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| 1 | +/* | |
| 2 | + * Copyright (c) 2000, 2004, Oracle and/or its affiliates. All rights reserved. | |
| 3 | + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. | |
| 4 | + * | |
| 5 | + * This code is free software; you can redistribute it and/or modify it | |
| 6 | + * under the terms of the GNU General Public License version 2 only, as | |
| 7 | + * published by the Free Software Foundation. Oracle designates this | |
| 8 | + * particular file as subject to the "Classpath" exception as provided | |
| 9 | + * by Oracle in the LICENSE file that accompanied this code. | |
| 10 | + * | |
| 11 | + * This code is distributed in the hope that it will be useful, but WITHOUT | |
| 12 | + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
| 13 | + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
| 14 | + * version 2 for more details (a copy is included in the LICENSE file that | |
| 15 | + * accompanied this code). | |
| 16 | + * | |
| 17 | + * You should have received a copy of the GNU General Public License version | |
| 18 | + * 2 along with this work; if not, write to the Free Software Foundation, | |
| 19 | + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | |
| 20 | + * | |
| 21 | + * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA | |
| 22 | + * or visit www.oracle.com if you need additional information or have any | |
| 23 | + * questions. | |
| 24 | + */ | |
| 25 | + | |
| 26 | +package java.util.logging; | |
| 27 | + | |
| 28 | +/** | |
| 29 | + * <tt>Handler</tt> that buffers requests in a circular buffer in memory. | |
| 30 | + * <p> | |
| 31 | + * Normally this <tt>Handler</tt> simply stores incoming <tt>LogRecords</tt> | |
| 32 | + * into its memory buffer and discards earlier records. This buffering | |
| 33 | + * is very cheap and avoids formatting costs. On certain trigger | |
| 34 | + * conditions, the <tt>MemoryHandler</tt> will push out its current buffer | |
| 35 | + * contents to a target <tt>Handler</tt>, which will typically publish | |
| 36 | + * them to the outside world. | |
| 37 | + * <p> | |
| 38 | + * There are three main models for triggering a push of the buffer: | |
| 39 | + * <ul> | |
| 40 | + * <li> | |
| 41 | + * An incoming <tt>LogRecord</tt> has a type that is greater than | |
| 42 | + * a pre-defined level, the <tt>pushLevel</tt>. | |
| 43 | + * <li> | |
| 44 | + * An external class calls the <tt>push</tt> method explicitly. | |
| 45 | + * <li> | |
| 46 | + * A subclass overrides the <tt>log</tt> method and scans each incoming | |
| 47 | + * <tt>LogRecord</tt> and calls <tt>push</tt> if a record matches some | |
| 48 | + * desired criteria. | |
| 49 | + * </ul> | |
| 50 | + * <p> | |
| 51 | + * <b>Configuration:</b> | |
| 52 | + * By default each <tt>MemoryHandler</tt> is initialized using the following | |
| 53 | + * LogManager configuration properties. If properties are not defined | |
| 54 | + * (or have invalid values) then the specified default values are used. | |
| 55 | + * If no default value is defined then a RuntimeException is thrown. | |
| 56 | + * <ul> | |
| 57 | + * <li> java.util.logging.MemoryHandler.level | |
| 58 | + * specifies the level for the <tt>Handler</tt> | |
| 59 | + * (defaults to <tt>Level.ALL</tt>). | |
| 60 | + * <li> java.util.logging.MemoryHandler.filter | |
| 61 | + * specifies the name of a <tt>Filter</tt> class to use | |
| 62 | + * (defaults to no <tt>Filter</tt>). | |
| 63 | + * <li> java.util.logging.MemoryHandler.size | |
| 64 | + * defines the buffer size (defaults to 1000). | |
| 65 | + * <li> java.util.logging.MemoryHandler.push | |
| 66 | + * defines the <tt>pushLevel</tt> (defaults to <tt>level.SEVERE</tt>). | |
| 67 | + * <li> java.util.logging.MemoryHandler.target | |
| 68 | + * specifies the name of the target <tt>Handler </tt> class. | |
| 69 | + * (no default). | |
| 70 | + * </ul> | |
| 71 | + * | |
| 72 | + * @since 1.4 | |
| 73 | + */ | |
| 74 | + | |
| 75 | +public class MemoryHandler extends Handler { | |
