src/bin/lttng-sessiond/rotation-thread.cpp

   1 /*
   2  * Copyright (C) 2017 Julien Desfossez <jdesfossez@efficios.com>
   3  * Copyright (C) 2018 Jérémie Galarneau <jeremie.galarneau@efficios.com>
   4  *
   5  * SPDX-License-Identifier: GPL-2.0-only
   6  *
   7  */
   8
   9 #define _LGPL_SOURCE
  10 #include "cmd.hpp"
  11 #include "health-sessiond.hpp"
  12 #include "lttng-sessiond.hpp"
  13 #include "notification-thread-commands.hpp"
  14 #include "rotate.hpp"
  15 #include "rotation-thread.hpp"
  16 #include "session.hpp"
  17 #include "thread.hpp"
  18 #include "timer.hpp"
  19 #include "utils.hpp"
  20
  21 #include <common/align.hpp>
  22 #include <common/config/session-config.hpp>
  23 #include <common/defaults.hpp>
  24 #include <common/error.hpp>
  25 #include <common/futex.hpp>
  26 #include <common/hashtable/utils.hpp>
  27 #include <common/kernel-ctl/kernel-ctl.hpp>
  28 #include <common/time.hpp>
  29 #include <common/urcu.hpp>
  30 #include <common/utils.hpp>
  31
  32 #include <lttng/condition/condition-internal.hpp>
  33 #include <lttng/location-internal.hpp>
  34 #include <lttng/notification/channel-internal.hpp>
  35 #include <lttng/notification/notification-internal.hpp>
  36 #include <lttng/rotate-internal.hpp>
  37 #include <lttng/trigger/trigger.h>
  38
  39 #include <inttypes.h>
  40 #include <signal.h>
  41 #include <sys/stat.h>
  42 #include <time.h>
  43 #include <urcu.h>
  44 #include <urcu/list.h>
  45
  46 struct lttng_notification_channel *rotate_notification_channel = nullptr;
  47
  48 struct rotation_thread {
  49         struct lttng_poll_event events;
  50 };
  51
  52 /*
  53  * The timer thread enqueues jobs and wakes up the rotation thread.
  54  * When the rotation thread wakes up, it empties the queue.
  55  */
  56 struct rotation_thread_timer_queue {
  57         struct lttng_pipe *event_pipe;
  58         struct cds_list_head list;
  59         pthread_mutex_t lock;
  60 };
  61
  62 struct rotation_thread_handle {
  63         struct rotation_thread_timer_queue *rotation_timer_queue;
  64         /* Access to the notification thread cmd_queue */
  65         struct notification_thread_handle *notification_thread_handle;
  66         /* Thread-specific quit pipe. */
  67         struct lttng_pipe *quit_pipe;
  68 };
  69
  70 namespace {
  71 struct rotation_thread_job {
  72         enum rotation_thread_job_type type;
  73         struct ltt_session *session;
  74         /* List member in struct rotation_thread_timer_queue. */
  75         struct cds_list_head head;
  76 };
  77 } /* namespace */
  78
  79 static const char *get_job_type_str(enum rotation_thread_job_type job_type)
  80 {
  81         switch (job_type) {
  82         case ROTATION_THREAD_JOB_TYPE_CHECK_PENDING_ROTATION:
  83                 return "CHECK_PENDING_ROTATION";
  84         case ROTATION_THREAD_JOB_TYPE_SCHEDULED_ROTATION:
  85                 return "SCHEDULED_ROTATION";
  86         default:
  87                 abort();
  88         }
  89 }
  90
  91 struct rotation_thread_timer_queue *rotation_thread_timer_queue_create()
  92 {
  93         struct rotation_thread_timer_queue *queue = nullptr;
  94
  95         queue = zmalloc<rotation_thread_timer_queue>();
  96         if (!queue) {
  97                 PERROR("Failed to allocate timer rotate queue");
  98                 goto end;
  99         }
 100
 101         queue->event_pipe = lttng_pipe_open(FD_CLOEXEC | O_NONBLOCK);
 102         CDS_INIT_LIST_HEAD(&queue->list);
 103         pthread_mutex_init(&queue->lock, nullptr);
 104 end:
 105         return queue;
 106 }
 107
 108 void rotation_thread_timer_queue_destroy(struct rotation_thread_timer_queue *queue)
 109 {
 110         if (!queue) {
 111                 return;
 112         }
 113
 114         lttng_pipe_destroy(queue->event_pipe);
 115
 116         pthread_mutex_lock(&queue->lock);
 117         LTTNG_ASSERT(cds_list_empty(&queue->list));
 118         pthread_mutex_unlock(&queue->lock);
 119         pthread_mutex_destroy(&queue->lock);
 120         free(queue);
 121 }
 122
 123 /*
 124  * Destroy the thread data previously created by the init function.
