src/bin/lttng-relayd/live.c

   1 /*
   2  * Copyright (C) 2013 - Julien Desfossez <jdesfossez@efficios.com>
   3  *                      David Goulet <dgoulet@efficios.com>
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License, version 2 only,
   7  * as published by the Free Software Foundation.
   8  *
   9  * This program 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 General Public License for
  12  * more details.
  13  *
  14  * You should have received a copy of the GNU General Public License along
  15  * with this program; if not, write to the Free Software Foundation, Inc.,
  16  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  17  */
  18
  19 #define _GNU_SOURCE
  20 #include <getopt.h>
  21 #include <grp.h>
  22 #include <limits.h>
  23 #include <pthread.h>
  24 #include <signal.h>
  25 #include <stdio.h>
  26 #include <stdlib.h>
  27 #include <string.h>
  28 #include <sys/mman.h>
  29 #include <sys/mount.h>
  30 #include <sys/resource.h>
  31 #include <sys/socket.h>
  32 #include <sys/stat.h>
  33 #include <sys/types.h>
  34 #include <sys/wait.h>
  35 #include <inttypes.h>
  36 #include <urcu/futex.h>
  37 #include <urcu/uatomic.h>
  38 #include <unistd.h>
  39 #include <fcntl.h>
  40 #include <config.h>
  41
  42 #include <lttng/lttng.h>
  43 #include <common/common.h>
  44 #include <common/compat/poll.h>
  45 #include <common/compat/socket.h>
  46 #include <common/defaults.h>
  47 #include <common/futex.h>
  48 #include <common/sessiond-comm/sessiond-comm.h>
  49 #include <common/sessiond-comm/inet.h>
  50 #include <common/sessiond-comm/relayd.h>
  51 #include <common/uri.h>
  52 #include <common/utils.h>
  53
  54 #include "cmd.h"
  55 #include "live.h"
  56 #include "lttng-relayd.h"
  57 #include "lttng-viewer.h"
  58 #include "utils.h"
  59 #include "health-relayd.h"
  60 #include "testpoint.h"
  61
  62 static struct lttng_uri *live_uri;
  63
  64 /*
  65  * This pipe is used to inform the worker thread that a command is queued and
  66  * ready to be processed.
  67  */
  68 static int live_relay_cmd_pipe[2] = { -1, -1 };
  69
  70 /* Shared between threads */
  71 static int live_dispatch_thread_exit;
  72
  73 static pthread_t live_listener_thread;
  74 static pthread_t live_dispatcher_thread;
  75 static pthread_t live_worker_thread;
  76
  77 /*
  78  * Relay command queue.
  79  *
  80  * The live_thread_listener and live_thread_dispatcher communicate with this
  81  * queue.
  82  */
  83 static struct relay_cmd_queue viewer_cmd_queue;
  84
  85 static uint64_t last_relay_viewer_session_id;
  86
  87 /*
  88  * Cleanup the daemon
  89  */
  90 static
  91 void cleanup(void)
  92 {
  93         DBG("Cleaning up");
  94
  95         free(live_uri);
  96 }
  97
  98 /*
  99  * Write to writable pipe used to notify a thread.
 100  */
 101 static
 102 int notify_thread_pipe(int wpipe)
 103 {
 104         ssize_t ret;
 105
 106         ret = lttng_write(wpipe, "!", 1);
 107         if (ret < 1) {
 108                 PERROR("write poll pipe");
 109         }
 110
 111         return (int) ret;
 112 }
 113
 114 /*
 115  * Stop all threads by closing the thread quit pipe.
 116  */
 117 static
 118 void stop_threads(void)
 119 {
 120         int ret;
 121
 122         /* Stopping all threads */
 123         DBG("Terminating all live threads");
 124         ret = notify_thread_pipe(thread_quit_pipe[1]);
 125         if (ret < 0) {
 126                 ERR("write error on thread quit pipe");
 127         }
 128
 129         /* Dispatch thread */
 130         CMM_STORE_SHARED(live_dispatch_thread_exit, 1);
 131         futex_nto1_wake(&viewer_cmd_queue.futex);
 132 }
 133
 134 /*
 135  * Create a poll set with O_CLOEXEC and add the thread quit pipe to the set.
 136  */
 137 static
 138 int create_thread_poll_set(struct lttng_poll_event *events, int size)
 139 {
 140         int ret;
 141
 142         if (events == NULL || size == 0) {
 143                 ret = -1;
 144                 goto error;
 145         }
 146
 147         ret = lttng_poll_create(events, size, LTTNG_CLOEXEC);
 148         if (ret < 0) {
 149                 goto error;
 150         }
 151
 152         /* Add quit pipe */
 153         ret = lttng_poll_add(events, thread_quit_pipe[0], LPOLLIN | LPOLLERR);
 154         if (ret < 0) {
 155                 goto error;
 156         }
 157
 158         return 0;
 159
 160 error:
 161         return ret;
 162 }
 163
 164 /*
 165  * Check if the thread quit pipe was triggered.
 166  *
 167  * Return 1 if it was triggered else 0;
 168  */
 169 static
 170 int check_thread_quit_pipe(int fd, uint32_t events)
 171 {
 172         if (fd == thread_quit_pipe[0] && (events & LPOLLIN)) {
 173                 return 1;
 174         }
 175
 176         return 0;
 177 }
 178
 179 /*
 180  * Create and init socket from uri.
 181  */
 182 static
 183 struct lttcomm_sock *init_socket(struct lttng_uri *uri)
 184 {
 185         int ret;
 186         struct lttcomm_sock *sock = NULL;
 187
 188         sock = lttcomm_alloc_sock_from_uri(uri);
 189         if (sock == NULL) {
 190                 ERR("Allocating socket");
 191                 goto error;
 192         }
 193
 194         ret = lttcomm_create_sock(sock);
 195         if (ret < 0) {
 196                 goto error;
 197         }
 198         DBG("Listening on sock %d for live", sock->fd);
 199
 200         ret = sock->ops->bind(sock);
 201         if (ret < 0) {
 202                 goto error;
 203         }
 204
 205         ret = sock->ops->listen(sock, -1);
 206         if (ret < 0) {
 207                 goto error;
 208
 209         }
 210
 211         return sock;
 212
 213 error:
 214         if (sock) {
 215                 lttcomm_destroy_sock(sock);
 216         }
 217         return NULL;
 218 }
 219
 220 /*
 221  * This thread manages the listening for new connections on the network
 222  */
 223 static
 224 void *thread_listener(void *data)
 225 {
 226         int i, ret, pollfd, err = -1;
 227         int val = 1;
 228         uint32_t revents, nb_fd;
 229         struct lttng_poll_event events;
 230         struct lttcomm_sock *live_control_sock;
 231
 232         DBG("[thread] Relay live listener started");
 233
 234         health_register(health_relayd, HEALTH_RELAYD_TYPE_LIVE_LISTENER);
 235
 236         health_code_update();
 237
 238         live_control_sock = init_socket(live_uri);
 239         if (!live_control_sock) {
 240                 goto error_sock_control;
 241         }
 242
 243         /* Pass 2 as size here for the thread quit pipe and control sockets. */
 244         ret = create_thread_poll_set(&events, 2);
 245         if (ret < 0) {
 246                 goto error_create_poll;
 247         }
 248
 249         /* Add the control socket */
 250         ret = lttng_poll_add(&events, live_control_sock->fd, LPOLLIN | LPOLLRDHUP);
 251         if (ret < 0) {
 252                 goto error_poll_add;
 253         }
 254
 255         lttng_relay_notify_ready();
 256
 257         if (testpoint(relayd_thread_live_listener)) {
 258                 goto error_testpoint;
 259         }
 260
 261         while (1) {
 262                 health_code_update();
 263
 264                 DBG("Listener accepting live viewers connections");
 265
 266 restart:
 267                 health_poll_entry();
 268                 ret = lttng_poll_wait(&events, -1);
 269                 health_poll_exit();
 270                 if (ret < 0) {
 271                         /*
 272                          * Restart interrupted system call.
 273                          */
 274                         if (errno == EINTR) {
 275                                 goto restart;
 276                         }
 277                         goto error;
 278                 }
 279                 nb_fd = ret;
 280
 281                 DBG("Relay new viewer connection received");
 282                 for (i = 0; i < nb_fd; i++) {
 283                         health_code_update();
 284
 285                         /* Fetch once the poll data */
 286                         revents = LTTNG_POLL_GETEV(&events, i);
 287                         pollfd = LTTNG_POLL_GETFD(&events, i);
 288
 289                         /* Thread quit pipe has been closed. Killing thread. */
 290                         ret = check_thread_quit_pipe(pollfd, revents);
 291                         if (ret) {
 292                                 err = 0;
 293                                 goto exit;
 294                         }
 295
 296                         if (revents & (LPOLLERR | LPOLLHUP | LPOLLRDHUP)) {
 297                                 ERR("socket poll error");
 298                                 goto error;
 299                         } else if (revents & LPOLLIN) {
 300                                 /*
 301                                  * Get allocated in this thread, enqueued to a global queue,
 302                                  * dequeued and freed in the worker thread.
