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 void dispose() {
  56                 synchronized (LTTngAgent.class) {
  57                         if (instance != null) {
  58                                 instance.disposeInstance();
  59                                 instance = null;
  60                         }
  61                 }
  62                 return;
  63         }
  64
  65         private ILttngHandler julHandler = null;
  66         private ILttngHandler log4jAppender = null;
  67
  68         /**
  69          * Private constructor. This is a singleton and a reference should be
  70          * acquired using {@link #getLTTngAgent()}.
  71          */
  72         private LTTngAgent() {
  73                 initJulHandler();
  74                 initLog4jAppender();
  75         }
  76
  77         /**
  78          * "Destructor" method.
  79          */
  80         private void disposeInstance() {
  81                 disposeJulHandler();
  82                 disposeLog4jAppender();
  83         }
  84
  85         /**
  86          * Create a LTTng-JUL handler, and attach it to the JUL root logger.
  87          */
  88         private void initJulHandler() {
  89                 try {
  90                         Class<?> julHandlerClass = Class.forName("org.lttng.ust.agent.jul.LttngLogHandler");
  91                         /*
  92                          * It is safer to use Constructor.newInstance() rather than
  93                          * Class.newInstance(), because it will catch the exceptions thrown
  94                          * by the constructor below (which happens if the Java library is
  95                          * present, but the matching JNI one is not).
  96                          */
  97                         Constructor<?> julHandlerCtor = julHandlerClass.getConstructor();
  98                         julHandler = (ILttngHandler) julHandlerCtor.newInstance();
  99
 100                         /* Attach the handler to the root JUL logger */
 101                         Logger.getLogger("").addHandler((Handler) julHandler);
 102
 103                         /*
 104                          * If any of the following exceptions happen, it means we could not
 105                          * find or initialize LTTng JUL classes. We will not setup LTTng JUL
 106                          * tracing in this case.
 107                          */
 108                 } catch (SecurityException e) {
 109                 } catch (IllegalAccessException e) {
 110                 } catch (IllegalArgumentException e) {
 111                 } catch (ClassNotFoundException e) {
 112                 } catch (NoSuchMethodException e) {
 113                 } catch (InstantiationException e) {
 114                 } catch (InvocationTargetException e) {
 115                 }
 116         }
 117
 118         /**
 119          * Create a LTTng-logj4 appender, and attach it to the log4j root logger.
 120          */
 121         private void initLog4jAppender() {
 122                 /*
 123                  * Since Log4j is a 3rd party library, we first need to check if we can
 124                  * load any of its classes.
 125                  */
 126                 if (!testLog4jClasses()) {
 127                         return;
 128                 }
 129
 130                 try {
 131                         Class<?> log4jAppenderClass = Class.forName("org.lttng.ust.agent.log4j.LttngLogAppender");
 132                         Constructor<?> log4jAppendCtor = log4jAppenderClass.getConstructor();
 133                         log4jAppender = (ILttngHandler) log4jAppendCtor.newInstance();
 134
 135                         /*
 136                          * If any of the following exceptions happen, it means we could not
 137                          * find or initialize LTTng log4j classes. We will not setup LTTng
 138                          * log4j tracing in this case.
 139                          */
 140                 } catch (SecurityException e) {
 141                         return;
 142                 } catch (ClassNotFoundException e) {
 143                         return;
 144                 } catch (NoSuchMethodException e) {
 145                         return;
 146                 } catch (IllegalArgumentException e) {
 147                         return;
 148                 } catch (InstantiationException e) {
 149                         return;
 150                 } catch (IllegalAccessException e) {
 151                         return;
 152                 } catch (InvocationTargetException e) {
 153                         return;
 154                 }
 155
 156                 /*
 157                  * Attach the appender to the root Log4j logger. Slightly more tricky
 158                  * here, as log4j.Logger is not in the base Java library, and we do not
 159                  * want the "common" package to depend on log4j. So we have to obtain it
 160                  * through reflection too.
 161                  */
 162                 try {
 163                         Class<?> loggerClass = Class.forName("org.apache.log4j.Logger");
 164                         Class<?> appenderClass = Class.forName("org.apache.log4j.Appender");
 165
 166                         Method getRootLoggerMethod = loggerClass.getMethod("getRootLogger", (Class<?>[]) null);
 167                         Method addAppenderMethod = loggerClass.getMethod("addAppender", appenderClass);
 168
 169                         Object rootLogger = getRootLoggerMethod.invoke(null, (Object[]) null);
 170                         addAppenderMethod.invoke(rootLogger, log4jAppender);
 171
 172                         /*
 173                          * We have checked for the log4j library version previously, none of
 174                          * the following exceptions should happen.
