1 /*
   2  * Copyright (c) 1996, 2011, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 package sun.misc;
  27 
  28 /**
  29  * The request processor allows functors (Request instances) to be created
  30  * in arbitrary threads, and to be posted for execution in a non-restricted
  31  * thread.
  32  *
  33  * @author      Steven B. Byrne
  34  */
  35 
  36 
  37 public class RequestProcessor implements Runnable {
  38 
  39     private static Queue<Request> requestQueue;
  40     private static Thread dispatcher;
  41 
  42     /**
  43      * Queues a Request instance for execution by the request procesor
  44      * thread.
  45      */
  46     public static void postRequest(Request req) {
  47         lazyInitialize();
  48         requestQueue.enqueue(req);
  49     }
  50 
  51     /**
  52      * Process requests as they are queued.
  53      */
  54     public void run() {
  55         lazyInitialize();
  56         while (true) {
  57             try {
  58                 Request req = requestQueue.dequeue();
  59                 try {
  60                     req.execute();
  61                 } catch (Throwable t) {
  62                     // do nothing at the moment...maybe report an error
  63                     // in the future
  64                 }
  65             } catch (InterruptedException e) {
  66                 // do nothing at the present time.
  67             }
  68         }
  69     }
  70 
  71 
  72     /**
  73      * This method initiates the request processor thread.  It is safe
  74      * to call it after the thread has been started.  It provides a way for
  75      * clients to deliberately control the context in which the request
  76      * processor thread is created
  77      */
  78     public static synchronized void startProcessing() {
  79         if (dispatcher == null) {
  80             dispatcher = new ManagedLocalsThread(new RequestProcessor(), "Request Processor");
  81             dispatcher.setPriority(Thread.NORM_PRIORITY + 2);
  82             dispatcher.start();
  83         }
  84     }
  85 
  86 
  87     /**
  88      * This method performs lazy initialization.
  89      */
  90     private static synchronized void lazyInitialize() {
  91         if (requestQueue == null) {
  92             requestQueue = new Queue<Request>();
  93         }
  94     }
  95 
  96 }
--- EOF ---