/*
+ * Copyright (C) 2015 - EfficiOS Inc., Alexandre Montplaisir <alexmonthy@efficios.com>
* Copyright (C) 2013 - David Goulet <dgoulet@efficios.com>
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
*/
import java.io.IOException;
-import java.util.logging.Level;
+import java.util.logging.Handler;
import java.util.logging.Logger;
-/*
- * That's the import you need being the path in the liblttng-ust-jul Jar file.
+import org.lttng.ust.agent.jul.LttngLogHandler;
+
+/**
+ * Example application using the LTTng-UST Java JUL agent.
+ *
+ * <p>
+ * Basically all that is required is to instantiate a {@link LttngLogHandler}
+ * and to attach it to a JUL {@link Logger}. Then use the Logger normally to log
+ * messages, which will be sent to UST as trace events.
+ * <p>
+ * </p>
+ * {@link Logger} names are used as event names on the UST side. This means that
+ * by enabling/disabling certain events in the tracing session, you are
+ * effectively enabling and disabling Loggers on the Java side. Note that this
+ * applies only to {@link LttngLogHandler}'s. If other handlers are attached to
+ * the Logger, those will continue logging events normally.
+ * </p>
+ *
+ * <p>
+ * To obtain LTTng trace events, you should run the following sequence of
+ * commands:
+ * </p>
+ *
+ * <ul>
+ * <li>$ lttng create</li>
+ * <li>$ lttng enable-event -j -a</li>
+ * <li>$ lttng start</li>
+ * <li>(run this program)</li>
+ * <li>$ lttng stop</li>
+ * <li>$ lttng view</li>
+ * <li>$ lttng destroy</li>
+ * </ul>
+ *
+ * @author Alexandre Montplaisir
+ * @author David Goulet
*/
-import org.lttng.ust.agent.LTTngAgent;
+public class Hello {
-public class Hello
-{
- /* Of course :) */
- private static final int answer = 42;
+ /** Class-wide JUL logger object */
+ private static final Logger LOGGER = Logger.getLogger(Hello.class.getName());
- /*
- * Static reference to the LTTngAgent. Used to dispose of it at the end
- * which is recommended but not mandatory to do.
+ /**
+ * Application start
+ *
+ * @param args
+ * Command-line arguments
+ * @throws IOException
+ * If the required native libraries cannot be found. You may
+ * have to specify "-Djava.library.path=..." on the "java"
+ * command line.
*/
- private static LTTngAgent lttngAgent;
-
- public static void main(String args[]) throws Exception
- {
- /*
- * For this example, a custom "hello" logger is created. Note that JUL
- * has a default "global" that can also be used.
- */
- Logger helloLog = Logger.getLogger("hello");
-
- /*
- * Get the LTTngAgent singelton reference. This will also initialize
- * the Agent and make it register to the session daemon if available.
- * When this returns, the Agent is registered and fully ready. If no
- * session daemon is found, it will return and retry every 3 seconds in
- * the background. TCP is used for communication.
- *
- * Note that the LTTngAgent once registered is a seperate thread in
- * your Java application.
- */
- lttngAgent = LTTngAgent.getLTTngAgent();
-
- /*
- * Gives you time to do some lttng commands before any event is hit.
- */
- Thread.sleep(5000);
-
- /* Trigger a tracing event using the JUL Logger created before. */
- helloLog.info("Hello World, the answer is " + answer);
-
- /*
- * From this point on, the above message will be collected in the trace
- * if the event "hello" is enabled for the JUL domain using the lttng
- * command line or the lttng-ctl API. For instance:
- *
- * $ lttng enable-event -j hello
- *
- * A new logger is created here and fired after. The Agent has an
- * internal timer that is fired every 5 seconds in order to enable
- * events that were not found at first but might need to be enabled
- * when new Logger appears. Unfortunately, there is no way right now to
- * get notify of that so we have to actively poll.
- *
- * Using the --all command for instance, it will make this Logger
- * available in a LTTng trace after the internal Agent's timer is
- * fired. (lttng enable-event -a -j).
- */
- Logger helloLogDelayed = Logger.getLogger("hello_delay");
+ public static void main(String args[]) throws IOException {
- System.out.println("Firing hello delay in 10 seconds...");
- Thread.sleep(10000);
- helloLogDelayed.info("Hello World delayed...");
+ /* Instantiate a LTTngLogHandler object, and attach it to our logger */
+ Handler lttngHandler = new LttngLogHandler();
+ LOGGER.addHandler(lttngHandler);
- System.out.println("Cleaning Hello");
+ /* Log events using the JUL Logger created before. */
+ LOGGER.info("Hello World, the answer is " + 42);
+ LOGGER.info("Another info event");
+ LOGGER.severe("A severe event");
- /*
- * Again, this is highly recommended so the session daemon socket gets
- * cleaned up explicitely but it is not mandatory to do this step.
- */
- lttngAgent.dispose();
+ /* Cleanup */
+ LOGGER.removeHandler(lttngHandler);
+ lttngHandler.close();
}
}
projects / lttng-ust.git / blobdiff