 303                                  */
 304                                 struct relay_command *relay_cmd;
 305                                 struct lttcomm_sock *newsock;
 306
 307                                 relay_cmd = zmalloc(sizeof(*relay_cmd));
 308                                 if (!relay_cmd) {
 309                                         PERROR("relay command zmalloc");
 310                                         goto error;
 311                                 }
 312
 313                                 assert(pollfd == live_control_sock->fd);
 314                                 newsock = live_control_sock->ops->accept(live_control_sock);
 315                                 if (!newsock) {
 316                                         PERROR("accepting control sock");
 317                                         free(relay_cmd);
 318                                         goto error;
 319                                 }
 320                                 DBG("Relay viewer connection accepted socket %d", newsock->fd);
 321                                 ret = setsockopt(newsock->fd, SOL_SOCKET, SO_REUSEADDR, &val,
 322                                                 sizeof(int));
 323                                 if (ret < 0) {
 324                                         PERROR("setsockopt inet");
 325                                         lttcomm_destroy_sock(newsock);
 326                                         free(relay_cmd);
 327                                         goto error;
 328                                 }
 329                                 relay_cmd->sock = newsock;
 330
 331                                 /*
 332                                  * Lock free enqueue the request.
 333                                  */
 334                                 cds_wfq_enqueue(&viewer_cmd_queue.queue, &relay_cmd->node);
 335
 336                                 /*
 337                                  * Wake the dispatch queue futex. Implicit memory
 338                                  * barrier with the exchange in cds_wfq_enqueue.
 339                                  */
 340                                 futex_nto1_wake(&viewer_cmd_queue.futex);
 341                         }
 342                 }
 343         }
 344
 345 exit:
 346 error:
 347 error_poll_add:
 348 error_testpoint:
 349         lttng_poll_clean(&events);
 350 error_create_poll:
 351         if (live_control_sock->fd >= 0) {
 352                 ret = live_control_sock->ops->close(live_control_sock);
 353                 if (ret) {
 354                         PERROR("close");
 355                 }
 356         }
 357         lttcomm_destroy_sock(live_control_sock);
 358 error_sock_control:
 359         if (err) {
 360                 health_error();
 361                 DBG("Live viewer listener thread exited with error");
 362         }
 363         health_unregister(health_relayd);
 364         DBG("Live viewer listener thread cleanup complete");
 365         stop_threads();
 366         return NULL;
 367 }
 368
 369 /*
 370  * This thread manages the dispatching of the requests to worker threads
 371  */
 372 static
 373 void *thread_dispatcher(void *data)
 374 {
 375         int err = -1;
 376         ssize_t ret;
 377         struct cds_wfq_node *node;
 378         struct relay_command *relay_cmd = NULL;
 379
 380         DBG("[thread] Live viewer relay dispatcher started");
 381
 382         health_register(health_relayd, HEALTH_RELAYD_TYPE_LIVE_DISPATCHER);
 383
 384         if (testpoint(relayd_thread_live_dispatcher)) {
 385                 goto error_testpoint;
 386         }
 387
 388         health_code_update();
 389
 390         while (!CMM_LOAD_SHARED(live_dispatch_thread_exit)) {
 391                 health_code_update();
 392
 393                 /* Atomically prepare the queue futex */
 394                 futex_nto1_prepare(&viewer_cmd_queue.futex);
 395
 396                 do {
 397                         health_code_update();
 398
 399                         /* Dequeue commands */
 400                         node = cds_wfq_dequeue_blocking(&viewer_cmd_queue.queue);
 401                         if (node == NULL) {
 402                                 DBG("Woken up but nothing in the live-viewer "
 403                                                 "relay command queue");
 404                                 /* Continue thread execution */
 405                                 break;
 406                         }
 407
 408                         relay_cmd = caa_container_of(node, struct relay_command, node);
 409                         DBG("Dispatching viewer request waiting on sock %d",
 410                                         relay_cmd->sock->fd);
 411
 412                         /*
 413                          * Inform worker thread of the new request. This call is blocking
 414                          * so we can be assured that the data will be read at some point in
 415                          * time or wait to the end of the world :)
 416                          */
 417                         ret = lttng_write(live_relay_cmd_pipe[1], relay_cmd,
 418                                         sizeof(*relay_cmd));
 419                         free(relay_cmd);
 420                         if (ret < sizeof(struct relay_command)) {
 421                                 PERROR("write cmd pipe");
 422                                 goto error;
 423                         }
 424                 } while (node != NULL);
 425
 426                 /* Futex wait on queue. Blocking call on futex() */
 427                 health_poll_entry();
 428                 futex_nto1_wait(&viewer_cmd_queue.futex);
 429                 health_poll_exit();
 430         }
 431
 432         /* Normal exit, no error */
 433         err = 0;
 434
 435 error:
 436 error_testpoint:
 437         if (err) {
 438                 health_error();
 439                 ERR("Health error occurred in %s", __func__);
 440         }
 441         health_unregister(health_relayd);
 442         DBG("Live viewer dispatch thread dying");
 443         stop_threads();
 444         return NULL;
 445 }
 446
 447 /*
 448  * Establish connection with the viewer and check the versions.
 449  *
 450  * Return 0 on success or else negative value.
 451  */
 452 static
 453 int viewer_connect(struct relay_command *cmd)
 454 {
 455         int ret;
 456         struct lttng_viewer_connect reply, msg;
 457
 458         assert(cmd);
 459
 460         cmd->version_check_done = 1;
 461
 462         health_code_update();
 463
 464         /* Get version from the other side. */
 465         ret = cmd->sock->ops->recvmsg(cmd->sock, &msg, sizeof(msg), 0);
 466         if (ret < 0 || ret != sizeof(msg)) {
 467                 if (ret == 0) {
 468                         /* Orderly shutdown. Not necessary to print an error. */
 469                         DBG("Socket %d did an orderly shutdown", cmd->sock->fd);
 470                 } else {
 471                         ERR("Relay failed to receive the version values.");
 472                 }
 473                 ret = -1;
 474                 goto end;
 475         }
 476
 477         health_code_update();
 478
 479         reply.major = RELAYD_VERSION_COMM_MAJOR;
 480         reply.minor = RELAYD_VERSION_COMM_MINOR;
 481
 482         /* Major versions must be the same */
 483         if (reply.major != be32toh(msg.major)) {
 484                 DBG("Incompatible major versions (%u vs %u)", reply.major,
 485                                 be32toh(msg.major));
 486                 ret = -1;
 487                 goto end;
 488         }
 489
 490         cmd->major = reply.major;
 491         /* We adapt to the lowest compatible version */
 492         if (reply.minor <= be32toh(msg.minor)) {
 493                 cmd->minor = reply.minor;
 494         } else {
 495                 cmd->minor = be32toh(msg.minor);
 496         }
 497
 498         if (be32toh(msg.type) == VIEWER_CLIENT_COMMAND) {
 499                 cmd->type = RELAY_VIEWER_COMMAND;
 500         } else if (be32toh(msg.type) == VIEWER_CLIENT_NOTIFICATION) {
 501                 cmd->type = RELAY_VIEWER_NOTIFICATION;
 502         } else {
 503                 ERR("Unknown connection type : %u", be32toh(msg.type));
 504                 ret = -1;
 505                 goto end;
 506         }
 507
 508         reply.major = htobe32(reply.major);
 509         reply.minor = htobe32(reply.minor);
 510         if (cmd->type == RELAY_VIEWER_COMMAND) {
 511                 reply.viewer_session_id = htobe64(++last_relay_viewer_session_id);
 512         }
 513
 514         health_code_update();
 515
 516         ret = cmd->sock->ops->sendmsg(cmd->sock, &reply,
 517                         sizeof(struct lttng_viewer_connect), 0);
 518         if (ret < 0) {
 519                 ERR("Relay sending version");
 520         }
 521
 522         health_code_update();
 523
 524         DBG("Version check done using protocol %u.%u", cmd->major, cmd->minor);
 525         ret = 0;
 526
 527 end:
 528         return ret;
 529 }
 530
 531 /*
 532  * Send the viewer the list of current sessions.
 533  *
 534  * Return 0 on success or else a negative value.
 535  */
 536 static
 537 int viewer_list_sessions(struct relay_command *cmd,
 538                 struct lttng_ht *sessions_ht)
 539 {
 540         int ret;
 541         struct lttng_viewer_list_sessions session_list;
 542         unsigned long count;
 543         long approx_before, approx_after;
 544         struct lttng_ht_node_ulong *node;
 545         struct lttng_ht_iter iter;
 546         struct lttng_viewer_session send_session;
 547         struct relay_session *session;
 548
 549         DBG("List sessions received");
 550
 551         if (cmd->version_check_done == 0) {
 552                 ERR("Trying to list sessions before version check");
 553                 ret = -1;
 554                 goto end_no_session;
 555         }
 556
 557         rcu_read_lock();
 558         cds_lfht_count_nodes(sessions_ht->ht, &approx_before, &count, &approx_after);
 559         session_list.sessions_count = htobe32(count);
 560
 561         health_code_update();
 562
 563         ret = cmd->sock->ops->sendmsg(cmd->sock, &session_list,
 564                         sizeof(session_list), 0);
 565         if (ret < 0) {
 566                 ERR("Relay sending sessions list");
 567                 goto end_unlock;
 568         }
 569
 570         health_code_update();
 571
 572         cds_lfht_for_each_entry(sessions_ht->ht, &iter.iter, node, node) {
 573                 health_code_update();
 574
 575                 node = lttng_ht_iter_get_node_ulong(&iter);
 576                 if (!node) {
 577                         goto end_unlock;
 578                 }
 579                 session = caa_container_of(node, struct relay_session, session_n);
 580
 581                 strncpy(send_session.session_name, session->session_name,
 582                                 sizeof(send_session.session_name));
 583                 strncpy(send_session.hostname, session->hostname,
 584                                 sizeof(send_session.hostname));
 585                 send_session.id = htobe64(session->id);
 586                 send_session.live_timer = htobe32(session->live_timer);
 587                 send_session.clients = htobe32(session->viewer_attached);
 588                 send_session.streams = htobe32(session->stream_count);
 589
 590                 health_code_update();
 591
 592                 ret = cmd->sock->ops->sendmsg(cmd->sock, &send_session,
 593                                 sizeof(send_session), 0);
 594                 if (ret < 0) {
 595                         ERR("Relay sending session info");
 596                         goto end_unlock;
 597                 }
 598         }
 599         health_code_update();
 600
 601         rcu_read_unlock();
 602         ret = 0;
 603         goto end;
 604
 605 end_unlock:
 606         rcu_read_unlock();
 607
 608 end:
 609 end_no_session:
 610         return ret;
 611 }
 612
 613 /*
 614  * Open index file using a given viewer stream.