 175                          */
 176                 } catch (SecurityException e) {
 177                         throw new IllegalStateException(e);
 178                 } catch (ClassNotFoundException e) {
 179                         throw new IllegalStateException(e);
 180                 } catch (NoSuchMethodException e) {
 181                         throw new IllegalStateException(e);
 182                 } catch (IllegalArgumentException e) {
 183                         throw new IllegalStateException(e);
 184                 } catch (IllegalAccessException e) {
 185                         throw new IllegalStateException(e);
 186                 } catch (InvocationTargetException e) {
 187                         throw new IllegalStateException(e);
 188                 }
 189         }
 190
 191         /**
 192          * Check if log4j >= 1.2.15 library is present.
 193          */
 194         private static boolean testLog4jClasses() {
 195                 Class<?> loggingEventClass;
 196
 197                 try {
 198                         loggingEventClass = Class.forName("org.apache.log4j.spi.LoggingEvent");
 199                 } catch (ClassNotFoundException e) {
 200                         /*
 201                          * Log4j classes not found, no need to create the relevant objects
 202                          */
 203                         return false;
 204                 }
 205
 206                 /*
 207                  * Detect capabilities of the log4j library. We only support log4j >=
 208                  * 1.2.15. The getTimeStamp() method was introduced in log4j 1.2.15, so
 209                  * verify that it is available.
 210                  *
 211                  * We can't rely on the getPackage().getImplementationVersion() call
 212                  * that would retrieves information from the manifest file found in the
 213                  * JAR since the manifest file shipped from upstream is known to be
 214                  * broken in several versions of the library.
 215                  *
 216                  * More info: https://issues.apache.org/bugzilla/show_bug.cgi?id=44370
 217                  */
 218                 try {
 219                         loggingEventClass.getDeclaredMethod("getTimeStamp");
 220                 } catch (NoSuchMethodException e) {
 221                         System.err.println(
 222                                         "Warning: The loaded log4j library is too old. Log4j tracing with LTTng will be disabled.");
 223                         return false;
 224                 } catch (SecurityException e) {
 225                         return false;
 226                 }
 227
 228                 return true;
 229         }
 230
 231         /**
 232          * Detach the JUL handler from its logger and close it.
 233          */
 234         private void disposeJulHandler() {
 235                 if (julHandler == null) {
 236                         /* The JUL handler was not activated, we have nothing to do */
 237                         return;
 238                 }
 239                 Logger.getLogger("").removeHandler((Handler) julHandler);
 240                 julHandler.close();
 241                 julHandler = null;
 242         }
 243
 244         /**
 245          * Detach the log4j appender from its logger and close it.
 246          */
 247         private void disposeLog4jAppender() {
 248                 if (log4jAppender == null) {
 249                         /* The log4j appender was not active, we have nothing to do */
 250                         return;
 251                 }
 252
 253                 /*
 254                  * Detach the appender from the log4j root logger. Again, we have to do
 255                  * this via reflection.
 256                  */
 257                 try {
 258                         Class<?> loggerClass = Class.forName("org.apache.log4j.Logger");
 259                         Class<?> appenderClass = Class.forName("org.apache.log4j.Appender");
 260
 261                         Method getRootLoggerMethod = loggerClass.getMethod("getRootLogger", (Class<?>[]) null);
 262                         Method removeAppenderMethod = loggerClass.getMethod("removeAppender", appenderClass);
 263
 264                         Object rootLogger = getRootLoggerMethod.invoke(null, (Object[]) null);
 265                         removeAppenderMethod.invoke(rootLogger, log4jAppender);
 266
 267                         /*
 268                          * We were able to attach the appender previously, we should not
 269                          * have problems here either!
 270                          */
 271                 } catch (SecurityException e) {
 272                         throw new IllegalStateException(e);
 273                 } catch (ClassNotFoundException e) {
 274                         throw new IllegalStateException(e);
 275                 } catch (NoSuchMethodException e) {
 276                         throw new IllegalStateException(e);
 277                 } catch (IllegalArgumentException e) {
 278                         throw new IllegalStateException(e);
 279                 } catch (IllegalAccessException e) {
 280                         throw new IllegalStateException(e);
 281                 } catch (InvocationTargetException e) {
 282                         throw new IllegalStateException(e);
 283                 }
 284
 285                 /* Close the appender */
 286                 log4jAppender.close();
 287                 log4jAppender = null;
 288         }
 289
 290 }