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

   1 /*
   2  * Copyright (C) 2015-2016 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.io.BufferedReader;
  22 import java.io.DataInputStream;
  23 import java.io.DataOutputStream;
  24 import java.io.FileNotFoundException;
  25 import java.io.FileReader;
  26 import java.io.IOException;
  27 import java.lang.management.ManagementFactory;
  28 import java.net.Socket;
  29 import java.net.UnknownHostException;
  30 import java.nio.ByteBuffer;
  31 import java.nio.ByteOrder;
  32 import java.util.concurrent.CountDownLatch;
  33 import java.util.concurrent.TimeUnit;
  34
  35 /**
  36  * Client for agents to connect to a local session daemon, using a TCP socket.
  37  *
  38  * @author David Goulet
  39  */
  40 public class LttngTcpSessiondClient implements Runnable {
  41
  42         private static final String SESSION_HOST = "127.0.0.1";
  43         private static final String ROOT_PORT_FILE = "/var/run/lttng/agent.port";
  44         private static final String USER_PORT_FILE = "/.lttng/agent.port";
  45
  46         private static final int PROTOCOL_MAJOR_VERSION = 2;
  47         private static final int PROTOCOL_MINOR_VERSION = 0;
  48
  49         /** Command header from the session deamon. */
  50         private final CountDownLatch registrationLatch = new CountDownLatch(1);
  51
  52         private Socket sessiondSock;
  53         private volatile boolean quit = false;
  54
  55         private DataInputStream inFromSessiond;
  56         private DataOutputStream outToSessiond;
  57
  58         private final ILttngTcpClientListener logAgent;
  59         private final int domainValue;
  60         private final boolean isRoot;
  61
  62         /**
  63          * Constructor
  64          *
  65          * @param logAgent
  66          *            The listener this client will operate on, typically an LTTng
  67          *            agent.
  68          * @param domainValue
  69          *            The integer to send to the session daemon representing the
  70          *            tracing domain to handle.
  71          * @param isRoot
  72          *            True if this client should connect to the root session daemon,
  73          *            false if it should connect to the user one.
  74          */
  75         public LttngTcpSessiondClient(ILttngTcpClientListener logAgent, int domainValue, boolean isRoot) {
  76                 this.logAgent = logAgent;
  77                 this.domainValue = domainValue;
  78                 this.isRoot = isRoot;
  79         }
  80
  81         /**
  82          * Wait until this client has successfully established a connection to its
  83          * target session daemon.
  84          *
  85          * @param seconds
  86          *            A timeout in seconds after which this method will return
  87          *            anyway.
  88          * @return True if the the client actually established the connection, false
  89          *         if we returned because the timeout has elapsed or the thread was
  90          *         interrupted.
  91          */
  92         public boolean waitForConnection(int seconds) {
  93                 try {
  94                         return registrationLatch.await(seconds, TimeUnit.SECONDS);
  95                 } catch (InterruptedException e) {
  96                         return false;
  97                 }
  98         }
  99
 100         @Override
 101         public void run() {
 102                 for (;;) {
 103                         if (this.quit) {
 104                                 break;
 105                         }
 106
 107                         try {
 108
 109                                 /*
 110                                  * Connect to the session daemon before anything else.
 111                                  */
 112                                 connectToSessiond();
 113
 114                                 /*
 115                                  * Register to the session daemon as the Java component of the
 116                                  * UST application.
 117                                  */
 118                                 registerToSessiond();
 119
 120                                 /*
 121                                  * Block on socket receive and wait for command from the
 122                                  * session daemon. This will return if and only if there is a
 123                                  * fatal error or the socket closes.
 124                                  */
 125                                 handleSessiondCmd();
 126                         } catch (UnknownHostException uhe) {
 127                                 uhe.printStackTrace();
 128                         } catch (IOException ioe) {
 129                                 try {
 130                                         Thread.sleep(3000);
 131                                 } catch (InterruptedException e) {
 132                                         e.printStackTrace();
 133                                 }
 134                         }
 135                 }
 136         }
 137
 138         /**
 139          * Dispose this client and close any socket connection it may hold.