 615  *
 616  * Return 0 on success or else a negative value.
 617  */
 618 static int open_index(struct relay_viewer_stream *stream)
 619 {
 620         int ret;
 621         char fullpath[PATH_MAX];
 622         struct ctf_packet_index_file_hdr hdr;
 623
 624         if (stream->tracefile_count > 0) {
 625                 ret = snprintf(fullpath, sizeof(fullpath), "%s/" DEFAULT_INDEX_DIR "/%s_%"
 626                                 PRIu64 DEFAULT_INDEX_FILE_SUFFIX, stream->path_name,
 627                                 stream->channel_name, stream->tracefile_count_current);
 628         } else {
 629                 ret = snprintf(fullpath, sizeof(fullpath), "%s/" DEFAULT_INDEX_DIR "/%s"
 630                                 DEFAULT_INDEX_FILE_SUFFIX, stream->path_name,
 631                                 stream->channel_name);
 632         }
 633         if (ret < 0) {
 634                 PERROR("snprintf index path");
 635                 goto error;
 636         }
 637
 638         DBG("Opening index file %s in read only", fullpath);
 639         ret = open(fullpath, O_RDONLY);
 640         if (ret < 0) {
 641                 if (errno == ENOENT) {
 642                         ret = -ENOENT;
 643                         goto error;
 644                 } else {
 645                         PERROR("opening index in read-only");
 646                 }
 647                 goto error;
 648         }
 649         stream->index_read_fd = ret;
 650         DBG("Opening index file %s in read only, (fd: %d)", fullpath, ret);
 651
 652         ret = lttng_read(stream->index_read_fd, &hdr, sizeof(hdr));
 653         if (ret < sizeof(hdr)) {
 654                 PERROR("Reading index header");
 655                 goto error;
 656         }
 657         if (be32toh(hdr.magic) != CTF_INDEX_MAGIC) {
 658                 ERR("Invalid header magic");
 659                 ret = -1;
 660                 goto error;
 661         }
 662         if (be32toh(hdr.index_major) != CTF_INDEX_MAJOR ||
 663                         be32toh(hdr.index_minor) != CTF_INDEX_MINOR) {
 664                 ERR("Invalid header version");
 665                 ret = -1;
 666                 goto error;
 667         }
 668         ret = 0;
 669
 670 error:
 671         return ret;
 672 }
 673
 674 /*
 675  * Allocate and init a new viewer_stream.
 676  *
 677  * Copies the values from the stream passed in parameter and insert the new
 678  * stream in the viewer_streams_ht.
 679  *
 680  * MUST be called with rcu_read_lock held.
 681  *
 682  * Returns 0 on success or a negative value on error.
 683  */
 684 static
 685 int init_viewer_stream(struct relay_stream *stream, int seek_last)
 686 {
 687         int ret;
 688         struct relay_viewer_stream *viewer_stream;
 689
 690         assert(stream);
 691
 692         viewer_stream = zmalloc(sizeof(*viewer_stream));
 693         if (!viewer_stream) {
 694                 PERROR("relay viewer stream zmalloc");
 695                 ret = -1;
 696                 goto error;
 697         }
 698         viewer_stream->session_id = stream->session->id;
 699         viewer_stream->stream_handle = stream->stream_handle;
 700         viewer_stream->path_name = strndup(stream->path_name,
 701                         LTTNG_VIEWER_PATH_MAX);
 702         viewer_stream->channel_name = strndup(stream->channel_name,
 703                         LTTNG_VIEWER_NAME_MAX);
 704         viewer_stream->tracefile_count = stream->tracefile_count;
 705         viewer_stream->metadata_flag = stream->metadata_flag;
 706         viewer_stream->tracefile_count_last = -1ULL;
 707         if (seek_last) {
 708                 viewer_stream->tracefile_count_current =
 709                         stream->tracefile_count_current;
 710         } else {
 711                 viewer_stream->tracefile_count_current =
 712                         stream->oldest_tracefile_id;
 713         }
 714
 715         viewer_stream->ctf_trace = stream->ctf_trace;
 716         if (viewer_stream->metadata_flag) {
 717                 viewer_stream->ctf_trace->viewer_metadata_stream =
 718                         viewer_stream;
 719         }
 720         uatomic_inc(&viewer_stream->ctf_trace->refcount);
 721
 722         lttng_ht_node_init_u64(&viewer_stream->stream_n, stream->stream_handle);
 723         lttng_ht_add_unique_u64(viewer_streams_ht, &viewer_stream->stream_n);
 724
 725         viewer_stream->index_read_fd = -1;
 726         viewer_stream->read_fd = -1;
 727
 728         /*
 729          * This is to avoid a race between the initialization of this object and
 730          * the close of the given stream. If the stream is unable to find this
 731          * viewer stream when closing, this copy will at least take the latest
 732          * value.
 733          * We also need that for the seek_last.
 734          */
 735         viewer_stream->total_index_received = stream->total_index_received;
 736
 737         /*
 738          * If we never received an index for the current stream, delay
 739          * the opening of the index, otherwise open it right now.
 740          */
 741         if (viewer_stream->tracefile_count_current ==
 742                         stream->tracefile_count_current &&
 743                         viewer_stream->total_index_received == 0) {
 744                 viewer_stream->index_read_fd = -1;
 745         } else {
 746                 ret = open_index(viewer_stream);
 747                 if (ret < 0) {
 748                         goto error;
 749                 }
 750         }
 751
 752         if (seek_last && viewer_stream->index_read_fd > 0) {
 753                 ret = lseek(viewer_stream->index_read_fd,
 754                                 viewer_stream->total_index_received *
 755                                         sizeof(struct ctf_packet_index),
 756                                 SEEK_CUR);
 757                 if (ret < 0) {
 758                         goto error;
 759                 }
 760                 viewer_stream->last_sent_index =
 761                         viewer_stream->total_index_received;
 762         }
 763
 764         ret = 0;
 765
 766 error:
 767         return ret;
 768 }
 769
 770 /*
 771  * Rotate a stream to the next tracefile.
 772  *
 773  * Returns 0 on success, 1 on EOF, a negative value on error.
 774  */
 775 static
 776 int rotate_viewer_stream(struct relay_viewer_stream *viewer_stream,
 777                 struct relay_stream *stream)
 778 {
 779         int ret;
 780         uint64_t tracefile_id;
 781
 782         assert(viewer_stream);
 783
 784         tracefile_id = (viewer_stream->tracefile_count_current + 1) %
 785                 viewer_stream->tracefile_count;
 786         /*
 787          * Detect the last tracefile to open.
 788          */
 789         if (viewer_stream->tracefile_count_last != -1ULL &&
 790                         viewer_stream->tracefile_count_last ==
 791                         viewer_stream->tracefile_count_current) {
 792                 ret = 1;
 793                 goto end;
 794         }
 795
 796         if (stream) {
 797                 pthread_mutex_lock(&stream->viewer_stream_rotation_lock);
 798         }
 799         /*
 800          * The writer and the reader are not working in the same
 801          * tracefile, we can read up to EOF, we don't care about the
 802          * total_index_received.
 803          */
 804         if (!stream || (stream->tracefile_count_current != tracefile_id)) {
 805                 viewer_stream->close_write_flag = 1;
 806         } else {
 807                 /*
 808                  * We are opening a file that is still open in write, make
 809                  * sure we limit our reading to the number of indexes
 810                  * received.
 811                  */
 812                 viewer_stream->close_write_flag = 0;
 813                 if (stream) {
 814                         viewer_stream->total_index_received =
 815                                 stream->total_index_received;
 816                 }
 817         }
 818         viewer_stream->tracefile_count_current = tracefile_id;
 819
 820         ret = close(viewer_stream->index_read_fd);
 821         if (ret < 0) {
 822                 PERROR("close index file %d",
 823                                 viewer_stream->index_read_fd);
 824         }
 825         viewer_stream->index_read_fd = -1;
 826         ret = close(viewer_stream->read_fd);
 827         if (ret < 0) {
 828                 PERROR("close tracefile %d",
 829                                 viewer_stream->read_fd);
 830         }
 831         viewer_stream->read_fd = -1;
 832
 833         pthread_mutex_lock(&viewer_stream->overwrite_lock);
 834         viewer_stream->abort_flag = 0;
 835         pthread_mutex_unlock(&viewer_stream->overwrite_lock);
 836
 837         viewer_stream->index_read_fd = -1;
 838         viewer_stream->read_fd = -1;
 839
 840         if (stream) {
 841                 pthread_mutex_unlock(&stream->viewer_stream_rotation_lock);
 842         }
 843         ret = open_index(viewer_stream);
 844         if (ret < 0) {
 845                 goto error;
 846         }
 847
 848         ret = 0;
 849
 850 end:
 851 error:
 852         return ret;
 853 }
 854
 855 /*
 856  * Send the viewer the list of current sessions.
