org.eclipse.jetty.util.thread.ShutdownThread Maven / Gradle / Ivy
// ========================================================================
// Copyright (c) 2009-2009 Mort Bay Consulting Pty. Ltd.
// ------------------------------------------------------------------------
// All rights reserved. This program and the accompanying materials
// are made available under the terms of the Eclipse Public License v1.0
// and Apache License v2.0 which accompanies this distribution.
// The Eclipse Public License is available at
// http://www.eclipse.org/legal/epl-v10.html
// The Apache License v2.0 is available at
// http://www.opensource.org/licenses/apache2.0.php
// You may elect to redistribute this code under either of these licenses.
// ========================================================================
package org.eclipse.jetty.util.thread;
import java.util.Arrays;
import java.util.List;
import java.util.concurrent.CopyOnWriteArrayList;
import org.eclipse.jetty.util.component.LifeCycle;
import org.eclipse.jetty.util.log.Log;
import org.eclipse.jetty.util.log.Logger;
/* ------------------------------------------------------------ */
/**
* ShutdownThread is a shutdown hook thread implemented as
* singleton that maintains a list of lifecycle instances
* that are registered with it and provides ability to stop
* these lifecycles upon shutdown of the Java Virtual Machine
*/
public class ShutdownThread extends Thread
{
private static final Logger LOG = Log.getLogger(ShutdownThread.class);
private static final ShutdownThread _thread = new ShutdownThread();
private boolean _hooked;
private final List _lifeCycles = new CopyOnWriteArrayList();
/* ------------------------------------------------------------ */
/**
* Default constructor for the singleton
*
* Registers the instance as shutdown hook with the Java Runtime
*/
private ShutdownThread()
{
}
/* ------------------------------------------------------------ */
private synchronized void hook()
{
try
{
if (!_hooked)
Runtime.getRuntime().addShutdownHook(this);
_hooked=true;
}
catch(Exception e)
{
LOG.ignore(e);
LOG.info("shutdown already commenced");
}
}
/* ------------------------------------------------------------ */
private synchronized void unhook()
{
try
{
_hooked=false;
Runtime.getRuntime().removeShutdownHook(this);
}
catch(Exception e)
{
LOG.ignore(e);
LOG.info("shutdown already commenced");
}
}
/* ------------------------------------------------------------ */
/**
* Returns the instance of the singleton
*
* @return the singleton instance of the {@link ShutdownThread}
*/
public static ShutdownThread getInstance()
{
return _thread;
}
/* ------------------------------------------------------------ */
public static synchronized void register(LifeCycle... lifeCycles)
{
_thread._lifeCycles.addAll(Arrays.asList(lifeCycles));
if (_thread._lifeCycles.size()>0)
_thread.hook();
}
/* ------------------------------------------------------------ */
public static synchronized void register(int index, LifeCycle... lifeCycles)
{
_thread._lifeCycles.addAll(index,Arrays.asList(lifeCycles));
if (_thread._lifeCycles.size()>0)
_thread.hook();
}
/* ------------------------------------------------------------ */
public static synchronized void deregister(LifeCycle lifeCycle)
{
_thread._lifeCycles.remove(lifeCycle);
if (_thread._lifeCycles.size()==0)
_thread.unhook();
}
/* ------------------------------------------------------------ */
@Override
public void run()
{
for (LifeCycle lifeCycle : _thread._lifeCycles)
{
try
{
lifeCycle.stop();
LOG.debug("Stopped " + lifeCycle);
}
catch (Exception ex)
{
LOG.debug(ex);
}
}
}
}