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 /**
  31  * Example application using the LTTng-UST Java JUL agent.
  32  *
  33  * @author David Goulet
  34  */
  35 public class Hello {
  36
  37         /* Of course :) */
  38         private static final int answer = 42;
  39
  40         /*
  41          * Static reference to the LTTngAgent. Used to dispose of it at the end
  42          * which is recommended but not mandatory to do.
  43          */
  44         private static LTTngAgent lttngAgent;
  45
  46         /**
  47          * Application start
  48          *
  49          * @param args
  50          *            Command-line arguments
  51          * @throws Exception
  52          */
  53         public static void main(String args[]) throws Exception {
  54                 /*
  55                  * For this example, a custom "hello" logger is created. Note that JUL
  56                  * has a default "global" that can also be used.
  57                  */
  58                 Logger helloLog = Logger.getLogger("hello");
  59
  60                 /*
  61                  * Get the LTTngAgent singleton reference. This will also initialize
  62                  * the Agent and make it register to the session daemon if available.
  63                  * When this returns, the Agent is registered and fully ready. If no
  64                  * session daemon is found, it will return and retry every 3 seconds in
  65                  * the background. TCP is used for communication.
  66                  *
  67                  * Note that the LTTngAgent once registered is a separate thread in
  68                  * your Java application.
  69                  */
  70                 lttngAgent = LTTngAgent.getLTTngAgent();
  71
  72                 /*
  73                  * Gives you time to do some lttng commands before any event is hit.
  74                  */
  75                 Thread.sleep(5000);
  76
  77                 /* Trigger a tracing event using the JUL Logger created before. */
  78                 helloLog.info("Hello World, the answer is " + answer);
  79
  80                 /*
  81                  * From this point on, the above message will be collected in the trace
  82                  * if the event "hello" is enabled for the JUL domain using the lttng
  83                  * command line or the lttng-ctl API. For instance:
  84                  *
  85                  *   $ lttng enable-event -j hello
  86                  *
  87                  * A new logger is created here and fired after. The Agent has an
  88                  * internal timer that is fired every 5 seconds in order to enable
  89                  * events that were not found at first but might need to be enabled
  90                  * when new Logger appears. Unfortunately, there is no way right now to
  91                  * get notify of that so we have to actively poll.
  92                  *
  93                  * Using the --all command for instance, it will make this Logger
  94                  * available in a LTTng trace after the internal Agent's timer is
  95                  * fired. (lttng enable-event -a -j).
  96                  */
  97                 Logger helloLogDelayed = Logger.getLogger("hello_delay");
  98
  99                 System.out.println("Firing hello delay in 10 seconds...");
 100                 Thread.sleep(10000);
 101                 helloLogDelayed.info("Hello World delayed...");
 102
 103                 System.out.println("Cleaning Hello");
 104
 105                 /*
 106                  * Again, this is highly recommended so the session daemon socket gets
 107                  * cleaned up explicitly but it is not mandatory to do this step.
 108                  */
 109                 lttngAgent.dispose();
 110         }
 111 }