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