 140          */
 141         public void close() {
 142                 this.quit = true;
 143
 144                 try {
 145                         if (this.sessiondSock != null) {
 146                                 this.sessiondSock.close();
 147                         }
 148                 } catch (IOException e) {
 149                         e.printStackTrace();
 150                 }
 151         }
 152
 153         private void connectToSessiond() throws IOException {
 154                 int port;
 155
 156                 if (this.isRoot) {
 157                         port = getPortFromFile(ROOT_PORT_FILE);
 158                         if (port == 0) {
 159                                 /* No session daemon available. Stop and retry later. */
 160                                 throw new IOException();
 161                         }
 162                 } else {
 163                         port = getPortFromFile(getHomePath() + USER_PORT_FILE);
 164                         if (port == 0) {
 165                                 /* No session daemon available. Stop and retry later. */
 166                                 throw new IOException();
 167                         }
 168                 }
 169
 170                 this.sessiondSock = new Socket(SESSION_HOST, port);
 171                 this.inFromSessiond = new DataInputStream(sessiondSock.getInputStream());
 172                 this.outToSessiond = new DataOutputStream(sessiondSock.getOutputStream());
 173         }
 174
 175         private static String getHomePath() {
 176                 return System.getProperty("user.home");
 177         }
 178
 179         /**
 180          * Read port number from file created by the session daemon.
 181          *
 182          * @return port value if found else 0.
 183          */
 184         private static int getPortFromFile(String path) throws IOException {
 185                 int port;
 186                 BufferedReader br = null;
 187
 188                 try {
 189                         br = new BufferedReader(new FileReader(path));
 190                         String line = br.readLine();
 191                         port = Integer.parseInt(line, 10);
 192                         if (port < 0 || port > 65535) {
 193                                 /* Invalid value. Ignore. */
 194                                 port = 0;
 195                         }
 196                 } catch (FileNotFoundException e) {
 197                         /* No port available. */
 198                         port = 0;
 199                 } finally {
 200                         if (br != null) {
 201                                 br.close();
 202                         }
 203                 }
 204
 205                 return port;
 206         }
 207
 208         private void registerToSessiond() throws IOException {
 209                 byte data[] = new byte[16];
 210                 ByteBuffer buf = ByteBuffer.wrap(data);
 211                 String pid = ManagementFactory.getRuntimeMXBean().getName().split("@")[0];
 212
 213                 buf.putInt(domainValue);
 214                 buf.putInt(Integer.parseInt(pid));
 215                 buf.putInt(PROTOCOL_MAJOR_VERSION);
 216                 buf.putInt(PROTOCOL_MINOR_VERSION);
 217                 this.outToSessiond.write(data, 0, data.length);
 218                 this.outToSessiond.flush();
 219         }
 220
 221         /**
 222          * Handle session command from the session daemon.
 223          */
 224         private void handleSessiondCmd() throws IOException {
 225                 /* Data read from the socket */
 226                 byte inputData[] = null;
 227                 /* Reply data written to the socket, sent to the sessiond */
 228                 byte responseData[] = null;
 229
 230                 while (true) {
 231                         /* Get header from session daemon. */
 232                         SessiondCommandHeader cmdHeader = recvHeader();
 233
 234                         if (cmdHeader.getDataSize() > 0) {
 235                                 inputData = recvPayload(cmdHeader);
 236                         }
 237
 238                         switch (cmdHeader.getCommandType()) {
 239                         case CMD_REG_DONE:
 240                         {
 241                                 /*
 242                                  * Countdown the registration latch, meaning registration is
 243                                  * done and we can proceed to continue tracing.
 244                                  */
 245                                 registrationLatch.countDown();
 246                                 /*
 247                                  * We don't send any reply to the registration done command.
 248                                  * This just marks the end of the initial session setup.
