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/*
* SPDX-License-Identifier: MIT
*
* Copyright (C) 2015 EfficiOS Inc., Alexandre Montplaisir <alexmonthy@efficios.com>
* Copyright (C) 2013 David Goulet <dgoulet@efficios.com>
*/
import java.io.IOException;
import java.util.logging.Handler;
import java.util.logging.Logger;
import org.lttng.ust.agent.jul.LttngLogHandler;
/**
* Example application using the LTTng-UST Java JUL agent.
*
* <p>
* Basically all that is required is to instantiate a {@link LttngLogHandler}
* and to attach it to a JUL {@link Logger}. Then use the Logger normally to log
* messages, which will be sent to UST as trace events.
* <p>
* </p>
* {@link Logger} names are used as event names on the UST side. This means that
* by enabling/disabling certain events in the tracing session, you are
* effectively enabling and disabling Loggers on the Java side. Note that this
* applies only to {@link LttngLogHandler}'s. If other handlers are attached to
* the Logger, those will continue logging events normally.
* </p>
*
* <p>
* To obtain LTTng trace events, you should run the following sequence of
* commands:
* </p>
*
* <ul>
* <li>$ lttng create</li>
* <li>$ lttng enable-event -j -a</li>
* <li>$ lttng start</li>
* <li>(run this program)</li>
* <li>$ lttng stop</li>
* <li>$ lttng view</li>
* <li>$ lttng destroy</li>
* </ul>
*
* @author Alexandre Montplaisir
* @author David Goulet
*/
public class Hello {
/** Class-wide JUL logger object */
private static final Logger LOGGER = Logger.getLogger(Hello.class.getName());
/**
* Application start
*
* @param args
* Command-line arguments
* @throws IOException
* If the required native libraries cannot be found. You may
* have to specify "-Djava.library.path=..." on the "java"
* command line.
*/
public static void main(String args[]) throws IOException {
/* Instantiate a LTTngLogHandler object, and attach it to our logger */
Handler lttngHandler = new LttngLogHandler();
LOGGER.addHandler(lttngHandler);
/* Log events using the JUL Logger created before. */
LOGGER.info("Hello World, the answer is " + 42);
LOGGER.info("Another info event");
LOGGER.severe("A severe event");
/* Cleanup */
LOGGER.removeHandler(lttngHandler);
lttngHandler.close();
}
}
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