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;
52 logger = new LoggerWrapper("Global.MRUCache");
54 configuration = MirPropertiesConfiguration.instance();
56 catch (PropertiesConfigExc e) {
57 throw new RuntimeException("Can't get configuration: " + e.getMessage());
59 cacheMaxItems=Integer.parseInt(configuration.getString("Global.Cache.Items"));
60 cache = new HashMap();
61 mruList= new LinkedList();
66 * Checks if the cache has an object with the specified key
69 public boolean hasObject(CacheKey aCacheKey) {
70 synchronized (cache) {
71 logger.info("MRUCache was this big : "+ mruList.size());
72 return cache.containsKey(aCacheKey);
77 * Stores an object in the cache by placing it at the top of the
78 * list If the object is in the cache, it promotes it to the top of
79 * the list. If the object is not in the cache, it adds it to the
80 * top of the list, and then checks the max size of the cache versus
81 * the new size to see if it needs to remove the last element from
85 public void storeObject(CacheKey aCacheKey,Object data) {
86 synchronized (cache) {
87 if (! hasObject(aCacheKey)){
89 cache.put(aCacheKey,data);
90 if (mruList.size() >= cacheMaxItems){
91 removeObject((CacheKey) mruList.getLast());
94 mruList.remove(aCacheKey);
95 mruList.addFirst(aCacheKey);
99 public void removeObject(CacheKey aCacheKey){
100 synchronized (cache) {
101 mruList.remove(aCacheKey);
102 cache.remove(aCacheKey);
107 * Moves requested item to front of cache
110 public Object getObject(CacheKey aCacheKey){
111 synchronized (cache) {
112 mruList.remove(aCacheKey);
113 mruList.addFirst(aCacheKey);
114 return cache.get(aCacheKey);