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.logging.Handler;
  25 import java.util.logging.LogManager;
  26 import java.util.logging.Logger;
  27
  28 import org.lttng.ust.agent.AbstractLttngAgent;
  29
  30 /**
  31  * Agent implementation for tracing from JUL loggers.
  32  *
  33  * @author Alexandre Montplaisir
  34  */
  35 class LttngJulAgent extends AbstractLttngAgent<LttngLogHandler> {
  36
  37         private static LttngJulAgent instance = null;
  38
  39         private LttngJulAgent() {
  40                 super(Domain.JUL);
  41         }
  42
  43         public static synchronized LttngJulAgent getInstance() {
  44                 if (instance == null) {
  45                         instance = new LttngJulAgent();
  46                 }
  47                 return instance;
  48         }
  49
  50         @Override
  51         public Collection<String> listAvailableEvents() {
  52                 List<String> ret = new ArrayList<String>();
  53
  54                 List<String> loggersNames = Collections.list(LogManager.getLogManager().getLoggerNames());
  55                 for (String name : loggersNames) {
  56                         /*
  57                          * Skip the root logger. An empty string is not a valid event name
  58                          * in LTTng.
  59                          */
  60                         if (name.equals("")) {
  61                                 continue;
  62                         }
  63
  64                         /*
  65                          * Check if that logger has at least one LTTng JUL handler attached.
  66                          */
  67                         Logger logger = Logger.getLogger(name);
  68                         if (hasLttngHandlerAttached(logger)) {
  69                                 ret.add(name);
  70                         }
  71                 }
  72
  73                 return ret;
  74         }
  75
  76         private static boolean hasLttngHandlerAttached(Logger logger) {
  77                 for (Handler handler : logger.getHandlers()) {
  78                         if (handler instanceof LttngLogHandler) {
  79                                 return true;
  80                         }
  81                 }
  82                 return false;
  83         }
  84
  85 }