src/common/consumer/consumer-timer.c

   1 /*
   2  * Copyright (C) 2012 Julien Desfossez <julien.desfossez@efficios.com>
   3  * Copyright (C) 2012 David Goulet <dgoulet@efficios.com>
   4  *
   5  * SPDX-License-Identifier: GPL-2.0-only
   6  *
   7  */
   8
   9 #define _LGPL_SOURCE
  10 #include <assert.h>
  11 #include <inttypes.h>
  12 #include <signal.h>
  13
  14 #include <bin/lttng-consumerd/health-consumerd.h>
  15 #include <common/common.h>
  16 #include <common/compat/endian.h>
  17 #include <common/kernel-ctl/kernel-ctl.h>
  18 #include <common/kernel-consumer/kernel-consumer.h>
  19 #include <common/consumer/consumer-stream.h>
  20 #include <common/consumer/consumer-timer.h>
  21 #include <common/consumer/consumer-testpoint.h>
  22 #include <common/ust-consumer/ust-consumer.h>
  23
  24 typedef int (*sample_positions_cb)(struct lttng_consumer_stream *stream);
  25 typedef int (*get_consumed_cb)(struct lttng_consumer_stream *stream,
  26                 unsigned long *consumed);
  27 typedef int (*get_produced_cb)(struct lttng_consumer_stream *stream,
  28                 unsigned long *produced);
  29 typedef int (*flush_index_cb)(struct lttng_consumer_stream *stream);
  30
  31 static struct timer_signal_data timer_signal = {
  32         .tid = 0,
  33         .setup_done = 0,
  34         .qs_done = 0,
  35         .lock = PTHREAD_MUTEX_INITIALIZER,
  36 };
  37
  38 /*
  39  * Set custom signal mask to current thread.
  40  */
  41 static void setmask(sigset_t *mask)
  42 {
  43         int ret;
  44
  45         ret = sigemptyset(mask);
  46         if (ret) {
  47                 PERROR("sigemptyset");
  48         }
  49         ret = sigaddset(mask, LTTNG_CONSUMER_SIG_SWITCH);
  50         if (ret) {
  51                 PERROR("sigaddset switch");
  52         }
  53         ret = sigaddset(mask, LTTNG_CONSUMER_SIG_TEARDOWN);
  54         if (ret) {
  55                 PERROR("sigaddset teardown");
  56         }
  57         ret = sigaddset(mask, LTTNG_CONSUMER_SIG_LIVE);
  58         if (ret) {
  59                 PERROR("sigaddset live");
  60         }
  61         ret = sigaddset(mask, LTTNG_CONSUMER_SIG_MONITOR);
  62         if (ret) {
  63                 PERROR("sigaddset monitor");
  64         }
  65         ret = sigaddset(mask, LTTNG_CONSUMER_SIG_EXIT);
  66         if (ret) {
  67                 PERROR("sigaddset exit");
  68         }
  69 }
  70
  71 static int channel_monitor_pipe = -1;
  72
  73 /*
  74  * Execute action on a timer switch.
  75  *
  76  * Beware: metadata_switch_timer() should *never* take a mutex also held
  77  * while consumer_timer_switch_stop() is called. It would result in
  78  * deadlocks.
  79  */
  80 static void metadata_switch_timer(struct lttng_consumer_local_data *ctx,
  81                 siginfo_t *si)
  82 {
  83         int ret;
  84         struct lttng_consumer_channel *channel;
  85
  86         channel = si->si_value.sival_ptr;
  87         assert(channel);
  88
  89         if (channel->switch_timer_error) {
  90                 return;
  91         }
  92
  93         DBG("Switch timer for channel %" PRIu64, channel->key);
  94         switch (ctx->type) {
  95         case LTTNG_CONSUMER32_UST:
  96         case LTTNG_CONSUMER64_UST:
  97                 /*
  98                  * Locks taken by lttng_ustconsumer_request_metadata():
  99                  * - metadata_socket_lock
 100                  *   - Calling lttng_ustconsumer_recv_metadata():
 101                  *     - channel->metadata_cache->lock
 102                  *     - Calling consumer_metadata_cache_flushed():
 103                  *       - channel->timer_lock
 104                  *         - channel->metadata_cache->lock
 105                  *
 106                  * Ensure that neither consumer_data.lock nor
 107                  * channel->lock are taken within this function, since
 108                  * they are held while consumer_timer_switch_stop() is
 109                  * called.