 125  */
 126 void rotation_thread_handle_destroy(struct rotation_thread_handle *handle)
 127 {
 128         lttng_pipe_destroy(handle->quit_pipe);
 129         free(handle);
 130 }
 131
 132 struct rotation_thread_handle *
 133 rotation_thread_handle_create(struct rotation_thread_timer_queue *rotation_timer_queue,
 134                               struct notification_thread_handle *notification_thread_handle)
 135 {
 136         struct rotation_thread_handle *handle;
 137
 138         handle = zmalloc<rotation_thread_handle>();
 139         if (!handle) {
 140                 goto end;
 141         }
 142
 143         handle->rotation_timer_queue = rotation_timer_queue;
 144         handle->notification_thread_handle = notification_thread_handle;
 145         handle->quit_pipe = lttng_pipe_open(FD_CLOEXEC);
 146         if (!handle->quit_pipe) {
 147                 goto error;
 148         }
 149
 150 end:
 151         return handle;
 152 error:
 153         rotation_thread_handle_destroy(handle);
 154         return nullptr;
 155 }
 156
 157 /*
 158  * Called with the rotation_thread_timer_queue lock held.
 159  * Return true if the same timer job already exists in the queue, false if not.
 160  */
 161 static bool timer_job_exists(const struct rotation_thread_timer_queue *queue,
 162                              enum rotation_thread_job_type job_type,
 163                              struct ltt_session *session)
 164 {
 165         bool exists = false;
 166         struct rotation_thread_job *job;
 167
 168         cds_list_for_each_entry (job, &queue->list, head) {
 169                 if (job->session == session && job->type == job_type) {
 170                         exists = true;
 171                         goto end;
 172                 }
 173         }
 174 end:
 175         return exists;
 176 }
 177
 178 void rotation_thread_enqueue_job(struct rotation_thread_timer_queue *queue,
 179                                  enum rotation_thread_job_type job_type,
 180                                  struct ltt_session *session)
 181 {
 182         int ret;
 183         const char dummy = '!';
 184         struct rotation_thread_job *job = nullptr;
 185         const char *job_type_str = get_job_type_str(job_type);
 186
 187         pthread_mutex_lock(&queue->lock);
 188         if (timer_job_exists(queue, job_type, session)) {
 189                 /*
 190                  * This timer job is already pending, we don't need to add
 191                  * it.
 192                  */
 193                 goto end;
 194         }
 195
 196         job = zmalloc<rotation_thread_job>();
 197         if (!job) {
 198                 PERROR("Failed to allocate rotation thread job of type \"%s\" for session \"%s\"",
 199                        job_type_str,
 200                        session->name);
 201                 goto end;
 202         }
 203         /* No reason for this to fail as the caller must hold a reference. */
 204         (void) session_get(session);
 205
 206         job->session = session;
 207         job->type = job_type;
 208         cds_list_add_tail(&job->head, &queue->list);
 209
 210         ret = lttng_write(lttng_pipe_get_writefd(queue->event_pipe), &dummy, sizeof(dummy));
 211         if (ret < 0) {
 212                 /*
 213                  * We do not want to block in the timer handler, the job has
 214                  * been enqueued in the list, the wakeup pipe is probably full,
 215                  * the job will be processed when the rotation_thread catches
 216                  * up.
 217                  */
 218                 DIAGNOSTIC_PUSH
 219                 DIAGNOSTIC_IGNORE_LOGICAL_OP
 220                 if (errno == EAGAIN || errno == EWOULDBLOCK) {
 221                         DIAGNOSTIC_POP
 222                         /*
 223                          * Not an error, but would be surprising and indicate
 224                          * that the rotation thread can't keep up with the
 225                          * current load.
