| 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 | } |