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From bugzi...@apache.org
Subject DO NOT REPLY [Bug 5125] New: - [PATCH] Execute.java now registers forked processes so they are destroyed when VM exits (i.e. ctrl-C)
Date Tue, 27 Nov 2001 14:09:00 GMT
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http://nagoya.apache.org/bugzilla/show_bug.cgi?id=5125

[PATCH] Execute.java now registers forked processes so they are destroyed when VM exits (i.e.
ctrl-C)

           Summary: [PATCH] Execute.java now registers forked processes so
                    they are destroyed when VM exits (i.e. ctrl-C)
           Product: Ant
           Version: 1.4.1
          Platform: PC
        OS/Version: Windows NT/2K
            Status: NEW
          Severity: Normal
          Priority: Other
         Component: Core tasks
        AssignedTo: ant-dev@jakarta.apache.org
        ReportedBy: mnewcomb@tacintel.com


When you fork off processes in Ant, they don't get notified when Ant is 
destroyed (via a ctrl-C for instance).  This patch registers a shutdown hook 
(if Runtime.addShutdownHook() is available, it is in post JDK 1.3 VMs) that 
destroys all processes that have been registered with it.  After the process 
finishes, it is removed from the list.  This then allows any shutdown hooks 
that the execed process has registered to be run.

new file: org/apache/tools/ant/taskdefs/ProcessDestroyer.java:

/*
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2000 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.Collections;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;

/**
 * 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 Set processes = Collections.synchronizedSet(new HashSet());

  /**
   * 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)
  {
    return processes.add(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.remove(process);
  }

  /**
   * Invoked by the VM when it is exiting.
   */
  public void run()
  {
    synchronized(processes)
    {
      Iterator i = processes.iterator();
      while (i.hasNext())
      {
        ((Process) i.next()).destroy();
      }
    }
  }
}


patch to org/apache/tools/ant/taskdefs/Execute.java:

--- Execute.java.orig	Fri Oct 12 00:58:28 2001
+++ Execute.java	Wed Nov 21 15:35:59 2001
@@ -97,6 +97,9 @@
     private static CommandLauncher shellLauncher = null;
     private static Vector procEnvironment = null;
 
+    /** Used to destroy processes when the VM exits. */
+    private static ProcessDestroyer processDestroyer = new ProcessDestroyer();
+
     /** 
      * Builds a command launcher for the OS and JVM we are running under
      */
@@ -391,8 +394,18 @@
             throw e;
         }
         streamHandler.start();
+
+        // add the process to the list of those to destroy if the VM exits
+        //
+        processDestroyer.add(process);
+
         if (watchdog != null) watchdog.start(process);
         waitFor(process);
+
+        // remove the process to the list of those to destroy if the VM exits
+        //
+        processDestroyer.remove(process);
+
         if (watchdog != null) watchdog.stop();
         streamHandler.stop();
         if (watchdog != null) watchdog.checkException();

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