 110                  */
 111                 ret = lttng_ustconsumer_request_metadata(ctx, channel, 1, 1);
 112                 if (ret < 0) {
 113                         channel->switch_timer_error = 1;
 114                 }
 115                 break;
 116         case LTTNG_CONSUMER_KERNEL:
 117         case LTTNG_CONSUMER_UNKNOWN:
 118                 assert(0);
 119                 break;
 120         }
 121 }
 122
 123 static int send_empty_index(struct lttng_consumer_stream *stream, uint64_t ts,
 124                 uint64_t stream_id)
 125 {
 126         int ret;
 127         struct ctf_packet_index index;
 128
 129         memset(&index, 0, sizeof(index));
 130         index.stream_id = htobe64(stream_id);
 131         index.timestamp_end = htobe64(ts);
 132         ret = consumer_stream_write_index(stream, &index);
 133         if (ret < 0) {
 134                 goto error;
 135         }
 136
 137 error:
 138         return ret;
 139 }
 140
 141 int consumer_flush_kernel_index(struct lttng_consumer_stream *stream)
 142 {
 143         uint64_t ts, stream_id;
 144         int ret;
 145
 146         ret = kernctl_get_current_timestamp(stream->wait_fd, &ts);
 147         if (ret < 0) {
 148                 ERR("Failed to get the current timestamp");
 149                 goto end;
 150         }
 151         ret = kernctl_buffer_flush(stream->wait_fd);
 152         if (ret < 0) {
 153                 ERR("Failed to flush kernel stream");
 154                 goto end;
 155         }
 156         ret = kernctl_snapshot(stream->wait_fd);
 157         if (ret < 0) {
 158                 if (ret != -EAGAIN && ret != -ENODATA) {
 159                         PERROR("live timer kernel snapshot");
 160                         ret = -1;
 161                         goto end;
 162                 }
 163                 ret = kernctl_get_stream_id(stream->wait_fd, &stream_id);
 164                 if (ret < 0) {
 165                         PERROR("kernctl_get_stream_id");
 166                         goto end;
 167                 }
 168                 DBG("Stream %" PRIu64 " empty, sending beacon", stream->key);
 169                 ret = send_empty_index(stream, ts, stream_id);
 170                 if (ret < 0) {
 171                         goto end;
 172                 }
 173         }
 174         ret = 0;
 175 end:
 176         return ret;
 177 }
 178
 179 static int check_stream(struct lttng_consumer_stream *stream,
 180                 flush_index_cb flush_index)
 181 {
 182         int ret;
 183
 184         /*
 185          * While holding the stream mutex, try to take a snapshot, if it
 186          * succeeds, it means that data is ready to be sent, just let the data
 187          * thread handle that. Otherwise, if the snapshot returns EAGAIN, it
 188          * means that there is no data to read after the flush, so we can
 189          * safely send the empty index.
 190          *
 191          * Doing a trylock and checking if waiting on metadata if
 192          * trylock fails. Bail out of the stream is indeed waiting for
 193          * metadata to be pushed. Busy wait on trylock otherwise.