 226                          */
 227                         DBG("Wake-up pipe of rotation thread job queue is full");
 228                         goto end;
 229                 }
 230                 PERROR("Failed to wake-up the rotation thread after pushing a job of type \"%s\" for session \"%s\"",
 231                        job_type_str,
 232                        session->name);
 233                 goto end;
 234         }
 235
 236 end:
 237         pthread_mutex_unlock(&queue->lock);
 238 }
 239
 240 static int init_poll_set(struct lttng_poll_event *poll_set, struct rotation_thread_handle *handle)
 241 {
 242         int ret;
 243
 244         /*
 245          * Create pollset with size 3:
 246          *      - rotation thread quit pipe,
 247          *      - rotation thread timer queue pipe,
 248          *      - notification channel sock,
 249          */
 250         ret = lttng_poll_create(poll_set, 5, LTTNG_CLOEXEC);
 251         if (ret < 0) {
 252                 goto error;
 253         }
 254
 255         ret = lttng_poll_add(poll_set, lttng_pipe_get_readfd(handle->quit_pipe), LPOLLIN);
 256         if (ret < 0) {
 257                 ERR("Failed to add quit pipe read fd to poll set");
 258                 goto error;
 259         }
 260
 261         ret = lttng_poll_add(
 262                 poll_set, lttng_pipe_get_readfd(handle->rotation_timer_queue->event_pipe), LPOLLIN);
 263         if (ret < 0) {
 264                 ERR("Failed to add rotate_pending fd to poll set");
 265                 goto error;
 266         }
 267
 268         return ret;
 269 error:
 270         lttng_poll_clean(poll_set);
 271         return ret;
 272 }
 273
 274 static void fini_thread_state(struct rotation_thread *state)
 275 {
 276         lttng_poll_clean(&state->events);
 277         if (rotate_notification_channel) {
 278                 lttng_notification_channel_destroy(rotate_notification_channel);
 279         }
 280 }
 281
 282 static int init_thread_state(struct rotation_thread_handle *handle, struct rotation_thread *state)
 283 {
 284         int ret;
 285
 286         memset(state, 0, sizeof(*state));
 287         lttng_poll_init(&state->events);
 288
 289         ret = init_poll_set(&state->events, handle);
 290         if (ret) {
 291                 ERR("Failed to initialize rotation thread poll set");
 292                 goto end;
 293         }
 294
 295         rotate_notification_channel =
 296                 lttng_notification_channel_create(lttng_session_daemon_notification_endpoint);
 297         if (!rotate_notification_channel) {
 298                 ERR("Could not create notification channel");
 299                 ret = -1;
 300                 goto end;
 301         }
 302         ret = lttng_poll_add(&state->events, rotate_notification_channel->socket, LPOLLIN);
 303         if (ret < 0) {
 304                 ERR("Failed to add notification fd to pollset");
 305                 goto end;
 306         }
 307
 308 end:
 309         return ret;
 310 }
 311
 312 static void check_session_rotation_pending_on_consumers(struct ltt_session *session,
 313                                                         bool *_rotation_completed)
 314 {
 315         int ret = 0;
 316         struct consumer_socket *socket;
 317         struct cds_lfht_iter iter;
 318         enum consumer_trace_chunk_exists_status exists_status;
 319         uint64_t relayd_id;
 320         bool chunk_exists_on_peer = false;
 321         enum lttng_trace_chunk_status chunk_status;
 322         lttng::urcu::read_lock_guard read_lock;
 323
 324         LTTNG_ASSERT(session->chunk_being_archived);
 325
 326         /*
 327          * Check for a local pending rotation on all consumers (32-bit
 328          * user space, 64-bit user space, and kernel).
 329          */
 330         if (!session->ust_session) {
 331                 goto skip_ust;
 332         }
 333
 334         cds_lfht_for_each_entry (
 335                 session->ust_session->consumer->socks->ht, &iter, socket, node.node) {
 336                 relayd_id = session->ust_session->consumer->type == CONSUMER_DST_LOCAL ?
