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 }