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.Collection;
  24
  25 /**
  26  * Session daemon command asking the Java agent to list its registered loggers,
  27  * which corresponds to event names in the tracing session.
  28  *
  29  * @author Alexandre Montplaisir
  30  * @author David Goulet
  31  */
  32 class SessiondListLoggersCommand extends SessiondCommand {
  33
  34         @Override
  35         public LttngAgentResponse execute(ILttngTcpClientListener agent) {
  36                 final Collection<String> loggerList = agent.listAvailableEvents();
  37                 return new SessiondListLoggersResponse(loggerList);
  38         }
  39
  40         private static class SessiondListLoggersResponse extends LttngAgentResponse {
  41
  42                 private final static int SIZE = 12;
  43
  44                 private final Collection<String> loggers;
  45
  46                 public SessiondListLoggersResponse(Collection<String> loggers) {
  47                         this.loggers = loggers;
  48                 }
  49
  50                 @Override
  51                 public ReturnCode getReturnCode() {
  52                         /* This command can't really fail */
  53                         return ReturnCode.CODE_SUCCESS_CMD;
  54                 }
  55
  56                 @Override
  57                 public byte[] getBytes() {
  58                         /*
  59                          * Compute the data size, which is the number of bytes of each
  60                          * encoded string, +1 per string for the \0
  61                          */
  62                         int dataSize = 0;
  63                         for (String logger : loggers) {
  64                                 dataSize += logger.getBytes(SESSIOND_PROTOCOL_CHARSET).length + 1;
  65                         }
  66
  67                         /* Prepare the buffer */
  68                         byte data[] = new byte[SIZE + dataSize];
  69                         ByteBuffer buf = ByteBuffer.wrap(data);
  70                         buf.order(ByteOrder.BIG_ENDIAN);
  71
  72                         /* Write the header section of the response */
  73                         buf.putInt(getReturnCode().getCode());
  74                         buf.putInt(dataSize);
  75                         buf.putInt(loggers.size());
  76
  77                         /* Write the payload */
  78                         for (String logger : loggers) {
  79                                 buf.put(logger.getBytes(SESSIOND_PROTOCOL_CHARSET));
  80                                 /* NULL terminated byte after the logger name. */
  81                                 buf.put((byte) 0x0);
  82                         }
  83                         return data;
  84                 }
  85         }
  86
  87 }