 337                         -1ULL :
 338                         session->ust_session->consumer->net_seq_index;
 339
 340                 pthread_mutex_lock(socket->lock);
 341                 ret = consumer_trace_chunk_exists(socket,
 342                                                   relayd_id,
 343                                                   session->id,
 344                                                   session->chunk_being_archived,
 345                                                   &exists_status);
 346                 if (ret) {
 347                         pthread_mutex_unlock(socket->lock);
 348                         ERR("Error occurred while checking rotation status on consumer daemon");
 349                         goto end;
 350                 }
 351
 352                 if (exists_status != CONSUMER_TRACE_CHUNK_EXISTS_STATUS_UNKNOWN_CHUNK) {
 353                         pthread_mutex_unlock(socket->lock);
 354                         chunk_exists_on_peer = true;
 355                         goto end;
 356                 }
 357                 pthread_mutex_unlock(socket->lock);
 358         }
 359
 360 skip_ust:
 361         if (!session->kernel_session) {
 362                 goto skip_kernel;
 363         }
 364         cds_lfht_for_each_entry (
 365                 session->kernel_session->consumer->socks->ht, &iter, socket, node.node) {
 366                 pthread_mutex_lock(socket->lock);
 367                 relayd_id = session->kernel_session->consumer->type == CONSUMER_DST_LOCAL ?
 368                         -1ULL :
 369                         session->kernel_session->consumer->net_seq_index;
 370
 371                 ret = consumer_trace_chunk_exists(socket,
 372                                                   relayd_id,
 373                                                   session->id,
 374                                                   session->chunk_being_archived,
 375                                                   &exists_status);
 376                 if (ret) {
 377                         pthread_mutex_unlock(socket->lock);
 378                         ERR("Error occurred while checking rotation status on consumer daemon");
 379                         goto end;
 380                 }
 381
 382                 if (exists_status != CONSUMER_TRACE_CHUNK_EXISTS_STATUS_UNKNOWN_CHUNK) {
 383                         pthread_mutex_unlock(socket->lock);
 384                         chunk_exists_on_peer = true;
 385                         goto end;
 386                 }
 387                 pthread_mutex_unlock(socket->lock);
 388         }
 389 skip_kernel:
 390 end:
 391
 392         if (!chunk_exists_on_peer) {
 393                 uint64_t chunk_being_archived_id;
 394
 395                 chunk_status = lttng_trace_chunk_get_id(session->chunk_being_archived,
 396                                                         &chunk_being_archived_id);
 397                 LTTNG_ASSERT(chunk_status == LTTNG_TRACE_CHUNK_STATUS_OK);
 398                 DBG("Rotation of trace archive %" PRIu64
 399                     " of session \"%s\" is complete on all consumers",
 400                     chunk_being_archived_id,
 401                     session->name);
 402         }
 403         *_rotation_completed = !chunk_exists_on_peer;
 404         if (ret) {
 405                 ret = session_reset_rotation_state(session, LTTNG_ROTATION_STATE_ERROR);
 406                 if (ret) {
 407                         ERR("Failed to reset rotation state of session \"%s\"", session->name);
 408                 }
 409         }
 410 }
 411
 412 /*
 413  * Check if the last rotation was completed, called with session lock held.
 414  * Should only return non-zero in the event of a fatal error. Doing so will
 415  * shutdown the thread.
 416  */
 417 static int
 418 check_session_rotation_pending(struct ltt_session *session,
 419                                struct notification_thread_handle *notification_thread_handle)
 420 {
 421         int ret;
 422         struct lttng_trace_archive_location *location;
 423         enum lttng_trace_chunk_status chunk_status;
 424         bool rotation_completed = false;
 425         const char *archived_chunk_name;
 426         uint64_t chunk_being_archived_id;
 427
 428         if (!session->chunk_being_archived) {
 429                 ret = 0;
 430                 goto end;
 431         }
 432
 433         chunk_status =
 434                 lttng_trace_chunk_get_id(session->chunk_being_archived, &chunk_being_archived_id);
 435         LTTNG_ASSERT(chunk_status == LTTNG_TRACE_CHUNK_STATUS_OK);
 436
 437         DBG("Checking for pending rotation on session \"%s\", trace archive %" PRIu64,
 438             session->name,
 439             chunk_being_archived_id);
 440
 441         /*
 442          * The rotation-pending check timer of a session is launched in
 443          * one-shot mode. If the rotation is incomplete, the rotation
 444          * thread will re-enable the pending-check timer.
