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Java > Open Source Codes > org > columba > core > base > Lock


1 //The contents of this file are subject to the Mozilla Public License Version 1.1
2 //(the "License"); you may not use this file except in compliance with the
3 //License. You may obtain a copy of the License at http://www.mozilla.org/MPL/
4 //
5 //Software distributed under the License is distributed on an "AS IS" basis,
6 //WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
7 //for the specific language governing rights and
8 //limitations under the License.
9 //
10 //The Original Code is "The Columba Project"
11 //
12 //The Initial Developers of the Original Code are Frederik Dietz and Timo Stich.
13 //Portions created by Frederik Dietz and Timo Stich are Copyright (C) 2003.
14 //
15 //All Rights Reserved.
16 package org.columba.core.base;
17
18 /**
19  * @author timo
20  *
21  * To change this generated comment edit the template variable "typecomment":
22  * Window>Preferences>Java>Templates. To enable and disable the creation of type
23  * comments go to Window>Preferences>Java>Code Generation.
24  */
25 public class Lock {
26     private boolean locked;
27
28     private Object JavaDoc locker;
29
30     private Mutex mutex;
31
32     public Lock() {
33     locked = false;
34     mutex = new Mutex();
35     }
36
37     public synchronized void getLock(Object JavaDoc theLocker) {
38     mutex.lock();
39     if (this.locker == theLocker) {
40         mutex.release();
41         return;
42     }
43     mutex.release();
44
45     while (!tryToGetLock(theLocker)) {
46         try {
47         wait();
48         } catch (InterruptedException JavaDoc e) {
49         // nothing to do
50 }
51     }
52     }
53
54     public boolean tryToGetLock(Object JavaDoc theLocker) {
55     mutex.lock();
56     // Is it already locked from locker ?
57 if ((this.locker == theLocker) && (theLocker != null)) {
58         mutex.release();
59         return true;
60     }
61
62     // Check if locked
63 if (locked) {
64         mutex.release();
65         return false;
66     }
67     locked = true;
68     this.locker = theLocker;
69     mutex.release();
70
71     return true;
72     }
73
74     public synchronized void release(Object JavaDoc theLocker) {
75     mutex.lock();
76     if ((this.locker == theLocker) || (this.locker == null)) {
77         locked = false;
78     }
79     notify();
80
81     mutex.release();
82     }
83 }
84
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