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Java > Open Source Codes > org > columba > ristretto > concurrency > Mutex


1 /* ***** BEGIN LICENSE BLOCK *****
2  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
3  *
4  * The contents of this file are subject to the Mozilla Public License Version
5  * 1.1 (the "License"); you may not use this file except in compliance with
6  * the License. You may obtain a copy of the License at
7  * http://www.mozilla.org/MPL/
8  *
9  * Software distributed under the License is distributed on an "AS IS" basis,
10  * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
11  * for the specific language governing rights and limitations under the
12  * License.
13  *
14  * The Original Code is Ristretto Mail API.
15  *
16  * The Initial Developers of the Original Code are
17  * Timo Stich and Frederik Dietz.
18  * Portions created by the Initial Developers are Copyright (C) 2004
19  * All Rights Reserved.
20  *
21  * Contributor(s):
22  *
23  * Alternatively, the contents of this file may be used under the terms of
24  * either the GNU General Public License Version 2 or later (the "GPL"), or
25  * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
26  * in which case the provisions of the GPL or the LGPL are applicable instead
27  * of those above. If you wish to allow use of your version of this file only
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29  * use your version of this file under the terms of the MPL, indicate your
30  * decision by deleting the provisions above and replace them with the notice
31  * and other provisions required by the GPL or the LGPL. If you do not delete
32  * the provisions above, a recipient may use your version of this file under
33  * the terms of any one of the MPL, the GPL or the LGPL.
34  *
35  * ***** END LICENSE BLOCK ***** */
36 package org.columba.ristretto.concurrency;
37
38 /**
39  * A simple Mutex implementation.
40  *
41  * @author Timo Stich <tstich@users.sourceforge.net>
42  */
43 public class Mutex {
44     private boolean mutex;
45
46     /**
47      * Constructs the Mutex.
48      *
49      */
50     public Mutex() {
51         mutex = false;
52     }
53
54     /**
55      * Locks the Mutex. If the Mutex is
56      * already locked, the calling Thread
57      * will wait until the Mutex is released.
58      *
59      */
60     public synchronized void lock() {
61         while (mutex) {
62             try {
63                 //ColumbaLogger.log.debug("thread " + Thread.currentThread().getName() + " waiting for " + name + " held by thread " + lockingThreadName);
64 wait();
65             } catch (InterruptedException JavaDoc e) {
66                 if (Thread.currentThread().isInterrupted()) {
67                     // gota go now
68 throw new RuntimeException JavaDoc(e);
69                 }
70                 // else keep waiting
71 }
72         }
73         mutex = true;
74     }
75
76     /**
77      * Releases the Mutex. If a Thread is waiting
78      * to lock the Mutex it is afterwards notified.
79      *
80      */
81     public synchronized void release() {
82         mutex = false;
83
84         notify();
85     }
86 }
87
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