src/common/consumer-timer.c

   1 /*
   2  * Copyright (C) 2012 - Julien Desfossez <julien.desfossez@efficios.com>
   3  *                      David Goulet <dgoulet@efficios.com>
   4  *
   5  * This program is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License, version 2 only, as
   7  * 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 with
  15  * this program; if not, write to the Free Software Foundation, Inc., 51
  16  * Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  17  */
  18
  19 #define _GNU_SOURCE
  20 #define _LGPL_SOURCE
  21 #include <assert.h>
  22 #include <inttypes.h>
  23 #include <signal.h>
  24
  25 #include <bin/lttng-consumerd/health-consumerd.h>
  26 #include <common/common.h>
  27 #include <common/compat/endian.h>
  28 #include <common/kernel-ctl/kernel-ctl.h>
  29 #include <common/kernel-consumer/kernel-consumer.h>
  30 #include <common/consumer-stream.h>
  31
  32 #include "consumer-timer.h"
  33 #include "consumer-testpoint.h"
  34 #include "ust-consumer/ust-consumer.h"
  35
  36 static struct timer_signal_data timer_signal = {
  37         .tid = 0,
  38         .setup_done = 0,
  39         .qs_done = 0,
  40         .lock = PTHREAD_MUTEX_INITIALIZER,
  41 };
  42
  43 /*
  44  * Set custom signal mask to current thread.
  45  */
  46 static void setmask(sigset_t *mask)
  47 {
  48         int ret;
  49
  50         ret = sigemptyset(mask);
  51         if (ret) {
  52                 PERROR("sigemptyset");
  53         }
  54         ret = sigaddset(mask, LTTNG_CONSUMER_SIG_SWITCH);
  55         if (ret) {
  56                 PERROR("sigaddset switch");
  57         }
  58         ret = sigaddset(mask, LTTNG_CONSUMER_SIG_TEARDOWN);
  59         if (ret) {
  60                 PERROR("sigaddset teardown");
  61         }
  62         ret = sigaddset(mask, LTTNG_CONSUMER_SIG_LIVE);
  63         if (ret) {
  64                 PERROR("sigaddset live");
  65         }
  66 }
  67
  68 /*
  69  * Execute action on a timer switch.
  70  *
  71  * Beware: metadata_switch_timer() should *never* take a mutex also held
  72  * while consumer_timer_switch_stop() is called. It would result in
  73  * deadlocks.
  74  */
  75 static void metadata_switch_timer(struct lttng_consumer_local_data *ctx,
  76                 int sig, siginfo_t *si, void *uc)
  77 {
  78         int ret;
  79         struct lttng_consumer_channel *channel;
  80
  81         channel = si->si_value.sival_ptr;
  82         assert(channel);
  83
  84         if (channel->switch_timer_error) {
  85                 return;
  86         }
  87
  88         DBG("Switch timer for channel %" PRIu64, channel->key);
  89         switch (ctx->type) {
  90         case LTTNG_CONSUMER32_UST:
  91         case LTTNG_CONSUMER64_UST:
  92                 /*
  93                  * Locks taken by lttng_ustconsumer_request_metadata():
  94                  * - metadata_socket_lock
  95                  *   - Calling lttng_ustconsumer_recv_metadata():
  96                  *     - channel->metadata_cache->lock
  97                  *     - Calling consumer_metadata_cache_flushed():
  98                  *       - channel->timer_lock
  99                  *         - channel->metadata_cache->lock
 100                  *
 101                  * Ensure that neither consumer_data.lock nor
 102                  * channel->lock are taken within this function, since
 103                  * they are held while consumer_timer_switch_stop() is
 104                  * called.
