01: /* Copyright (C) 2004 - 2007 db4objects Inc. http://www.db4o.com
02:
03: This file is part of the db4o open source object database.
04:
05: db4o is free software; you can redistribute it and/or modify it under
06: the terms of version 2 of the GNU General Public License as published
07: by the Free Software Foundation and as clarified by db4objects' GPL
08: interpretation policy, available at
09: http://www.db4o.com/about/company/legalpolicies/gplinterpretation/
10: Alternatively you can write to db4objects, Inc., 1900 S Norfolk Street,
11: Suite 350, San Mateo, CA 94403, USA.
12:
13: db4o is distributed in the hope that it will be useful, but WITHOUT ANY
14: WARRANTY; without even the implied warranty of MERCHANTABILITY or
15: FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
16: for more details.
17:
18: You should have received a copy of the GNU General Public License along
19: with this program; if not, write to the Free Software Foundation, Inc.,
20: 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
21: package com.db4o.internal;
22:
23: import com.db4o.foundation.*;
24:
25: /**
26: *
27: */
28: class WeakReferenceCollector implements Runnable {
29:
30: final Object _queue;
31: private final ObjectContainerBase _stream;
32: private SimpleTimer _timer;
33: public final boolean _weak;
34:
35: WeakReferenceCollector(ObjectContainerBase a_stream) {
36: _stream = a_stream;
37: _weak = (!(a_stream instanceof TransportObjectContainer)
38: && Platform4.hasWeakReferences() && a_stream
39: .configImpl().weakReferences());
40: _queue = _weak ? Platform4.createReferenceQueue() : null;
41: }
42:
43: Object createYapRef(ObjectReference a_yo, Object obj) {
44:
45: if (!_weak) {
46: return obj;
47: }
48:
49: return Platform4.createActiveObjectReference(_queue, a_yo, obj);
50: }
51:
52: void pollReferenceQueue() {
53: if (_weak) {
54: Platform4.pollReferenceQueue(_stream, _queue);
55: }
56: }
57:
58: public void run() {
59: pollReferenceQueue();
60: }
61:
62: void startTimer() {
63: if (!_weak) {
64: return;
65: }
66:
67: if (!_stream.configImpl().weakReferences()) {
68: return;
69: }
70:
71: if (_stream.configImpl().weakReferenceCollectionInterval() <= 0) {
72: return;
73: }
74:
75: if (_timer != null) {
76: return;
77: }
78:
79: _timer = new SimpleTimer(this , _stream.configImpl()
80: .weakReferenceCollectionInterval(),
81: "db4o WeakReference collector");
82: _timer.start();
83: }
84:
85: void stopTimer() {
86: if (_timer == null) {
87: return;
88: }
89: _timer.stop();
90: _timer = null;
91: }
92:
93: }
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