 857  */
 858 static
 859 int viewer_attach_session(struct relay_command *cmd,
 860                 struct lttng_ht *sessions_ht)
 861 {
 862         int ret, send_streams = 0;
 863         uint32_t nb_streams = 0, nb_streams_ready = 0;
 864         struct lttng_viewer_attach_session_request request;
 865         struct lttng_viewer_attach_session_response response;
 866         struct lttng_viewer_stream send_stream;
 867         struct relay_stream *stream;
 868         struct relay_viewer_stream *viewer_stream;
 869         struct lttng_ht_node_ulong *node;
 870         struct lttng_ht_node_u64 *node64;
 871         struct lttng_ht_iter iter;
 872         struct relay_session *session;
 873         int seek_last = 0;
 874
 875         assert(cmd);
 876         assert(sessions_ht);
 877
 878         DBG("Attach session received");
 879
 880         if (cmd->version_check_done == 0) {
 881                 ERR("Trying to attach session before version check");
 882                 ret = -1;
 883                 goto end_no_session;
 884         }
 885
 886         health_code_update();
 887
 888         ret = cmd->sock->ops->recvmsg(cmd->sock, &request, sizeof(request), 0);
 889         if (ret < 0 || ret != sizeof(request)) {
 890                 if (ret == 0) {
 891                         /* Orderly shutdown. Not necessary to print an error. */
 892                         DBG("Socket %d did an orderly shutdown", cmd->sock->fd);
 893                 } else {
 894                         ERR("Relay failed to receive the attach parameters.");
 895                 }
 896                 ret = -1;
 897                 goto error;
 898         }
 899
 900         health_code_update();
 901
 902         rcu_read_lock();
 903         lttng_ht_lookup(sessions_ht,
 904                         (void *)((unsigned long) be64toh(request.session_id)), &iter);
 905         node = lttng_ht_iter_get_node_ulong(&iter);
 906         if (node == NULL) {
 907                 DBG("Relay session %" PRIu64 " not found",
 908                                 be64toh(request.session_id));
 909                 response.status = htobe32(VIEWER_ATTACH_UNK);
 910                 goto send_reply;
 911         }
 912
 913         session = caa_container_of(node, struct relay_session, session_n);
 914         if (cmd->session_id == session->id) {
 915                 /* Same viewer already attached, just send the stream list. */
 916                 send_streams = 1;
 917                 response.status = htobe32(VIEWER_ATTACH_OK);
 918         } else if (session->viewer_attached != 0) {
 919                 DBG("Already a viewer attached");
 920                 response.status = htobe32(VIEWER_ATTACH_ALREADY);
 921                 goto send_reply;
 922         } else if (session->live_timer == 0) {
 923                 DBG("Not live session");
 924                 response.status = htobe32(VIEWER_ATTACH_NOT_LIVE);
 925                 goto send_reply;
 926         } else {
 927                 session->viewer_attached++;
 928                 send_streams = 1;
 929                 response.status = htobe32(VIEWER_ATTACH_OK);
 930                 cmd->session_id = session->id;
 931                 cmd->session = session;
 932         }
 933
 934         switch (be32toh(request.seek)) {
 935         case VIEWER_SEEK_BEGINNING:
 936                 /* Default behaviour. */
 937                 break;
 938         case VIEWER_SEEK_LAST:
 939                 seek_last = 1;
 940                 break;
 941         default:
 942                 ERR("Wrong seek parameter");
 943                 response.status = htobe32(VIEWER_ATTACH_SEEK_ERR);
 944                 send_streams = 0;
 945                 goto send_reply;
 946         }
 947
 948         if (send_streams) {
 949                 /* We should only be there if we have a session to attach to. */
 950                 assert(session);
 951
 952                 /*
 953                  * Fill the viewer_streams_ht to count the number of streams
 954                  * ready to be sent and avoid concurrency issues on the
 955                  * relay_streams_ht and don't rely on a total session stream count.
 956                  */
 957                 cds_lfht_for_each_entry(relay_streams_ht->ht, &iter.iter, node, node) {
 958                         struct relay_viewer_stream *vstream;
 959
 960                         health_code_update();
 961
 962                         node = lttng_ht_iter_get_node_ulong(&iter);
 963                         if (!node) {
 964                                 continue;
 965                         }
 966                         stream = caa_container_of(node, struct relay_stream, stream_n);
 967                         if (stream->session != cmd->session) {
 968                                 continue;
 969                         }
 970                         nb_streams++;
 971
 972                         /*
 973                          * Don't send streams with no ctf_trace, they are not
 974                          * ready to be read.
 975                          */
 976                         if (!stream->ctf_trace || !stream->viewer_ready) {
 977                                 continue;
 978                         }
 979                         nb_streams_ready++;
 980
 981                         vstream = live_find_viewer_stream_by_id(stream->stream_handle);
 982                         if (!vstream) {
 983                                 ret = init_viewer_stream(stream, seek_last);
 984                                 if (ret < 0) {
 985                                         goto end_unlock;
 986                                 }
 987                         }
 988                 }
 989
 990                 /* We must have the same amount of existing stream and ready stream. */
 991                 if (nb_streams != nb_streams_ready) {
 992                         nb_streams = 0;
 993                 }
 994                 response.streams_count = htobe32(nb_streams);
 995         }
 996
 997 send_reply:
 998         health_code_update();
 999         ret = cmd->sock->ops->sendmsg(cmd->sock, &response, sizeof(response), 0);
1000         if (ret < 0) {
1001                 ERR("Relay sending viewer attach response");
1002                 goto end_unlock;
1003         }
1004         health_code_update();
1005
1006         /*
1007          * Unknown or empty session, just return gracefully, the viewer knows what
1008          * is happening.
1009          */
1010         if (!send_streams || !nb_streams) {
1011                 ret = 0;
1012                 goto end_unlock;
1013         }
1014
1015         /* We should only be there if we have a session to attach to. */
1016         assert(session);
1017         cds_lfht_for_each_entry(viewer_streams_ht->ht, &iter.iter, node, node) {
1018                 health_code_update();
1019
1020                 node64 = lttng_ht_iter_get_node_u64(&iter);
1021                 if (!node64) {
1022                         continue;
1023                 }
1024                 viewer_stream = caa_container_of(node64, struct relay_viewer_stream,
1025                                 stream_n);
1026                 if (viewer_stream->session_id != cmd->session->id) {
1027                         continue;
1028                 }
1029
1030                 send_stream.id = htobe64(viewer_stream->stream_handle);
1031                 send_stream.ctf_trace_id = htobe64(viewer_stream->ctf_trace->id);
1032                 send_stream.metadata_flag = htobe32(viewer_stream->metadata_flag);
1033                 strncpy(send_stream.path_name, viewer_stream->path_name,
1034                                 sizeof(send_stream.path_name));
1035                 strncpy(send_stream.channel_name, viewer_stream->channel_name,
1036                                 sizeof(send_stream.channel_name));
1037
1038                 ret = cmd->sock->ops->sendmsg(cmd->sock, &send_stream,
1039                                 sizeof(send_stream), 0);
1040                 if (ret < 0) {
1041                         ERR("Relay sending stream %" PRIu64, viewer_stream->stream_handle);
1042                         goto end_unlock;
1043                 }
1044                 DBG("Sent stream %" PRIu64 " to viewer", viewer_stream->stream_handle);
1045         }
1046         ret = 0;
1047
1048 end_unlock:
1049         rcu_read_unlock();
1050 end_no_session:
1051 error:
1052         return ret;
1053 }
1054
1055 /*
1056  * Get viewer stream from stream id.
1057  *
1058  * RCU read side lock MUST be acquired.
1059  */
1060 struct relay_viewer_stream *live_find_viewer_stream_by_id(uint64_t stream_id)
1061 {
1062         struct lttng_ht_node_u64 *node;
1063         struct lttng_ht_iter iter;
1064         struct relay_viewer_stream *stream = NULL;
1065
1066         lttng_ht_lookup(viewer_streams_ht, &stream_id, &iter);
1067         node = lttng_ht_iter_get_node_u64(&iter);
1068         if (node == NULL) {
1069                 DBG("Relay viewer stream %" PRIu64 " not found", stream_id);
1070                 goto end;
1071         }
1072         stream = caa_container_of(node, struct relay_viewer_stream, stream_n);
1073
1074 end:
1075         return stream;
1076 }
1077
1078 static
1079 void deferred_free_viewer_stream(struct rcu_head *head)
1080 {
1081         struct relay_viewer_stream *stream =
1082                 caa_container_of(head, struct relay_viewer_stream, rcu_node);
1083
1084         free(stream->path_name);
1085         free(stream->channel_name);
1086         free(stream);
1087 }
1088
1089 static
1090 void delete_viewer_stream(struct relay_viewer_stream *vstream)
1091 {
1092         int delret;
1093         struct lttng_ht_iter iter;
1094
1095         iter.iter.node = &vstream->stream_n.node;
1096         delret = lttng_ht_del(viewer_streams_ht, &iter);
1097         assert(!delret);
1098 }
1099
1100 static
1101 void destroy_viewer_stream(struct relay_viewer_stream *vstream)
1102 {
1103         unsigned long ret_ref;
1104         int ret;
1105
1106         assert(vstream);
1107         ret_ref = uatomic_add_return(&vstream->ctf_trace->refcount, -1);
1108         assert(ret_ref >= 0);
1109
1110         if (vstream->read_fd >= 0) {
1111                 ret = close(vstream->read_fd);
1112                 if (ret < 0) {
1113                         PERROR("close read_fd");
1114                 }
1115         }
1116         if (vstream->index_read_fd >= 0) {
1117                 ret = close(vstream->index_read_fd);
1118                 if (ret < 0) {
1119                         PERROR("close index_read_fd");
1120                 }
1121         }
1122
1123         /*
1124          * If the only stream left in the HT is the metadata stream,
1125          * we need to remove it because we won't detect a EOF for this
1126          * stream.
