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org.apache.jcs.engine.memory.AbstractMemoryCache |
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1 | package org.apache.jcs.engine.memory; |
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2 | ||
3 | /* |
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4 | * Licensed to the Apache Software Foundation (ASF) under one |
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5 | * or more contributor license agreements. See the NOTICE file |
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6 | * distributed with this work for additional information |
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7 | * regarding copyright ownership. The ASF licenses this file |
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8 | * to you under the Apache License, Version 2.0 (the |
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9 | * "License"); you may not use this file except in compliance |
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10 | * with the License. You may obtain a copy of the License at |
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11 | * |
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12 | * http://www.apache.org/licenses/LICENSE-2.0 |
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13 | * |
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14 | * Unless required by applicable law or agreed to in writing, |
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15 | * software distributed under the License is distributed on an |
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16 | * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY |
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17 | * KIND, either express or implied. See the License for the |
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18 | * specific language governing permissions and limitations |
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19 | * under the License. |
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20 | */ |
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21 | ||
22 | import java.io.IOException; |
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23 | import java.io.Serializable; |
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24 | import java.util.HashSet; |
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25 | import java.util.Hashtable; |
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26 | import java.util.Iterator; |
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27 | import java.util.Map; |
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28 | import java.util.Set; |
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29 | ||
30 | import org.apache.commons.logging.Log; |
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31 | import org.apache.commons.logging.LogFactory; |
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32 | import org.apache.jcs.engine.CacheConstants; |
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33 | import org.apache.jcs.engine.behavior.ICacheElement; |
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34 | import org.apache.jcs.engine.behavior.ICompositeCacheAttributes; |
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35 | import org.apache.jcs.engine.behavior.IElementAttributes; |
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36 | import org.apache.jcs.engine.control.CompositeCache; |
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37 | import org.apache.jcs.engine.control.group.GroupAttrName; |
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38 | import org.apache.jcs.engine.control.group.GroupId; |
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39 | import org.apache.jcs.engine.memory.shrinking.ShrinkerThread; |
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40 | import org.apache.jcs.engine.stats.Stats; |
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41 | import org.apache.jcs.engine.stats.behavior.IStats; |
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42 | ||
43 | import EDU.oswego.cs.dl.util.concurrent.ClockDaemon; |
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44 | import EDU.oswego.cs.dl.util.concurrent.ThreadFactory; |
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45 | ||
46 | /** |
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47 | * Some common code for the LRU and MRU caches. |
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48 | * <p> |
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49 | * This keeps a static reference to a memory shrinker clock daemon. If this |
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50 | * region is configured to use the shrinker, the clock daemon will be setup to |
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51 | * run the shrinker on this region. |
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52 | * @version $Id: AbstractMemoryCache.java 536904 2007-05-10 16:03:42Z tv $ |
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53 | */ |
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54 | 6 | public abstract class AbstractMemoryCache |
55 | implements MemoryCache, Serializable |
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56 | { |
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57 | 410 | private final static Log log = LogFactory.getLog( AbstractMemoryCache.class ); |
58 | ||
59 | private static final int DEFAULT_CHUNK_SIZE = 2; |
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60 | ||
61 | /** The region name. This defines a namespace of sorts. */ |
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62 | protected String cacheName; |
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63 | ||
64 | /** |
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65 | * Map where items are stored by key |
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66 | */ |
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67 | protected Map map; |
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68 | ||
69 | /** |
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70 | * Region Elemental Attributes, used as a default. |
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71 | */ |
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72 | public IElementAttributes attr; |
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73 | ||
74 | /** |
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75 | * Cache Attributes |
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76 | */ |
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77 | public ICompositeCacheAttributes cattr; |
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78 | ||
79 | /** |
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80 | * The cache region this store is associated with |
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81 | */ |
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82 | protected CompositeCache cache; |
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83 | ||
84 | /** status */ |
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85 | protected int status; |
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86 | ||
87 | /** How many to spool at a time. TODO make configurable */ |
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88 | 676 | protected int chunkSize = DEFAULT_CHUNK_SIZE; |
89 | ||
90 | /** |
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91 | * The background memory shrinker, one for all regions. |
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92 | */ |
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93 | private static ClockDaemon shrinkerDaemon; |
