/*
 * Copyright (C) 2010 Teleal GmbH, Switzerland
 *
 * This program 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 3 of
 * the License, or (at your option) any later version.
 *
 * This program 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 program.  If not, see <http://www.gnu.org/licenses/>.
 */
package org.teleal.common.util;

import java.lang.management.ManagementFactory;
import java.lang.management.ThreadMXBean;

/**
 * @author Christian Bauer
 */
public class Threads {

    public static ThreadGroup getRootThreadGroup() {
        ThreadGroup tg = Thread.currentThread().getThreadGroup();
        ThreadGroup ptg;
        while ((ptg = tg.getParent()) != null)
            tg = ptg;
        return tg;
    }

    public static Thread[] getAllThreads() {
        final ThreadGroup root = getRootThreadGroup();
        final ThreadMXBean thbean = ManagementFactory.getThreadMXBean();
        int nAlloc = thbean.getThreadCount();
        int n = 0;
        Thread[] threads;
        do {
            nAlloc *= 2;
            threads = new Thread[nAlloc];
            n = root.enumerate(threads, true);
        } while (n == nAlloc);
        return java.util.Arrays.copyOf(threads, n);
    }

    public static Thread getThread(final long id) {
        final Thread[] threads = getAllThreads();
        for (Thread thread : threads)
            if (thread.getId() == id)
                return thread;
        return null;
    }

}
