1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
|
/*
* Copyright 1999-2008 Sun Microsystems, Inc. All Rights Reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Sun designates this
* particular file as subject to the "Classpath" exception as provided
* by Sun in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
* CA 95054 USA or visit www.sun.com if you need additional information or
* have any questions.
*
*/
package javax.media.j3d;
class GeometryLock {
// Current thread holding the lock
Thread threadId = null;
// Whether the lock is currently owned
boolean lockOwned = false;
// Count > 1 , if there is nested lock by the same thread
int count = 0;
// Number of outstanding threads waiting for the lock
int waiting = 0;
synchronized void getLock() {
Thread curThread = Thread.currentThread();
// If the thread already has the lock, incr
// a count and return
if (threadId == curThread) {
count++;
return;
}
// Otherwise, wait until the lock is released
while (lockOwned) {
try {
waiting++;
wait();
} catch (InterruptedException e) {
System.err.println(e);
}
waiting--;
}
count++;
// Acquire the lock
lockOwned = true;
threadId = curThread;
}
synchronized void unLock() {
Thread curThread = Thread.currentThread();
if (threadId == curThread) {
// If the lock count > 0, then return
if (--count > 0) {
return;
}
lockOwned = false;
threadId = null;
if (waiting > 0) {
notify();
}
}
}
}
|
