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.
  53          */
  54         public static synchronized void dispose() {
  55                 if (instance != null) {
  56                         instance.disposeInstance();
  57                         instance = null;
  58                 }
  59                 return;
  60         }
  61
  62         private ILttngHandler julHandler = null;
  63         private ILttngHandler log4jAppender = null;
  64
  65         /**
  66          * Private constructor. This is a singleton and a reference should be
  67          * acquired using {@link #getLTTngAgent()}.
  68          */
  69         private LTTngAgent() {
  70                 initJulHandler();
  71                 initLog4jAppender();
  72         }
  73
  74         /**
  75          * "Destructor" method.
  76          */
  77         private void disposeInstance() {
  78                 disposeJulHandler();
  79                 disposeLog4jAppender();
  80         }
  81
  82         /**
  83          * Create a LTTng-JUL handler, and attach it to the JUL root logger.
  84          */
  85         private void initJulHandler() {
  86                 try {
  87                         Class<?> julHandlerClass = Class.forName("org.lttng.ust.agent.jul.LttngLogHandler");
  88                         /*
  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).
  93                          */
  94                         Constructor<?> julHandlerCtor = julHandlerClass.getConstructor();
  95                         julHandler = (ILttngHandler) julHandlerCtor.newInstance();
  96
  97                         /* Attach the handler to the root JUL logger */
  98                         Logger.getLogger("").addHandler((Handler) julHandler);
  99
 100                         /*
 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.
 104                          */
 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) {
 112                 }
 113         }
 114
 115         /**
 116          * Create a LTTng-logj4 appender, and attach it to the log4j root logger.
 117          */
 118         private void initLog4jAppender() {
 119                 /*
 120                  * Since Log4j is a 3rd party library, we first need to check if we can
 121                  * load any of its classes.
 122                  */
 123                 if (!testLog4jClasses()) {
 124                         return;
 125                 }
 126
 127                 try {
 128                         Class<?> log4jAppenderClass = Class.forName("org.lttng.ust.agent.log4j.LttngLogAppender");
 129                         Constructor<?> log4jAppendCtor = log4jAppenderClass.getConstructor();
 130                         log4jAppender = (ILttngHandler) log4jAppendCtor.newInstance();
 131
 132                         /*
 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.
 136                          */
 137                 } catch (SecurityException e) {
 138                         return;
 139                 } catch (ClassNotFoundException e) {
 140                         return;
 141                 } catch (NoSuchMethodException e) {
 142                         return;
 143                 } catch (IllegalArgumentException e) {
 144                         return;
 145                 } catch (InstantiationException e) {
 146                         return;
 147                 } catch (IllegalAccessException e) {
 148                         return;
 149                 } catch (InvocationTargetException e) {
 150                         return;
 151                 }
 152
 153                 /*
 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.
 158                  */
 159                 try {
 160                         Class<?> loggerClass = Class.forName("org.apache.log4j.Logger");
 161                         Class<?> appenderClass = Class.forName("org.apache.log4j.Appender");
 162
 163                         Method getRootLoggerMethod = loggerClass.getMethod("getRootLogger", (Class<?>[]) null);
 164                         Method addAppenderMethod = loggerClass.getMethod("addAppender", appenderClass);
 165
 166                         Object rootLogger = getRootLoggerMethod.invoke(null, (Object[]) null);
 167                         addAppenderMethod.invoke(rootLogger, log4jAppender);
 168
 169                         /*
 170                          * We have checked for the log4j library version previously, none of
 171                          * the following exceptions should happen.
 172                          */
 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);
 185                 }
 186         }
 187
 188         /**
 189          * Check if log4j >= 1.2.15 library is present.
 190          */
 191         private static boolean testLog4jClasses() {
 192                 Class<?> loggingEventClass;
 193
 194                 try {
 195                         loggingEventClass = Class.forName("org.apache.log4j.spi.LoggingEvent");
 196                 } catch (ClassNotFoundException e) {
 197                         /*
 198                          * Log4j classes not found, no need to create the relevant objects
 199                          */
 200                         return false;
 201                 }
 202
 203                 /*
 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.
 207                  *
 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.
 212                  *
 213                  * More info: https://issues.apache.org/bugzilla/show_bug.cgi?id=44370
 214                  */
 215                 try {
 216                         loggingEventClass.getDeclaredMethod("getTimeStamp");
 217                 } catch (NoSuchMethodException e) {
 218                         System.err.println(
 219                                         "Warning: The loaded log4j library is too old. Log4j tracing with LTTng will be disabled.");
 220                         return false;
 221                 } catch (SecurityException e) {
 222                         return false;
 223                 }
 224
 225                 return true;
 226         }
 227
 228         /**
 229          * Detach the JUL handler from its logger and close it.
 230          */
 231         private void disposeJulHandler() {
 232                 if (julHandler == null) {
 233                         /* The JUL handler was not activated, we have nothing to do */
 234                         return;
 235                 }
 236                 Logger.getLogger("").removeHandler((Handler) julHandler);
 237                 julHandler.close();
 238                 julHandler = null;
 239         }
 240
 241         /**
 242          * Detach the log4j appender from its logger and close it.
 243          */
 244         private void disposeLog4jAppender() {
 245                 if (log4jAppender == null) {
 246                         /* The log4j appender was not active, we have nothing to do */
 247                         return;
 248                 }
 249
 250                 /*
 251                  * Detach the appender from the log4j root logger. Again, we have to do
 252                  * this via reflection.
 253                  */
 254                 try {
 255                         Class<?> loggerClass = Class.forName("org.apache.log4j.Logger");
 256                         Class<?> appenderClass = Class.forName("org.apache.log4j.Appender");
 257
 258                         Method getRootLoggerMethod = loggerClass.getMethod("getRootLogger", (Class<?>[]) null);
 259                         Method removeAppenderMethod = loggerClass.getMethod("removeAppender", appenderClass);
 260
 261                         Object rootLogger = getRootLoggerMethod.invoke(null, (Object[]) null);
 262                         removeAppenderMethod.invoke(rootLogger, log4jAppender);
 263
 264                         /*
 265                          * We were able to attach the appender previously, we should not
 266                          * have problems here either!
 267                          */
 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);
 280                 }
 281
 282                 /* Close the appender */
 283                 log4jAppender.close();
 284                 log4jAppender = null;
 285         }
 286
 287 }