Clarify and simplify the Java agent "Hello" examples

[lttng-ust.git] / doc / examples / java-jul / Hello.java

diff --git a/doc/examples/java-jul/Hello.java b/doc/examples/java-jul/Hello.java
index 7016cf4956bc90736d3eeeafc2a817bfa281b879..cb9f24b198fc7be376b9a2d91f541e9e9b4e0e4e 100644 (file)
--- a/doc/examples/java-jul/Hello.java
+++ b/doc/examples/java-jul/Hello.java
@@ -43,6 +43,21 @@ import org.lttng.ust.agent.jul.LttngLogHandler;
  * 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
  */
@@ -57,65 +72,23 @@ public class Hello {
         * @param args
         *            Command-line arguments
         * @throws IOException
-        * @throws InterruptedException
+        *             If the required native libraries cannot be found. You may
+        *             have to specify "-Djava.library.path=..." on the "java"
+        *             command line.
         */
-       public static void main(String args[]) throws IOException, InterruptedException {
+       public static void main(String args[]) throws IOException {
 
                /* 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. */
+               /* 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");
 
-               /*
-                * 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. 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.
-                *
-                * 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 -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");
-
-               /*
-                * Do not forget to close() all handlers so that the agent can shutdown
-                * and the session daemon socket gets cleaned up explicitly.
-                */
+               /* Cleanup */
+               LOGGER.removeHandler(lttngHandler);
                lttngHandler.close();
-               lttngHandler2.close();
        }
 }