liblttng-ust-java-agent/java/lttng-ust-agent-common/org/lttng/ust/agent/client/SessiondListLoggersCommand.java

   1 /*
   2  * Copyright (C) 2015 - EfficiOS Inc., Alexandre Montplaisir <alexmonthy@efficios.com>
   3  * Copyright (C) 2013 - David Goulet <dgoulet@efficios.com>
   4  *
   5  * This library is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU Lesser General Public License, version 2.1 only,
   7  * as published by the Free Software Foundation.
   8  *
   9  * This library is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
  12  * for more details.
  13  *
  14  * You should have received a copy of the GNU Lesser General Public License
  15  * along with this library; if not, write to the Free Software Foundation,
  16  * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  17  */
  18
  19 package org.lttng.ust.agent.client;
  20
  21 import java.nio.ByteBuffer;
  22 import java.nio.ByteOrder;
  23 import java.util.ArrayList;
  24 import java.util.List;
  25
  26 import org.lttng.ust.agent.AbstractLttngAgent;
  27
  28 /**
  29  * Session daemon command asking the Java agent to list its registered loggers,
  30  * which corresponds to event names in the tracing session.
  31  *
  32  * @author Alexandre Montplaisir
  33  * @author David Goulet
  34  */
  35 class SessiondListLoggersCommand implements ISessiondCommand {
  36
  37         @Override
  38         public LttngAgentResponse execute(AbstractLttngAgent<?> agent) {
  39                 final List<String> loggerList = new ArrayList<String>();
  40                 int dataSize = 0;
  41
  42                 for (String event : agent.listEnabledEvents()) {
  43                         loggerList.add(event);
  44                         dataSize += event.length() + 1;
  45                 }
  46
  47                 return new SessiondListLoggersResponse(loggerList, dataSize);
  48         }
  49
  50         private static class SessiondListLoggersResponse extends LttngAgentResponse {
  51
  52                 private final static int SIZE = 12;
  53
  54                 private final List<String> loggers;
  55                 private final int dataSize;
  56
  57                 public SessiondListLoggersResponse(List<String> loggers, int dataSize) {
  58                         this.loggers = loggers;
  59                         this.dataSize = dataSize;
  60                 }
  61
  62                 @Override
  63                 public ReturnCode getReturnCode() {
  64                         /* This command can't really fail */
  65                         return ReturnCode.CODE_SUCCESS_CMD;
  66                 }
  67
  68                 @Override
  69                 public byte[] getBytes() {
  70                         byte data[] = new byte[SIZE + dataSize];
  71                         ByteBuffer buf = ByteBuffer.wrap(data);
  72                         buf.order(ByteOrder.BIG_ENDIAN);
  73
  74                         /* Returned code */
  75                         buf.putInt(getReturnCode().getCode());
  76                         buf.putInt(dataSize);
  77                         buf.putInt(loggers.size());
  78
  79                         for (String logger : loggers) {
  80                                 buf.put(logger.getBytes());
  81                                 /* NULL terminated byte after the logger name. */
  82                                 buf.put((byte) 0x0);
  83                         }
  84                         return data;
  85                 }
  86         }
  87
  88 }