liblttng-ust-java-agent/java/lttng-ust-agent-common/org/lttng/ust/agent/client/SessiondEnableEventCommand.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
  24 import org.lttng.ust.agent.session.EventRule;
  25 import org.lttng.ust.agent.session.LogLevelSelector;
  26
  27 /**
  28  * Session daemon command indicating to the Java agent that some events were
  29  * enabled in the tracing session.
  30  *
  31  * @author Alexandre Montplaisir
  32  * @author David Goulet
  33  */
  34 class SessiondEnableEventCommand implements ISessiondCommand {
  35
  36         /** Fixed event name length. Value defined by the lttng agent protocol. */
  37         private static final int EVENT_NAME_LENGTH = 256;
  38
  39         private final boolean commandIsValid;
  40
  41         /* Parameters of the event rule being enabled */
  42         private final String eventName;
  43         private final LogLevelSelector logLevelFilter;
  44         private final String filterString;
  45
  46         public SessiondEnableEventCommand(byte[] data) {
  47                 if (data == null) {
  48                         throw new IllegalArgumentException();
  49                 }
  50                 ByteBuffer buf = ByteBuffer.wrap(data);
  51                 buf.order(ByteOrder.BIG_ENDIAN);
  52                 int logLevel = buf.getInt();
  53                 int logLevelType = buf.getInt();
  54                 logLevelFilter = new LogLevelSelector(logLevel, logLevelType);
  55
  56                 /* Read the event name */
  57                 byte[] eventNameBytes = new byte[EVENT_NAME_LENGTH];
  58                 buf.get(eventNameBytes);
  59                 eventName = new String(eventNameBytes).trim();
  60
  61                 /*
  62                  * Read the filter string. The buffer contains the length (number of
  63                  * bytes), then the bytes themselves.
  64                  *
  65                  * The length is represented as an unsigned int, but it should never
  66                  * be greater than Integer.MAX_VALUE.
  67                  */
  68                 int filterStringLength = buf.getInt();
  69                 if (filterStringLength < 0) {
  70                         /*
  71                          * The (unsigned) length is above what the sessiond should send. The
  72                          * command cannot be processed.
  73                          */
  74                         filterString = null;
  75                         commandIsValid = false;
  76                         return;
  77                 }
  78                 if (filterStringLength == 0) {
  79                         /* There is explicitly no filter string */
  80                         filterString = "";
  81                         commandIsValid = true;
  82                         return;
  83                 }
  84
  85                 byte[] filterStringBytes = new byte[filterStringLength];
  86                 buf.get(filterStringBytes);
  87                 filterString = new String(filterStringBytes).trim();
  88
  89                 commandIsValid = true;
  90         }
  91
  92         @Override
  93         public LttngAgentResponse execute(ILttngTcpClientListener agent) {
  94                 if (!commandIsValid) {
  95                         return LttngAgentResponse.FAILURE_RESPONSE;
  96                 }
  97
  98                 EventRule rule = new EventRule(eventName, logLevelFilter, filterString);
  99                 boolean success = agent.eventEnabled(rule);
 100                 return (success ? LttngAgentResponse.SUCESS_RESPONSE : LttngAgentResponse.FAILURE_RESPONSE);
 101         }
 102 }