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94 | ||
95 | /** |
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96 | * Constructor for the LRUMemoryCache object |
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97 | */ |
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98 | 15 | public AbstractMemoryCache() |
99 | 661 | { |
100 | 676 | status = CacheConstants.STATUS_ERROR; |
101 | 676 | map = new Hashtable(); |
102 | 676 | } |
103 | ||
104 | /** |
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105 | * For post reflection creation initialization |
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106 | * @param hub |
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107 | */ |
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108 | public synchronized void initialize( CompositeCache hub ) |
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109 | { |
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110 | 676 | this.cacheName = hub.getCacheName(); |
111 | 676 | this.cattr = hub.getCacheAttributes(); |
112 | 676 | this.cache = hub; |
113 | ||
114 | 676 | status = CacheConstants.STATUS_ALIVE; |
115 | ||
116 | 676 | if ( cattr.getUseMemoryShrinker() ) |
117 | { |
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118 | 48 | if ( shrinkerDaemon == null ) |
119 | { |
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120 | 16 | shrinkerDaemon = new ClockDaemon(); |
121 | 16 | shrinkerDaemon.setThreadFactory( new MyThreadFactory() ); |
122 | } |
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123 | 54 | shrinkerDaemon.executePeriodically( cattr.getShrinkerIntervalSeconds() * 1000, new ShrinkerThread( this ), |
124 | 6 | false ); |
125 | ||
126 | } |
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127 | 676 | } |
128 | ||
129 | /** |
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130 | * Removes an item from the cache |
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131 | * @param key |
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132 | * Identifies item to be removed |
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133 | * @return Description of the Return Value |
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134 | * @exception IOException |
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135 | * Description of the Exception |
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136 | */ |
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137 | public abstract boolean remove( Serializable key ) |
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138 | throws IOException; |
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139 | ||
140 | /** |
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141 | * Get an item from the cache |
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142 | * @param key |
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143 | * Description of the Parameter |
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144 | * @return Description of the Return Value |
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145 | * @exception IOException |
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146 | * Description of the Exception |
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147 | */ |
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148 | public abstract ICacheElement get( Serializable key ) |
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149 | throws IOException; |
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150 | ||
151 | /** |
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152 | * Get an item from the cache without affecting its order or last access |
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153 | * time |
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154 | * @param key |
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155 | * Description of the Parameter |
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156 | * @return The quiet value |
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157 | * @exception IOException |
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158 | * Description of the Exception |
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159 | */ |
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160 | public abstract ICacheElement getQuiet( Serializable key ) |
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161 | throws IOException; |
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162 | ||
163 | /** |
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164 | * Puts an item to the cache. |
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165 | * @param ce |
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166 | * Description of the Parameter |
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167 | * @exception IOException |
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168 | * Description of the Exception |
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169 | */ |
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170 | public abstract void update( ICacheElement ce ) |
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171 | throws IOException; |
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172 | ||
173 | /** |
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174 | * Get an Array of the keys for all elements in the memory cache |
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175 | * @return An Object[] |
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176 | */ |
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177 | public abstract Object[] getKeyArray(); |
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178 | ||
179 | /** |
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180 | * Removes all cached items from the cache. |
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181 | * @exception IOException |
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182 | */ |
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183 | public void removeAll() |
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184 | throws IOException |
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185 | { |
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186 | 8 | map = new Hashtable(); |
187 | 8 | } |
188 | ||
189 | /** |
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190 | * Prepares for shutdown. |
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191 | * @exception IOException |
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192 | */ |
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193 | public void dispose() |
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194 | throws IOException |
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195 | { |
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196 | 0 | log.info( "Memory Cache dispose called. Shutting down shrinker thread if it is running." ); |
197 | 0 | if ( shrinkerDaemon != null ) |
198 | { |
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199 | 0 | shrinkerDaemon.shutDown(); |
200 | } |
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201 | 0 | } |
202 | ||
203 | /* |
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204 | * (non-Javadoc) |
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205 | * @see org.apache.jcs.engine.memory.MemoryCache#getStatistics() |
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206 | */ |
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207 | public IStats getStatistics() |
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208 | { |