 105                  */
 106                 ret = lttng_ustconsumer_request_metadata(ctx, channel, 1, 1);
 107                 if (ret < 0) {
 108                         channel->switch_timer_error = 1;
 109                 }
 110                 break;
 111         case LTTNG_CONSUMER_KERNEL:
 112         case LTTNG_CONSUMER_UNKNOWN:
 113                 assert(0);
 114                 break;
 115         }
 116 }
 117
 118 static int send_empty_index(struct lttng_consumer_stream *stream, uint64_t ts,
 119                 uint64_t stream_id)
 120 {
 121         int ret;
 122         struct ctf_packet_index index;
 123
 124         memset(&index, 0, sizeof(index));
 125         index.stream_id = htobe64(stream_id);
 126         index.timestamp_end = htobe64(ts);
 127         ret = consumer_stream_write_index(stream, &index);
 128         if (ret < 0) {
 129                 goto error;
 130         }
 131
 132 error:
 133         return ret;
 134 }
 135
 136 int consumer_flush_kernel_index(struct lttng_consumer_stream *stream)
 137 {
 138         uint64_t ts, stream_id;
 139         int ret;
 140
 141         ret = kernctl_get_current_timestamp(stream->wait_fd, &ts);
 142         if (ret < 0) {
 143                 ERR("Failed to get the current timestamp");
 144                 goto end;
 145         }
 146         ret = kernctl_buffer_flush(stream->wait_fd);
 147         if (ret < 0) {
 148                 ERR("Failed to flush kernel stream");
 149                 goto end;
 150         }
 151         ret = kernctl_snapshot(stream->wait_fd);
 152         if (ret < 0) {
 153                 if (errno != EAGAIN && errno != ENODATA) {
 154                         PERROR("live timer kernel snapshot");
 155                         ret = -1;
 156                         goto end;
 157                 }
 158                 ret = kernctl_get_stream_id(stream->wait_fd, &stream_id);
 159                 if (ret < 0) {
 160                         PERROR("kernctl_get_stream_id");
 161                         goto end;
 162                 }
 163                 DBG("Stream %" PRIu64 " empty, sending beacon", stream->key);
 164                 ret = send_empty_index(stream, ts, stream_id);
 165                 if (ret < 0) {
 166                         goto end;
 167                 }
 168         }
 169         ret = 0;
 170 end:
 171         return ret;
 172 }
 173
 174 static int check_kernel_stream(struct lttng_consumer_stream *stream)
 175 {
 176         int ret;
 177
 178         /*
 179          * While holding the stream mutex, try to take a snapshot, if it
 180          * succeeds, it means that data is ready to be sent, just let the data
 181          * thread handle that. Otherwise, if the snapshot returns EAGAIN, it
 182          * means that there is no data to read after the flush, so we can
 183          * safely send the empty index.
 184          *
 185          * Doing a trylock and checking if waiting on metadata if
 186          * trylock fails. Bail out of the stream is indeed waiting for
 187          * metadata to be pushed. Busy wait on trylock otherwise.
 188          */
 189         for (;;) {
 190                 ret = pthread_mutex_trylock(&stream->lock);
 191                 switch (ret) {
 192                 case 0:
 193                         break;  /* We have the lock. */
 194                 case EBUSY:
 195                         pthread_mutex_lock(&stream->metadata_timer_lock);
 196                         if (stream->waiting_on_metadata) {
 197                                 ret = 0;
 198                                 stream->missed_metadata_flush = true;
 199                                 pthread_mutex_unlock(&stream->metadata_timer_lock);
 200                                 goto end;       /* Bail out. */
 201                         }
 202                         pthread_mutex_unlock(&stream->metadata_timer_lock);
 203                         /* Try again. */
 204                         caa_cpu_relax();
 205                         continue;
 206                 default:
 207                         ERR("Unexpected pthread_mutex_trylock error %d", ret);
 208                         ret = -1;
 209                         goto end;
 210                 }
 211                 break;
 212         }
 213         ret = consumer_flush_kernel_index(stream);
 214         pthread_mutex_unlock(&stream->lock);
 215 end:
 216         return ret;
 217 }
 218
 219 int consumer_flush_ust_index(struct lttng_consumer_stream *stream)
 220 {
 221         uint64_t ts, stream_id;
 222         int ret;
 223
 224         ret = cds_lfht_is_node_deleted(&stream->node.node);
 225         if (ret) {
 226                 goto end;
 227         }
 228
 229         ret = lttng_ustconsumer_get_current_timestamp(stream, &ts);
 230         if (ret < 0) {
 231                 ERR("Failed to get the current timestamp");
 232                 goto end;
 233         }
 234         lttng_ustconsumer_flush_buffer(stream, 1);
 235         ret = lttng_ustconsumer_take_snapshot(stream);
 236         if (ret < 0) {
 237                 if (ret != -EAGAIN) {
 238                         ERR("Taking UST snapshot");
 239                         ret = -1;
 240                         goto end;
 241                 }
 242                 ret = lttng_ustconsumer_get_stream_id(stream, &stream_id);
 243                 if (ret < 0) {
 244                         PERROR("ustctl_get_stream_id");
 245                         goto end;
 246                 }
 247                 DBG("Stream %" PRIu64 " empty, sending beacon", stream->key);
 248                 ret = send_empty_index(stream, ts, stream_id);
 249                 if (ret < 0) {
 250                         goto end;
 251                 }
 252         }
 253         ret = 0;
 254 end:
 255         return ret;
 256 }
 257
 258 static int check_ust_stream(struct lttng_consumer_stream *stream)
 259 {
 260         int ret;
 261
 262         assert(stream);
 263         assert(stream->ustream);
 264         /*
 265          * While holding the stream mutex, try to take a snapshot, if it
 266          * succeeds, it means that data is ready to be sent, just let the data
 267          * thread handle that. Otherwise, if the snapshot returns EAGAIN, it
 268          * means that there is no data to read after the flush, so we can
 269          * safely send the empty index.
