/* ===============================================================================
*
* Part of the InfoGlue Content Management Platform (www.infoglue.org)
*
* ===============================================================================
*
* Copyright (C)
*
* 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. See the file LICENSE.html for more information.
*
* This program is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY, including 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. / 59 Temple
* Place, Suite 330 / Boston, MA 02111-1307 / USA.
*
* ===============================================================================
*/
package org.infoglue.cms.controllers.kernel.impl.simple;
import java.sql.ResultSet;
import org.infoglue.cms.util.ChangeNotificationController;
import org.infoglue.cms.util.NotificationMessage;
/**
* ReplicationController.java
* Created on 2002-okt-30
* @author Stefan Sik, ss@frovi.com
* ss
*
* In this description I use the words Master, Slave and versions
*
* Versions are rows in cmContentVersion and in cmSiteNodeVersion
*
* In this context Slave is synonym with the MySQL database
* running and feeding the deliver1.0 application on the Live Site
* (www.frovi.com)
*
* Master is the MySQL database used by cmstool1.0
*
* Refactoring needed.
* Should implement generic replication interface
* that is used by the tool. This controller is specific
* for mysql and for our current server topology.
*
* Also write another replication implementation that
* uses a simpler replication mechanism, to ensure that
* the interface is generic and complete. (nice to have)
*
*
* Purpose of this controller is to ensure that the replika
* (the Live Database that the deliver engine uses), are
* up to date with the tool database.
*
* But wait, there is more. The replika may NOT contain
* any versions that has state <> 3 and isActive flag <> 1
*
* To fulfill these requirements with our current setup,
* we are going to use the replication mechanism built in to mySQL.
*
* In mySQL repl. The responsibility for syncronizing the slave with the master
* lies on the slave in the form of a thread that runs in mySQL on the slave.
* The slave thread reads from the masters log-bin file and executes the sql
* commands required for updating itself. It's a pull type of arrangement.
*
* We can start and stop this slave thread with sql commands to the slave server.
*
* We are going to solve it like this:
* 1 - Lock the master tables (no updates during sync)
* 1.1 - maybe read lock (if possible) the slave tables
* 2 - Start the slave thread on the slave.
* 3 - Wait for the update to finish.
* 4 - Unlock the master tables.
* 5 - Delete all unwanted rows on the slave.
*
* This solution has one little problem. At one moment we do have working material
* on the slave server. What happens if this controller dies before it deletes the
* unwanted versions. Maybe we should read lock on the slave during update?
* What happens if for some unknown reason the slave-tread starts. There is no
* way (I know of) to filter data that is to be replicated.
*
* Alternate solutions:
* sol 1 - Always run the slave-thread.
* Ensure that the deliver engine only delivers versions with
* the required criterias. Then this controller class would be
* redundant.
*
* sol 2 - On the slave server run a process that check (and deletes) the versions.
* and always run the slave thread. (This class is redundant)
*
* sol 3 - In the tool, on publish, push the wanted versions to a publishing table
* or possibly a publishing database. Then setup slave to replicate only
* that database or tables. Always run the slave thread.
*
*
*
*
* This controller should be called from PublishingController.
*
* References:
* http://www.mysql.com/doc/en/Replication_HOWTO.html
* http://www.mysql.com/doc/en/Replication_SQL.html
* http://www.mysql.com/doc/en/Replication_FAQ.html
*
*
*/
public class ReplicationMySqlController // implements IGenericCmsReplication
{
public static void updateSlaveServer() throws Exception
{
String bin_log = "";
Integer position = new Integer(0);
// Sync the servers
MysqlJDBCService mySql = new MysqlJDBCService();
// If mysql is not setup for replication, dont try it
if(mySql.isEnabled())
{
ResultSet res = mySql.executeMasterSQL("SHOW MASTER STATUS");
if (res.first())
{
bin_log = res.getString("File");
position = new Integer(res.getInt("Position"));
// mySql.executeSlaveSQL("SLAVE START");
mySql.executeSlaveSQL("SELECT MASTER_POS_WAIT('" + bin_log + "', " + position + ")");
// mySql.executeSlaveSQL("SLAVE STOP");
}
mySql.closeMaster();
mySql.closeSlave();
// Expire cache on livesites?
NotificationMessage notificationMessage = new NotificationMessage("ReplicationMySqlController.updateSlaveServer():", NotificationMessage.PUBLISHING_TEXT, "Editor - name unknown", NotificationMessage.PUBLISHING, new Integer(-1), "");
ChangeNotificationController.getInstance().addNotificationMessage(notificationMessage);
}
}
}