2 * Copyright (C) 2013 - David Goulet <dgoulet@efficios.com>
4 * This library is free software; you can redistribute it and/or modify it
5 * under the terms of the GNU Lesser General Public License, version 2.1 only,
6 * as published by the Free Software Foundation.
8 * This library is distributed in the hope that it will be useful, but WITHOUT
9 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
10 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
13 * You should have received a copy of the GNU Lesser General Public License
14 * along with this library; if not, write to the Free Software Foundation,
15 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
18 package org
.lttng
.ust
.agent
;
20 import java
.lang
.reflect
.Constructor
;
21 import java
.lang
.reflect
.InvocationTargetException
;
22 import java
.lang
.reflect
.Method
;
23 import java
.util
.logging
.Handler
;
24 import java
.util
.logging
.Logger
;
27 * The central agent managing the JUL and Log4j handlers.
29 * @author David Goulet
30 * @deprecated Applications are now expected to manage their Logger and Handler
34 public class LTTngAgent
{
36 private static LTTngAgent instance
= null;
39 * Public getter to acquire a reference to this singleton object.
41 * @return The agent instance
43 public static synchronized LTTngAgent
getLTTngAgent() {
44 if (instance
== null) {
45 instance
= new LTTngAgent();
51 * Dispose the agent. Applications should call this once they are done
54 public static synchronized void dispose() {
55 if (instance
!= null) {
56 instance
.disposeInstance();
62 private ILttngHandler julHandler
= null;
63 private ILttngHandler log4jAppender
= null;
66 * Private constructor. This is a singleton and a reference should be
67 * acquired using {@link #getLTTngAgent()}.
69 private LTTngAgent() {
75 * "Destructor" method.
77 private void disposeInstance() {
79 disposeLog4jAppender();
83 * Create a LTTng-JUL handler, and attach it to the JUL root logger.
85 private void initJulHandler() {
87 Class
<?
> julHandlerClass
= Class
.forName("org.lttng.ust.agent.jul.LttngLogHandler");
89 * It is safer to use Constructor.newInstance() rather than
90 * Class.newInstance(), because it will catch the exceptions thrown
91 * by the constructor below (which happens if the Java library is
92 * present, but the matching JNI one is not).
94 Constructor
<?
> julHandlerCtor
= julHandlerClass
.getConstructor();
95 julHandler
= (ILttngHandler
) julHandlerCtor
.newInstance();
97 /* Attach the handler to the root JUL logger */
98 Logger
.getLogger("").addHandler((Handler
) julHandler
);
101 * If any of the following exceptions happen, it means we could not
102 * find or initialize LTTng JUL classes. We will not setup LTTng JUL
103 * tracing in this case.
105 } catch (SecurityException e
) {
106 } catch (IllegalAccessException e
) {
107 } catch (IllegalArgumentException e
) {
108 } catch (ClassNotFoundException e
) {
109 } catch (NoSuchMethodException e
) {
110 } catch (InstantiationException e
) {
111 } catch (InvocationTargetException e
) {
116 * Create a LTTng-logj4 appender, and attach it to the log4j root logger.
118 private void initLog4jAppender() {
120 * Since Log4j is a 3rd party library, we first need to check if we can
121 * load any of its classes.
123 if (!testLog4jClasses()) {
128 Class
<?
> log4jAppenderClass
= Class
.forName("org.lttng.ust.agent.log4j.LttngLogAppender");
129 Constructor
<?
> log4jAppendCtor
= log4jAppenderClass
.getConstructor();
130 log4jAppender
= (ILttngHandler
) log4jAppendCtor
.newInstance();
133 * If any of the following exceptions happen, it means we could not
134 * find or initialize LTTng log4j classes. We will not setup LTTng
135 * log4j tracing in this case.
137 } catch (SecurityException e
) {
139 } catch (ClassNotFoundException e
) {
141 } catch (NoSuchMethodException e
) {
143 } catch (IllegalArgumentException e
) {
145 } catch (InstantiationException e
) {
147 } catch (IllegalAccessException e
) {
149 } catch (InvocationTargetException e
) {
154 * Attach the appender to the root Log4j logger. Slightly more tricky
155 * here, as log4j.Logger is not in the base Java library, and we do not
156 * want the "common" package to depend on log4j. So we have to obtain it
157 * through reflection too.