 270          *
 271          * Doing a trylock and checking if waiting on metadata if
 272          * trylock fails. Bail out of the stream is indeed waiting for
 273          * metadata to be pushed. Busy wait on trylock otherwise.
 274          */
 275         for (;;) {
 276                 ret = pthread_mutex_trylock(&stream->lock);
 277                 switch (ret) {
 278                 case 0:
 279                         break;  /* We have the lock. */
 280                 case EBUSY:
 281                         pthread_mutex_lock(&stream->metadata_timer_lock);
 282                         if (stream->waiting_on_metadata) {
 283                                 ret = 0;
 284                                 stream->missed_metadata_flush = true;
 285                                 pthread_mutex_unlock(&stream->metadata_timer_lock);
 286                                 goto end;       /* Bail out. */
 287                         }
 288                         pthread_mutex_unlock(&stream->metadata_timer_lock);
 289                         /* Try again. */
 290                         caa_cpu_relax();
 291                         continue;
 292                 default:
 293                         ERR("Unexpected pthread_mutex_trylock error %d", ret);
 294                         ret = -1;
 295                         goto end;
 296                 }
 297                 break;
 298         }
 299         ret = consumer_flush_ust_index(stream);
 300         pthread_mutex_unlock(&stream->lock);
 301 end:
 302         return ret;
 303 }
 304
 305 /*
 306  * Execute action on a live timer
 307  */
 308 static void live_timer(struct lttng_consumer_local_data *ctx,
 309                 int sig, siginfo_t *si, void *uc)
 310 {
 311         int ret;
 312         struct lttng_consumer_channel *channel;
 313         struct lttng_consumer_stream *stream;
 314         struct lttng_ht *ht;
 315         struct lttng_ht_iter iter;
 316
 317         channel = si->si_value.sival_ptr;
 318         assert(channel);
 319
 320         if (channel->switch_timer_error) {
 321                 goto error;
 322         }
 323         ht = consumer_data.stream_per_chan_id_ht;
 324
 325         DBG("Live timer for channel %" PRIu64, channel->key);
 326
 327         rcu_read_lock();
 328         switch (ctx->type) {
 329         case LTTNG_CONSUMER32_UST:
 330         case LTTNG_CONSUMER64_UST:
 331                 cds_lfht_for_each_entry_duplicate(ht->ht,
 332                                 ht->hash_fct(&channel->key, lttng_ht_seed),
 333                                 ht->match_fct, &channel->key, &iter.iter,
 334                                 stream, node_channel_id.node) {
 335                         ret = check_ust_stream(stream);
 336                         if (ret < 0) {
 337                                 goto error_unlock;
 338                         }
 339                 }
 340                 break;
 341         case LTTNG_CONSUMER_KERNEL:
 342                 cds_lfht_for_each_entry_duplicate(ht->ht,
 343                                 ht->hash_fct(&channel->key, lttng_ht_seed),
 344                                 ht->match_fct, &channel->key, &iter.iter,
 345                                 stream, node_channel_id.node) {
 346                         ret = check_kernel_stream(stream);
 347                         if (ret < 0) {
 348                                 goto error_unlock;
 349                         }
 350                 }
 351                 break;
 352         case LTTNG_CONSUMER_UNKNOWN:
 353                 assert(0);
 354                 break;
 355         }
 356
 357 error_unlock:
 358         rcu_read_unlock();
 359
 360 error:
 361         return;
 362 }
 363
 364 static
 365 void consumer_timer_signal_thread_qs(unsigned int signr)
 366 {
 367         sigset_t pending_set;
 368         int ret;
 369
 370         /*
 371          * We need to be the only thread interacting with the thread
 372          * that manages signals for teardown synchronization.
