/*
+ * 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
* IN THE SOFTWARE.
*/
+import java.io.IOException;
+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.LTTngAgent;
+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>
+ *
+ * @author Alexandre Montplaisir
* @author David Goulet
*/
public class Hello {
- /* Of course :) */
- private static final int answer = 42;
-
- /*
- * Static reference to the LTTngAgent. Used to dispose of it at the end
- * which is recommended but not mandatory to do.
- */
- private static LTTngAgent lttngAgent;
+ /** Class-wide JUL logger object */
+ private static final Logger LOGGER = Logger.getLogger(Hello.class.getName());
/**
* Application start
*
* @param args
* Command-line arguments
- * @throws Exception
+ * @throws IOException
+ * @throws InterruptedException
*/
- 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");
+ public static void main(String args[]) throws IOException, InterruptedException {
- /*
- * Get the LTTngAgent singleton 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 separate thread in
- * your Java application.
- */
- lttngAgent = LTTngAgent.getLTTngAgent();
+ /* Instantiate a LTTngLogHandler object, and attach it to our logger */
+ Handler lttngHandler = new LttngLogHandler();
+ LOGGER.addHandler(lttngHandler);
/*
* 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);
+ LOGGER.info("Hello World, the answer is " + 42);
/*
* 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
+ * 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
+ * $ lttng enable-event -j Hello
+ */
+
+ /*
+ * A new logger is created here and fired after. Typically with JUL, you
+ * use one static Logger per class. This example here can represent a
+ * class being lazy-loaded later in the execution of the application.
*
- * 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.
+ * 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 a new Logger appears. Unfortunately, there is no way
+ * right now to get notified 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).
+ * available in a LTTng trace after the internal agent's timer is fired.
+ * (lttng enable-event -j -a).
*/
Logger helloLogDelayed = Logger.getLogger("hello_delay");
+ /*
+ * Attach a handler to this new logger.
+ *
+ * Using the same handler as before would also work.
+ */
+ Handler lttngHandler2 = new LttngLogHandler();
+ helloLogDelayed.addHandler(lttngHandler2);
+
System.out.println("Firing hello delay in 10 seconds...");
Thread.sleep(10000);
helloLogDelayed.info("Hello World delayed...");
System.out.println("Cleaning Hello");
/*
- * Again, this is highly recommended so the session daemon socket gets
- * cleaned up explicitly but it is not mandatory to do this step.
+ * Do not forget to close() all handlers so that the agent can shutdown
+ * and the session daemon socket gets cleaned up explicitly.
*/
- lttngAgent.dispose();
+ lttngHandler.close();
+ lttngHandler2.close();
}
}
projects / deliverable / lttng-ust.git / blobdiff