1127          */
1128         if (ret_ref == 1 && vstream->ctf_trace->viewer_metadata_stream) {
1129                 delete_viewer_stream(vstream->ctf_trace->viewer_metadata_stream);
1130                 destroy_viewer_stream(vstream->ctf_trace->viewer_metadata_stream);
1131                 vstream->ctf_trace->metadata_stream = NULL;
1132                 DBG("Freeing ctf_trace %" PRIu64, vstream->ctf_trace->id);
1133                 /*
1134                  * The streaming-side is already closed and we can't receive a new
1135                  * stream concurrently at this point (since the session is being
1136                  * destroyed), so when we detect the refcount equals 0, we are the
1137                  * only owners of the ctf_trace and we can free it ourself.
1138                  */
1139                 free(vstream->ctf_trace);
1140         }
1141
1142         call_rcu(&vstream->rcu_node, deferred_free_viewer_stream);
1143 }
1144
1145 /*
1146  * Send the next index for a stream.
1147  *
1148  * Return 0 on success or else a negative value.
1149  */
1150 static
1151 int viewer_get_next_index(struct relay_command *cmd,
1152                 struct lttng_ht *sessions_ht)
1153 {
1154         int ret;
1155         struct lttng_viewer_get_next_index request_index;
1156         struct lttng_viewer_index viewer_index;
1157         struct ctf_packet_index packet_index;
1158         struct relay_viewer_stream *vstream;
1159         struct relay_stream *rstream;
1160
1161         assert(cmd);
1162         assert(sessions_ht);
1163
1164         DBG("Viewer get next index");
1165
1166         if (cmd->version_check_done == 0) {
1167                 ERR("Trying to request index before version check");
1168                 ret = -1;
1169                 goto end_no_session;
1170         }
1171
1172         health_code_update();
1173         ret = cmd->sock->ops->recvmsg(cmd->sock, &request_index,
1174                         sizeof(request_index), 0);
1175         if (ret < 0 || ret != sizeof(request_index)) {
1176                 ret = -1;
1177                 ERR("Relay didn't receive the whole packet");
1178                 goto end;
1179         }
1180         health_code_update();
1181
1182         rcu_read_lock();
1183         vstream = live_find_viewer_stream_by_id(be64toh(request_index.stream_id));
1184         if (!vstream) {
1185                 ret = -1;
1186                 goto end_unlock;
1187         }
1188
1189         memset(&viewer_index, 0, sizeof(viewer_index));
1190
1191         /*
1192          * The viewer should not ask for index on metadata stream.
1193          */
1194         if (vstream->metadata_flag) {
1195                 viewer_index.status = htobe32(VIEWER_INDEX_HUP);
1196                 goto send_reply;
1197         }
1198
1199         /* First time, we open the index file */
1200         if (vstream->index_read_fd < 0) {
1201                 ret = open_index(vstream);
1202                 if (ret == -ENOENT) {
1203                         /*
1204                          * The index is created only when the first data packet arrives, it
1205                          * might not be ready at the beginning of the session
1206                          */
1207                         viewer_index.status = htobe32(VIEWER_INDEX_RETRY);
1208                         goto send_reply;
1209                 } else if (ret < 0) {
1210                         viewer_index.status = htobe32(VIEWER_INDEX_ERR);
1211                         goto send_reply;
1212                 }
1213         }
1214
1215         rstream = relay_stream_find_by_id(vstream->stream_handle);
1216         if (rstream) {
1217                 if (vstream->abort_flag) {
1218                         /* Rotate on abort (overwrite). */
1219                         DBG("Viewer rotate because of overwrite");
1220                         ret = rotate_viewer_stream(vstream, rstream);
1221                         if (ret < 0) {
1222                                 goto end_unlock;
1223                         } else if (ret == 1) {
1224                                 viewer_index.status = htobe32(VIEWER_INDEX_HUP);
1225                                 delete_viewer_stream(vstream);
1226                                 destroy_viewer_stream(vstream);
1227                                 goto send_reply;
1228                         }
1229                 }
1230                 pthread_mutex_lock(&rstream->viewer_stream_rotation_lock);
1231                 if (rstream->tracefile_count_current == vstream->tracefile_count_current) {
1232                         if (rstream->beacon_ts_end != -1ULL &&
1233                                 vstream->last_sent_index == rstream->total_index_received) {
1234                                 viewer_index.status = htobe32(VIEWER_INDEX_INACTIVE);
1235                                 viewer_index.timestamp_end = htobe64(rstream->beacon_ts_end);
1236                                 pthread_mutex_unlock(&rstream->viewer_stream_rotation_lock);
1237                                 goto send_reply;
1238                         /*
1239                          * Reader and writer are working in the same tracefile, so we care
1240                          * about the number of index received and sent. Otherwise, we read
1241                          * up to EOF.
1242                          */
1243                         } else if (rstream->total_index_received <= vstream->last_sent_index
1244                                         && !vstream->close_write_flag) {
1245                                 pthread_mutex_unlock(&rstream->viewer_stream_rotation_lock);
1246                                 /* No new index to send, retry later. */
1247                                 viewer_index.status = htobe32(VIEWER_INDEX_RETRY);
1248                                 goto send_reply;
1249                         }
1250                 }
1251                 pthread_mutex_unlock(&rstream->viewer_stream_rotation_lock);
1252         } else if (!rstream && vstream->close_write_flag &&
1253                         vstream->total_index_received == vstream->last_sent_index) {
1254                 /* Last index sent and current tracefile closed in write */
1255                 viewer_index.status = htobe32(VIEWER_INDEX_HUP);
1256                 delete_viewer_stream(vstream);
1257                 destroy_viewer_stream(vstream);
1258                 goto send_reply;
1259         } else {
1260                 vstream->close_write_flag = 1;
1261         }
1262
1263         if (!vstream->ctf_trace->metadata_received ||
1264                         vstream->ctf_trace->metadata_received >
1265                         vstream->ctf_trace->metadata_sent) {
1266                 viewer_index.flags |= LTTNG_VIEWER_FLAG_NEW_METADATA;
1267         }
1268
1269         pthread_mutex_lock(&vstream->overwrite_lock);
1270         if (vstream->abort_flag) {
1271                 /*
1272                  * The file is being overwritten by the writer, we cannot
1273                  * use it.
1274                  */
1275                 viewer_index.status = htobe32(VIEWER_INDEX_RETRY);
1276                 pthread_mutex_unlock(&vstream->overwrite_lock);
1277                 ret = rotate_viewer_stream(vstream, rstream);
1278                 if (ret < 0) {
1279                         goto end_unlock;
1280                 } else if (ret == 1) {
1281                         viewer_index.status = htobe32(VIEWER_INDEX_HUP);
1282                         delete_viewer_stream(vstream);
1283                         destroy_viewer_stream(vstream);
1284                         goto send_reply;
1285                 }
1286                 goto send_reply;
1287         }
1288         ret = lttng_read(vstream->index_read_fd, &packet_index,
1289                         sizeof(packet_index));
1290         pthread_mutex_unlock(&vstream->overwrite_lock);
1291         if (ret < sizeof(packet_index)) {
1292                 /*
1293                  * The tracefile is closed in write, so we read up to EOF.
1294                  */
1295                 if (vstream->close_write_flag == 1) {
1296                         viewer_index.status = htobe32(VIEWER_INDEX_RETRY);
1297                         /* Rotate on normal EOF */
1298                         ret = rotate_viewer_stream(vstream, rstream);
1299                         if (ret < 0) {
1300                                 goto end_unlock;
1301                         } else if (ret == 1) {
1302                                 viewer_index.status = htobe32(VIEWER_INDEX_HUP);
1303                                 delete_viewer_stream(vstream);
1304                                 destroy_viewer_stream(vstream);
1305                                 goto send_reply;
1306                         }
1307                 } else {
1308                         PERROR("Relay reading index file %d",
1309                                         vstream->index_read_fd);
1310                         viewer_index.status = htobe32(VIEWER_INDEX_ERR);
1311                 }
1312                 goto send_reply;
1313         } else {
1314                 viewer_index.status = htobe32(VIEWER_INDEX_OK);
1315                 vstream->last_sent_index++;
1316         }
1317
1318         /*
1319          * Indexes are stored in big endian, no need to switch before sending.