 373          */
 374         pthread_mutex_lock(&timer_signal.lock);
 375
 376         /* Ensure we don't have any signal queued for this channel. */
 377         for (;;) {
 378                 ret = sigemptyset(&pending_set);
 379                 if (ret == -1) {
 380                         PERROR("sigemptyset");
 381                 }
 382                 ret = sigpending(&pending_set);
 383                 if (ret == -1) {
 384                         PERROR("sigpending");
 385                 }
 386                 if (!sigismember(&pending_set, LTTNG_CONSUMER_SIG_SWITCH)) {
 387                         break;
 388                 }
 389                 caa_cpu_relax();
 390         }
 391
 392         /*
 393          * From this point, no new signal handler will be fired that would try to
 394          * access "chan". However, we still need to wait for any currently
 395          * executing handler to complete.
 396          */
 397         cmm_smp_mb();
 398         CMM_STORE_SHARED(timer_signal.qs_done, 0);
 399         cmm_smp_mb();
 400
 401         /*
 402          * Kill with LTTNG_CONSUMER_SIG_TEARDOWN, so signal management thread wakes
 403          * up.
 404          */
 405         kill(getpid(), LTTNG_CONSUMER_SIG_TEARDOWN);
 406
 407         while (!CMM_LOAD_SHARED(timer_signal.qs_done)) {
 408                 caa_cpu_relax();
 409         }
 410         cmm_smp_mb();
 411
 412         pthread_mutex_unlock(&timer_signal.lock);
 413 }
 414
 415 /*
 416  * Set the timer for periodical metadata flush.
 417  */
 418 void consumer_timer_switch_start(struct lttng_consumer_channel *channel,
 419                 unsigned int switch_timer_interval)
 420 {
 421         int ret;
 422         struct sigevent sev;
 423         struct itimerspec its;
 424
 425         assert(channel);
 426         assert(channel->key);
 427
 428         if (switch_timer_interval == 0) {
 429                 return;
 430         }
 431
 432         sev.sigev_notify = SIGEV_SIGNAL;
 433         sev.sigev_signo = LTTNG_CONSUMER_SIG_SWITCH;
 434         sev.sigev_value.sival_ptr = channel;
 435         ret = timer_create(CLOCKID, &sev, &channel->switch_timer);
 436         if (ret == -1) {
 437                 PERROR("timer_create");
 438         }
 439         channel->switch_timer_enabled = 1;
 440
 441         its.it_value.tv_sec = switch_timer_interval / 1000000;
 442         its.it_value.tv_nsec = (switch_timer_interval % 1000000) * 1000;
 443         its.it_interval.tv_sec = its.it_value.tv_sec;
 444         its.it_interval.tv_nsec = its.it_value.tv_nsec;
 445
 446         ret = timer_settime(channel->switch_timer, 0, &its, NULL);
 447         if (ret == -1) {
 448                 PERROR("timer_settime");
 449         }
 450 }
 451
 452 /*
 453  * Stop and delete timer.
 454  */
 455 void consumer_timer_switch_stop(struct lttng_consumer_channel *channel)
 456 {
 457         int ret;
 458
 459         assert(channel);
 460
 461         ret = timer_delete(channel->switch_timer);
 462         if (ret == -1) {
 463                 PERROR("timer_delete");
 464         }
 465
 466         consumer_timer_signal_thread_qs(LTTNG_CONSUMER_SIG_SWITCH);
 467
 468         channel->switch_timer = 0;
 469         channel->switch_timer_enabled = 0;
 470 }
 471
 472 /*
 473  * Set the timer for the live mode.