 445          *
 446          * The timer thread can't stop the timer itself since it is involved
 447          * in the check for the timer's quiescence.
 448          */
 449         ret = timer_session_rotation_pending_check_stop(session);
 450         if (ret) {
 451                 goto check_ongoing_rotation;
 452         }
 453
 454         check_session_rotation_pending_on_consumers(session, &rotation_completed);
 455         if (!rotation_completed || session->rotation_state == LTTNG_ROTATION_STATE_ERROR) {
 456                 goto check_ongoing_rotation;
 457         }
 458
 459         /*
 460          * Now we can clear the "ONGOING" state in the session. New
 461          * rotations can start now.
 462          */
 463         chunk_status = lttng_trace_chunk_get_name(
 464                 session->chunk_being_archived, &archived_chunk_name, nullptr);
 465         LTTNG_ASSERT(chunk_status == LTTNG_TRACE_CHUNK_STATUS_OK);
 466         free(session->last_archived_chunk_name);
 467         session->last_archived_chunk_name = strdup(archived_chunk_name);
 468         if (!session->last_archived_chunk_name) {
 469                 PERROR("Failed to duplicate archived chunk name");
 470         }
 471         session_reset_rotation_state(session, LTTNG_ROTATION_STATE_COMPLETED);
 472
 473         if (!session->quiet_rotation) {
 474                 location = session_get_trace_archive_location(session);
 475                 ret = notification_thread_command_session_rotation_completed(
 476                         notification_thread_handle,
 477                         session->id,
 478                         session->last_archived_chunk_id.value,
 479                         location);
 480                 lttng_trace_archive_location_put(location);
 481                 if (ret != LTTNG_OK) {
 482                         ERR("Failed to notify notification thread of completed rotation for session %s",
 483                             session->name);
 484                 }
 485         }
 486
 487         ret = 0;
 488 check_ongoing_rotation:
 489         if (session->rotation_state == LTTNG_ROTATION_STATE_ONGOING) {
 490                 chunk_status = lttng_trace_chunk_get_id(session->chunk_being_archived,
 491                                                         &chunk_being_archived_id);
 492                 LTTNG_ASSERT(chunk_status == LTTNG_TRACE_CHUNK_STATUS_OK);
 493
 494                 DBG("Rotation of trace archive %" PRIu64 " is still pending for session %s",
 495                     chunk_being_archived_id,
 496                     session->name);
 497                 ret = timer_session_rotation_pending_check_start(session,
 498                                                                  DEFAULT_ROTATE_PENDING_TIMER);
 499                 if (ret) {
 500                         ERR("Failed to re-enable rotation pending timer");
 501                         ret = -1;
 502                         goto end;
 503                 }
 504         }
 505
 506 end:
 507         return ret;
 508 }
 509
 510 /* Call with the session and session_list locks held. */
 511 static int launch_session_rotation(struct ltt_session *session)
 512 {
 513         int ret;
 514         struct lttng_rotate_session_return rotation_return;
 515
 516         DBG("Launching scheduled time-based rotation on session \"%s\"", session->name);
 517
 518         ret = cmd_rotate_session(
 519                 session, &rotation_return, false, LTTNG_TRACE_CHUNK_COMMAND_TYPE_MOVE_TO_COMPLETED);
 520         if (ret == LTTNG_OK) {
 521                 DBG("Scheduled time-based rotation successfully launched on session \"%s\"",
 522                     session->name);
 523         } else {
 524                 /* Don't consider errors as fatal. */
 525                 DBG("Scheduled time-based rotation aborted for session %s: %s",
 526                     session->name,
 527                     lttng_strerror(ret));
 528         }
 529         return 0;
 530 }
 531
 532 static int run_job(struct rotation_thread_job *job,
 533                    struct ltt_session *session,
 534                    struct notification_thread_handle *notification_thread_handle)
 535 {
 536         int ret;
 537
 538         switch (job->type) {
 539         case ROTATION_THREAD_JOB_TYPE_SCHEDULED_ROTATION:
 540                 ret = launch_session_rotation(session);
 541                 break;
 542         case ROTATION_THREAD_JOB_TYPE_CHECK_PENDING_ROTATION:
 543                 ret = check_session_rotation_pending(session, notification_thread_handle);
 544                 break;
 545         default:
 546                 abort();
 547         }
 548         return ret;
 549 }
 550
 551 static int handle_job_queue(struct rotation_thread_handle *handle,
