1 /*
2 * Copyright (c) 2000, 2012, 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 import java.security.AccessController;
29 import java.security.PrivilegedAction;
30
31 /**
32 * <tt>Handler</tt> that buffers requests in a circular buffer in memory.
33 * <p>
34 * Normally this <tt>Handler</tt> simply stores incoming <tt>LogRecords</tt>
35 * into its memory buffer and discards earlier records. This buffering
36 * is very cheap and avoids formatting costs. On certain trigger
37 * conditions, the <tt>MemoryHandler</tt> will push out its current buffer
38 * contents to a target <tt>Handler</tt>, which will typically publish
39 * them to the outside world.
40 * <p>
41 * There are three main models for triggering a push of the buffer:
42 * <ul>
43 * <li>
44 * An incoming <tt>LogRecord</tt> has a type that is greater than
45 * a pre-defined level, the <tt>pushLevel</tt>. </li>
46 * <li>
47 * An external class calls the <tt>push</tt> method explicitly. </li>
48 * <li>
49 * A subclass overrides the <tt>log</tt> method and scans each incoming
50 * <tt>LogRecord</tt> and calls <tt>push</tt> if a record matches some
51 * desired criteria. </li>
52 * </ul>
53 * <p>
54 * <b>Configuration:</b>
55 * By default each <tt>MemoryHandler</tt> is initialized using the following
56 * <tt>LogManager</tt> configuration properties where <tt><handler-name></tt>
57 * refers to the fully-qualified class name of the handler.
58 * If properties are not defined
59 * (or have invalid values) then the specified default values are used.
60 * If no default value is defined then a RuntimeException is thrown.
61 * <ul>
62 * <li> <handler-name>.level
63 * specifies the level for the <tt>Handler</tt>
64 * (defaults to <tt>Level.ALL</tt>). </li>
65 * <li> <handler-name>.filter
66 * specifies the name of a <tt>Filter</tt> class to use
67 * (defaults to no <tt>Filter</tt>). </li>
68 * <li> <handler-name>.size
69 * defines the buffer size (defaults to 1000). </li>
70 * <li> <handler-name>.push
71 * defines the <tt>pushLevel</tt> (defaults to <tt>level.SEVERE</tt>). </li>
72 * <li> <handler-name>.target
73 * specifies the name of the target <tt>Handler </tt> class.
74 * (no default). </li>
75 * </ul>
76 * <p>
77 * For example, the properties for {@code MemoryHandler} would be:
78 * <ul>
79 * <li> java.util.logging.MemoryHandler.level=INFO </li>
80 * <li> java.util.logging.MemoryHandler.formatter=java.util.logging.SimpleFormatter </li>
81 * </ul>
82 * <p>
83 * For a custom handler, e.g. com.foo.MyHandler, the properties would be:
84 * <ul>
85 * <li> com.foo.MyHandler.level=INFO </li>
86 * <li> com.foo.MyHandler.formatter=java.util.logging.SimpleFormatter </li>
87 * </ul>
88 * <p>
89 * @since 1.4
90 */
91
92 public class MemoryHandler extends Handler {
93 private final static int DEFAULT_SIZE = 1000;
94 private volatile Level pushLevel;
95 private int size;
96 private Handler target;
97 private LogRecord buffer[];
98 int start, count;
99
100 // Private PrivilegedAction to configure a MemoryHandler from LogManager
101 // properties and/or default values as specified in the class
102 // javadoc.
103 private class ConfigureAction implements PrivilegedAction<Void> {
104 @Override
105 public Void run() {
106 LogManager manager = LogManager.getLogManager();
107 String cname = MemoryHandler.this.getClass().getName();
108
109 pushLevel = manager.getLevelProperty(cname +".push", Level.SEVERE);
110 size = manager.getIntProperty(cname + ".size", DEFAULT_SIZE);
111 if (size <= 0) {
112 size = DEFAULT_SIZE;
113 }
114 setLevel(manager.getLevelProperty(cname +".level", Level.ALL));
115 setFilter(manager.getFilterProperty(cname +".filter", null));
116 setFormatter(manager.getFormatterProperty(cname +".formatter", new SimpleFormatter()));
117 return null;
118 }
119 }
120
121 /**
122 * Create a <tt>MemoryHandler</tt> and configure it based on
123 * <tt>LogManager</tt> configuration properties.
124 */
125 public MemoryHandler() {
126 AccessController.doPrivileged(new ConfigureAction(), null, LogManager.controlPermission);
127
128 LogManager manager = LogManager.getLogManager();
129 String handlerName = getClass().getName();
130 String targetName = manager.getProperty(handlerName+".target");
131 if (targetName == null) {
132 throw new RuntimeException("The handler " + handlerName
133 + " does not specify a target");
134 }
135 Class<?> clz;
136 try {
137 clz = ClassLoader.getSystemClassLoader().loadClass(targetName);
138 target = (Handler) clz.newInstance();
139 } catch (ClassNotFoundException | InstantiationException | IllegalAccessException e) {
140 throw new RuntimeException("MemoryHandler can't load handler target \"" + targetName + "\"" , e);
141 }
142 init();
143 }
144
145 // Initialize. Size is a count of LogRecords.
