1 /*
2  * Copyright (c) 1999, 2000, Oracle and/or its affiliates. All rights reserved.
3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4  *
5  * This code is free software; you can redistribute it and/or modify it
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7  * published by the Free Software Foundation.  Oracle designates this
8  * particular file as subject to the "Classpath" exception as provided
9  * by Oracle in the LICENSE file that accompanied this code.
10  *
11  * This code is distributed in the hope that it will be useful, but WITHOUT
12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14  * version 2 for more details (a copy is included in the LICENSE file that
15  * accompanied this code).
16  *
17  * You should have received a copy of the GNU General Public License version
18  * 2 along with this work; if not, write to the Free Software Foundation,
19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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24  */
25 
26 package sun.awt;
27 
28 public class Mutex {
29     private boolean locked;
30     private Thread owner;
31 
lock()32     public synchronized void lock() {
33         if (locked && Thread.currentThread() == owner) {
34             throw new IllegalMonitorStateException();
35         }
36         do {
37             if (!locked) {
38                 locked = true;
39                 owner = Thread.currentThread();
40             } else {
41                 try {
42                     wait();
43                 } catch (InterruptedException e) {
44                     // try again
45                 }
46             }
47         } while (owner != Thread.currentThread());
48     }
49 
unlock()50     public synchronized void unlock() {
51         if (Thread.currentThread() != owner) {
52             throw new IllegalMonitorStateException();
53         }
54         owner = null;
55         locked = false;
56         notify();
57     }
58 
isOwned()59     protected boolean isOwned() {
60         return (locked && Thread.currentThread() == owner);
61     }
62 }
63