1320          */
1321         viewer_index.offset = packet_index.offset;
1322         viewer_index.packet_size = packet_index.packet_size;
1323         viewer_index.content_size = packet_index.content_size;
1324         viewer_index.timestamp_begin = packet_index.timestamp_begin;
1325         viewer_index.timestamp_end = packet_index.timestamp_end;
1326         viewer_index.events_discarded = packet_index.events_discarded;
1327         viewer_index.stream_id = packet_index.stream_id;
1328
1329 send_reply:
1330         viewer_index.flags = htobe32(viewer_index.flags);
1331         health_code_update();
1332         ret = cmd->sock->ops->sendmsg(cmd->sock, &viewer_index,
1333                         sizeof(viewer_index), 0);
1334         if (ret < 0) {
1335                 ERR("Relay index to viewer");
1336                 goto end_unlock;
1337         }
1338         health_code_update();
1339
1340         DBG("Index %" PRIu64 "for stream %" PRIu64 "sent",
1341                         vstream->last_sent_index, vstream->stream_handle);
1342
1343 end_unlock:
1344         rcu_read_unlock();
1345
1346 end_no_session:
1347 end:
1348         return ret;
1349 }
1350
1351 /*
1352  * Send the next index for a stream
1353  *
1354  * Return 0 on success or else a negative value.
1355  */
1356 static
1357 int viewer_get_packet(struct relay_command *cmd)
1358 {
1359         int ret, send_data = 0;
1360         char *data = NULL;
1361         uint32_t len = 0;
1362         ssize_t read_len;
1363         struct lttng_viewer_get_packet get_packet_info;
1364         struct lttng_viewer_trace_packet reply;
1365         struct relay_viewer_stream *stream;
1366
1367         assert(cmd);
1368
1369         DBG2("Relay get data packet");
1370
1371         if (cmd->version_check_done == 0) {
1372                 ERR("Trying to get packet before version check");
1373                 ret = -1;
1374                 goto end;
1375         }
1376
1377         health_code_update();
1378         ret = cmd->sock->ops->recvmsg(cmd->sock, &get_packet_info,
1379                         sizeof(get_packet_info), 0);
1380         if (ret < 0 || ret != sizeof(get_packet_info)) {
1381                 ret = -1;
1382                 ERR("Relay didn't receive the whole packet");
1383                 goto end;
1384         }
1385         health_code_update();
1386
1387         /* From this point on, the error label can be reached. */
1388         memset(&reply, 0, sizeof(reply));
1389
1390         rcu_read_lock();
1391         stream = live_find_viewer_stream_by_id(be64toh(get_packet_info.stream_id));
1392         if (!stream) {
1393                 goto error;
1394         }
1395         assert(stream->ctf_trace);
1396
1397         /*
1398          * First time we read this stream, we need open the tracefile, we should
1399          * only arrive here if an index has already been sent to the viewer, so the
1400          * tracefile must exist, if it does not it is a fatal error.
1401          */
1402         if (stream->read_fd < 0) {
1403                 char fullpath[PATH_MAX];
1404
1405                 if (stream->tracefile_count > 0) {
1406                         ret = snprintf(fullpath, PATH_MAX, "%s/%s_%" PRIu64, stream->path_name,
1407                                         stream->channel_name,
1408                                         stream->tracefile_count_current);
1409                 } else {
1410                         ret = snprintf(fullpath, PATH_MAX, "%s/%s", stream->path_name,
1411                                         stream->channel_name);
1412                 }
1413                 if (ret < 0) {
1414                         goto error;
1415                 }
1416                 ret = open(fullpath, O_RDONLY);
1417                 if (ret < 0) {
1418                         PERROR("Relay opening trace file");
1419                         goto error;
1420                 }
1421                 stream->read_fd = ret;
1422         }
1423
1424         if (!stream->ctf_trace->metadata_received ||
1425                         stream->ctf_trace->metadata_received >
1426                         stream->ctf_trace->metadata_sent) {
1427                 reply.status = htobe32(VIEWER_GET_PACKET_ERR);
1428                 reply.flags |= LTTNG_VIEWER_FLAG_NEW_METADATA;
1429                 goto send_reply;
1430         }
1431
1432         len = be32toh(get_packet_info.len);
1433         data = zmalloc(len);
1434         if (!data) {
1435                 PERROR("relay data zmalloc");
1436                 goto error;
1437         }
1438
1439         ret = lseek(stream->read_fd, be64toh(get_packet_info.offset), SEEK_SET);
1440         if (ret < 0) {
1441                 /*
1442                  * If the read fd was closed by the streaming side, the
1443                  * abort_flag will be set to 1, otherwise it is an error.
1444                  */
1445                 if (stream->abort_flag == 0) {
1446                         PERROR("lseek");
1447                         goto error;
1448                 }
1449                 reply.status = htobe32(VIEWER_GET_PACKET_EOF);
1450                 goto send_reply;
1451         }
1452         read_len = lttng_read(stream->read_fd, data, len);
1453         if (read_len < len) {
1454                 /*
1455                  * If the read fd was closed by the streaming side, the
1456                  * abort_flag will be set to 1, otherwise it is an error.
1457                  */
1458                 if (stream->abort_flag == 0) {
1459                         PERROR("Relay reading trace file, fd: %d, offset: %" PRIu64,
1460                                         stream->read_fd,
1461                                         be64toh(get_packet_info.offset));
1462                         goto error;
1463                 } else {
1464                         reply.status = htobe32(VIEWER_GET_PACKET_EOF);
1465                         goto send_reply;
1466                 }
1467         }
1468         reply.status = htobe32(VIEWER_GET_PACKET_OK);
1469         reply.len = htobe32(len);
1470         send_data = 1;
1471         goto send_reply;
1472
1473 error:
1474         reply.status = htobe32(VIEWER_GET_PACKET_ERR);
1475
1476 send_reply:
1477         reply.flags = htobe32(reply.flags);
1478
1479         health_code_update();
1480         ret = cmd->sock->ops->sendmsg(cmd->sock, &reply, sizeof(reply), 0);
1481         if (ret < 0) {
1482                 ERR("Relay data header to viewer");
1483                 goto end_unlock;
1484         }
1485         health_code_update();
1486
1487         if (send_data) {
1488                 health_code_update();
1489                 ret = cmd->sock->ops->sendmsg(cmd->sock, data, len, 0);
1490                 if (ret < 0) {
1491                         ERR("Relay send data to viewer");
1492                         goto end_unlock;
1493                 }
1494                 health_code_update();
1495         }
1496
1497         DBG("Sent %u bytes for stream %" PRIu64, len,
1498                         be64toh(get_packet_info.stream_id));
1499
1500 end_unlock:
1501         free(data);
1502         rcu_read_unlock();
1503
1504 end:
1505         return ret;
1506 }
1507
1508 /*
1509  * Send the session's metadata
1510  *
1511  * Return 0 on success else a negative value.
