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Java > Open Source Codes > common > MessageQueue


1 /*- MessageQueue.java ---------------------------------------------+
2  | |
3  | Copyright (C) 2002-2003 Joseph Monti, LlamaChat |
4  | countjoe@users.sourceforge.net |
5  | http://www.42llamas.com/LlamaChat/ |
6  | |
7  | This program is free software; you can redistribute it and/or |
8  | modify it under the terms of the GNU General Public License |
9  | as published by the Free Software Foundation; either version 2 |
10  | of the License, or (at your option) any later version |
11  | |
12  | This program is distributed in the hope that it will be useful, |
13  | but WITHOUT ANY WARRANTY; without even the implied warranty of |
14  | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
15  | GNU General Public License for more details. |
16  | |
17  | A copy of the GNU General Public License may be found in the |
18  | installation directory named "GNUGPL.txt" |
19  | |
20  +-----------------------------------------------------------------+
21  */
22
23 package common;
24
25 import java.util.LinkedList JavaDoc;
26
27 /* -------------------- JavaDoc Information ----------------------*/
28 /**
29  * It defines 2 methods, enqueu, to put SocketData items into the internal
30  * Vector, and run, which is requred be Runnable (this is a threaded class)
31  * and grabs any items off the Vector. It uses a combination of wait() and
32  * notify() to keep the run method from polling on an empty queue.
33  * @author Joseph Monti
34  * <a HREF="mailto:countjoe@users.sourceforge.net">countjoe@users.sourceforge.net</a>
35  * @author <a HREF="http://codeconnector.sf.net/">Code Connector</a>
36  * @version 0.8
37  */
38
39 public class MessageQueue implements Runnable JavaDoc {
40     private static final int MAX_SIZE = 15;
41     private LinkedList JavaDoc queue;
42     private SocketConnection writer;
43     private boolean running;
44     private boolean empty;
45     
46     public MessageQueue(SocketConnection w) {
47         writer = w;
48         queue = new LinkedList JavaDoc();
49         running = true;
50         empty = true;
51         new Thread JavaDoc(this).start();
52     }
53     
54     synchronized public boolean enqueue(Object JavaDoc obj) {
55         queue.addLast(obj);
56         if (empty) {
57             empty = false;
58             notify();
59         }
60         if (queue.size() > MAX_SIZE) {
61             writer.close();
62         }
63         return true;
64     }
65     
66     public void run() {
67         while (running) {
68             try {
69                 if (queue.size() != 0) {
70                     writer._writeObject(queue.removeFirst());
71                 } else {
72                     empty = true;
73                     synchronized(this) {
74                         while (empty) {
75                             wait();
76                         }
77                     }
78                 }
79                 Thread.sleep(10);
80             } catch ( InterruptedException JavaDoc inte ) {
81                 running = false;
82             }
83         }
84     }
85 }
86
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