160 Class
<?
> loggerClass
= Class
.forName("org.apache.log4j.Logger");
161 Class
<?
> appenderClass
= Class
.forName("org.apache.log4j.Appender");
163 Method getRootLoggerMethod
= loggerClass
.getMethod("getRootLogger", (Class
<?
>[]) null);
164 Method addAppenderMethod
= loggerClass
.getMethod("addAppender", appenderClass
);
166 Object rootLogger
= getRootLoggerMethod
.invoke(null, (Object
[]) null);
167 addAppenderMethod
.invoke(rootLogger
, log4jAppender
);
170 * We have checked for the log4j library version previously, none of
171 * the following exceptions should happen.
173 } catch (SecurityException e
) {
174 throw new IllegalStateException(e
);
175 } catch (ClassNotFoundException e
) {
176 throw new IllegalStateException(e
);
177 } catch (NoSuchMethodException e
) {
178 throw new IllegalStateException(e
);
179 } catch (IllegalArgumentException e
) {
180 throw new IllegalStateException(e
);
181 } catch (IllegalAccessException e
) {
182 throw new IllegalStateException(e
);
183 } catch (InvocationTargetException e
) {
184 throw new IllegalStateException(e
);
189 * Check if log4j >= 1.2.15 library is present.
191 private static boolean testLog4jClasses() {
192 Class
<?
> loggingEventClass
;
195 loggingEventClass
= Class
.forName("org.apache.log4j.spi.LoggingEvent");
196 } catch (ClassNotFoundException e
) {
198 * Log4j classes not found, no need to create the relevant objects
204 * Detect capabilities of the log4j library. We only support log4j >=
205 * 1.2.15. The getTimeStamp() method was introduced in log4j 1.2.15, so
206 * verify that it is available.
208 * We can't rely on the getPackage().getImplementationVersion() call
209 * that would retrieves information from the manifest file found in the
210 * JAR since the manifest file shipped from upstream is known to be
211 * broken in several versions of the library.
213 * More info: https://issues.apache.org/bugzilla/show_bug.cgi?id=44370
216 loggingEventClass
.getDeclaredMethod("getTimeStamp");
217 } catch (NoSuchMethodException e
) {
219 "Warning: The loaded log4j library is too old. Log4j tracing with LTTng will be disabled.");
221 } catch (SecurityException e
) {
229 * Detach the JUL handler from its logger and close it.
231 private void disposeJulHandler() {
232 if (julHandler
== null) {
233 /* The JUL handler was not activated, we have nothing to do */
236 Logger
.getLogger("").removeHandler((Handler
) julHandler
);
242 * Detach the log4j appender from its logger and close it.
244 private void disposeLog4jAppender() {
245 if (log4jAppender
== null) {
246 /* The log4j appender was not active, we have nothing to do */
251 * Detach the appender from the log4j root logger. Again, we have to do
252 * this via reflection.
255 Class
<?
> loggerClass
= Class
.forName("org.apache.log4j.Logger");
256 Class
<?
> appenderClass
= Class
.forName("org.apache.log4j.Appender");
258 Method getRootLoggerMethod
= loggerClass
.getMethod("getRootLogger", (Class
<?
>[]) null);
259 Method removeAppenderMethod
= loggerClass
.getMethod("removeAppender", appenderClass
);
261 Object rootLogger
= getRootLoggerMethod
.invoke(null, (Object
[]) null);
262 removeAppenderMethod
.invoke(rootLogger
, log4jAppender
);
265 * We were able to attach the appender previously, we should not
266 * have problems here either!
268 } catch (SecurityException e
) {
269 throw new IllegalStateException(e
);
270 } catch (ClassNotFoundException e
) {
271 throw new IllegalStateException(e
);
272 } catch (NoSuchMethodException e
) {
273 throw new IllegalStateException(e
);
274 } catch (IllegalArgumentException e
) {
275 throw new IllegalStateException(e
);
276 } catch (IllegalAccessException e
) {
277 throw new IllegalStateException(e
);
278 } catch (InvocationTargetException e
) {
279 throw new IllegalStateException(e
);
282 /* Close the appender */
283 log4jAppender
.close();
284 log4jAppender
= null;