liblttng-ust-java-agent/java/lttng-ust-agent-common/org/lttng/ust/agent/LTTngAgent.java

   1 /*
   2  * Copyright (C) 2013 - David Goulet <dgoulet@efficios.com>
   3  *
   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.
   7  *
   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
  11  * for more details.
  12  *
  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
  16  */
  17
  18 package org.lttng.ust.agent;
  19
  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;
  25
  26 /**
  27  * The central agent managing the JUL and Log4j handlers.
  28  *
  29  * @author David Goulet
  30  * @deprecated Applications are now expected to manage their Logger and Handler
  31  *             objects.
  32  */
  33 @Deprecated
  34 public class LTTngAgent {
  35
  36         private static LTTngAgent instance = null;
  37
  38         /**
  39          * Public getter to acquire a reference to this singleton object.
  40          *
  41          * @return The agent instance
  42          */
  43         public static synchronized LTTngAgent getLTTngAgent() {
  44                 if (instance == null) {
  45                         instance = new LTTngAgent();
  46                 }
  47                 return instance;
  48         }
  49
  50         /**
  51          * Dispose the agent. Applications should call this once they are done
  52          * logging. This dispose function is non-static for backwards
  53          * compatibility purposes.
  54          */
  55         public synchronized void dispose() {
  56                 if (instance != null) {
  57                         instance.disposeInstance();
  58                         instance = null;
  59                 }
  60                 return;
  61         }
  62
  63         private ILttngHandler julHandler = null;
  64         private ILttngHandler log4jAppender = null;
  65
  66         /**
  67          * Private constructor. This is a singleton and a reference should be
  68          * acquired using {@link #getLTTngAgent()}.
  69          */
  70         private LTTngAgent() {
  71                 initJulHandler();
  72                 initLog4jAppender();
  73         }
  74
  75         /**
  76          * "Destructor" method.
  77          */
  78         private void disposeInstance() {
  79                 disposeJulHandler();
  80                 disposeLog4jAppender();
  81         }
  82
  83         /**
  84          * Create a LTTng-JUL handler, and attach it to the JUL root logger.
  85          */
  86         private void initJulHandler() {
  87                 try {
  88                         Class<?> julHandlerClass = Class.forName("org.lttng.ust.agent.jul.LttngLogHandler");
  89                         /*
  90                          * It is safer to use Constructor.newInstance() rather than
  91                          * Class.newInstance(), because it will catch the exceptions thrown
  92                          * by the constructor below (which happens if the Java library is
  93                          * present, but the matching JNI one is not).
  94                          */
  95                         Constructor<?> julHandlerCtor = julHandlerClass.getConstructor();
  96                         julHandler = (ILttngHandler) julHandlerCtor.newInstance();
  97
  98                         /* Attach the handler to the root JUL logger */
  99                         Logger.getLogger("").addHandler((Handler) julHandler);
 100
 101                         /*
 102                          * If any of the following exceptions happen, it means we could not
 103                          * find or initialize LTTng JUL classes. We will not setup LTTng JUL
 104                          * tracing in this case.
 105                          */
 106                 } catch (SecurityException e) {
 107                 } catch (IllegalAccessException e) {
 108                 } catch (IllegalArgumentException e) {
 109                 } catch (ClassNotFoundException e) {
 110                 } catch (NoSuchMethodException e) {
 111                 } catch (InstantiationException e) {
 112                 } catch (InvocationTargetException e) {
 113                 }
 114         }
 115
 116         /**
 117          * Create a LTTng-logj4 appender, and attach it to the log4j root logger.
 118          */
 119         private void initLog4jAppender() {
 120                 /*
 121                  * Since Log4j is a 3rd party library, we first need to check if we can
 122                  * load any of its classes.
 123                  */
 124                 if (!testLog4jClasses()) {
 125                         return;
 126                 }
 127
 128                 try {
 129                         Class<?> log4jAppenderClass = Class.forName("org.lttng.ust.agent.log4j.LttngLogAppender");
 130                         Constructor<?> log4jAppendCtor = log4jAppenderClass.getConstructor();
 131                         log4jAppender = (ILttngHandler) log4jAppendCtor.newInstance();
 132
 133                         /*
 134                          * If any of the following exceptions happen, it means we could not
 135                          * find or initialize LTTng log4j classes. We will not setup LTTng
 136                          * log4j tracing in this case.
 137                          */
 138                 } catch (SecurityException e) {
 139                         return;
 140                 } catch (ClassNotFoundException e) {
 141                         return;
 142                 } catch (NoSuchMethodException e) {
 143                         return;
 144                 } catch (IllegalArgumentException e) {
 145                         return;
 146                 } catch (InstantiationException e) {
 147                         return;
 148                 } catch (IllegalAccessException e) {
 149                         return;
 150                 } catch (InvocationTargetException e) {
 151                         return;
 152                 }
 153
 154                 /*
 155                  * Attach the appender to the root Log4j logger. Slightly more tricky
 156                  * here, as log4j.Logger is not in the base Java library, and we do not
 157                  * want the "common" package to depend on log4j. So we have to obtain it
 158                  * through reflection too.
