01: package com.quadcap.sql.lock;
02:
03: /* Copyright 1999 - 2003 Quadcap Software. All rights reserved.
04: *
05: * This software is distributed under the Quadcap Free Software License.
06: * This software may be used or modified for any purpose, personal or
07: * commercial. Open Source redistributions are permitted. Commercial
08: * redistribution of larger works derived from, or works which bundle
09: * this software requires a "Commercial Redistribution License"; see
10: * http://www.quadcap.com/purchase.
11: *
12: * Redistributions qualify as "Open Source" under one of the following terms:
13: *
14: * Redistributions are made at no charge beyond the reasonable cost of
15: * materials and delivery.
16: *
17: * Redistributions are accompanied by a copy of the Source Code or by an
18: * irrevocable offer to provide a copy of the Source Code for up to three
19: * years at the cost of materials and delivery. Such redistributions
20: * must allow further use, modification, and redistribution of the Source
21: * Code under substantially the same terms as this license.
22: *
23: * Redistributions of source code must retain the copyright notices as they
24: * appear in each source code file, these license terms, and the
25: * disclaimer/limitation of liability set forth as paragraph 6 below.
26: *
27: * Redistributions in binary form must reproduce this Copyright Notice,
28: * these license terms, and the disclaimer/limitation of liability set
29: * forth as paragraph 6 below, in the documentation and/or other materials
30: * provided with the distribution.
31: *
32: * The Software is provided on an "AS IS" basis. No warranty is
33: * provided that the Software is free of defects, or fit for a
34: * particular purpose.
35: *
36: * Limitation of Liability. Quadcap Software shall not be liable
37: * for any damages suffered by the Licensee or any third party resulting
38: * from use of the Software.
39: */
40:
41: import java.util.HashMap;
42:
43: import java.lang.ref.SoftReference;
44:
45: import com.quadcap.util.Debug;
46:
47: /**
48: * Cache of lock objects
49: *
50: * @author Stan Bailes
51: */
52: public class LockPool {
53: HashMap locks = new HashMap();
54:
55: public LockPool() {
56: }
57:
58: public final Lock get(Lock parent, String name) {
59: SoftReference ref = (SoftReference) locks.get(name);
60: Lock lock = null;
61: if (ref != null) {
62: Object obj = ref.get();
63: if (obj != null) {
64: lock = (Lock) obj;
65: } else {
66: locks.remove(name); // lock was gc'ed.
67: }
68: }
69: if (lock == null) {
70: lock = new Lock();
71: lock.init(parent, name);
72: ref = new SoftReference(lock);
73: locks.put(name, ref);
74: }
75: return lock;
76: }
77: }
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