1512  */
1513 static
1514 int viewer_get_metadata(struct relay_command *cmd)
1515 {
1516         int ret = 0;
1517         ssize_t read_len;
1518         uint64_t len = 0;
1519         char *data = NULL;
1520         struct lttng_viewer_get_metadata request;
1521         struct lttng_viewer_metadata_packet reply;
1522         struct relay_viewer_stream *stream;
1523
1524         assert(cmd);
1525
1526         DBG("Relay get metadata");
1527
1528         if (cmd->version_check_done == 0) {
1529                 ERR("Trying to get metadata before version check");
1530                 ret = -1;
1531                 goto end;
1532         }
1533
1534         health_code_update();
1535         ret = cmd->sock->ops->recvmsg(cmd->sock, &request,
1536                         sizeof(request), 0);
1537         if (ret < 0 || ret != sizeof(request)) {
1538                 ret = -1;
1539                 ERR("Relay didn't receive the whole packet");
1540                 goto end;
1541         }
1542         health_code_update();
1543
1544         rcu_read_lock();
1545         stream = live_find_viewer_stream_by_id(be64toh(request.stream_id));
1546         if (!stream || !stream->metadata_flag) {
1547                 ERR("Invalid metadata stream");
1548                 goto error;
1549         }
1550         assert(stream->ctf_trace);
1551         assert(stream->ctf_trace->metadata_sent <=
1552                         stream->ctf_trace->metadata_received);
1553
1554         len = stream->ctf_trace->metadata_received -
1555                 stream->ctf_trace->metadata_sent;
1556         if (len == 0) {
1557                 reply.status = htobe32(VIEWER_NO_NEW_METADATA);
1558                 goto send_reply;
1559         }
1560
1561         /* first time, we open the metadata file */
1562         if (stream->read_fd < 0) {
1563                 char fullpath[PATH_MAX];
1564
1565                 ret = snprintf(fullpath, PATH_MAX, "%s/%s", stream->path_name,
1566                                 stream->channel_name);
1567                 if (ret < 0) {
1568                         goto error;
1569                 }
1570                 ret = open(fullpath, O_RDONLY);
1571                 if (ret < 0) {
1572                         PERROR("Relay opening metadata file");
1573                         goto error;
1574                 }
1575                 stream->read_fd = ret;
1576         }
1577
1578         reply.len = htobe64(len);
1579         data = zmalloc(len);
1580         if (!data) {
1581                 PERROR("viewer metadata zmalloc");
1582                 goto error;
1583         }
1584
1585         read_len = lttng_read(stream->read_fd, data, len);
1586         if (read_len < len) {
1587                 PERROR("Relay reading metadata file");
1588                 goto error;
1589         }
1590         stream->ctf_trace->metadata_sent += read_len;
1591         reply.status = htobe32(VIEWER_METADATA_OK);
1592         goto send_reply;
1593
1594 error:
1595         reply.status = htobe32(VIEWER_METADATA_ERR);
1596
1597 send_reply:
1598         health_code_update();
1599         ret = cmd->sock->ops->sendmsg(cmd->sock, &reply, sizeof(reply), 0);
1600         if (ret < 0) {
1601                 ERR("Relay data header to viewer");
1602                 goto end_unlock;
1603         }
1604         health_code_update();
1605
1606         if (len > 0) {
1607                 ret = cmd->sock->ops->sendmsg(cmd->sock, data, len, 0);
1608                 if (ret < 0) {
1609                         ERR("Relay send data to viewer");
1610                         goto end_unlock;
1611                 }
1612         }
1613
1614         DBG("Sent %" PRIu64 " bytes of metadata for stream %" PRIu64, len,
1615                         be64toh(request.stream_id));
1616
1617         DBG("Metadata sent");
1618
1619 end_unlock:
1620         free(data);
1621         rcu_read_unlock();
1622 end:
1623         return ret;
1624 }
1625
1626 /*
1627  * live_relay_unknown_command: send -1 if received unknown command
1628  */
1629 static
1630 void live_relay_unknown_command(struct relay_command *cmd)
1631 {
1632         struct lttcomm_relayd_generic_reply reply;
1633         int ret;
1634
1635         reply.ret_code = htobe32(LTTNG_ERR_UNK);
1636         ret = cmd->sock->ops->sendmsg(cmd->sock, &reply,
1637                         sizeof(struct lttcomm_relayd_generic_reply), 0);
1638         if (ret < 0) {
1639                 ERR("Relay sending unknown command");
1640         }
1641 }
1642
1643 /*
1644  * Process the commands received on the control socket
1645  */
1646 static
1647 int process_control(struct lttng_viewer_cmd *recv_hdr,
1648                 struct relay_command *cmd, struct lttng_ht *sessions_ht)
1649 {
1650         int ret = 0;
1651
1652         switch (be32toh(recv_hdr->cmd)) {
1653         case VIEWER_CONNECT:
1654                 ret = viewer_connect(cmd);
1655                 break;
1656         case VIEWER_LIST_SESSIONS:
1657                 ret = viewer_list_sessions(cmd, sessions_ht);
1658                 break;
1659         case VIEWER_ATTACH_SESSION:
1660                 ret = viewer_attach_session(cmd, sessions_ht);
1661                 break;
1662         case VIEWER_GET_NEXT_INDEX:
1663                 ret = viewer_get_next_index(cmd, sessions_ht);
1664                 break;
1665         case VIEWER_GET_PACKET:
1666                 ret = viewer_get_packet(cmd);
1667                 break;
1668         case VIEWER_GET_METADATA:
1669                 ret = viewer_get_metadata(cmd);
1670                 break;
1671         default:
1672                 ERR("Received unknown viewer command (%u)", be32toh(recv_hdr->cmd));
1673                 live_relay_unknown_command(cmd);
1674                 ret = -1;
1675                 goto end;
1676         }
1677
1678 end:
1679         return ret;
1680 }
1681
1682 static
1683 void cleanup_poll_connection(struct lttng_poll_event *events, int pollfd)
1684 {
1685         int ret;
1686
1687         assert(events);
1688
1689         lttng_poll_del(events, pollfd);
1690
1691         ret = close(pollfd);
1692         if (ret < 0) {
1693                 ERR("Closing pollfd %d", pollfd);
1694         }
1695 }
1696
1697 /*
1698  * Create and add connection to the given hash table.
1699  *
1700  * Return poll add value or else -1 on error.
1701  */
1702 static
1703 int add_connection(int fd, struct lttng_poll_event *events,
1704                 struct lttng_ht *relay_connections_ht)
1705 {
1706         int ret;
1707         struct relay_command *relay_connection;
1708
1709         assert(events);
1710         assert(relay_connections_ht);
1711
1712         relay_connection = zmalloc(sizeof(struct relay_command));
1713         if (relay_connection == NULL) {
1714                 PERROR("Relay command zmalloc");
1715                 goto error;
1716         }
1717
1718         ret = lttng_read(fd, relay_connection, sizeof(*relay_connection));
1719         if (ret < sizeof(*relay_connection)) {
1720                 PERROR("read relay cmd pipe");
1721                 goto error_read;
1722         }
1723
1724         lttng_ht_node_init_ulong(&relay_connection->sock_n,
1725                         (unsigned long) relay_connection->sock->fd);
1726         rcu_read_lock();
1727         lttng_ht_add_unique_ulong(relay_connections_ht,
1728                         &relay_connection->sock_n);
1729         rcu_read_unlock();
1730
1731         return lttng_poll_add(events, relay_connection->sock->fd,
1732                         LPOLLIN | LPOLLRDHUP);
1733
1734 error_read:
1735         free(relay_connection);
1736 error:
1737         return -1;
1738 }
1739
1740 static
1741 void deferred_free_connection(struct rcu_head *head)
1742 {
1743         struct relay_command *relay_connection =
1744                 caa_container_of(head, struct relay_command, rcu_node);
1745
1746         if (relay_connection->session &&
1747                         relay_connection->session->viewer_attached > 0) {
1748                 relay_connection->session->viewer_attached--;
1749         }
1750         lttcomm_destroy_sock(relay_connection->sock);
1751         free(relay_connection);
1752 }
1753
1754 /*
1755  * Delete all streams for a specific session ID.
1756  */
1757 static
1758 void viewer_del_streams(uint64_t session_id)
1759 {
1760         struct relay_viewer_stream *stream;
1761         struct lttng_ht_iter iter;
1762
1763         rcu_read_lock();
1764         cds_lfht_for_each_entry(viewer_streams_ht->ht, &iter.iter, stream,
1765                         stream_n.node) {
1766                 health_code_update();
1767
1768                 if (stream->session_id != session_id) {
1769                         continue;
1770                 }
1771
1772                 delete_viewer_stream(stream);
1773                 assert(stream->ctf_trace);
1774
1775                 if (stream->metadata_flag) {
1776                         /*
1777                          * The metadata viewer stream is destroyed once the refcount on the
1778                          * ctf trace goes to 0 in the destroy stream function thus there is
1779                          * no explicit call to that function here.
1780                          */
1781                         stream->ctf_trace->metadata_sent = 0;
1782                         stream->ctf_trace->viewer_metadata_stream = NULL;
1783                 } else {
1784                         destroy_viewer_stream(stream);
1785                 }
1786         }
1787         rcu_read_unlock();
1788 }
1789
1790 /*
1791  * Delete and free a connection.
1792  *
1793  * RCU read side lock MUST be acquired.
1794  */
1795 static
1796 void del_connection(struct lttng_ht *relay_connections_ht,
1797                 struct lttng_ht_iter *iter, struct relay_command *relay_connection)
1798 {
1799         int ret;
1800
1801         assert(relay_connections_ht);
1802         assert(iter);
1803         assert(relay_connection);
1804
1805         DBG("Cleaning connection of session ID %" PRIu64,
1806                         relay_connection->session_id);
1807
1808         ret = lttng_ht_del(relay_connections_ht, iter);
1809         assert(!ret);
1810
1811         viewer_del_streams(relay_connection->session_id);
1812
1813         call_rcu(&relay_connection->rcu_node, deferred_free_connection);
1814 }
1815
1816 /*
1817  * This thread does the actual work
1818  */
1819 static
1820 void *thread_worker(void *data)
1821 {
1822         int ret, err = -1;
1823         uint32_t nb_fd;
1824         struct relay_command *relay_connection;
1825         struct lttng_poll_event events;
1826         struct lttng_ht *relay_connections_ht;
1827         struct lttng_ht_node_ulong *node;
1828         struct lttng_ht_iter iter;
1829         struct lttng_viewer_cmd recv_hdr;
1830         struct relay_local_data *relay_ctx = (struct relay_local_data *) data;
1831         struct lttng_ht *sessions_ht = relay_ctx->sessions_ht;
1832
1833         DBG("[thread] Live viewer relay worker started");
1834
1835         rcu_register_thread();
1836
1837         health_register(health_relayd, HEALTH_RELAYD_TYPE_LIVE_WORKER);
1838
1839         if (testpoint(relayd_thread_live_worker)) {
1840                 goto error_testpoint;
1841         }
1842
1843         /* table of connections indexed on socket */
1844         relay_connections_ht = lttng_ht_new(0, LTTNG_HT_TYPE_ULONG);
1845         if (!relay_connections_ht) {
1846                 goto relay_connections_ht_error;
1847         }
1848
1849         ret = create_thread_poll_set(&events, 2);
1850         if (ret < 0) {
1851                 goto error_poll_create;
1852         }
1853
1854         ret = lttng_poll_add(&events, live_relay_cmd_pipe[0], LPOLLIN | LPOLLRDHUP);
1855         if (ret < 0) {
1856                 goto error;
1857         }
1858
1859 restart:
1860         while (1) {
1861                 int i;
1862
1863                 health_code_update();
1864
1865                 /* Infinite blocking call, waiting for transmission */
1866                 DBG3("Relayd live viewer worker thread polling...");
1867                 health_poll_entry();
1868                 ret = lttng_poll_wait(&events, -1);
1869                 health_poll_exit();
1870                 if (ret < 0) {
1871                         /*
1872                          * Restart interrupted system call.
