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  * @author Alexandre Montplaisir
  47  * @author David Goulet
  48  */
  49 public class Hello {
  50
  51         /** Class-wide JUL logger object */
  52         private static final Logger LOGGER = Logger.getLogger(Hello.class.getName());
  53
  54         /**
  55          * Application start
  56          *
  57          * @param args
  58          *            Command-line arguments
  59          * @throws IOException
  60          * @throws InterruptedException
  61          */
  62         public static void main(String args[]) throws IOException, InterruptedException {
  63
  64                 /* Instantiate a LTTngLogHandler object, and attach it to our logger */
  65                 Handler lttngHandler = new LttngLogHandler();
  66                 LOGGER.addHandler(lttngHandler);
  67
  68                 /*
  69                  * Gives you time to do some lttng commands before any event is hit.
  70                  */
  71                 Thread.sleep(5000);
  72
  73                 /* Trigger a tracing event using the JUL Logger created before. */
  74                 LOGGER.info("Hello World, the answer is " + 42);
  75
  76                 /*
  77                  * From this point on, the above message will be collected in the trace
  78                  * if the event "Hello" is enabled for the JUL domain using the lttng
  79                  * command line or the lttng-ctl API. For instance:
  80                  *
  81                  *   $ lttng enable-event -j Hello
  82                  */
  83
  84                 /*
  85                  * A new logger is created here and fired after. Typically with JUL, you
  86                  * use one static Logger per class. This example here can represent a
  87                  * class being lazy-loaded later in the execution of the application.
  88                  *
  89                  * The agent has an internal timer that is fired every 5 seconds in
  90                  * order to enable events that were not found at first but might need to
  91                  * be enabled when a new Logger appears. Unfortunately, there is no way
  92                  * right now to get notified of that so we have to actively poll.
  93                  *
  94                  * Using the --all command for instance, it will make this Logger
  95                  * available in a LTTng trace after the internal agent's timer is fired.
  96                  * (lttng enable-event -j -a).
  97                  */
  98                 Logger helloLogDelayed = Logger.getLogger("hello_delay");
  99
 100                 /*
 101                  * Attach a handler to this new logger.
 102                  *
 103                  * Using the same handler as before would also work.
 104                  */
 105                 Handler lttngHandler2 = new LttngLogHandler();
 106                 helloLogDelayed.addHandler(lttngHandler2);
 107
 108                 System.out.println("Firing hello delay in 10 seconds...");
 109                 Thread.sleep(10000);
 110                 helloLogDelayed.info("Hello World delayed...");
 111
 112                 System.out.println("Cleaning Hello");
 113
 114                 /*
 115                  * Do not forget to close() all handlers so that the agent can shutdown
 116                  * and the session daemon socket gets cleaned up explicitly.
 117                  */
 118                 lttngHandler.close();
 119                 lttngHandler2.close();
 120         }
 121 }