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/*
* This library is part of OpenCms -
* the Open Source Content Management System
*
* Copyright (c) Alkacon Software GmbH (http://www.alkacon.com)
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* For further information about Alkacon Software, please see the
* company website: http://www.alkacon.com
*
* For further information about OpenCms, please see the
* project website: http://www.opencms.org
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
package org.opencms.gwt.client;
import com.google.gwt.core.client.Scheduler;
import com.google.gwt.core.client.Scheduler.RepeatingCommand;
import com.google.gwt.user.client.rpc.AsyncCallback;
import com.google.gwt.user.client.rpc.StatusCodeException;
/**
* A timer which sends an RPC call regularly to keep the session alive.
*
* @since 8.0.0
*/
public class CmsPingTimer {
/**
* The interval for the RPC calls.
*/
public static final int PING_INTERVAL = 1000 * 60 * 5;
/**
* The static instance.
*/
private static CmsPingTimer INSTANCE;
/** Flag indicating if the ping timer should keep running. */
private static boolean m_keepRunning;
/**
* Aborts the ping timer.
*/
public static void abort() {
m_keepRunning = false;
}
/**
* Starts the timer.
*/
public static void start() {
if (!CmsCoreProvider.get().isKeepAlive()) {
return;
}
if (INSTANCE == null) {
m_keepRunning = true;
CmsPingTimer timer = new CmsPingTimer();
timer.run();
INSTANCE = timer;
}
}
/**
* Returns if the ping timer should keep running.
*
* @return true if the ping timer should keep running
*/
protected static boolean shouldKeepRunning() {
return m_keepRunning;
}
/**
* Installs the timer which fires the RPC calls.
*/
protected void run() {
Scheduler.get().scheduleFixedDelay(new RepeatingCommand() {
public boolean execute() {
if (CmsPingTimer.shouldKeepRunning()) {
CmsCoreProvider.getService().ping(new AsyncCallback() {
public void onFailure(Throwable caught) {
// in case of a status code exception abort, indicates the session is no longer valid
if ((caught instanceof StatusCodeException)
&& (((StatusCodeException)caught).getStatusCode() == 500)) {
CmsPingTimer.abort();
}
}
public void onSuccess(Void result) {
//do nothing
}
});
return true;
}
return false;
}
},
PING_INTERVAL);
}
}