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// 
// ========================================================================
// Copyright (c) 1995-2022 Mort Bay Consulting Pty Ltd and others.
// ------------------------------------------------------------------------
// 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.security.AccessController;
import java.security.PrivilegedAction;
import java.util.Arrays;
import java.util.List;
import java.util.concurrent.CopyOnWriteArrayList;
import org.eclipse.jetty.util.component.Destroyable;
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
 *
 * @deprecated The Eclipse Jetty and Apache Felix Http Jetty packages are no longer supported.
 */
@Deprecated(since = "2021-05-27")
public class ShutdownThread extends Thread {

    private static final Logger LOG = Log.getLogger(ShutdownThread.class);

    private static final ShutdownThread _thread = PrivilegedThreadFactory.newThread(() -> {
        return 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() {
        super("JettyShutdownThread");
    }

    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.debug("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();
    }

    public static synchronized boolean isRegistered(LifeCycle lifeCycle) {
        return _thread._lifeCycles.contains(lifeCycle);
    }

    @Override
    public void run() {
        for (LifeCycle lifeCycle : _thread._lifeCycles) {
            try {
                if (lifeCycle.isStarted()) {
                    lifeCycle.stop();
                    LOG.debug("Stopped {}", lifeCycle);
                }
                if (lifeCycle instanceof Destroyable) {
                    ((Destroyable) lifeCycle).destroy();
                    LOG.debug("Destroyed {}", lifeCycle);
                }
            } catch (Exception ex) {
                LOG.debug(ex);
            }
        }
    }
}