| 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.Method; |
| 22 | import java.util.logging.Handler; |
| 23 | import java.util.logging.Logger; |
| 24 | |
| 25 | /** |
| 26 | * The central agent managing the JUL and Log4j handlers. |
| 27 | * |
| 28 | * @author David Goulet |
| 29 | * @deprecated Applications are now expected to manage their Logger and Handler |
| 30 | * objects. |
| 31 | */ |
| 32 | @Deprecated |
| 33 | public class LTTngAgent { |
| 34 | |
| 35 | private static LTTngAgent instance = null; |
| 36 | |
| 37 | /** |
| 38 | * Public getter to acquire a reference to this singleton object. |
| 39 | * |
| 40 | * @return The agent instance |
| 41 | */ |
| 42 | public static synchronized LTTngAgent getLTTngAgent() { |
| 43 | if (instance == null) { |
| 44 | instance = new LTTngAgent(); |
| 45 | } |
| 46 | return instance; |
| 47 | } |
| 48 | |
| 49 | /** |
| 50 | * Dispose the agent. Applications should call this once they are done |
| 51 | * logging. |
| 52 | */ |
| 53 | public static synchronized void dispose() { |
| 54 | if (instance != null) { |
| 55 | instance.disposeInstance(); |
| 56 | instance = null; |
| 57 | } |
| 58 | return; |
| 59 | } |
| 60 | |
| 61 | private ILttngHandler julHandler = null; |
| 62 | private ILttngHandler log4jAppender = null; |
| 63 | |
| 64 | /** |
| 65 | * Private constructor. This is a singleton and a reference should be |
| 66 | * acquired using {@link #getLTTngAgent()}. |
| 67 | */ |
| 68 | private LTTngAgent() { |
| 69 | initJulHandler(); |
| 70 | initLog4jAppender(); |
| 71 | } |
| 72 | |
| 73 | /** |
| 74 | * "Destructor" method. |
| 75 | */ |
| 76 | private void disposeInstance() { |
| 77 | disposeJulHandler(); |
| 78 | disposeLog4jAppender(); |
| 79 | } |
| 80 | |
| 81 | /** |
| 82 | * Create a LTTng-JUL handler, and attach it to the JUL root logger. |
| 83 | */ |
| 84 | private void initJulHandler() { |
| 85 | try { |
| 86 | Class<?> julHandlerClass = Class.forName("org.lttng.ust.agent.jul.LttngLogHandler"); |
| 87 | /* |
| 88 | * It is safer to use Constructor.newInstance() rather than |
| 89 | * Class.newInstance(), because it will catch the exceptions thrown |
| 90 | * by the constructor below (which happens if the Java library is |
| 91 | * present, but the matching JNI one is not). |
| 92 | */ |
| 93 | Constructor<?> julHandlerCtor = julHandlerClass.getConstructor(); |
| 94 | julHandler = (ILttngHandler) julHandlerCtor.newInstance(); |
| 95 | |
| 96 | /* Attach the handler to the root JUL logger */ |
| 97 | Logger.getLogger("").addHandler((Handler) julHandler); |
| 98 | } catch (ReflectiveOperationException e) { |
| 99 | /* |
| 100 | * LTTng JUL classes not found, no need to create the relevant |
| 101 | * objects |
| 102 | */ |
| 103 | } |
| 104 | } |
| 105 | |
| 106 | /** |
| 107 | * Create a LTTng-logj4 appender, and attach it to the log4j root logger. |
| 108 | */ |
| 109 | private void initLog4jAppender() { |
| 110 | /* |
| 111 | * Since Log4j is a 3rd party library, we first need to check if we can |
| 112 | * load any of its classes. |
| 113 | */ |
| 114 | if (!testLog4jClasses()) { |
| 115 | return; |
| 116 | } |
| 117 | |
| 118 | try { |
| 119 | Class<?> log4jAppenderClass = Class.forName("org.lttng.ust.agent.log4j.LttngLogAppender"); |
| 120 | Constructor<?> log4jAppendCtor = log4jAppenderClass.getConstructor(); |
| 121 | log4jAppender = (ILttngHandler) log4jAppendCtor.newInstance(); |
| 122 | } catch (ReflectiveOperationException e) { |
| 123 | /* |
| 124 | * LTTng Log4j classes not found, no need to create the relevant |
| 125 | * objects. |
| 126 | */ |
| 127 | return; |
| 128 | } |
| 129 | |
| 130 | /* |
| 131 | * Attach the appender to the root Log4j logger. Slightly more tricky |
| 132 | * here, as log4j.Logger is not in the base Java library, and we do not |
| 133 | * want the "common" package to depend on log4j. So we have to obtain it |
| 134 | * through reflection too. |
| 135 | */ |
| 136 | try { |
| 137 | Class<?> loggerClass = Class.forName("org.apache.log4j.Logger"); |
