doc/examples/java-jul/Hello.java

   1 /*
   2  * Copyright (C) 2013 - David Goulet <dgoulet@efficios.com>
   3  *
   4  * Permission is hereby granted, free of charge, to any person obtaining a copy
   5  * of this software and associated documentation files (the "Software"), to
   6  * deal in the Software without restriction, including without limitation the
   7  * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
   8  * sell copies of the Software, and to permit persons to whom the Software is
   9  * furnished to do so, subject to the following conditions:
  10  *
  11  * The above copyright notice and this permission notice shall be included in
  12  * all copies or substantial portions of the Software.
  13  *
  14  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  15  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  16  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  17  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  18  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  19  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
  20  * IN THE SOFTWARE.
  21  */
  22
  23 import java.util.logging.Logger;
  24
  25 /*
  26  * That's the import you need being the path in the liblttng-ust-jul Jar file.
  27  */
  28 import org.lttng.ust.agent.LTTngAgent;
  29
  30 public class Hello
  31 {
  32         /* Of course :) */
  33         private static final int answer = 42;
  34
  35         /*
  36          * Static reference to the LTTngAgent. Used to dispose of it at the end
  37          * which is recommended but not mandatory to do.
  38          */
  39         private static LTTngAgent lttngAgent;
  40
  41         public static void main(String args[]) throws Exception
  42         {
  43                 /*
  44                  * For this example, a custom "hello" logger is created. Note that JUL
  45                  * has a default "global" that can also be used.
  46                  */
  47                 Logger helloLog = Logger.getLogger("hello");
  48
  49                 /*
  50                  * Get the LTTngAgent singleton reference. This will also initialize
  51                  * the Agent and make it register to the session daemon if available.
  52                  * When this returns, the Agent is registered and fully ready. If no
  53                  * session daemon is found, it will return and retry every 3 seconds in
  54                  * the background. TCP is used for communication.
  55                  *
  56                  * Note that the LTTngAgent once registered is a separate thread in
  57                  * your Java application.
  58                  */
  59                 lttngAgent = LTTngAgent.getLTTngAgent();
  60
  61                 /*
  62                  * Gives you time to do some lttng commands before any event is hit.
  63                  */
  64                 Thread.sleep(5000);
  65
  66                 /* Trigger a tracing event using the JUL Logger created before. */
  67                 helloLog.info("Hello World, the answer is " + answer);
  68
  69                 /*
  70                  * From this point on, the above message will be collected in the trace
  71                  * if the event "hello" is enabled for the JUL domain using the lttng
  72                  * command line or the lttng-ctl API. For instance:
  73                  *
  74                  *   $ lttng enable-event -j hello
  75                  *
  76                  * A new logger is created here and fired after. The Agent has an
  77                  * internal timer that is fired every 5 seconds in order to enable
  78                  * events that were not found at first but might need to be enabled
  79                  * when new Logger appears. Unfortunately, there is no way right now to
  80                  * get notify of that so we have to actively poll.
  81                  *
  82                  * Using the --all command for instance, it will make this Logger
  83                  * available in a LTTng trace after the internal Agent's timer is
  84                  * fired. (lttng enable-event -a -j).
  85                  */
  86                 Logger helloLogDelayed = Logger.getLogger("hello_delay");
  87
  88                 System.out.println("Firing hello delay in 10 seconds...");
  89                 Thread.sleep(10000);
  90                 helloLogDelayed.info("Hello World delayed...");
  91
  92                 System.out.println("Cleaning Hello");
  93
  94                 /*
  95                  * Again, this is highly recommended so the session daemon socket gets
  96                  * cleaned up explicitly but it is not mandatory to do this step.
  97                  */
  98                 lttngAgent.dispose();
  99         }
 100 }