/*
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2001 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution, if
 *    any, must include the following acknowlegement:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowlegement may appear in the software itself,
 *    if and wherever such third-party acknowlegements normally appear.
 *
 * 4. The names "The Jakarta Project", "Ant", and "Apache Software
 *    Foundation" must not be used to endorse or promote products derived
 *    from this software without prior written permission. For written
 *    permission, please contact apache@apache.org.
 *
 * 5. Products derived from this software may not be called "Apache"
 *    nor may "Apache" appear in their names without prior written
 *    permission of the Apache Group.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */

package org.apache.tools.ant.taskdefs;

import java.lang.reflect.Method;
import java.util.Enumeration;
import java.util.Vector;

/**
 * Destroys all registered <code>Process</code>es when the VM exits.
 *
 * @author <a href="mailto:mnewcomb@tacintel.com">Michael Newcomb</a>
 */
class ProcessDestroyer
    extends Thread
{

    private Vector processes = new Vector();

    /**
     * Constructs a <code>ProcessDestroyer</code> and registers it as
     * a shutdown hook.
     */
    public ProcessDestroyer()
    {
        try
        {
            // check to see if the method exists (support pre-JDK 1.3 VMs)
            //
            Class[] paramTypes = {Thread.class};
            Method addShutdownHook =
                Runtime.class.getMethod("addShutdownHook", paramTypes);

            // add the hook
            //
            Object[] args = {this};
            addShutdownHook.invoke(Runtime.getRuntime(), args);
        }
        catch (Exception e)
        {
            // it just won't be added as a shutdown hook... :(
        }
    }

    /**
     * Returns <code>true</code> if the specified <code>Process</code> was
     * successfully added to the list of processes to destroy upon VM exit.
     *
     * @param   process the process to add
     * @return  <code>true</code> if the specified <code>Process</code> was
     *          successfully added
     */
    public boolean add(Process process)
    {
        processes.addElement(process);
        return processes.contains(process);
    }

    /**
     * Returns <code>true</code> if the specified <code>Process</code> was
     * successfully removed from the list of processes to destroy upon VM exit.
     *
     * @param   process the process to remove
     * @return  <code>true</code> if the specified <code>Process</code> was
     *          successfully removed
     */
    public boolean remove(Process process)
    {
        return processes.removeElement(process);
    }

    /**
     * Invoked by the VM when it is exiting.
     */
    public void run()
    {
        synchronized(processes)
        {
            Enumeration e = processes.elements();
            while (e.hasMoreElements())
            {
                ((Process) e.nextElement()).destroy();
            }
        }
    }
}