 194          */
 195         for (;;) {
 196                 ret = pthread_mutex_trylock(&stream->lock);
 197                 switch (ret) {
 198                 case 0:
 199                         break;  /* We have the lock. */
 200                 case EBUSY:
 201                         pthread_mutex_lock(&stream->metadata_timer_lock);
 202                         if (stream->waiting_on_metadata) {
 203                                 ret = 0;
 204                                 stream->missed_metadata_flush = true;
 205                                 pthread_mutex_unlock(&stream->metadata_timer_lock);
 206                                 goto end;       /* Bail out. */
 207                         }
 208                         pthread_mutex_unlock(&stream->metadata_timer_lock);
 209                         /* Try again. */
 210                         caa_cpu_relax();
 211                         continue;
 212                 default:
 213                         ERR("Unexpected pthread_mutex_trylock error %d", ret);
 214                         ret = -1;
 215                         goto end;
 216                 }
 217                 break;
 218         }
 219         ret = flush_index(stream);
 220         pthread_mutex_unlock(&stream->lock);
 221 end:
 222         return ret;
 223 }
 224
 225 int consumer_flush_ust_index(struct lttng_consumer_stream *stream)
 226 {
 227         uint64_t ts, stream_id;
 228         int ret;
 229
 230         ret = cds_lfht_is_node_deleted(&stream->node.node);
 231         if (ret) {
 232                 goto end;
 233         }
 234
 235         ret = lttng_ustconsumer_get_current_timestamp(stream, &ts);
 236         if (ret < 0) {
 237                 ERR("Failed to get the current timestamp");
 238                 goto end;
 239         }
 240         lttng_ustconsumer_flush_buffer(stream, 1);
 241         ret = lttng_ustconsumer_take_snapshot(stream);
 242         if (ret < 0) {
 243                 if (ret != -EAGAIN) {
 244                         ERR("Taking UST snapshot");
 245                         ret = -1;
 246                         goto end;
 247                 }
 248                 ret = lttng_ustconsumer_get_stream_id(stream, &stream_id);
 249                 if (ret < 0) {
 250                         PERROR("ustctl_get_stream_id");
 251                         goto end;
 252                 }
 253                 DBG("Stream %" PRIu64 " empty, sending beacon", stream->key);
 254                 ret = send_empty_index(stream, ts, stream_id);
 255                 if (ret < 0) {
 256                         goto end;
 257                 }
 258         }
 259         ret = 0;
 260 end:
 261         return ret;
 262 }
 263
 264 /*
 265  * Execute action on a live timer
 266  */
 267 static void live_timer(struct lttng_consumer_local_data *ctx,
 268                 siginfo_t *si)
 269 {
 270         int ret;
 271         struct lttng_consumer_channel *channel;
 272         struct lttng_consumer_stream *stream;
 273         struct lttng_ht_iter iter;
 274         const struct lttng_ht *ht = consumer_data.stream_per_chan_id_ht;
 275         const flush_index_cb flush_index =
 276                         ctx->type == LTTNG_CONSUMER_KERNEL ?
 277                                         consumer_flush_kernel_index :
 278                                         consumer_flush_ust_index;
 279
 280         channel = si->si_value.sival_ptr;
 281         assert(channel);
 282
 283         if (channel->switch_timer_error) {
 284                 goto error;
 285         }
 286
 287         DBG("Live timer for channel %" PRIu64, channel->key);
 288
 289         rcu_read_lock();
 290         cds_lfht_for_each_entry_duplicate(ht->ht,
 291                         ht->hash_fct(&channel->key, lttng_ht_seed),
 292                         ht->match_fct, &channel->key, &iter.iter,
 293                         stream, node_channel_id.node) {
 294                 ret = check_stream(stream, flush_index);
 295                 if (ret < 0) {
 296                         goto error_unlock;
 297                 }
 298         }
 299
 300 error_unlock:
 301         rcu_read_unlock();
 302
 303 error:
 304         return;
 305 }
 306
 307 static
 308 void consumer_timer_signal_thread_qs(unsigned int signr)
 309 {
 310         sigset_t pending_set;
 311         int ret;
 312
 313         /*
 314          * We need to be the only thread interacting with the thread
 315          * that manages signals for teardown synchronization.
 316          */
 317         pthread_mutex_lock(&timer_signal.lock);
 318
 319         /* Ensure we don't have any signal queued for this channel. */
 320         for (;;) {
 321                 ret = sigemptyset(&pending_set);
 322                 if (ret == -1) {
 323                         PERROR("sigemptyset");
 324                 }
 325                 ret = sigpending(&pending_set);
 326                 if (ret == -1) {
 327                         PERROR("sigpending");
 328                 }
 329                 if (!sigismember(&pending_set, signr)) {
 330                         break;
 331                 }
 332                 caa_cpu_relax();
 333         }
 334
 335         /*
 336          * From this point, no new signal handler will be fired that would try to
 337          * access "chan". However, we still need to wait for any currently
 338          * executing handler to complete.
