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
6 * under the terms of the GNU General Public License version 2 only, as
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.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26package sun.awt;
27
28public class Mutex {
29    private boolean locked;
30    private Thread owner;
31
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
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
59    protected boolean isOwned() {
60        return (locked && Thread.currentThread() == owner);
61    }
62}
63