ThreadUtil.java

/*
 * JBoss, Home of Professional Open Source
 * Copyright 2006, Red Hat Middleware LLC, and individual contributors 
 * as indicated by the @author tags. 
 * See the copyright.txt in the distribution for a
 * full listing of individual contributors. 
 * This copyrighted material is made available to anyone wishing to use,
 * modify, copy, or redistribute it subject to the terms and conditions
 * of the GNU Lesser General Public License, v. 2.1.
 * This program is distributed in the hope that it will be useful, but WITHOUT A 
 * 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,
 * v.2.1 along with this distribution; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, 
 * MA  02110-1301, USA.
 * 
 * (C) 2005-2006,
 * @author JBoss Inc.
 */
package com.arjuna.ats.arjuna.utils;

import java.util.WeakHashMap;
import java.util.concurrent.atomic.AtomicLong;

/**
 * Provides utilities to manage thread ids.
 */
public class ThreadUtil
{
    /**
     * The ID associated with the thread.
     */
    private static final WeakHashMap<Thread,String> THREAD_ID = new WeakHashMap<Thread,String>() ;
    /**
     * The thread id counter.
     */
    private static AtomicLong id = new AtomicLong();
    
    /**
     * Get the string ID for the current thread.
     * @return The thread id
     */
    public static String getThreadId()
    {
	return getThreadId(Thread.currentThread()) ;
    }
    
    /**
     * Get the string ID for the specified thread.
     * @param thread The thread.
     * @return The thread id
     */
    public static synchronized String getThreadId(final Thread thread)
    {
	final String id = THREAD_ID.get(thread) ;
	if (id != null)
	{
	    return id ;
	}
	
	final String newId = getNextId() ;
	THREAD_ID.put(thread,newId) ;
	return newId ;
    }
    
    /**
     * Get the next thread id to use.
     * @return The next thread id.
     */
    private static String getNextId()
    {
	return Long.toHexString(id.incrementAndGet()) ;
    }
}