/*
* $Id$
*
* Copyright (C) 2003-2014 JNode.org
*
* 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.
*
* 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.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
package org.jnode.command.system;
import java.io.PrintWriter;
import org.jnode.shell.AbstractCommand;
import org.jnode.shell.syntax.Argument;
import org.jnode.shell.syntax.FlagArgument;
import org.jnode.shell.syntax.IntegerArgument;
/**
* @author Andreas H\u00e4nel
* @author crawley@jnode.org
*/
public class KillCommand extends AbstractCommand {
private static final String help_tid = "the id of the thread to kill";
private static final String help_debug = "if set, print debug information";
private static final String help_super = "Kill the thread with the supplied ID";
private static final String fmt_prep_kill = "Preparing to kill thread with ID(%d)%n";
private static final String str_found = "Found the Thread: ";
private static final String fmt_killed = "Killed thread %d%n";
private static final String fmt_not_found = "Thread %d not found%n";
private final IntegerArgument argThreadID;
private final FlagArgument argDebug;
public KillCommand() {
super(help_super);
argThreadID = new IntegerArgument("threadId", Argument.MANDATORY, help_tid);
argDebug = new FlagArgument("debug", Argument.OPTIONAL, help_debug);
registerArguments(argThreadID, argDebug);
}
public static void main(String[] args) throws Exception {
new KillCommand().execute(args);
}
@SuppressWarnings("deprecation")
public void execute() throws Exception {
PrintWriter out = getError().getPrintWriter();
boolean debug = argDebug.isSet();
int threadId = argThreadID.getValue();
if (debug) {
out.format(fmt_prep_kill, threadId);
}
// In order to kill the thread, we need to traverse the thread group tree, looking
// for the thread whose 'id' matches the supplied one. First, find the tree root.
ThreadGroup grp = Thread.currentThread().getThreadGroup();
while (grp.getParent() != null) {
grp = grp.getParent();
}
// Next search the tree
Thread t = findThread(grp, threadId);
// Finally, kill the thread if we found one.
if (t != null) {
if (debug) {
out.print(str_found);
}
out.println(threadId);
// FIXME ... this is bad. Killing a thread this way could in theory bring down the
// entire system if we do it at a point where the application thread is executing
// a method that is updating OS data structures.
t.stop(new ThreadDeath());
out.format(fmt_killed, threadId);
} else {
out.format(fmt_not_found, threadId);
exit(1);
}
}
/**
* Search thread group 'grp' and its dependents groups for a given thread.
* @param grp the thread group to search
* @param id the id of the thread we are looking for
* @return the Thread found or <code>null</code>
*/
private Thread findThread(ThreadGroup grp, int id) {
// Search the current thread group
final int max = grp.activeCount() * 2;
final Thread[] ts = new Thread[max];
grp.enumerate(ts);
for (int i = 0; i < max; i++) {
final Thread t = ts[i];
if (t != null) {
if (t.getId() == id) {
return t;
}
}
}
// Recursively search the child thread groups
final int gmax = grp.activeGroupCount() * 2;
final ThreadGroup[] tgs = new ThreadGroup[gmax];
grp.enumerate(tgs);
for (int i = 0; i < gmax; i++) {
final ThreadGroup tg = tgs[i];
if (tg != null) {
Thread t = findThread(tg, id);
if (t != null) {
return t;
}
}
}
// Didn't find it here
return null;
}
}