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Java > Open Source Codes > com > sun > jts > CosTransactions > EventSemaphore


1 /*
2  * The contents of this file are subject to the terms
3  * of the Common Development and Distribution License
4  * (the License). You may not use this file except in
5  * compliance with the License.
6  *
7  * You can obtain a copy of the license at
8  * https://glassfish.dev.java.net/public/CDDLv1.0.html or
9  * glassfish/bootstrap/legal/CDDLv1.0.txt.
10  * See the License for the specific language governing
11  * permissions and limitations under the License.
12  *
13  * When distributing Covered Code, include this CDDL
14  * Header Notice in each file and include the License file
15  * at glassfish/bootstrap/legal/CDDLv1.0.txt.
16  * If applicable, add the following below the CDDL Header,
17  * with the fields enclosed by brackets [] replaced by
18  * you own identifying information:
19  * "Portions Copyrighted [year] [name of copyright owner]"
20  *
21  * Copyright 2006 Sun Microsystems, Inc. All rights reserved.
22  */
23
24 /*
25  * Copyright 2004-2005 Sun Microsystems, Inc. All rights reserved.
26  * Use is subject to license terms.
27  */
28 //----------------------------------------------------------------------------
29 //
30 // Module: EventSemaphore.java
31 //
32 // Description: Event semaphore implementation.
33 //
34 // Product: com.sun.jts.CosTransactions
35 //
36 // Author: Simon Holdsworth
37 //
38 // Date: March, 1997
39 //
40 // Copyright (c): 1995-1997 IBM Corp.
41 //
42 // The source code for this program is not published or otherwise divested
43 // of its trade secrets, irrespective of what has been deposited with the
44 // U.S. Copyright Office.
45 //
46 // This software contains confidential and proprietary information of
47 // IBM Corp.
48 //----------------------------------------------------------------------------
49
50 package com.sun.jts.CosTransactions;
51
52 /**The EventSemaphore interface provides operations that wait for and post an
53  * event semaphore.
54  * <p>
55  * This is specifically to handle the situation where the event may have been
56  * posted before the wait method is called. This behaviour is not supported by
57  * the existing wait and notify methods.
58  *
59  * @version 0.01
60  *
61  * @author Simon Holdsworth, IBM Corporation
62  *
63  * @see
64 */
65 //----------------------------------------------------------------------------
66 // CHANGE HISTORY
67 //
68 // Version By Change Description
69 // 0.01 SAJH Initial implementation.
70 //-----------------------------------------------------------------------------
71
72 public class EventSemaphore {
73     boolean posted = false;
74
75     /**Default EventSemaphore constructor.
76      *
77      * @param
78      *
79      * @return
80      *
81      * @see
82      */
83     EventSemaphore() {
84     }
85
86     /**Creates the event semaphore in the given posted state.
87      *
88      * @param posted Indicates whether the semaphore should be posted.
89      *
90      * @return
91      *
92      * @see
93      */
94     EventSemaphore( boolean posted ) {
95         this.posted = posted;
96     }
97
98     /**
99      * @return true if semaphore has already been posted.
100      */
101     synchronized public boolean isPosted() {
102         return posted;
103     }
104
105     /**Waits for the event to be posted.
106      * <p>
107      * If the event has already been posted, then the operation returns immediately.
108      *
109      * @param
110      *
111      * @return
112      *
113      * @exception InterruptedException The wait was interrupted.
114      *
115      * @see
116      */
117     synchronized public void waitEvent()
118         throws InterruptedException JavaDoc {
119         if( !posted )
120             wait();
121     }
122
123     /**Posts the event semaphore.
124      * <p>
125      * All waiters are notified.
126      *
127      * @param
128      *
129      * @return
130      *
131      * @see
132      */
133     synchronized void post() {
134         if( !posted )
135             notifyAll();
136         posted = true;
137     }
138
139     /**Clears a posted event semaphore.
140      *
141      * @param
142      *
143      * @return
144      *
145      * @see
146      */
147     synchronized void clear() {
148         posted = false;
149     }
150 }
151
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