/*
* RHQ Management Platform
* Copyright (C) 2005-2013 Red Hat, Inc.
* All rights reserved.
*
* 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 version 2 of the License.
*
* 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 org.rhq.plugins.database;
import java.sql.Driver;
import java.sql.DriverManager;
import java.util.Enumeration;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.rhq.core.pluginapi.plugin.PluginContext;
import org.rhq.core.pluginapi.plugin.PluginLifecycleListener;
import org.rhq.core.util.exception.ThrowableUtil;
/**
* This is a plugin lifecycle listener object for database plugins. It is used to
* deregister any JDBC drivers that happened to have been
* cached by the plugin. This is needed to avoid leaking perm gen
* memory when a plugin's classloader is destroyed because
* java.sql.DriverManager will maintain references that prevent the
* plugin's classloader and its resources from being garbaged collected.
*
* All database plugins should have their own class that does this but
* due to the odd way java.sql.DriverManager caches drivers, plugins that
* extend the database plugin cannot simply reuse or subclass this object.
*
* @author John Mazzitelli
*/
public class DatabasePluginLifecycleListener implements PluginLifecycleListener {
private final Log log = LogFactory.getLog(DatabasePluginLifecycleListener.class);
public void initialize(PluginContext context) throws Exception {
// no-op
}
public void shutdown() {
// so we do not cause our classloader to leak perm gen, we need to de-register
// any and all JDBC drivers this plugin registered
Enumeration<Driver> drivers = DriverManager.getDrivers();
while (drivers.hasMoreElements()) {
try {
Driver driver = drivers.nextElement();
DriverManager.deregisterDriver(driver);
log.debug("Deregistered JDBC driver: " + driver.getClass());
} catch (Exception e) {
log.warn("Failed to deregister JDBC drivers - memory might leak" + ThrowableUtil.getAllMessages(e));
}
}
log.debug(this.getClass().getSimpleName() + " completed shutdown.");
return;
}
}