 552                             struct rotation_thread *state __attribute__((unused)),
 553                             struct rotation_thread_timer_queue *queue)
 554 {
 555         int ret = 0;
 556
 557         for (;;) {
 558                 struct ltt_session *session;
 559                 struct rotation_thread_job *job;
 560
 561                 /* Take the queue lock only to pop an element from the list. */
 562                 pthread_mutex_lock(&queue->lock);
 563                 if (cds_list_empty(&queue->list)) {
 564                         pthread_mutex_unlock(&queue->lock);
 565                         break;
 566                 }
 567                 job = cds_list_first_entry(&queue->list, typeof(*job), head);
 568                 cds_list_del(&job->head);
 569                 pthread_mutex_unlock(&queue->lock);
 570
 571                 session_lock_list();
 572                 session = job->session;
 573                 if (!session) {
 574                         DBG("Session \"%s\" not found", session->name != NULL ? session->name : "");
 575                         /*
 576                          * This is a non-fatal error, and we cannot report it to
 577                          * the user (timer), so just print the error and
 578                          * continue the processing.
 579                          *
 580                          * While the timer thread will purge pending signals for
 581                          * a session on the session's destruction, it is
 582                          * possible for a job targeting that session to have
 583                          * already been queued before it was destroyed.
 584                          */
 585                         free(job);
 586                         session_put(session);
 587                         session_unlock_list();
 588                         continue;
 589                 }
 590
 591                 session_lock(session);
 592                 ret = run_job(job, session, handle->notification_thread_handle);
 593                 session_unlock(session);
 594                 /* Release reference held by the job. */
 595                 session_put(session);
 596                 session_unlock_list();
 597                 free(job);
 598                 if (ret) {
 599                         goto end;
 600                 }
 601         }
 602
 603         ret = 0;
 604
 605 end:
 606         return ret;
 607 }
 608
 609 static int handle_condition(const struct lttng_notification *notification,
 610                             struct notification_thread_handle *notification_thread_handle)
 611 {
 612         int ret = 0;
 613         const char *condition_session_name = nullptr;
 614         enum lttng_condition_type condition_type;
 615         enum lttng_condition_status condition_status;
 616         enum lttng_evaluation_status evaluation_status;
 617         uint64_t consumed;
 618         struct ltt_session *session;
 619         const struct lttng_condition *condition =
 620                 lttng_notification_get_const_condition(notification);
 621         const struct lttng_evaluation *evaluation =
 622                 lttng_notification_get_const_evaluation(notification);
 623
 624         condition_type = lttng_condition_get_type(condition);
 625
 626         if (condition_type != LTTNG_CONDITION_TYPE_SESSION_CONSUMED_SIZE) {
 627                 ret = -1;
 628                 ERR("Condition type and session usage type are not the same");
 629                 goto end;
 630         }
 631
 632         /* Fetch info to test */
 633         condition_status = lttng_condition_session_consumed_size_get_session_name(
 634                 condition, &condition_session_name);
 635         if (condition_status != LTTNG_CONDITION_STATUS_OK) {
 636                 ERR("Session name could not be fetched");
 637                 ret = -1;
 638                 goto end;
 639         }
 640         evaluation_status =
 641                 lttng_evaluation_session_consumed_size_get_consumed_size(evaluation, &consumed);
 642         if (evaluation_status != LTTNG_EVALUATION_STATUS_OK) {
 643                 ERR("Failed to get evaluation");
 644                 ret = -1;
 645                 goto end;
 646         }
 647
 648         session_lock_list();
 649         session = session_find_by_name(condition_session_name);
 650         if (!session) {
 651                 DBG("Failed to find session while handling notification: notification type = %s, session name = `%s`",
 652                     lttng_condition_type_str(condition_type),
 653                     condition_session_name);
 654                 /*
 655                  * Not a fatal error: a session can be destroyed before we get
 656                  * the chance to handle the notification.
