JUL: add Hello.java in doc/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
new file mode 100644 (file)
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+++ b/doc/examples/java-jul/Hello.java
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+/*
+ * Copyright (C) 2013 - David Goulet <dgoulet@efficios.com>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+import java.io.IOException;
+import java.util.logging.Level;
+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.jul.LTTngAgent;
+
+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;
+
+       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");
+
+               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 explicitely but it is not mandatory to do this step.
+                */
+               lttngAgent.dispose();
+       }
+}