| 76 | + private final static int DEFAULT_SIZE = 1000; | |
| 77 | + private Level pushLevel; | |
| 78 | + private int size; | |
| 79 | + private Handler target; | |
| 80 | + private LogRecord buffer[]; | |
| 81 | + int start, count; | |
| 82 | + | |
| 83 | + // Private method to configure a ConsoleHandler from LogManager | |
| 84 | + // properties and/or default values as specified in the class | |
| 85 | + // javadoc. | |
| 86 | + private void configure() { | |
| 87 | + LogManager manager = LogManager.getLogManager(); | |
| 88 | + String cname = getClass().getName(); | |
| 89 | + | |
| 90 | + pushLevel = manager.getLevelProperty(cname +".push", Level.SEVERE); | |
| 91 | + size = manager.getIntProperty(cname + ".size", DEFAULT_SIZE); | |
| 92 | + if (size <= 0) { | |
| 93 | + size = DEFAULT_SIZE; | |
| 94 | + } | |
| 95 | + setLevel(manager.getLevelProperty(cname +".level", Level.ALL)); | |
| 96 | + setFilter(manager.getFilterProperty(cname +".filter", null)); | |
| 97 | + setFormatter(manager.getFormatterProperty(cname +".formatter", new SimpleFormatter())); | |
| 98 | + } | |
| 99 | + | |
| 100 | + /** | |
| 101 | + * Create a <tt>MemoryHandler</tt> and configure it based on | |
| 102 | + * <tt>LogManager</tt> configuration properties. | |
| 103 | + */ | |
| 104 | + public MemoryHandler() { | |
| 105 | + sealed = false; | |
| 106 | + configure(); | |
| 107 | + sealed = true; | |
| 108 | + | |
| 109 | + String name = "???"; | |
| 110 | + try { | |
| 111 | + LogManager manager = LogManager.getLogManager(); | |
| 112 | + name = manager.getProperty("java.util.logging.MemoryHandler.target"); | |
| 113 | + Class clz = ClassLoader.getSystemClassLoader().loadClass(name); | |
| 114 | + target = (Handler) clz.newInstance(); | |
| 115 | + } catch (Exception ex) { | |
| 116 | + throw new RuntimeException("MemoryHandler can't load handler \"" + name + "\"" , ex); | |
| 117 | + } | |
| 118 | + init(); | |
| 119 | + } | |
| 120 | + | |
| 121 | + // Initialize. Size is a count of LogRecords. | |
| 122 | + private void init() { | |
| 123 | + buffer = new LogRecord[size]; | |
| 124 | + start = 0; | |
| 125 | + count = 0; | |
| 126 | + } | |
| 127 | + | |
| 128 | + /** | |
| 129 | + * Create a <tt>MemoryHandler</tt>. | |
| 130 | + * <p> | |
| 131 | + * The <tt>MemoryHandler</tt> is configured based on <tt>LogManager</tt> | |
| 132 | + * properties (or their default values) except that the given <tt>pushLevel</tt> | |
| 133 | + * argument and buffer size argument are used. | |
| 134 | + * | |
| 135 | + * @param target the Handler to which to publish output. | |
| 136 | + * @param size the number of log records to buffer (must be greater than zero) | |
| 137 | + * @param pushLevel message level to push on | |
| 138 | + * | |
| 139 | + * @throws IllegalArgumentException if size is <= 0 | |
| 140 | + */ | |
| 141 | + public MemoryHandler(Handler target, int size, Level pushLevel) { | |
| 142 | + if (target == null || pushLevel == null) { | |
| 143 | + throw new NullPointerException(); | |
| 144 | + } | |
| 145 | + if (size <= 0) { | |
| 146 | + throw new IllegalArgumentException(); | |
| 147 | + } | |
| 148 | + sealed = false; | |
| 149 | + configure(); | |
| 150 | + sealed = true; | |
| 151 | + this.target = target; | |
| 152 | + this.pushLevel = pushLevel; | |
| 153 | + this.size = size; | |
| 154 | + init(); | |
| 155 | + } | |
| 156 | + | |
| 157 | + /** | |
| 158 | + * Store a <tt>LogRecord</tt> in an internal buffer. | |
| 159 | + * <p> | |
| 160 | + * If there is a <tt>Filter</tt>, its <tt>isLoggable</tt> | |
| 161 | + * method is called to check if the given log record is loggable. | |
| 162 | + * If not we return. Otherwise the given record is copied into | |
| 163 | + * an internal circular buffer. Then the record's level property is | |
| 164 | + * compared with the <tt>pushLevel</tt>. If the given level is | |
| 165 | + * greater than or equal to the <tt>pushLevel</tt> then <tt>push</tt> | |
| 166 | + * is called to write all buffered records to the target output | |
| 167 | + * <tt>Handler</tt>. | |
| 168 | + * | |