 657                  */
 658                 ret = 0;
 659                 session_unlock_list();
 660                 goto end;
 661         }
 662         session_lock(session);
 663
 664         if (!lttng_trigger_is_equal(session->rotate_trigger,
 665                                     lttng_notification_get_const_trigger(notification))) {
 666                 /* Notification does not originate from our rotation trigger. */
 667                 ret = 0;
 668                 goto end_unlock;
 669         }
 670
 671         ret = unsubscribe_session_consumed_size_rotation(session, notification_thread_handle);
 672         if (ret) {
 673                 goto end_unlock;
 674         }
 675
 676         ret = cmd_rotate_session(
 677                 session, nullptr, false, LTTNG_TRACE_CHUNK_COMMAND_TYPE_MOVE_TO_COMPLETED);
 678         switch (ret) {
 679         case LTTNG_OK:
 680                 break;
 681         case -LTTNG_ERR_ROTATION_PENDING:
 682                 DBG("Rotate already pending, subscribe to the next threshold value");
 683                 break;
 684         case -LTTNG_ERR_ROTATION_MULTIPLE_AFTER_STOP:
 685                 DBG("Rotation already happened since last stop, subscribe to the next threshold value");
 686                 break;
 687         case -LTTNG_ERR_ROTATION_AFTER_STOP_CLEAR:
 688                 DBG("Rotation already happened since last stop and clear, subscribe to the next threshold value");
 689                 break;
 690         default:
 691                 ERR("Failed to rotate on size notification with error: %s", lttng_strerror(ret));
 692                 ret = -1;
 693                 goto end_unlock;
 694         }
 695
 696         ret = subscribe_session_consumed_size_rotation(
 697                 session, consumed + session->rotate_size, notification_thread_handle);
 698         if (ret) {
 699                 ERR("Failed to subscribe to session consumed size condition");
 700                 goto end_unlock;
 701         }
 702         ret = 0;
 703
 704 end_unlock:
 705         session_unlock(session);
 706         session_put(session);
 707         session_unlock_list();
 708 end:
 709         return ret;
 710 }
 711
 712 static int handle_notification_channel(int fd __attribute__((unused)),
 713                                        struct rotation_thread_handle *handle,
 714                                        struct rotation_thread *state __attribute__((unused)))
 715 {
 716         int ret;
 717         bool notification_pending;
 718         struct lttng_notification *notification = nullptr;
 719         enum lttng_notification_channel_status status;
 720
 721         status = lttng_notification_channel_has_pending_notification(rotate_notification_channel,
 722                                                                      &notification_pending);
 723         if (status != LTTNG_NOTIFICATION_CHANNEL_STATUS_OK) {
 724                 ERR("Error occurred while checking for pending notification");
 725                 ret = -1;
 726                 goto end;
 727         }
 728
 729         if (!notification_pending) {
 730                 ret = 0;
 731                 goto end;
 732         }
 733
 734         /* Receive the next notification. */
 735         status = lttng_notification_channel_get_next_notification(rotate_notification_channel,
 736                                                                   &notification);
 737
 738         switch (status) {
 739         case LTTNG_NOTIFICATION_CHANNEL_STATUS_OK:
 740                 break;
 741         case LTTNG_NOTIFICATION_CHANNEL_STATUS_NOTIFICATIONS_DROPPED:
 742                 /* Not an error, we will wait for the next one */
 743                 ret = 0;
 744                 goto end;
 745                 ;
 746         case LTTNG_NOTIFICATION_CHANNEL_STATUS_CLOSED:
 747                 ERR("Notification channel was closed");
 748                 ret = -1;
 749                 goto end;
 750         default:
 751                 /* Unhandled conditions / errors. */
 752                 ERR("Unknown notification channel status");
 753                 ret = -1;
 754                 goto end;
 755         }
 756
 757         ret = handle_condition(notification, handle->notification_thread_handle);
 758
 759 end:
 760         lttng_notification_destroy(notification);
 761         return ret;
 762 }
 763
 764 static void *thread_rotation(void *data)
 765 {
 766         int ret;
 767         struct rotation_thread_handle *handle = (rotation_thread_handle *) data;
 768         struct rotation_thread thread;
 769         int queue_pipe_fd;
 770
 771         DBG("Started rotation thread");
 772         rcu_register_thread();
 773         rcu_thread_online();
 774         health_register(the_health_sessiond, HEALTH_SESSIOND_TYPE_ROTATION);
 775         health_code_update();
 776
 777         if (!handle) {
 778                 ERR("Invalid thread context provided");
 779                 goto end;
 780         }
 781
 782         queue_pipe_fd = lttng_pipe_get_readfd(handle->rotation_timer_queue->event_pipe);
 783
 784         ret = init_thread_state(handle, &thread);
 785         if (ret) {
 786                 goto error;
 787         }
 788
 789         while (true) {
 790                 int fd_count, i;
 791
 792                 health_poll_entry();
 793                 DBG("Entering poll wait");
 794                 ret = lttng_poll_wait(&thread.events, -1);
 795                 DBG("Poll wait returned (%i)", ret);
 796                 health_poll_exit();
 797                 if (ret < 0) {
 798                         /*
 799                          * Restart interrupted system call.