 339          */
 340         cmm_smp_mb();
 341         CMM_STORE_SHARED(timer_signal.qs_done, 0);
 342         cmm_smp_mb();
 343
 344         /*
 345          * Kill with LTTNG_CONSUMER_SIG_TEARDOWN, so signal management thread wakes
 346          * up.
 347          */
 348         kill(getpid(), LTTNG_CONSUMER_SIG_TEARDOWN);
 349
 350         while (!CMM_LOAD_SHARED(timer_signal.qs_done)) {
 351                 caa_cpu_relax();
 352         }
 353         cmm_smp_mb();
 354
 355         pthread_mutex_unlock(&timer_signal.lock);
 356 }
 357
 358 /*
 359  * Start a timer channel timer which will fire at a given interval
 360  * (timer_interval_us)and fire a given signal (signal).
 361  *
 362  * Returns a negative value on error, 0 if a timer was created, and
 363  * a positive value if no timer was created (not an error).
 364  */
 365 static
 366 int consumer_channel_timer_start(timer_t *timer_id,
 367                 struct lttng_consumer_channel *channel,
 368                 unsigned int timer_interval_us, int signal)
 369 {
 370         int ret = 0, delete_ret;
 371         struct sigevent sev = {};
 372         struct itimerspec its;
 373
 374         assert(channel);
 375         assert(channel->key);
 376
 377         if (timer_interval_us == 0) {
 378                 /* No creation needed; not an error. */
 379                 ret = 1;
 380                 goto end;
 381         }
 382
 383         sev.sigev_notify = SIGEV_SIGNAL;
 384         sev.sigev_signo = signal;
 385         sev.sigev_value.sival_ptr = channel;
 386         ret = timer_create(CLOCKID, &sev, timer_id);
 387         if (ret == -1) {
 388                 PERROR("timer_create");
 389                 goto end;
 390         }
 391
 392         its.it_value.tv_sec = timer_interval_us / 1000000;
 393         its.it_value.tv_nsec = (timer_interval_us % 1000000) * 1000;
 394         its.it_interval.tv_sec = its.it_value.tv_sec;
 395         its.it_interval.tv_nsec = its.it_value.tv_nsec;
 396
 397         ret = timer_settime(*timer_id, 0, &its, NULL);
 398         if (ret == -1) {
 399                 PERROR("timer_settime");
 400                 goto error_destroy_timer;
 401         }
 402 end:
 403         return ret;
 404 error_destroy_timer:
 405         delete_ret = timer_delete(*timer_id);
 406         if (delete_ret == -1) {
 407                 PERROR("timer_delete");
 408         }
 409         goto end;
 410 }
 411
 412 static
 413 int consumer_channel_timer_stop(timer_t *timer_id, int signal)
 414 {
 415         int ret = 0;
 416
 417         ret = timer_delete(*timer_id);
 418         if (ret == -1) {
 419                 PERROR("timer_delete");
 420                 goto end;
 421         }
 422
 423         consumer_timer_signal_thread_qs(signal);
 424         *timer_id = 0;
 425 end:
 426         return ret;
 427 }
 428
 429 /*
 430  * Set the channel's switch timer.
 431  */
 432 void consumer_timer_switch_start(struct lttng_consumer_channel *channel,
 433                 unsigned int switch_timer_interval_us)
 434 {
 435         int ret;
 436
 437         assert(channel);
 438         assert(channel->key);
 439
 440         ret = consumer_channel_timer_start(&channel->switch_timer, channel,
 441                         switch_timer_interval_us, LTTNG_CONSUMER_SIG_SWITCH);
 442
 443         channel->switch_timer_enabled = !!(ret == 0);
 444 }
 445
 446 /*
 447  * Stop and delete the channel's switch timer.
 448  */
 449 void consumer_timer_switch_stop(struct lttng_consumer_channel *channel)
 450 {
 451         int ret;
 452
 453         assert(channel);
 454
 455         ret = consumer_channel_timer_stop(&channel->switch_timer,
 456                         LTTNG_CONSUMER_SIG_SWITCH);
 457         if (ret == -1) {
 458                 ERR("Failed to stop switch timer");
 459         }
 460
 461         channel->switch_timer_enabled = 0;
 462 }
 463
 464 /*
 465  * Set the channel's live timer.
