liblttng-ust-java-agent/java/lttng-ust-agent-log4j/org/lttng/ust/agent/log4j/LttngLog4jAgent.java

   1 /*
   2  * Copyright (C) 2015 - EfficiOS Inc., Alexandre Montplaisir <alexmonthy@efficios.com>
   3  *
   4  * This library is free software; you can redistribute it and/or modify it
   5  * under the terms of the GNU Lesser General Public License, version 2.1 only,
   6  * as published by the Free Software Foundation.
   7  *
   8  * This library is distributed in the hope that it will be useful, but WITHOUT
   9  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  10  * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
  11  * for more details.
  12  *
  13  * You should have received a copy of the GNU Lesser General Public License
  14  * along with this library; if not, write to the Free Software Foundation,
  15  * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  16  */
  17
  18 package org.lttng.ust.agent.log4j;
  19
  20 import java.util.ArrayList;
  21 import java.util.Collection;
  22 import java.util.Collections;
  23 import java.util.List;
  24
  25 import org.apache.log4j.Appender;
  26 import org.apache.log4j.LogManager;
  27 import org.apache.log4j.Logger;
  28 import org.lttng.ust.agent.AbstractLttngAgent;
  29
  30 /**
  31  * Agent implementation for using the Log4j logger, connecting to a root session
  32  * daemon.
  33  *
  34  * @author Alexandre Montplaisir
  35  */
  36 class LttngLog4jAgent extends AbstractLttngAgent<LttngLogAppender> {
  37
  38         private static LttngLog4jAgent instance = null;
  39
  40         private LttngLog4jAgent() {
  41                 super(Domain.LOG4J);
  42         }
  43
  44         public static synchronized LttngLog4jAgent getInstance() {
  45                 if (instance == null) {
  46                         instance = new LttngLog4jAgent();
  47                 }
  48                 return instance;
  49         }
  50
  51         @Override
  52         public Collection<String> listAvailableEvents() {
  53                 List<String> ret = new ArrayList<String>();
  54
  55                 @SuppressWarnings("unchecked")
  56                 List<Logger> loggers = Collections.list(LogManager.getCurrentLoggers());
  57                 for (Logger logger : loggers) {
  58                         /*
  59                          * Check if that logger has at least one LTTng log4j appender
  60                          * attached.
  61                          */
  62                         if (hasLttngAppenderAttached(logger)) {
  63                                 ret.add(logger.getName());
  64                         }
  65                 }
  66
  67                 return ret;
  68         }
  69
  70         private static boolean hasLttngAppenderAttached(Logger logger) {
  71                 @SuppressWarnings("unchecked")
  72                 List<Appender> appenders = Collections.list(logger.getAllAppenders());
  73                 for (Appender appender : appenders) {
  74                         if (appender instanceof LttngLogAppender) {
  75                                 return true;
  76                         }
  77                 }
  78                 return false;
  79         }
  80 }