2 * Copyright (C) 2001, 2002 The Mir-coders group
4 * This file is part of Mir.
6 * Mir is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License, or
9 * (at your option) any later version.
11 * Mir is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
16 * You should have received a copy of the GNU General Public License
17 * along with Mir; if not, write to the Free Software
18 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
20 * In addition, as a special exception, The Mir-coders gives permission to link
21 * the code of this program with any library licensed under the Apache Software License,
22 * The Sun (tm) Java Advanced Imaging library (JAI), The Sun JIMI library
23 * (or with modified versions of the above that use the same license as the above),
24 * and distribute linked combinations including the two. You must obey the
25 * GNU General Public License in all respects for all of the code used other than
26 * the above mentioned libraries. If you modify this file, you may extend this
27 * exception to your version of the file, but you are not obligated to do so.
28 * If you do not wish to do so, delete this exception statement from your version.
30 package mircoders.global;
33 import java.util.HashMap;
34 import java.util.LinkedList;
37 import mir.config.MirPropertiesConfiguration;
38 import mir.config.MirPropertiesConfiguration.PropertiesConfigExc;
39 import mir.log.LoggerWrapper;
41 public class MRUCache {
43 private LinkedList mruList;
44 private int cacheMaxItems;
46 private MirPropertiesConfiguration configuration;
47 private LoggerWrapper logger;
50 logger = new LoggerWrapper("Global.MRUCache");
51 configuration = MirPropertiesConfiguration.instance();
52 cacheMaxItems=Integer.parseInt(configuration.getString("Global.Cache.Items"));
53 cache = new HashMap();
54 mruList= new LinkedList();
58 * Checks if the cache has an object with the specified key
61 public boolean hasObject(CacheKey aCacheKey) {
62 synchronized (cache) {
63 logger.info("MRUCache was this big : "+ mruList.size());
64 return cache.containsKey(aCacheKey);
69 * Stores an object in the cache by placing it at the top of the
70 * list If the object is in the cache, it promotes it to the top of
71 * the list. If the object is not in the cache, it adds it to the
72 * top of the list, and then checks the max size of the cache versus
73 * the new size to see if it needs to remove the last element from
77 public void storeObject(CacheKey aCacheKey,Object data) {
78 synchronized (cache) {
79 if (!hasObject(aCacheKey)) {
81 cache.put(aCacheKey, data);
82 if (mruList.size() >= cacheMaxItems) {
83 removeObject((CacheKey) mruList.getLast());
86 mruList.remove(aCacheKey);
87 mruList.addFirst(aCacheKey);
91 public void removeObject(CacheKey aCacheKey) {
92 synchronized (cache) {
93 mruList.remove(aCacheKey);
94 cache.remove(aCacheKey);
99 * Moves requested item to front of cache
102 public Object getObject(CacheKey aCacheKey) {
103 synchronized (cache) {
104 mruList.remove(aCacheKey);
105 mruList.addFirst(aCacheKey);
106 return cache.get(aCacheKey);