01: /*
02: * Distributed as part of c3p0 v.0.9.1.2
03: *
04: * Copyright (C) 2005 Machinery For Change, Inc.
05: *
06: * Author: Steve Waldman <swaldman@mchange.com>
07: *
08: * This library is free software; you can redistribute it and/or modify
09: * it under the terms of the GNU Lesser General Public License version 2.1, as
10: * published by the Free Software Foundation.
11: *
12: * This software is distributed in the hope that it will be useful,
13: * but WITHOUT ANY WARRANTY; without even the implied warranty of
14: * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15: * GNU Lesser General Public License for more details.
16: *
17: * You should have received a copy of the GNU Lesser General Public License
18: * along with this software; see the file LICENSE. If not, write to the
19: * Free Software Foundation, Inc., 59 Temple Place, Suite 330,
20: * Boston, MA 02111-1307, USA.
21: */
22:
23: package com.mchange.v2.coalesce;
24:
25: import java.util.*;
26: import java.lang.ref.WeakReference;
27:
28: class AbstractWeakCoalescer implements Coalescer {
29: Map wcoalesced;
30:
31: AbstractWeakCoalescer(Map wcoalesced) {
32: this .wcoalesced = wcoalesced;
33: }
34:
35: public Object coalesce(Object o) {
36: //System.err.println("AbstractWeakCoalescer.coalesce( " + o + " )");
37: Object out = null;
38:
39: WeakReference wr = (WeakReference) wcoalesced.get(o);
40: if (wr != null)
41: out = wr.get(); //there is a conceivable race that would
42: //permit wr be cleared
43: if (out == null) {
44: wcoalesced.put(o, new WeakReference(o));
45: out = o;
46: }
47: return out;
48: }
49:
50: public int countCoalesced() {
51: return wcoalesced.size();
52: }
53:
54: public Iterator iterator() {
55: return new CoalescerIterator(wcoalesced.keySet().iterator());
56: }
57: }
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