| 138 | Class<?> appenderClass = Class.forName("org.apache.log4j.Appender"); |
| 139 | |
| 140 | Method getRootLoggerMethod = loggerClass.getMethod("getRootLogger", (Class<?>[]) null); |
| 141 | Method addAppenderMethod = loggerClass.getMethod("addAppender", appenderClass); |
| 142 | |
| 143 | Object rootLogger = getRootLoggerMethod.invoke(null, (Object[]) null); |
| 144 | addAppenderMethod.invoke(rootLogger, log4jAppender); |
| 145 | |
| 146 | } catch (ReflectiveOperationException e) { |
| 147 | /* |
| 148 | * We have checked for the log4j library version previously, these |
| 149 | * classes should exist. |
| 150 | */ |
| 151 | throw new IllegalStateException(); |
| 152 | } |
| 153 | } |
| 154 | |
| 155 | /** |
| 156 | * Check if log4j >= 1.2.15 library is present. |
| 157 | */ |
| 158 | private static boolean testLog4jClasses() { |
| 159 | Class<?> loggingEventClass; |
| 160 | |
| 161 | try { |
| 162 | loggingEventClass = Class.forName("org.apache.log4j.spi.LoggingEvent"); |
| 163 | } catch (ClassNotFoundException e) { |
| 164 | /* |
| 165 | * Log4j classes not found, no need to create the relevant objects |
| 166 | */ |
| 167 | return false; |
| 168 | } |
| 169 | |
| 170 | /* |
| 171 | * Detect capabilities of the log4j library. We only support log4j >= |
| 172 | * 1.2.15. The getTimeStamp() method was introduced in log4j 1.2.15, so |
| 173 | * verify that it is available. |
| 174 | * |
| 175 | * We can't rely on the getPackage().getImplementationVersion() call |
| 176 | * that would retrieves information from the manifest file found in the |
| 177 | * JAR since the manifest file shipped from upstream is known to be |
| 178 | * broken in several versions of the library. |
| 179 | * |
| 180 | * More info: https://issues.apache.org/bugzilla/show_bug.cgi?id=44370 |
| 181 | */ |
| 182 | try { |
| 183 | loggingEventClass.getDeclaredMethod("getTimeStamp"); |
| 184 | } catch (NoSuchMethodException e) { |
| 185 | System.err.println( |
| 186 | "Warning: The loaded log4j library is too old. Log4j tracing with LTTng will be disabled."); |
| 187 | return false; |
| 188 | } catch (SecurityException e) { |
| 189 | return false; |
| 190 | } |
| 191 | |
| 192 | return true; |
| 193 | } |
| 194 | |
| 195 | /** |
| 196 | * Detach the JUL handler from its logger and close it. |
| 197 | */ |
| 198 | private void disposeJulHandler() { |
| 199 | if (julHandler == null) { |
| 200 | /* The JUL handler was not activated, we have nothing to do */ |
| 201 | return; |
| 202 | } |
| 203 | Logger.getLogger("").removeHandler((Handler) julHandler); |
| 204 | julHandler.close(); |
| 205 | julHandler = null; |
| 206 | } |
| 207 | |
| 208 | /** |
| 209 | * Detach the log4j appender from its logger and close it. |
| 210 | */ |
| 211 | private void disposeLog4jAppender() { |
| 212 | if (log4jAppender == null) { |
| 213 | /* The log4j appender was not active, we have nothing to do */ |
| 214 | return; |
| 215 | } |
| 216 | |
| 217 | /* |
| 218 | * Detach the appender from the log4j root logger. Again, we have to do |
| 219 | * this via reflection. |
| 220 | */ |
| 221 | try { |
| 222 | Class<?> loggerClass = Class.forName("org.apache.log4j.Logger"); |
| 223 | Class<?> appenderClass = Class.forName("org.apache.log4j.Appender"); |
| 224 | |
| 225 | Method getRootLoggerMethod = loggerClass.getMethod("getRootLogger", (Class<?>[]) null); |
| 226 | Method removeAppenderMethod = loggerClass.getMethod("removeAppender", appenderClass); |
| 227 | |
| 228 | Object rootLogger = getRootLoggerMethod.invoke(null, (Object[]) null); |
| 229 | removeAppenderMethod.invoke(rootLogger, log4jAppender); |
| 230 | |
| 231 | } catch (ReflectiveOperationException e) { |
| 232 | /* |
| 233 | * We were able to attach the appender, we should not have problems |
| 234 | * here either! |
| 235 | */ |
| 236 | throw new IllegalStateException(); |
| 237 | } |
| 238 | |
| 239 | /* Close the appender */ |
| 240 | log4jAppender.close(); |
| 241 | log4jAppender = null; |
| 242 | } |
| 243 | |
| 244 | } |