146 private void init() {
147 buffer = new LogRecord[size];
148 start = 0;
149 count = 0;
150 }
151
152 /**
153 * Create a <tt>MemoryHandler</tt>.
154 * <p>
155 * The <tt>MemoryHandler</tt> is configured based on <tt>LogManager</tt>
156 * properties (or their default values) except that the given <tt>pushLevel</tt>
157 * argument and buffer size argument are used.
158 *
159 * @param target the Handler to which to publish output.
160 * @param size the number of log records to buffer (must be greater than zero)
161 * @param pushLevel message level to push on
162 *
163 * @throws IllegalArgumentException if {@code size is <= 0}
164 */
165 public MemoryHandler(Handler target, int size, Level pushLevel) {
166 if (target == null || pushLevel == null) {
167 throw new NullPointerException();
168 }
169 if (size <= 0) {
170 throw new IllegalArgumentException();
171 }
172 AccessController.doPrivileged(new ConfigureAction(), null, LogManager.controlPermission);
173 this.target = target;
174 this.pushLevel = pushLevel;
175 this.size = size;
176 init();
177 }
178
179 /**
180 * Store a <tt>LogRecord</tt> in an internal buffer.
181 * <p>
182 * If there is a <tt>Filter</tt>, its <tt>isLoggable</tt>
183 * method is called to check if the given log record is loggable.
184 * If not we return. Otherwise the given record is copied into
185 * an internal circular buffer. Then the record's level property is
186 * compared with the <tt>pushLevel</tt>. If the given level is
187 * greater than or equal to the <tt>pushLevel</tt> then <tt>push</tt>
188 * is called to write all buffered records to the target output
189 * <tt>Handler</tt>.
190 *
191 * @param record description of the log event. A null record is
192 * silently ignored and is not published
193 */
194 @Override
195 public synchronized void publish(LogRecord record) {
196 if (!isLoggable(record)) {
197 return;
198 }
199 int ix = (start+count)%buffer.length;
200 buffer[ix] = record;
201 if (count < buffer.length) {
202 count++;
203 } else {
204 start++;
205 start %= buffer.length;
206 }
207 if (record.getLevel().intValue() >= pushLevel.intValue()) {
208 push();
209 }
210 }
211
212 /**
213 * Push any buffered output to the target <tt>Handler</tt>.
214 * <p>
215 * The buffer is then cleared.
216 */
217 public synchronized void push() {
218 for (int i = 0; i < count; i++) {
219 int ix = (start+i)%buffer.length;
220 LogRecord record = buffer[ix];
221 target.publish(record);
222 }
223 // Empty the buffer.
224 start = 0;
225 count = 0;
226 }
227
228 /**
229 * Causes a flush on the target <tt>Handler</tt>.
230 * <p>
231 * Note that the current contents of the <tt>MemoryHandler</tt>
232 * buffer are <b>not</b> written out. That requires a "push".
233 */
234 @Override
235 public void flush() {
236 target.flush();
237 }
238
239 /**
240 * Close the <tt>Handler</tt> and free all associated resources.
241 * This will also close the target <tt>Handler</tt>.
242 *
243 * @exception SecurityException if a security manager exists and if
244 * the caller does not have <tt>LoggingPermission("control")</tt>.
245 */
246 @Override
247 public void close() throws SecurityException {
248 target.close();
249 setLevel(Level.OFF);
250 }
251
252 /**
253 * Set the <tt>pushLevel</tt>. After a <tt>LogRecord</tt> is copied
254 * into our internal buffer, if its level is greater than or equal to
255 * the <tt>pushLevel</tt>, then <tt>push</tt> will be called.
256 *
257 * @param newLevel the new value of the <tt>pushLevel</tt>
258 * @exception SecurityException if a security manager exists and if
259 * the caller does not have <tt>LoggingPermission("control")</tt>.
260 */
261 public synchronized void setPushLevel(Level newLevel) throws SecurityException {
262 if (newLevel == null) {
263 throw new NullPointerException();
264 }
265 checkPermission();
266 pushLevel = newLevel;
267 }
268
269 /**
270 * Get the <tt>pushLevel</tt>.
271 *
272 * @return the value of the <tt>pushLevel</tt>
273 */
274 public Level getPushLevel() {
275 return pushLevel;
276 }
277
278 /**
279 * Check if this <tt>Handler</tt> would actually log a given
280 * <tt>LogRecord</tt> into its internal buffer.
281 * <p>
282 * This method checks if the <tt>LogRecord</tt> has an appropriate level and
283 * whether it satisfies any <tt>Filter</tt>. However it does <b>not</b>
284 * check whether the <tt>LogRecord</tt> would result in a "push" of the
285 * buffer contents. It will return false if the <tt>LogRecord</tt> is null.
286 * <p>
287 * @param record a <tt>LogRecord</tt>
288 * @return true if the <tt>LogRecord</tt> would be logged.
289 *
290 */
291 @Override
292 public boolean isLoggable(LogRecord record) {
293 return super.isLoggable(record);
294 }
295 }