doc/examples/java-jul/Hello.java

   1 /*
   2  * Copyright (C) 2015 - EfficiOS Inc., Alexandre Montplaisir <alexmonthy@efficios.com>
   3  * Copyright (C) 2013 - David Goulet <dgoulet@efficios.com>
   4  *
   5  * Permission is hereby granted, free of charge, to any person obtaining a copy
   6  * of this software and associated documentation files (the "Software"), to
   7  * deal in the Software without restriction, including without limitation the
   8  * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
   9  * sell copies of the Software, and to permit persons to whom the Software is
  10  * furnished to do so, subject to the following conditions:
  11  *
  12  * The above copyright notice and this permission notice shall be included in
  13  * all copies or substantial portions of the Software.
  14  *
  15  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  16  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  18  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  19  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  20  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
  21  * IN THE SOFTWARE.
  22  */
  23
  24 import java.io.IOException;
  25 import java.util.logging.Handler;
  26 import java.util.logging.Logger;
  27
  28 import org.lttng.ust.agent.jul.LttngLogHandler;
  29
  30 /**
  31  * Example application using the LTTng-UST Java JUL agent.
  32  *
  33  * <p>
  34  * Basically all that is required is to instantiate a {@link LttngLogHandler}
  35  * and to attach it to a JUL {@link Logger}. Then use the Logger normally to log
  36  * messages, which will be sent to UST as trace events.
  37  * <p>
  38  * </p>
  39  * {@link Logger} names are used as event names on the UST side. This means that
  40  * by enabling/disabling certain events in the tracing session, you are
  41  * effectively enabling and disabling Loggers on the Java side. Note that this
  42  * applies only to {@link LttngLogHandler}'s. If other handlers are attached to
  43  * the Logger, those will continue logging events normally.
  44  * </p>
  45  *
  46  * <p>
  47  * To obtain LTTng trace events, you should run the following sequence of
  48  * commands:
  49  * </p>
  50  *
  51  * <ul>
  52  * <li>$ lttng create</li>
  53  * <li>$ lttng enable-event -j -a</li>
  54  * <li>$ lttng start</li>
  55  * <li>(run this program)</li>
  56  * <li>$ lttng stop</li>
  57  * <li>$ lttng view</li>
  58  * <li>$ lttng destroy</li>
  59  * </ul>
  60  *
  61  * @author Alexandre Montplaisir
  62  * @author David Goulet
  63  */
  64 public class Hello {
  65
  66         /** Class-wide JUL logger object */
  67         private static final Logger LOGGER = Logger.getLogger(Hello.class.getName());
  68
  69         /**
  70          * Application start
  71          *
  72          * @param args
  73          *            Command-line arguments
  74          * @throws IOException
  75          *             If the required native libraries cannot be found. You may
  76          *             have to specify "-Djava.library.path=..." on the "java"
  77          *             command line.
  78          */
  79         public static void main(String args[]) throws IOException {
  80
  81                 /* Instantiate a LTTngLogHandler object, and attach it to our logger */
  82                 Handler lttngHandler = new LttngLogHandler();
  83                 LOGGER.addHandler(lttngHandler);
  84
  85                 /* Log events using the JUL Logger created before. */
  86                 LOGGER.info("Hello World, the answer is " + 42);
  87                 LOGGER.info("Another info event");
  88                 LOGGER.severe("A severe event");
  89
  90                 /* Cleanup */
  91                 LOGGER.removeHandler(lttngHandler);
  92                 lttngHandler.close();
  93         }
  94 }