor; no instance state to initialise. */
034    public QSingleInstancePortBasedManager() {}
035
036    ServerSocket ss;
037
038    int          port;
039
040    /*
041     * (non-Javadoc)
042     *
043     * @see org.jpos.q2.QBeanSupport#initService()
044     */
045    @Override
046    protected void initService() throws Exception {
047
048        try {
049            // attempt to bind, if another instance is already bound, an
050            // exception will get throwm
051            ss = new ServerSocket(port);
052        }
053        catch (IOException e) {
054            getLog().error("An instance of Q2 is already running. Shutting this instance");
055            getServer().shutdown();
056        }
057
058    }
059
060    @Override
061    public void setConfiguration(Configuration cfg) throws ConfigurationException {
062
063        super.setConfiguration(cfg);
064
065        port = cfg.getInt("port", 65000);
066    }
067
068}