 249                                  */
 250                                 continue;
 251                         }
 252                         case CMD_LIST:
 253                         {
 254                                 SessiondCommand listLoggerCmd = new SessiondListLoggersCommand();
 255                                 LttngAgentResponse response = listLoggerCmd.execute(logAgent);
 256                                 responseData = response.getBytes();
 257                                 break;
 258                         }
 259                         case CMD_EVENT_ENABLE:
 260                         {
 261                                 if (inputData == null) {
 262                                         /* Invalid command */
 263                                         responseData = LttngAgentResponse.FAILURE_RESPONSE.getBytes();
 264                                         break;
 265                                 }
 266                                 SessiondCommand enableEventCmd = new SessiondEnableEventCommand(inputData);
 267                                 LttngAgentResponse response = enableEventCmd.execute(logAgent);
 268                                 responseData = response.getBytes();
 269                                 break;
 270                         }
 271                         case CMD_EVENT_DISABLE:
 272                         {
 273                                 if (inputData == null) {
 274                                         /* Invalid command */
 275                                         responseData = LttngAgentResponse.FAILURE_RESPONSE.getBytes();
 276                                         break;
 277                                 }
 278                                 SessiondCommand disableEventCmd = new SessiondDisableEventCommand(inputData);
 279                                 LttngAgentResponse response = disableEventCmd.execute(logAgent);
 280                                 responseData = response.getBytes();
 281                                 break;
 282                         }
 283                         case CMD_APP_CTX_ENABLE:
 284                         {
 285                                 if (inputData == null) {
 286                                         /* This commands expects a payload, invalid command */
 287                                         responseData = LttngAgentResponse.FAILURE_RESPONSE.getBytes();
 288                                         break;
 289                                 }
 290                                 SessiondCommand enableAppCtxCmd = new SessiondEnableAppContextCommand(inputData);
 291                                 LttngAgentResponse response = enableAppCtxCmd.execute(logAgent);
 292                                 responseData = response.getBytes();
 293                                 break;
 294                         }
 295                         case CMD_APP_CTX_DISABLE:
 296                         {
 297                                 if (inputData == null) {
 298                                         /* This commands expects a payload, invalid command */
 299                                         responseData = LttngAgentResponse.FAILURE_RESPONSE.getBytes();
 300                                         break;
 301                                 }
 302                                 SessiondCommand disableAppCtxCmd = new SessiondDisableAppContextCommand(inputData);
 303                                 LttngAgentResponse response = disableAppCtxCmd.execute(logAgent);
 304                                 responseData = response.getBytes();
 305                                 break;
 306                         }
 307                         default:
 308                         {
 309                                 /* Unknown command, send empty reply */
 310                                 responseData = new byte[4];
 311                                 ByteBuffer buf = ByteBuffer.wrap(responseData);
 312                                 buf.order(ByteOrder.BIG_ENDIAN);
 313                                 break;
 314                         }
 315                         }
 316
 317                         /* Send response to the session daemon. */
 318                         this.outToSessiond.write(responseData, 0, responseData.length);
 319                         this.outToSessiond.flush();
 320                 }
 321         }
 322
 323         /**
 324          * Receive header data from the session daemon using the LTTng command
 325          * static buffer of the right size.
 326          */
 327         private SessiondCommandHeader recvHeader() throws IOException {
 328                 byte data[] = new byte[SessiondCommandHeader.HEADER_SIZE];
 329
 330                 int readLen = this.inFromSessiond.read(data, 0, data.length);
 331                 if (readLen != data.length) {
 332                         throw new IOException();
 333                 }
 334                 return new SessiondCommandHeader(data);
 335         }
 336
 337         /**
 338          * Receive payload from the session daemon. This MUST be done after a
 339          * recvHeader() so the header value of a command are known.
 340          *
 341          * The caller SHOULD use isPayload() before which returns true if a payload
 342          * is expected after the header.
 343          */
 344         private byte[] recvPayload(SessiondCommandHeader headerCmd) throws IOException {
 345                 byte payload[] = new byte[(int) headerCmd.getDataSize()];
 346
 347                 /* Failsafe check so we don't waste our time reading 0 bytes. */
 348                 if (payload.length == 0) {
 349                         return null;
 350                 }
 351
 352                 this.inFromSessiond.read(payload, 0, payload.length);
 353                 return payload;
 354         }
 355
 356 }