 466  */
 467 void consumer_timer_live_start(struct lttng_consumer_channel *channel,
 468                 unsigned int live_timer_interval_us)
 469 {
 470         int ret;
 471
 472         assert(channel);
 473         assert(channel->key);
 474
 475         ret = consumer_channel_timer_start(&channel->live_timer, channel,
 476                         live_timer_interval_us, LTTNG_CONSUMER_SIG_LIVE);
 477
 478         channel->live_timer_enabled = !!(ret == 0);
 479 }
 480
 481 /*
 482  * Stop and delete the channel's live timer.
 483  */
 484 void consumer_timer_live_stop(struct lttng_consumer_channel *channel)
 485 {
 486         int ret;
 487
 488         assert(channel);
 489
 490         ret = consumer_channel_timer_stop(&channel->live_timer,
 491                         LTTNG_CONSUMER_SIG_LIVE);
 492         if (ret == -1) {
 493                 ERR("Failed to stop live timer");
 494         }
 495
 496         channel->live_timer_enabled = 0;
 497 }
 498
 499 /*
 500  * Set the channel's monitoring timer.
 501  *
 502  * Returns a negative value on error, 0 if a timer was created, and
 503  * a positive value if no timer was created (not an error).
 504  */
 505 int consumer_timer_monitor_start(struct lttng_consumer_channel *channel,
 506                 unsigned int monitor_timer_interval_us)
 507 {
 508         int ret;
 509
 510         assert(channel);
 511         assert(channel->key);
 512         assert(!channel->monitor_timer_enabled);
 513
 514         ret = consumer_channel_timer_start(&channel->monitor_timer, channel,
 515                         monitor_timer_interval_us, LTTNG_CONSUMER_SIG_MONITOR);
 516         channel->monitor_timer_enabled = !!(ret == 0);
 517         return ret;
 518 }
 519
 520 /*
 521  * Stop and delete the channel's monitoring timer.
 522  */
 523 int consumer_timer_monitor_stop(struct lttng_consumer_channel *channel)
 524 {
 525         int ret;
 526
 527         assert(channel);
 528         assert(channel->monitor_timer_enabled);
 529
 530         ret = consumer_channel_timer_stop(&channel->monitor_timer,
 531                         LTTNG_CONSUMER_SIG_MONITOR);
 532         if (ret == -1) {
 533                 ERR("Failed to stop live timer");
 534                 goto end;
 535         }
 536
 537         channel->monitor_timer_enabled = 0;
 538 end:
 539         return ret;
 540 }
 541
 542 /*
 543  * Block the RT signals for the entire process. It must be called from the
 544  * consumer main before creating the threads
 545  */
 546 int consumer_signal_init(void)
 547 {
 548         int ret;
 549         sigset_t mask;
 550
 551         /* Block signal for entire process, so only our thread processes it. */
 552         setmask(&mask);
 553         ret = pthread_sigmask(SIG_BLOCK, &mask, NULL);
 554         if (ret) {
 555                 errno = ret;
 556                 PERROR("pthread_sigmask");
 557                 return -1;
 558         }
 559         return 0;
 560 }
 561
 562 static
 563 int sample_channel_positions(struct lttng_consumer_channel *channel,
 564                 uint64_t *_highest_use, uint64_t *_lowest_use, uint64_t *_total_consumed,
 565                 sample_positions_cb sample, get_consumed_cb get_consumed,
 566                 get_produced_cb get_produced)
 567 {
 568         int ret = 0;
 569         struct lttng_ht_iter iter;
 570         struct lttng_consumer_stream *stream;
 571         bool empty_channel = true;
 572         uint64_t high = 0, low = UINT64_MAX;
 573         struct lttng_ht *ht = consumer_data.stream_per_chan_id_ht;
 574
 575         *_total_consumed = 0;
 576
 577         rcu_read_lock();
 578
 579         cds_lfht_for_each_entry_duplicate(ht->ht,
 580                         ht->hash_fct(&channel->key, lttng_ht_seed),
 581                         ht->match_fct, &channel->key,
 582                         &iter.iter, stream, node_channel_id.node) {
 583                 unsigned long produced, consumed, usage;
 584
 585                 empty_channel = false;
 586
 587                 pthread_mutex_lock(&stream->lock);
