/*
 * %W% %E%
 *
 * Copyright (c) 2006, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */

package sun.misc;

/**
 * The request processor allows functors (Request instances) to be created
 * in arbitrary threads, and to be posted for execution in a non-restricted
 * thread.
 *
 * @version     %I%, %G%
 * @author  Steven B. Byrne
 */


public class RequestProcessor implements Runnable {

    private static Queue requestQueue;
    private static Thread dispatcher;

    /**
     * Queues a Request instance for execution by the request procesor
     * thread.
     */
    public static void postRequest(Request req) {
    lazyInitialize();
    requestQueue.enqueue(req);
    }

    /**
     * Process requests as they are queued.
     */
    public void run() {
    lazyInitialize();
    while (true) {
        try {
        Object obj = requestQueue.dequeue();
        if (obj instanceof Request) { // ignore bogons
            Request req = (Request)obj;
            try {
            req.execute();
            } catch (Throwable t) {
            // do nothing at the moment...maybe report an error
            // in the future
            }
        }
        } catch (InterruptedException e) {
        // do nothing at the present time.
        }
    }
    }


    /**
     * This method initiates the request processor thread.  It is safe
     * to call it after the thread has been started.  It provides a way for
     * clients to deliberately control the context in which the request
     * processor thread is created
     */
    public static synchronized void startProcessing() {
    if (dispatcher == null) {
        dispatcher = new Thread(new RequestProcessor(), "Request Processor");
        dispatcher.setPriority(Thread.NORM_PRIORITY + 2);
        dispatcher.start();
    }   
    }


    /**
     * This method performs lazy initialization.
     */
    private static synchronized void lazyInitialize() {
    if (requestQueue == null) {
        requestQueue = new Queue();
    }
    }

}