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org.apache.jcs.auxiliary.disk.jdbc.JDBCDiskCacheManagerAbstractTemplate$MyThreadFactory |
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1 | package org.apache.jcs.auxiliary.disk.jdbc; |
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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.util.Enumeration; |
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23 | import java.util.Hashtable; |
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24 | import java.util.Map; |
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25 | ||
26 | import org.apache.commons.logging.Log; |
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27 | import org.apache.commons.logging.LogFactory; |
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28 | import org.apache.jcs.auxiliary.AuxiliaryCache; |
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29 | import org.apache.jcs.auxiliary.AuxiliaryCacheManager; |
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30 | ||
31 | import EDU.oswego.cs.dl.util.concurrent.ClockDaemon; |
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32 | import EDU.oswego.cs.dl.util.concurrent.ThreadFactory; |
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33 | ||
34 | /** |
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35 | * This class serves as an abstract template for JDBCDiskCache Manager. The MySQL JDBC Disk Cache |
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36 | * needs many of the same features as the generic maanger. |
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37 | * <p> |
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38 | * @author Aaron Smuts |
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39 | */ |
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40 | public abstract class JDBCDiskCacheManagerAbstractTemplate |
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41 | implements AuxiliaryCacheManager |
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42 | { |
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43 | /** The logger. */ |
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44 | private static final Log log = LogFactory.getLog( JDBCDiskCacheManagerAbstractTemplate.class ); |
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45 | ||
46 | /** |
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47 | * Incremented on getIntance, decremented on release. |
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48 | */ |
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49 | protected static int clients; |
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50 | ||
51 | /** |
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52 | * A map of JDBCDiskCache objects to region names. |
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53 | */ |
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54 | protected static Hashtable caches = new Hashtable(); |
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55 | ||
56 | /** |
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57 | * A map of TableState objects to table names. Each cache has a table state object, which is |
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58 | * used to determin if any long processes such as deletes or optimizations are running. |
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59 | */ |
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60 | protected static Hashtable tableStates = new Hashtable(); |
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61 | ||
62 | /** |
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63 | * The background disk shrinker, one for all regions. |
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64 | */ |
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65 | private ClockDaemon shrinkerDaemon; |
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66 | ||
67 | /** |
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68 | * A map of table name to shrinker threads. This allows each table to have a different setting. |
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69 | * It assumes that there is only one jdbc disk cache auxiliary defined per table. |
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70 | */ |
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71 | private Map shrinkerThreadMap = new Hashtable(); |
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72 | ||
73 | /** |
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74 | * Children must implement this method. |
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75 | * <p> |
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76 | * @param cattr |
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77 | * @param tableState An object used by multiple processes to indicate state. |
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78 | * @return AuxiliaryCache -- a JDBCDiskCache |
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79 | */ |
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80 | protected abstract AuxiliaryCache createJDBCDiskCache( JDBCDiskCacheAttributes cattr, TableState tableState ); |
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81 | ||
82 | /** |
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83 | * Creates a JDBCDiskCache for the region if one doesn't exist, else it returns the precreated |
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84 | * instance. It also adds the region to the shrinker thread if needed. |
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85 | * <p> |
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86 | * @param cattr |
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87 | * @return The cache value |
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88 | */ |
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89 | public AuxiliaryCache getCache( JDBCDiskCacheAttributes cattr ) |
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90 | { |
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91 | AuxiliaryCache diskCache = null; |
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92 | ||
93 | log.debug( "cacheName = " + cattr.getCacheName() ); |
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94 | ||
95 | synchronized ( caches ) |
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96 | { |
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97 | diskCache = (AuxiliaryCache) caches.get( cattr.getCacheName() ); |
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98 | ||
99 | if ( diskCache == null ) |
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100 | { |
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101 | TableState tableState = (TableState) tableStates.get( cattr.getTableName() ); |
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102 | ||
103 | if ( tableState == null ) |
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104 | { |
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105 | tableState = new TableState( cattr.getTableName() ); |
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106 | } |
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107 | ||
108 | diskCache = createJDBCDiskCache( cattr, tableState ); |
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109 | ||
110 | caches.put( cattr.getCacheName(), diskCache ); |
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111 | } |
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112 | } |
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113 | ||
114 | if ( log.isDebugEnabled() ) |
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115 | { |
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116 | log.debug( "JDBC cache = " + diskCache ); |
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117 | } |
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118 | ||
119 | // create a shrinker if we need it. |