 588                 if (cds_lfht_is_node_deleted(&stream->node.node)) {
 589                         goto next;
 590                 }
 591
 592                 ret = sample(stream);
 593                 if (ret) {
 594                         ERR("Failed to take buffer position snapshot in monitor timer (ret = %d)", ret);
 595                         pthread_mutex_unlock(&stream->lock);
 596                         goto end;
 597                 }
 598                 ret = get_consumed(stream, &consumed);
 599                 if (ret) {
 600                         ERR("Failed to get buffer consumed position in monitor timer");
 601                         pthread_mutex_unlock(&stream->lock);
 602                         goto end;
 603                 }
 604                 ret = get_produced(stream, &produced);
 605                 if (ret) {
 606                         ERR("Failed to get buffer produced position in monitor timer");
 607                         pthread_mutex_unlock(&stream->lock);
 608                         goto end;
 609                 }
 610
 611                 usage = produced - consumed;
 612                 high = (usage > high) ? usage : high;
 613                 low = (usage < low) ? usage : low;
 614
 615                 /*
 616                  * We don't use consumed here for 2 reasons:
 617                  *  - output_written takes into account the padding written in the
 618                  *    tracefiles when we stop the session;
 619                  *  - the consumed position is not the accurate representation of what
 620                  *    was extracted from a buffer in overwrite mode.
 621                  */
 622                 *_total_consumed += stream->output_written;
 623         next:
 624                 pthread_mutex_unlock(&stream->lock);
 625         }
 626
 627         *_highest_use = high;
 628         *_lowest_use = low;
 629 end:
 630         rcu_read_unlock();
 631         if (empty_channel) {
 632                 ret = -1;
 633         }
 634         return ret;
 635 }
 636
 637 /*
 638  * Execute action on a monitor timer.
 639  */
 640 static
 641 void monitor_timer(struct lttng_consumer_channel *channel)
 642 {
 643         int ret;
 644         int channel_monitor_pipe =
 645                         consumer_timer_thread_get_channel_monitor_pipe();
 646         struct lttcomm_consumer_channel_monitor_msg msg = {
 647                 .key = channel->key,
 648         };
 649         sample_positions_cb sample;
 650         get_consumed_cb get_consumed;
 651         get_produced_cb get_produced;
 652         uint64_t lowest = 0, highest = 0, total_consumed = 0;
 653
 654         assert(channel);
 655
 656         if (channel_monitor_pipe < 0) {
 657                 return;
 658         }
 659
 660         switch (consumer_data.type) {
 661         case LTTNG_CONSUMER_KERNEL:
 662                 sample = lttng_kconsumer_sample_snapshot_positions;
 663                 get_consumed = lttng_kconsumer_get_consumed_snapshot;
 664                 get_produced = lttng_kconsumer_get_produced_snapshot;
 665                 break;
 666         case LTTNG_CONSUMER32_UST:
 667         case LTTNG_CONSUMER64_UST:
 668                 sample = lttng_ustconsumer_sample_snapshot_positions;
 669                 get_consumed = lttng_ustconsumer_get_consumed_snapshot;
 670                 get_produced = lttng_ustconsumer_get_produced_snapshot;
 671                 break;
 672         default:
 673                 abort();
 674         }
 675
 676         ret = sample_channel_positions(channel, &highest, &lowest,
 677                         &total_consumed, sample, get_consumed, get_produced);
 678         if (ret) {
 679                 return;
 680         }
 681         msg.highest = highest;
 682         msg.lowest = lowest;
 683         msg.total_consumed = total_consumed;
 684
 685         /*
 686          * Writes performed here are assumed to be atomic which is only
 687          * guaranteed for sizes < than PIPE_BUF.