 474  */
 475 void consumer_timer_live_start(struct lttng_consumer_channel *channel,
 476                 int live_timer_interval)
 477 {
 478         int ret;
 479         struct sigevent sev;
 480         struct itimerspec its;
 481
 482         assert(channel);
 483         assert(channel->key);
 484
 485         if (live_timer_interval <= 0) {
 486                 return;
 487         }
 488
 489         sev.sigev_notify = SIGEV_SIGNAL;
 490         sev.sigev_signo = LTTNG_CONSUMER_SIG_LIVE;
 491         sev.sigev_value.sival_ptr = channel;
 492         ret = timer_create(CLOCKID, &sev, &channel->live_timer);
 493         if (ret == -1) {
 494                 PERROR("timer_create");
 495         }
 496         channel->live_timer_enabled = 1;
 497
 498         its.it_value.tv_sec = live_timer_interval / 1000000;
 499         its.it_value.tv_nsec = (live_timer_interval % 1000000) * 1000;
 500         its.it_interval.tv_sec = its.it_value.tv_sec;
 501         its.it_interval.tv_nsec = its.it_value.tv_nsec;
 502
 503         ret = timer_settime(channel->live_timer, 0, &its, NULL);
 504         if (ret == -1) {
 505                 PERROR("timer_settime");
 506         }
 507 }
 508
 509 /*
 510  * Stop and delete timer.
 511  */
 512 void consumer_timer_live_stop(struct lttng_consumer_channel *channel)
 513 {
 514         int ret;
 515
 516         assert(channel);
 517
 518         ret = timer_delete(channel->live_timer);
 519         if (ret == -1) {
 520                 PERROR("timer_delete");
 521         }
 522
 523         consumer_timer_signal_thread_qs(LTTNG_CONSUMER_SIG_LIVE);
 524
 525         channel->live_timer = 0;
 526         channel->live_timer_enabled = 0;
 527 }
 528
 529 /*
 530  * Block the RT signals for the entire process. It must be called from the
 531  * consumer main before creating the threads
 532  */
 533 int consumer_signal_init(void)
 534 {
 535         int ret;
 536         sigset_t mask;
 537
 538         /* Block signal for entire process, so only our thread processes it. */
 539         setmask(&mask);
 540         ret = pthread_sigmask(SIG_BLOCK, &mask, NULL);
 541         if (ret) {
 542                 errno = ret;
 543                 PERROR("pthread_sigmask");
 544                 return -1;
 545         }
 546         return 0;
 547 }
 548
 549 /*
 550  * This thread is the sighandler for signals LTTNG_CONSUMER_SIG_SWITCH,
 551  * LTTNG_CONSUMER_SIG_TEARDOWN and LTTNG_CONSUMER_SIG_LIVE.
 552  */
 553 void *consumer_timer_thread(void *data)
 554 {
 555         int signr;
 556         sigset_t mask;
 557         siginfo_t info;
 558         struct lttng_consumer_local_data *ctx = data;
 559
 560         rcu_register_thread();
 561
 562         health_register(health_consumerd, HEALTH_CONSUMERD_TYPE_METADATA_TIMER);
 563
 564         if (testpoint(consumerd_thread_metadata_timer)) {
 565                 goto error_testpoint;
 566         }
 567
 568         health_code_update();
 569
 570         /* Only self thread will receive signal mask. */
 571         setmask(&mask);
 572         CMM_STORE_SHARED(timer_signal.tid, pthread_self());
 573
 574         while (1) {
 575                 health_code_update();
 576
 577                 health_poll_entry();
 578                 signr = sigwaitinfo(&mask, &info);
 579                 health_poll_exit();
 580                 if (signr == -1) {
 581                         if (errno != EINTR) {
 582                                 PERROR("sigwaitinfo");
 583                         }
 584                         continue;
 585                 } else if (signr == LTTNG_CONSUMER_SIG_SWITCH) {
 586                         metadata_switch_timer(ctx, info.si_signo, &info, NULL);
 587                 } else if (signr == LTTNG_CONSUMER_SIG_TEARDOWN) {
 588                         cmm_smp_mb();
 589                         CMM_STORE_SHARED(timer_signal.qs_done, 1);
 590                         cmm_smp_mb();
 591                         DBG("Signal timer metadata thread teardown");
 592                 } else if (signr == LTTNG_CONSUMER_SIG_LIVE) {
 593                         live_timer(ctx, info.si_signo, &info, NULL);
 594                 } else {
 595                         ERR("Unexpected signal %d\n", info.si_signo);
 596                 }
 597         }
 598
 599 error_testpoint:
 600         /* Only reached in testpoint error */
 601         health_error();
 602         health_unregister(health_consumerd);
 603
 604         rcu_unregister_thread();
 605
 606         /* Never return */
 607         return NULL;
 608 }