1873                          */
1874                         if (errno == EINTR) {
1875                                 goto restart;
1876                         }
1877                         goto error;
1878                 }
1879
1880                 nb_fd = ret;
1881
1882                 /*
1883                  * Process control. The control connection is prioritised so we don't
1884                  * starve it with high throughput tracing data on the data
1885                  * connection.
1886                  */
1887                 for (i = 0; i < nb_fd; i++) {
1888                         /* Fetch once the poll data */
1889                         uint32_t revents = LTTNG_POLL_GETEV(&events, i);
1890                         int pollfd = LTTNG_POLL_GETFD(&events, i);
1891
1892                         health_code_update();
1893
1894                         /* Thread quit pipe has been closed. Killing thread. */
1895                         ret = check_thread_quit_pipe(pollfd, revents);
1896                         if (ret) {
1897                                 err = 0;
1898                                 goto exit;
1899                         }
1900
1901                         /* Inspect the relay cmd pipe for new connection */
1902                         if (pollfd == live_relay_cmd_pipe[0]) {
1903                                 if (revents & (LPOLLERR | LPOLLHUP | LPOLLRDHUP)) {
1904                                         ERR("Relay live pipe error");
1905                                         goto error;
1906                                 } else if (revents & LPOLLIN) {
1907                                         DBG("Relay live viewer command received");
1908                                         ret = add_connection(live_relay_cmd_pipe[0],
1909                                                         &events, relay_connections_ht);
1910                                         if (ret < 0) {
1911                                                 goto error;
1912                                         }
1913                                 }
1914                         } else if (revents) {
1915                                 rcu_read_lock();
1916                                 lttng_ht_lookup(relay_connections_ht,
1917                                                 (void *)((unsigned long) pollfd), &iter);
1918                                 node = lttng_ht_iter_get_node_ulong(&iter);
1919                                 if (node == NULL) {
1920                                         DBG2("Relay viewer sock %d not found", pollfd);
1921                                         rcu_read_unlock();
1922                                         goto error;
1923                                 }
1924                                 relay_connection = caa_container_of(node, struct relay_command,
1925                                                 sock_n);
1926
1927                                 if (revents & (LPOLLERR)) {
1928                                         cleanup_poll_connection(&events, pollfd);
1929                                         del_connection(relay_connections_ht, &iter,
1930                                                         relay_connection);
1931                                 } else if (revents & (LPOLLHUP | LPOLLRDHUP)) {
1932                                         DBG("Viewer socket %d hung up", pollfd);
1933                                         cleanup_poll_connection(&events, pollfd);
1934                                         del_connection(relay_connections_ht, &iter,
1935                                                         relay_connection);
1936                                 } else if (revents & LPOLLIN) {
1937                                         ret = relay_connection->sock->ops->recvmsg(
1938                                                         relay_connection->sock, &recv_hdr,
1939                                                         sizeof(struct lttng_viewer_cmd),
1940                                                         0);
1941                                         /* connection closed */
1942                                         if (ret <= 0) {
1943                                                 cleanup_poll_connection(&events, pollfd);
1944                                                 del_connection(relay_connections_ht, &iter,
1945                                                                 relay_connection);
1946                                                 DBG("Viewer control connection closed with %d",
1947                                                                 pollfd);
1948                                         } else {
1949                                                 if (relay_connection->session) {
1950                                                         DBG2("Relay viewer worker receiving data for "
1951                                                                         "session: %" PRIu64,
1952                                                                         relay_connection->session->id);
1953                                                 }
1954                                                 ret = process_control(&recv_hdr, relay_connection,
1955                                                                 sessions_ht);
1956                                                 if (ret < 0) {
1957                                                         /* Clear the session on error. */
1958                                                         cleanup_poll_connection(&events, pollfd);
1959                                                         del_connection(relay_connections_ht, &iter,
1960                                                                         relay_connection);
1961                                                         DBG("Viewer connection closed with %d", pollfd);
1962                                                 }
1963                                         }
1964                                 }
1965                                 rcu_read_unlock();
1966                         }
1967                 }
1968         }
1969
1970 exit:
1971 error:
1972         lttng_poll_clean(&events);
1973
1974         /* empty the hash table and free the memory */
1975         rcu_read_lock();
1976         cds_lfht_for_each_entry(relay_connections_ht->ht, &iter.iter, node, node) {
1977                 health_code_update();
1978
1979                 node = lttng_ht_iter_get_node_ulong(&iter);
1980                 if (!node) {
1981                         continue;
1982                 }
1983
1984                 relay_connection = caa_container_of(node, struct relay_command,
1985                                 sock_n);
1986                 del_connection(relay_connections_ht, &iter, relay_connection);
1987         }
1988         rcu_read_unlock();
1989 error_poll_create:
1990         lttng_ht_destroy(relay_connections_ht);
1991 relay_connections_ht_error:
1992         /* Close relay cmd pipes */
1993         utils_close_pipe(live_relay_cmd_pipe);
1994         if (err) {
1995                 DBG("Viewer worker thread exited with error");
1996         }
1997         DBG("Viewer worker thread cleanup complete");
1998 error_testpoint:
1999         if (err) {
2000                 health_error();
2001                 ERR("Health error occurred in %s", __func__);
2002         }
2003         health_unregister(health_relayd);
2004         stop_threads();
2005         rcu_unregister_thread();
2006         return NULL;
2007 }
2008
2009 /*
2010  * Create the relay command pipe to wake thread_manage_apps.
2011  * Closed in cleanup().
2012  */
2013 static int create_relay_cmd_pipe(void)
2014 {
2015         int ret;
2016
2017         ret = utils_create_pipe_cloexec(live_relay_cmd_pipe);
2018
2019         return ret;
2020 }
2021
2022 void live_stop_threads(void)
2023 {
2024         int ret;
2025         void *status;
2026
2027         stop_threads();
2028
2029         ret = pthread_join(live_listener_thread, &status);
2030         if (ret != 0) {
2031                 PERROR("pthread_join live listener");
2032                 goto error;     /* join error, exit without cleanup */
2033         }
2034
2035         ret = pthread_join(live_worker_thread, &status);
2036         if (ret != 0) {
2037                 PERROR("pthread_join live worker");
2038                 goto error;     /* join error, exit without cleanup */
2039         }
2040
2041         ret = pthread_join(live_dispatcher_thread, &status);
2042         if (ret != 0) {
2043                 PERROR("pthread_join live dispatcher");
2044                 goto error;     /* join error, exit without cleanup */
2045         }
2046
2047         cleanup();
2048
2049 error:
2050         return;
2051 }
2052
2053 /*
2054  * main
2055  */
2056 int live_start_threads(struct lttng_uri *uri,
2057                 struct relay_local_data *relay_ctx)
2058 {
2059         int ret = 0;
2060         void *status;
2061         int is_root;
2062
2063         assert(uri);
2064         live_uri = uri;
2065
2066         /* Check if daemon is UID = 0 */
2067         is_root = !getuid();
2068
2069         if (!is_root) {
2070                 if (live_uri->port < 1024) {
2071                         ERR("Need to be root to use ports < 1024");
2072                         ret = -1;
2073                         goto exit;
2074                 }
2075         }
2076
2077         /* Setup the thread apps communication pipe. */
2078         if ((ret = create_relay_cmd_pipe()) < 0) {
2079                 goto exit;
2080         }
2081
2082         /* Init relay command queue. */
2083         cds_wfq_init(&viewer_cmd_queue.queue);
2084
2085         /* Set up max poll set size */
2086         lttng_poll_set_max_size();
2087
2088         /* Setup the dispatcher thread */
2089         ret = pthread_create(&live_dispatcher_thread, NULL,
2090                         thread_dispatcher, (void *) NULL);
2091         if (ret != 0) {
2092                 PERROR("pthread_create viewer dispatcher");
2093                 goto exit_dispatcher;
2094         }
2095
2096         /* Setup the worker thread */
2097         ret = pthread_create(&live_worker_thread, NULL,
2098                         thread_worker, relay_ctx);
2099         if (ret != 0) {
2100                 PERROR("pthread_create viewer worker");
2101                 goto exit_worker;
2102         }
2103
2104         /* Setup the listener thread */
2105         ret = pthread_create(&live_listener_thread, NULL,
2106                         thread_listener, (void *) NULL);
2107         if (ret != 0) {
2108                 PERROR("pthread_create viewer listener");
2109                 goto exit_listener;
2110         }
2111
2112         ret = 0;
2113         goto end;
2114
2115 exit_listener:
2116         ret = pthread_join(live_listener_thread, &status);
2117         if (ret != 0) {
2118                 PERROR("pthread_join live listener");
2119                 goto error;     /* join error, exit without cleanup */
2120         }
2121
2122 exit_worker:
2123         ret = pthread_join(live_worker_thread, &status);
2124         if (ret != 0) {
2125                 PERROR("pthread_join live worker");
2126                 goto error;     /* join error, exit without cleanup */
2127         }
2128
2129 exit_dispatcher:
2130         ret = pthread_join(live_dispatcher_thread, &status);
2131         if (ret != 0) {
2132                 PERROR("pthread_join live dispatcher");
2133                 goto error;     /* join error, exit without cleanup */
2134         }
2135
2136 exit:
2137         cleanup();
2138
2139 end:
2140 error:
2141         return ret;
2142 }