 800                          */
 801                         if (errno == EINTR) {
 802                                 continue;
 803                         }
 804                         ERR("Error encountered during lttng_poll_wait (%i)", ret);
 805                         goto error;
 806                 }
 807
 808                 fd_count = ret;
 809                 for (i = 0; i < fd_count; i++) {
 810                         int fd = LTTNG_POLL_GETFD(&thread.events, i);
 811                         uint32_t revents = LTTNG_POLL_GETEV(&thread.events, i);
 812
 813                         DBG("Handling fd (%i) activity (%u)", fd, revents);
 814
 815                         if (revents & LPOLLERR) {
 816                                 ERR("Polling returned an error on fd %i", fd);
 817                                 goto error;
 818                         }
 819
 820                         if (fd == rotate_notification_channel->socket) {
 821                                 ret = handle_notification_channel(fd, handle, &thread);
 822                                 if (ret) {
 823                                         ERR("Error occurred while handling activity on notification channel socket");
 824                                         goto error;
 825                                 }
 826                         } else {
 827                                 /* Job queue or quit pipe activity. */
 828
 829                                 /*
 830                                  * The job queue is serviced if there is
 831                                  * activity on the quit pipe to ensure it is
 832                                  * flushed and all references held in the queue
 833                                  * are released.
 834                                  */
 835                                 ret = handle_job_queue(
 836                                         handle, &thread, handle->rotation_timer_queue);
 837                                 if (ret) {
 838                                         ERR("Failed to handle rotation timer pipe event");
 839                                         goto error;
 840                                 }
 841
 842                                 if (fd == queue_pipe_fd) {
 843                                         char buf;
 844
 845                                         ret = lttng_read(fd, &buf, 1);
 846                                         if (ret != 1) {
 847                                                 ERR("Failed to read from wakeup pipe (fd = %i)",
 848                                                     fd);
 849                                                 goto error;
 850                                         }
 851                                 } else {
 852                                         DBG("Quit pipe activity");
 853                                         goto exit;
 854                                 }
 855                         }
 856                 }
 857         }
 858 exit:
 859 error:
 860         DBG("Thread exit");
 861         fini_thread_state(&thread);
 862 end:
 863         health_unregister(the_health_sessiond);
 864         rcu_thread_offline();
 865         rcu_unregister_thread();
 866         return nullptr;
 867 }
 868
 869 static bool shutdown_rotation_thread(void *thread_data)
 870 {
 871         struct rotation_thread_handle *handle = (rotation_thread_handle *) thread_data;
 872         const int write_fd = lttng_pipe_get_writefd(handle->quit_pipe);
 873
 874         return notify_thread_pipe(write_fd) == 1;
 875 }
 876
 877 bool launch_rotation_thread(struct rotation_thread_handle *handle)
 878 {
 879         struct lttng_thread *thread;
 880
 881         thread = lttng_thread_create(
 882                 "Rotation", thread_rotation, shutdown_rotation_thread, nullptr, handle);
 883         if (!thread) {
 884                 goto error;
 885         }
 886         lttng_thread_put(thread);
 887         return true;
 888 error:
 889         return false;
 890 }