 159                  */
 160                 try {
 161                         Class<?> loggerClass = Class.forName("org.apache.log4j.Logger");
 162                         Class<?> appenderClass = Class.forName("org.apache.log4j.Appender");
 163
 164                         Method getRootLoggerMethod = loggerClass.getMethod("getRootLogger", (Class<?>[]) null);
 165                         Method addAppenderMethod = loggerClass.getMethod("addAppender", appenderClass);
 166
 167                         Object rootLogger = getRootLoggerMethod.invoke(null, (Object[]) null);
 168                         addAppenderMethod.invoke(rootLogger, log4jAppender);
 169
 170                         /*
 171                          * We have checked for the log4j library version previously, none of
 172                          * the following exceptions should happen.
 173                          */
 174                 } catch (SecurityException e) {
 175                         throw new IllegalStateException(e);
 176                 } catch (ClassNotFoundException e) {
 177                         throw new IllegalStateException(e);
 178                 } catch (NoSuchMethodException e) {
 179                         throw new IllegalStateException(e);
 180                 } catch (IllegalArgumentException e) {
 181                         throw new IllegalStateException(e);
 182                 } catch (IllegalAccessException e) {
 183                         throw new IllegalStateException(e);
 184                 } catch (InvocationTargetException e) {
 185                         throw new IllegalStateException(e);
 186                 }
 187         }
 188
 189         /**
 190          * Check if log4j >= 1.2.15 library is present.
 191          */
 192         private static boolean testLog4jClasses() {
 193                 Class<?> loggingEventClass;
 194
 195                 try {
 196                         loggingEventClass = Class.forName("org.apache.log4j.spi.LoggingEvent");
 197                 } catch (ClassNotFoundException e) {
 198                         /*
 199                          * Log4j classes not found, no need to create the relevant objects
 200                          */
 201                         return false;
 202                 }
 203
 204                 /*
 205                  * Detect capabilities of the log4j library. We only support log4j >=
 206                  * 1.2.15. The getTimeStamp() method was introduced in log4j 1.2.15, so
 207                  * verify that it is available.
 208                  *
 209                  * We can't rely on the getPackage().getImplementationVersion() call
 210                  * that would retrieves information from the manifest file found in the
 211                  * JAR since the manifest file shipped from upstream is known to be
 212                  * broken in several versions of the library.
 213                  *
 214                  * More info: https://issues.apache.org/bugzilla/show_bug.cgi?id=44370
 215                  */
 216                 try {
 217                         loggingEventClass.getDeclaredMethod("getTimeStamp");
 218                 } catch (NoSuchMethodException e) {
 219                         System.err.println(
 220                                         "Warning: The loaded log4j library is too old. Log4j tracing with LTTng will be disabled.");
 221                         return false;
 222                 } catch (SecurityException e) {
 223                         return false;
 224                 }
 225
 226                 return true;
 227         }
 228
 229         /**
 230          * Detach the JUL handler from its logger and close it.
 231          */
 232         private void disposeJulHandler() {
 233                 if (julHandler == null) {
 234                         /* The JUL handler was not activated, we have nothing to do */
 235                         return;
 236                 }
 237                 Logger.getLogger("").removeHandler((Handler) julHandler);
 238                 julHandler.close();
 239                 julHandler = null;
 240         }
 241
 242         /**
 243          * Detach the log4j appender from its logger and close it.
 244          */
 245         private void disposeLog4jAppender() {
 246                 if (log4jAppender == null) {
 247                         /* The log4j appender was not active, we have nothing to do */
 248                         return;
 249                 }
 250
 251                 /*
 252                  * Detach the appender from the log4j root logger. Again, we have to do
 253                  * this via reflection.
 254                  */
 255                 try {
 256                         Class<?> loggerClass = Class.forName("org.apache.log4j.Logger");
 257                         Class<?> appenderClass = Class.forName("org.apache.log4j.Appender");
 258
 259                         Method getRootLoggerMethod = loggerClass.getMethod("getRootLogger", (Class<?>[]) null);
 260                         Method removeAppenderMethod = loggerClass.getMethod("removeAppender", appenderClass);
 261
 262                         Object rootLogger = getRootLoggerMethod.invoke(null, (Object[]) null);
 263                         removeAppenderMethod.invoke(rootLogger, log4jAppender);
 264
 265                         /*
 266                          * We were able to attach the appender previously, we should not
 267                          * have problems here either!
 268                          */
 269                 } catch (SecurityException e) {
 270                         throw new IllegalStateException(e);
 271                 } catch (ClassNotFoundException e) {
 272                         throw new IllegalStateException(e);
 273                 } catch (NoSuchMethodException e) {
 274                         throw new IllegalStateException(e);
 275                 } catch (IllegalArgumentException e) {
 276                         throw new IllegalStateException(e);
 277                 } catch (IllegalAccessException e) {
 278                         throw new IllegalStateException(e);
 279                 } catch (InvocationTargetException e) {
 280                         throw new IllegalStateException(e);
 281                 }
 282
 283                 /* Close the appender */
 284                 log4jAppender.close();
 285                 log4jAppender = null;
 286         }
 287
 288 }