liblttng-ust-java-agent/java/lttng-ust-agent-jul/org/lttng/ust/agent/jul/LttngJulAgent.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.jul;
  19
  20 import java.util.ArrayList;
  21 import java.util.Collection;
  22 import java.util.Collections;
  23 import java.util.List;
  24 import java.util.Set;
  25 import java.util.TreeSet;
  26 import java.util.logging.Handler;
  27 import java.util.logging.LogManager;
  28 import java.util.logging.Logger;
  29
  30 import org.lttng.ust.agent.AbstractLttngAgent;
  31
  32 /**
  33  * Agent implementation for tracing from JUL loggers.
  34  *
  35  * @author Alexandre Montplaisir
  36  */
  37 class LttngJulAgent extends AbstractLttngAgent<LttngLogHandler> {
  38
  39         private static LttngJulAgent instance = null;
  40
  41         private LttngJulAgent() {
  42                 super(Domain.JUL);
  43         }
  44
  45         public static synchronized LttngJulAgent getInstance() {
  46                 if (instance == null) {
  47                         instance = new LttngJulAgent();
  48                 }
  49                 return instance;
  50         }
  51
  52         @Override
  53         public Collection<String> listAvailableEvents() {
  54                 Set<String> ret = new TreeSet<String>();
  55
  56                 List<String> loggersNames = Collections.list(LogManager.getLogManager().getLoggerNames());
  57                 for (String name : loggersNames) {
  58                         /*
  59                          * Skip the root logger. An empty string is not a valid event name
  60                          * in LTTng.
  61                          */
  62                         if (name.equals("") || name.equals("global")) {
  63                                 continue;
  64                         }
  65
  66                         /*
  67                          * Check if that logger has at least one LTTng JUL handler attached.
  68                          */
  69                         Logger logger = Logger.getLogger(name);
  70                         if (hasLttngHandlerAttached(logger)) {
  71                                 ret.add(name);
  72                         }
  73                 }
  74
  75                 return ret;
  76         }
  77
  78         private static boolean hasLttngHandlerAttached(Logger logger) {
  79                 for (Handler handler : logger.getHandlers()) {
  80                         if (handler instanceof LttngLogHandler) {
  81                                 return true;
  82                         }
  83                 }
  84
  85                 /*
  86                  * A parent logger, if any, may be connected to an LTTng handler. In
  87                  * this case, we will want to include this child logger in the output,
  88                  * since it will be accessible by LTTng.
  89                  */
  90                 Logger parent = logger.getParent();
  91                 if (parent != null) {
  92                         return hasLttngHandlerAttached(parent);
  93                 }
  94
  95                 /*
  96                  * We have reached the root logger and have not found any LTTng handler,
  97                  * this event will not be accessible.
  98                  */
  99                 return false;
 100         }
 101
 102 }