X-Git-Url: http://git.lttng.org./?a=blobdiff_plain;ds=sidebyside;f=liblttng-ust-java-agent%2Fjava%2Forg%2Flttng%2Fust%2Fagent%2FLTTngAgent.java;h=f7e1e386be9bd5a56e0016ef235081490782c299;hb=85e091331484d860fc5f781e645341f37875b6ab;hp=342ccfae15c0c0bb45c29291c2f236bc2e60d9fc;hpb=501f6777610d7f8d855453c0083a10912d5fac4b;p=lttng-ust.git

diff --git a/liblttng-ust-java-agent/java/org/lttng/ust/agent/LTTngAgent.java b/liblttng-ust-java-agent/java/org/lttng/ust/agent/LTTngAgent.java
index 342ccfae..f7e1e386 100644
--- a/liblttng-ust-java-agent/java/org/lttng/ust/agent/LTTngAgent.java
+++ b/liblttng-ust-java-agent/java/org/lttng/ust/agent/LTTngAgent.java
@@ -29,7 +29,6 @@ import java.util.Enumeration;
 import java.lang.reflect.InvocationTargetException;
 
 import java.util.logging.Logger;
-import java.util.logging.FileHandler;;
 import java.util.logging.SimpleFormatter;
 
 public class LTTngAgent {
@@ -92,23 +91,66 @@ public class LTTngAgent {
 	}
 
 	private Boolean loadLog4jClasses() {
-		Boolean loaded = false;
+		Class<?> logging;
+
 		try {
-			ClassLoader loader = ClassLoader.getSystemClassLoader();
-			loader.loadClass("org.apache.log4j.Logger");
-			loaded = true;
+			logging = loadClass("org.apache.log4j.spi.LoggingEvent");
 		} catch (ClassNotFoundException e) {
 			/* Log4j classes not found, no need to create the relevant objects */
-			loaded = false;
+			return false;
+		}
+
+		/*
+		 * Detect capabilities of the log4j library. We only
+		 * support log4j >= 1.2.15.  The getTimeStamp() method
+		 * was introduced in log4j 1.2.15, so verify that it
+		 * is available.
+		 *
+		 * We can't rely on the getPackage().getImplementationVersion()
+		 * call that would retrieves information from the manifest file
+		 * found in the JAR since the manifest file shipped
+		 * from upstream is known to be broken in several
+		 * versions of the library.
+		 *
+		 * More info:
+		 * https://issues.apache.org/bugzilla/show_bug.cgi?id=44370
+		 */
+
+		try {
+			logging.getDeclaredMethod("getTimeStamp");
+		} catch (NoSuchMethodException e) {
+			System.err.println("Warning: The loaded log4j library is too old. Log4j tracing with LTTng will be disabled.");
+			return false;
+		} catch (NullPointerException e) {
+			/* Should never happen */
+			return false;
+		} catch (SecurityException e) {
+			return false;
+		}
+
+		return true;
+	}
+
+	private Class<?> loadClass(String className) throws ClassNotFoundException {
+		ClassLoader loader;
+		Class<?> loadedClass;
+
+		try {
+			/* Try to load class using the current thread's context class loader */
+			loader = Thread.currentThread().getContextClassLoader();
+			loadedClass = loader.loadClass(className);
+		} catch (ClassNotFoundException e) {
+			/* Loading failed, try using the system class loader */
+			loader = ClassLoader.getSystemClassLoader();
+			loadedClass = loader.loadClass(className);
 		}
 
-		return loaded;
+		return loadedClass;
 	}
 
 	private void initAgentJULClasses() {
 		try {
-			ClassLoader loader = ClassLoader.getSystemClassLoader();
-			Class<?> lttngJUL = loader.loadClass("org.lttng.ust.agent.jul.LTTngJUL");
+			Class<?> lttngJUL = loadClass("org.lttng.ust.agent.jul.LTTngJUL");
 			this.julUser = (LogFramework)lttngJUL.getDeclaredConstructor(new Class[] {Boolean.class}).newInstance(false);
 			this.julRoot = (LogFramework)lttngJUL.getDeclaredConstructor(new Class[] {Boolean.class}).newInstance(true);
 			this.useJUL = true;
@@ -128,8 +170,7 @@ public class LTTngAgent {
 
 	private void initAgentLog4jClasses() {
 		try {
-			ClassLoader loader = ClassLoader.getSystemClassLoader();
-			Class<?> lttngLog4j = loader.loadClass("org.lttng.ust.agent.log4j.LTTngLog4j");
+			Class<?> lttngLog4j = loadClass("org.lttng.ust.agent.log4j.LTTngLog4j");
 			this.log4jUser = (LogFramework)lttngLog4j.getDeclaredConstructor(new Class[] {Boolean.class}).newInstance(false);
 			this.log4jRoot = (LogFramework)lttngLog4j.getDeclaredConstructor(new Class[] {Boolean.class}).newInstance(true);
 			this.useLog4j = true;