 688          */
 689         assert(sizeof(msg) <= PIPE_BUF);
 690
 691         do {
 692                 ret = write(channel_monitor_pipe, &msg, sizeof(msg));
 693         } while (ret == -1 && errno == EINTR);
 694         if (ret == -1) {
 695                 if (errno == EAGAIN) {
 696                         /* Not an error, the sample is merely dropped. */
 697                         DBG("Channel monitor pipe is full; dropping sample for channel key = %"PRIu64,
 698                                         channel->key);
 699                 } else {
 700                         PERROR("write to the channel monitor pipe");
 701                 }
 702         } else {
 703                 DBG("Sent channel monitoring sample for channel key %" PRIu64
 704                                 ", (highest = %" PRIu64 ", lowest = %"PRIu64")",
 705                                 channel->key, msg.highest, msg.lowest);
 706         }
 707 }
 708
 709 int consumer_timer_thread_get_channel_monitor_pipe(void)
 710 {
 711         return uatomic_read(&channel_monitor_pipe);
 712 }
 713
 714 int consumer_timer_thread_set_channel_monitor_pipe(int fd)
 715 {
 716         int ret;
 717
 718         ret = uatomic_cmpxchg(&channel_monitor_pipe, -1, fd);
 719         if (ret != -1) {
 720                 ret = -1;
 721                 goto end;
 722         }
 723         ret = 0;
 724 end:
 725         return ret;
 726 }
 727
 728 /*
 729  * This thread is the sighandler for signals LTTNG_CONSUMER_SIG_SWITCH,
 730  * LTTNG_CONSUMER_SIG_TEARDOWN, LTTNG_CONSUMER_SIG_LIVE, and
 731  * LTTNG_CONSUMER_SIG_MONITOR, LTTNG_CONSUMER_SIG_EXIT.
 732  */
 733 void *consumer_timer_thread(void *data)
 734 {
 735         int signr;
 736         sigset_t mask;
 737         siginfo_t info;
 738         struct lttng_consumer_local_data *ctx = data;
 739
 740         rcu_register_thread();
 741
 742         health_register(health_consumerd, HEALTH_CONSUMERD_TYPE_METADATA_TIMER);
 743
 744         if (testpoint(consumerd_thread_metadata_timer)) {
 745                 goto error_testpoint;
 746         }
 747
 748         health_code_update();
 749
 750         /* Only self thread will receive signal mask. */
 751         setmask(&mask);
 752         CMM_STORE_SHARED(timer_signal.tid, pthread_self());
 753
 754         while (1) {
 755                 health_code_update();
 756
 757                 health_poll_entry();
 758                 signr = sigwaitinfo(&mask, &info);
 759                 health_poll_exit();
 760
 761                 /*
 762                  * NOTE: cascading conditions are used instead of a switch case
 763                  * since the use of SIGRTMIN in the definition of the signals'
 764                  * values prevents the reduction to an integer constant.
 765                  */
 766                 if (signr == -1) {
 767                         if (errno != EINTR) {
 768                                 PERROR("sigwaitinfo");
 769                         }
 770                         continue;
 771                 } else if (signr == LTTNG_CONSUMER_SIG_SWITCH) {
 772                         metadata_switch_timer(ctx, &info);
 773                 } else if (signr == LTTNG_CONSUMER_SIG_TEARDOWN) {
 774                         cmm_smp_mb();
 775                         CMM_STORE_SHARED(timer_signal.qs_done, 1);
 776                         cmm_smp_mb();
 777                         DBG("Signal timer metadata thread teardown");
 778                 } else if (signr == LTTNG_CONSUMER_SIG_LIVE) {
 779                         live_timer(ctx, &info);
 780                 } else if (signr == LTTNG_CONSUMER_SIG_MONITOR) {
 781                         struct lttng_consumer_channel *channel;
 782
 783                         channel = info.si_value.sival_ptr;
 784                         monitor_timer(channel);
 785                 } else if (signr == LTTNG_CONSUMER_SIG_EXIT) {
 786                         assert(CMM_LOAD_SHARED(consumer_quit));
 787                         goto end;
 788                 } else {
 789                         ERR("Unexpected signal %d\n", info.si_signo);
 790                 }
 791         }
 792
 793 error_testpoint:
 794         /* Only reached in testpoint error */
 795         health_error();
 796 end:
 797         health_unregister(health_consumerd);
 798         rcu_unregister_thread();
 799         return NULL;
 800 }