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