public class Engine extends Thread {
    /**
     * Thread pool that sets {@link #CURRENT}.
     */
    private final ExecutorService executor = Executors.newCachedThreadPool(new ThreadFactory() {
        private final ThreadFactory defaultFactory = Executors.defaultThreadFactory();
        public Thread newThread(final Runnable r) {
            Thread t = defaultFactory.newThread(new Runnable() {
                public void run() {
                    CURRENT.set(Engine.this);
                    r.run();
                }
            });
            t.setDaemon(true);
            return t;
        }
    });