| 169 | + * @param record description of the log event. A null record is | |
| 170 | + * silently ignored and is not published | |
| 171 | + */ | |
| 172 | + public synchronized void publish(LogRecord record) { | |
| 173 | + if (!isLoggable(record)) { | |
| 174 | + return; | |
| 175 | + } | |
| 176 | + int ix = (start+count)%buffer.length; | |
| 177 | + buffer[ix] = record; | |
| 178 | + if (count < buffer.length) { | |
| 179 | + count++; | |
| 180 | + } else { | |
| 181 | + start++; | |
| 182 | + start %= buffer.length; | |
| 183 | + } | |
| 184 | + if (record.getLevel().intValue() >= pushLevel.intValue()) { | |
| 185 | + push(); | |
| 186 | + } | |
| 187 | + } | |
| 188 | + | |
| 189 | + /** | |
| 190 | + * Push any buffered output to the target <tt>Handler</tt>. | |
| 191 | + * <p> | |
| 192 | + * The buffer is then cleared. | |
| 193 | + */ | |
| 194 | + public synchronized void push() { | |
| 195 | + for (int i = 0; i < count; i++) { | |
| 196 | + int ix = (start+i)%buffer.length; | |
| 197 | + LogRecord record = buffer[ix]; | |
| 198 | + target.publish(record); | |
| 199 | + } | |
| 200 | + // Empty the buffer. | |
| 201 | + start = 0; | |
| 202 | + count = 0; | |
| 203 | + } | |
| 204 | + | |
| 205 | + /** | |
| 206 | + * Causes a flush on the target <tt>Handler</tt>. | |
| 207 | + * <p> | |
| 208 | + * Note that the current contents of the <tt>MemoryHandler</tt> | |
| 209 | + * buffer are <b>not</b> written out. That requires a "push". | |
| 210 | + */ | |
| 211 | + public void flush() { | |
| 212 | + target.flush(); | |
| 213 | + } | |
| 214 | + | |
| 215 | + /** | |
| 216 | + * Close the <tt>Handler</tt> and free all associated resources. | |
| 217 | + * This will also close the target <tt>Handler</tt>. | |
| 218 | + * | |
| 219 | + * @exception SecurityException if a security manager exists and if | |
| 220 | + * the caller does not have <tt>LoggingPermission("control")</tt>. | |
| 221 | + */ | |
| 222 | + public void close() throws SecurityException { | |
| 223 | + target.close(); | |
| 224 | + setLevel(Level.OFF); | |
| 225 | + } | |
| 226 | + | |
| 227 | + /** | |
| 228 | + * Set the <tt>pushLevel</tt>. After a <tt>LogRecord</tt> is copied | |
| 229 | + * into our internal buffer, if its level is greater than or equal to | |
| 230 | + * the <tt>pushLevel</tt>, then <tt>push</tt> will be called. | |
| 231 | + * | |
| 232 | + * @param newLevel the new value of the <tt>pushLevel</tt> | |
| 233 | + * @exception SecurityException if a security manager exists and if | |
| 234 | + * the caller does not have <tt>LoggingPermission("control")</tt>. | |
| 235 | + */ | |
| 236 | + public void setPushLevel(Level newLevel) throws SecurityException { | |
| 237 | + if (newLevel == null) { | |
| 238 | + throw new NullPointerException(); | |
| 239 | + } | |
| 240 | + LogManager manager = LogManager.getLogManager(); | |
| 241 | + checkAccess(); | |
| 242 | + pushLevel = newLevel; | |
| 243 | + } | |
| 244 | + | |
| 245 | + /** | |
| 246 | + * Get the <tt>pushLevel</tt>. | |
| 247 | + * | |
| 248 | + * @return the value of the <tt>pushLevel</tt> | |
| 249 | + */ | |
| 250 | + public synchronized Level getPushLevel() { | |
| 251 | + return pushLevel; | |
| 252 | + } | |
| 253 | + | |
| 254 | + /** | |
| 255 | + * Check if this <tt>Handler</tt> would actually log a given | |
| 256 | + * <tt>LogRecord</tt> into its internal buffer. | |
| 257 | + * <p> | |
| 258 | + * This method checks if the <tt>LogRecord</tt> has an appropriate level and | |
| 259 | + * whether it satisfies any <tt>Filter</tt>. However it does <b>not</b> | |
| 260 | + * check whether the <tt>LogRecord</tt> would result in a "push" of the | |
| 261 | + * buffer contents. It will return false if the <tt>LogRecord</tt> is null. | |
| 262 | + * <p> | |
| 263 | + * @param record a <tt>LogRecord</tt> | |
| 264 | + * @return true if the <tt>LogRecord</tt> would be logged. | |
| 265 | + * | |
| 266 | + */ | |
| 267 | + public boolean isLoggable(LogRecord record) { | |
| 268 | + return super.isLoggable(record); | |
| 269 | + } | |
| 270 | +} | |