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120 | createShrinkerWhenNeeded( cattr, diskCache ); |
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121 | ||
122 | return diskCache; |
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123 | } |
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124 | ||
125 | /** |
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126 | * If UseDiskShrinker is true then we will create a shrinker daemon if necessary. |
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127 | * <p> |
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128 | * @param cattr |
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129 | * @param raf |
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130 | */ |
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131 | protected void createShrinkerWhenNeeded( JDBCDiskCacheAttributes cattr, AuxiliaryCache raf ) |
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132 | { |
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133 | // add cache to shrinker. |
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134 | if ( cattr.isUseDiskShrinker() ) |
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135 | { |
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136 | if ( shrinkerDaemon == null ) |
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137 | { |
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138 | shrinkerDaemon = new ClockDaemon(); |
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139 | shrinkerDaemon.setThreadFactory( new MyThreadFactory() ); |
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140 | } |
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141 | ||
142 | ShrinkerThread shrinkerThread = (ShrinkerThread) shrinkerThreadMap.get( cattr.getTableName() ); |
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143 | if ( shrinkerThread == null ) |
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144 | { |
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145 | shrinkerThread = new ShrinkerThread(); |
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146 | shrinkerThreadMap.put( cattr.getTableName(), shrinkerThread ); |
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147 | ||
148 | long intervalMillis = Math.max( 999, cattr.getShrinkerIntervalSeconds() * 1000 ); |
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149 | if ( log.isInfoEnabled() ) |
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150 | { |
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151 | log.info( "Setting the shrinker to run every [" + intervalMillis + "] ms. for table [" |
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152 | + cattr.getTableName() + "]" ); |
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153 | } |
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154 | shrinkerDaemon.executePeriodically( intervalMillis, shrinkerThread, false ); |
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155 | } |
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156 | shrinkerThread.addDiskCacheToShrinkList( (JDBCDiskCache) raf ); |
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157 | } |
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158 | } |
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159 | ||
160 | /** |
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161 | * @param name |
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162 | */ |
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163 | public void freeCache( String name ) |
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164 | { |
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165 | JDBCDiskCache raf = (JDBCDiskCache) caches.get( name ); |
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166 | if ( raf != null ) |
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167 | { |
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168 | raf.dispose(); |
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169 | } |
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170 | } |
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171 | ||
172 | /** |
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173 | * Gets the cacheType attribute of the HSQLCacheManager object |
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174 | * <p> |
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175 | * @return The cacheType value |
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176 | */ |
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177 | public int getCacheType() |
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178 | { |
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179 | return DISK_CACHE; |
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180 | } |
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181 | ||
182 | /** Disposes of all regions. */ |
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183 | public void release() |
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184 | { |
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185 | // Wait until called by the last client |
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186 | if ( --clients != 0 ) |
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187 | { |
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188 | return; |
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189 | } |
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190 | synchronized ( caches ) |
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191 | { |
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192 | Enumeration allCaches = caches.elements(); |
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193 | ||
194 | while ( allCaches.hasMoreElements() ) |
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195 | { |
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196 | JDBCDiskCache raf = (JDBCDiskCache) allCaches.nextElement(); |
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197 | if ( raf != null ) |
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198 | { |
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199 | raf.dispose(); |
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200 | } |
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201 | } |
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202 | } |
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203 | } |
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204 | ||
205 | /** |
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206 | * Allows us to set the daemon status on the clockdaemon |
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207 | * <p> |
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208 | * @author aaronsm |
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209 | */ |
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210 | 28 | class MyThreadFactory |
211 | implements ThreadFactory |
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212 | { |
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213 | /** |
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214 | * Set the priority to min and daemon to true. |
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215 | * <p> |
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216 | * @param runner |
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217 | * @return the daemon thread. |
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218 | */ |
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219 | public Thread newThread( Runnable runner ) |
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220 | { |
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221 | 28 | Thread t = new Thread( runner ); |
222 | 28 | t.setDaemon( true ); |
223 | 28 | t.setPriority( Thread.MIN_PRIORITY ); |
224 | 28 | return t; |
225 | } |
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226 | } |
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227 | } |
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