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(),
127 null, LogManager.controlPermission);
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(),
173 null, LogManager.controlPermission);
174 this.target = target;
175 this.pushLevel = pushLevel;
176 this.size = size;
177 init();
178 }
179
180 /**
181 * Store a <tt>LogRecord</tt> in an internal buffer.
182 * <p>
183 * If there is a <tt>Filter</tt>, its <tt>isLoggable</tt>
184 * method is called to check if the given log record is loggable.
185 * If not we return. Otherwise the given record is copied into
186 * an internal circular buffer. Then the record's level property is
187 * compared with the <tt>pushLevel</tt>. If the given level is
188 * greater than or equal to the <tt>pushLevel</tt> then <tt>push</tt>
189 * is called to write all buffered records to the target output
190 * <tt>Handler</tt>.
191 *
192 * @param record description of the log event. A null record is
193 * silently ignored and is not published
194 */
195 @Override
196 public synchronized void publish(LogRecord record) {
197 if (!isLoggable(record)) {
198 return;
199 }
200 int ix = (start+count)%buffer.length;
201 buffer[ix] = record;
202 if (count < buffer.length) {
203 count++;
204 } else {
205 start++;
206 start %= buffer.length;
207 }
208 if (record.getLevel().intValue() >= pushLevel.intValue()) {
209 push();
210 }
211 }
212
213 /**
214 * Push any buffered output to the target <tt>Handler</tt>.
215 * <p>
216 * The buffer is then cleared.
217 */
218 public synchronized void push() {
219 for (int i = 0; i < count; i++) {
220 int ix = (start+i)%buffer.length;
221 LogRecord record = buffer[ix];
222 target.publish(record);
223 }
224 // Empty the buffer.
225 start = 0;
226 count = 0;
227 }
228
229 /**
230 * Causes a flush on the target <tt>Handler</tt>.
231 * <p>
232 * Note that the current contents of the <tt>MemoryHandler</tt>
233 * buffer are <b>not</b> written out. That requires a "push".
234 */
235 @Override
236 public void flush() {
237 target.flush();
238 }
239
240 /**
241 * Close the <tt>Handler</tt> and free all associated resources.
242 * This will also close the target <tt>Handler</tt>.
243 *
244 * @exception SecurityException if a security manager exists and if
245 * the caller does not have <tt>LoggingPermission("control")</tt>.
246 */
247 @Override
248 public void close() throws SecurityException {
249 target.close();
250 setLevel(Level.OFF);
251 }
252
253 /**
254 * Set the <tt>pushLevel</tt>. After a <tt>LogRecord</tt> is copied
255 * into our internal buffer, if its level is greater than or equal to
256 * the <tt>pushLevel</tt>, then <tt>push</tt> will be called.
257 *
258 * @param newLevel the new value of the <tt>pushLevel</tt>
259 * @exception SecurityException if a security manager exists and if
260 * the caller does not have <tt>LoggingPermission("control")</tt>.
261 */
262 public synchronized void setPushLevel(Level newLevel) throws SecurityException {
263 if (newLevel == null) {
264 throw new NullPointerException();
265 }
266 checkPermission();
267 pushLevel = newLevel;
268 }
269
270 /**
271 * Get the <tt>pushLevel</tt>.
272 *
273 * @return the value of the <tt>pushLevel</tt>
274 */
275 public Level getPushLevel() {
276 return pushLevel;
277 }
278
279 /**
280 * Check if this <tt>Handler</tt> would actually log a given
281 * <tt>LogRecord</tt> into its internal buffer.
282 * <p>
283 * This method checks if the <tt>LogRecord</tt> has an appropriate level and
284 * whether it satisfies any <tt>Filter</tt>. However it does <b>not</b>
285 * check whether the <tt>LogRecord</tt> would result in a "push" of the
286 * buffer contents. It will return false if the <tt>LogRecord</tt> is null.
287 * <p>
288 * @param record a <tt>LogRecord</tt>
289 * @return true if the <tt>LogRecord</tt> would be logged.
290 *
291 */
292 @Override
293 public boolean isLoggable(LogRecord record) {
294 return super.isLoggable(record);
295 }
296 }