/*
* Copyright (C) 2015 - EfficiOS Inc., Alexandre Montplaisir <alexmonthy@efficios.com>
*
* This library is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License, version 2.1 only,
* as published by the Free Software Foundation.
*
* This library is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
* for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this library; if not, write to the Free Software Foundation,
* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
package org.lttng.ust.agent.log4j;
import java.util.Collection;
import java.util.Collections;
import java.util.Enumeration;
import java.util.List;
import java.util.Set;
import java.util.TreeSet;
import org.apache.log4j.Appender;
import org.apache.log4j.Category;
import org.apache.log4j.LogManager;
import org.apache.log4j.Logger;
import org.lttng.ust.agent.AbstractLttngAgent;
/**
* Agent implementation for using the Log4j logger, connecting to a root session
* daemon.
*
* @author Alexandre Montplaisir
*/
class LttngLog4jAgent extends AbstractLttngAgent<LttngLogAppender> {
private static LttngLog4jAgent instance = null;
private LttngLog4jAgent() {
super(Domain.LOG4J);
}
public static synchronized LttngLog4jAgent getInstance() {
if (instance == null) {
instance = new LttngLog4jAgent();
}
return instance;
}
@Override
public Collection<String> listAvailableEvents() {
Set<String> ret = new TreeSet<String>();
@SuppressWarnings("unchecked")
List<Logger> loggers = Collections.list(LogManager.getCurrentLoggers());
for (Logger logger : loggers) {
if (logger == null) {
continue;
}
/*
* Check if that logger has at least one LTTng log4j appender
* attached.
*/
if (hasLttngAppenderAttached(logger)) {
ret.add(logger.getName());
}
}
return ret;
}
private static boolean hasLttngAppenderAttached(Category logger) {
@SuppressWarnings("unchecked")
Enumeration<Appender> appenders = logger.getAllAppenders();
if (appenders != null) {
for (Appender appender : Collections.list(appenders)) {
if (appender instanceof LttngLogAppender) {
return true;
}
}
}
/*
* A parent logger, if any, may be connected to an LTTng handler. In
* this case, we will want to include this child logger in the output,
* since it will be accessible by LTTng.
*/
Category parent = logger.getParent();
if (parent != null) {
return hasLttngAppenderAttached(parent);
}
/*
* We have reached the root logger and have not found any LTTng handler,
* this event will not be accessible.
*/
return false;
}
}