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Java > Open Source Codes > org > netbeans > mdr > util > RWMutex


1 /*
2  * The contents of this file are subject to the terms of the Common Development
3  * and Distribution License (the License). You may not use this file except in
4  * compliance with the License.
5  *
6  * You can obtain a copy of the License at http://www.netbeans.org/cddl.html
7  * or http://www.netbeans.org/cddl.txt.
8  *
9  * When distributing Covered Code, include this CDDL Header Notice in each file
10  * and include the License file at http://www.netbeans.org/cddl.txt.
11  * If applicable, add the following below the CDDL Header, with the fields
12  * enclosed by brackets [] replaced by your own identifying information:
13  * "Portions Copyrighted [year] [name of copyright owner]"
14  *
15  * The Original Software is NetBeans. The Initial Developer of the Original
16  * Software is Sun Microsystems, Inc. Portions Copyright 1997-2006 Sun
17  * Microsystems, Inc. All Rights Reserved.
18  */
19 package org.netbeans.mdr.util;
20
21 import java.util.LinkedList JavaDoc;
22 import java.util.WeakHashMap JavaDoc;
23
24 /**
25  *
26  * @author Martin Matula
27  * @version
28  */
29 public class RWMutex {
30     private Thread JavaDoc thread = null;
31     private int counter = 0;
32     private final RWMutex dependent;
33
34     /** Creates new Mutex */
35     public RWMutex() {
36         dependent = null;
37     }
38
39     /** Creates new mutex which will lock the provided dependent mutex for reading.
40      * @param dependent mutex that will be locked by this mutex for reading
41      */
42     public RWMutex(RWMutex dependent) {
43         this.dependent = dependent;
44     }
45
46     public synchronized void enter(boolean writer) {
47         Thread JavaDoc thread = Thread.currentThread();
48         while (counter > 0 && this.thread != thread) {
49             try {
50                 this.wait();
51             } catch (InterruptedException JavaDoc e) {
52                 Logger.getDefault().notify(Logger.INFORMATIONAL, e);
53             }
54         }
55         
56         this.thread = thread;
57         counter++;
58         if (dependent != null) dependent.enter(false);
59     }
60     
61     public synchronized void leave() {
62         if (dependent != null) dependent.leave();
63         counter--;
64         this.notifyAll();
65     }
66 }
67
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