Mercurial > hg > blitz_stable
comparison src/com/go/trove/util/WrappedCache.java @ 0:3dc0c5604566
Initial checkin of blitz 2.0 fcs - no installer yet.
author | Dan Creswell <dan.creswell@gmail.com> |
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date | Sat, 21 Mar 2009 11:00:06 +0000 |
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-1:000000000000 | 0:3dc0c5604566 |
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1 /* ==================================================================== | |
2 * Trove - Copyright (c) 1997-2001 Walt Disney Internet Group | |
3 * ==================================================================== | |
4 * The Tea Software License, Version 1.1 | |
5 * | |
6 * Copyright (c) 2000 Walt Disney Internet Group. All rights reserved. | |
7 * | |
8 * Redistribution and use in source and binary forms, with or without | |
9 * modification, are permitted provided that the following conditions | |
10 * are met: | |
11 * | |
12 * 1. Redistributions of source code must retain the above copyright | |
13 * notice, this list of conditions and the following disclaimer. | |
14 * | |
15 * 2. Redistributions in binary form must reproduce the above copyright | |
16 * notice, this list of conditions and the following disclaimer in | |
17 * the documentation and/or other materials provided with the | |
18 * distribution. | |
19 * | |
20 * 3. The end-user documentation included with the redistribution, | |
21 * if any, must include the following acknowledgment: | |
22 * "This product includes software developed by the | |
23 * Walt Disney Internet Group (http://opensource.go.com/)." | |
24 * Alternately, this acknowledgment may appear in the software itself, | |
25 * if and wherever such third-party acknowledgments normally appear. | |
26 * | |
27 * 4. The names "Tea", "TeaServlet", "Kettle", "Trove" and "BeanDoc" must | |
28 * not be used to endorse or promote products derived from this | |
29 * software without prior written permission. For written | |
30 * permission, please contact opensource@dig.com. | |
31 * | |
32 * 5. Products derived from this software may not be called "Tea", | |
33 * "TeaServlet", "Kettle" or "Trove", nor may "Tea", "TeaServlet", | |
34 * "Kettle", "Trove" or "BeanDoc" appear in their name, without prior | |
35 * written permission of the Walt Disney Internet Group. | |
36 * | |
37 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED | |
38 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES | |
39 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE | |
40 * DISCLAIMED. IN NO EVENT SHALL THE WALT DISNEY INTERNET GROUP OR ITS | |
41 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, | |
42 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, | |
43 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR | |
44 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY | |
45 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT | |
46 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE | |
47 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | |
48 * ==================================================================== | |
49 * | |
50 * For more information about Tea, please see http://opensource.go.com/. | |
51 */ | |
52 | |
53 package com.go.trove.util; | |
54 | |
55 import java.util.*; | |
56 | |
57 /****************************************************************************** | |
58 * A Map that implements a write-through cache to another map. Two maps are | |
59 * supplied: one for caching and one for main storage. WrappedCache is not | |
60 * thread-safe and must be wrapped with Collections.synchronizedMap to be made | |
61 * thread-safe. | |
62 * | |
63 * @author Brian S O'Neill | |
64 * @version | |
65 * <!--$$Revision:--> 2 <!-- $-->, <!--$$JustDate:--> 01/07/31 <!-- $--> | |
66 */ | |
67 public class WrappedCache extends AbstractMap implements Map { | |
68 private final Map mCacheMap; | |
69 private final Map mBackingMap; | |
70 | |
71 /** | |
72 * @param cacheMap the cache map should offer fast access, but it should | |
73 * automatically limit its maximum size | |
74 * @param backingMap the backingMap will be read from only if the requested | |
75 * entry isn't in the cache | |
76 */ | |
77 public WrappedCache(Map cacheMap, Map backingMap) { | |
78 mCacheMap = cacheMap; | |
79 mBackingMap = backingMap; | |
80 } | |
81 | |
82 /** | |
83 * Returns the size of the backing map. | |
84 */ | |
85 public int size() { | |
86 return mBackingMap.size(); | |
87 } | |
88 | |
89 /** | |
90 * Returns the empty status of the backing map. | |
91 */ | |
92 public boolean isEmpty() { | |
93 return mBackingMap.isEmpty(); | |
94 } | |
95 | |
96 /** | |
97 * Returns true if the cache contains the key or else if the backing map | |
98 * contains the key. | |
99 */ | |
100 public boolean containsKey(Object key) { | |
101 return mCacheMap.containsKey(key) || mBackingMap.containsKey(key); | |
102 } | |
103 | |
104 /** | |
105 * Returns true if the cache contains the value or else if the backing map | |
106 * contains the value. | |
107 */ | |
108 public boolean containsValue(Object value) { | |
109 return mCacheMap.containsValue(value) || | |
110 mBackingMap.containsValue(value); | |
111 } | |
112 | |
113 /** | |
114 * Returns the value from the cache, or if not found, the backing map. | |
115 * If the backing map is accessed, the value is saved in the cache for | |
116 * future gets. | |
117 */ | |
118 public Object get(Object key) { | |
119 Object value = mCacheMap.get(key); | |
120 if (value != null || mCacheMap.containsKey(key)) { | |
121 return value; | |
122 } | |
123 value = mBackingMap.get(key); | |
124 if (value != null || mBackingMap.containsKey(key)) { | |
125 mCacheMap.put(key, value); | |
126 } | |
127 return value; | |
128 } | |
129 | |
130 /** | |
131 * Puts the entry into both the cache and backing map. The old value in | |
132 * the backing map is returned. | |
133 */ | |
134 public Object put(Object key, Object value) { | |
135 mCacheMap.put(key, value); | |
136 return mBackingMap.put(key, value); | |
137 } | |
138 | |
139 /** | |
140 * Removes the key from both the cache and backing map. The old value in | |
141 * the backing map is returned. | |
142 */ | |
143 public Object remove(Object key) { | |
144 mCacheMap.remove(key); | |
145 return mBackingMap.remove(key); | |
146 } | |
147 | |
148 /** | |
149 * Clears both the cache and backing map. | |
150 */ | |
151 public void clear() { | |
152 mCacheMap.clear(); | |
153 mBackingMap.clear(); | |
154 } | |
155 | |
156 /** | |
157 * Returns the key set of the backing map. | |
158 */ | |
159 public Set keySet() { | |
160 return mBackingMap.keySet(); | |
161 } | |
162 | |
163 /** | |
164 * Returns the values of the backing map. | |
165 */ | |
166 public Collection values() { | |
167 return mBackingMap.values(); | |
168 } | |
169 | |
170 /** | |
171 * Returns the entry set of the backing map. | |
172 */ | |
173 public Set entrySet() { | |
174 return mBackingMap.entrySet(); | |
175 } | |
176 } |