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209 | 0 | IStats stats = new Stats(); |
210 | 0 | stats.setTypeName( "Abstract Memory Cache" ); |
211 | 0 | return stats; |
212 | } |
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213 | ||
214 | /** |
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215 | * Returns the current cache size. |
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216 | * @return The size value |
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217 | */ |
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218 | public int getSize() |
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219 | { |
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220 | 0 | return this.map.size(); |
221 | } |
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222 | ||
223 | /** |
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224 | * Returns the cache status. |
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225 | * @return The status value |
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226 | */ |
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227 | public int getStatus() |
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228 | { |
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229 | 0 | return this.status; |
230 | } |
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231 | ||
232 | /** |
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233 | * Returns the cache name. |
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234 | * @return The cacheName value |
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235 | */ |
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236 | public String getCacheName() |
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237 | { |
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238 | 0 | return this.cattr.getCacheName(); |
239 | } |
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240 | ||
241 | /** |
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242 | * Puts an item to the cache. |
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243 | * @param ce |
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244 | * @exception IOException |
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245 | */ |
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246 | public void waterfal( ICacheElement ce ) |
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247 | throws IOException |
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248 | { |
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249 | 0 | this.cache.spoolToDisk( ce ); |
250 | 0 | } |
251 | ||
252 | /** |
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253 | * Gets the iterator attribute of the LRUMemoryCache object |
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254 | * @return The iterator value |
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255 | */ |
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256 | public Iterator getIterator() |
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257 | { |
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258 | 0 | return map.entrySet().iterator(); |
259 | } |
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260 | ||
261 | /** |
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262 | * Returns the CacheAttributes. |
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263 | * @return The CacheAttributes value |
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264 | */ |
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265 | public ICompositeCacheAttributes getCacheAttributes() |
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266 | { |
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267 | 407351 | return this.cattr; |
268 | } |
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269 | ||
270 | /** |
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271 | * Sets the CacheAttributes. |
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272 | * @param cattr |
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273 | * The new CacheAttributes value |
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274 | */ |
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275 | public void setCacheAttributes( ICompositeCacheAttributes cattr ) |
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276 | { |
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277 | 0 | this.cattr = cattr; |
278 | 0 | } |
279 | ||
280 | /** |
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281 | * Gets the cache hub / region that the MemoryCache is used by |
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282 | * @return The cache value |
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283 | */ |
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284 | public CompositeCache getCompositeCache() |
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285 | { |
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286 | 0 | return this.cache; |
287 | } |
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288 | ||
289 | public Set getGroupKeys( String groupName ) |
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290 | { |
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291 | 0 | GroupId groupId = new GroupId( getCacheName(), groupName ); |
292 | 0 | HashSet keys = new HashSet(); |
293 | 0 | synchronized ( map ) |
294 | { |
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295 | 0 | for ( Iterator itr = map.entrySet().iterator(); itr.hasNext(); ) |
296 | { |
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297 | 0 | Map.Entry entry = (Map.Entry) itr.next(); |
298 | 0 | Object k = entry.getKey(); |
299 | ||
300 | 0 | if ( k instanceof GroupAttrName && ( (GroupAttrName) k ).groupId.equals( groupId ) ) |
301 | { |
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302 | 0 | keys.add( ( (GroupAttrName) k ).attrName ); |
303 | } |
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304 | 0 | } |
305 | 0 | } |
306 | 0 | return keys; |
307 | } |
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308 | ||
309 | /** |
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310 | * Allows us to set the daemon status on the clockdaemon |
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311 | * @author aaronsm |
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312 | */ |
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313 | class MyThreadFactory |
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314 | implements ThreadFactory |
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315 | { |
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316 | ||
317 | /* |
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318 | * (non-Javadoc) |
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319 | * @see EDU.oswego.cs.dl.util.concurrent.ThreadFactory#newThread(java.lang.Runnable) |
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320 | */ |
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321 | public Thread newThread( Runnable runner ) |
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322 | { |
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323 | Thread t = new Thread( runner ); |
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324 | t.setDaemon( true ); |
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325 | t.setPriority( Thread.MIN_PRIORITY ); |
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326 | return t; |
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327 | } |
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328 | } |
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329 | } |
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