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

   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 <lttng/trigger/trigger.h>
  11 #include <common/error.h>
  12 #include <common/config/session-config.h>
  13 #include <common/defaults.h>
  14 #include <common/utils.h>
  15 #include <common/futex.h>
  16 #include <common/align.h>
  17 #include <common/time.h>
  18 #include <common/hashtable/utils.h>
  19 #include <sys/stat.h>
  20 #include <time.h>
  21 #include <signal.h>
  22 #include <inttypes.h>
  23
  24 #include <common/kernel-ctl/kernel-ctl.h>
  25 #include <lttng/notification/channel-internal.h>
  26 #include <lttng/rotate-internal.h>
  27
  28 #include "rotation-thread.h"
  29 #include "lttng-sessiond.h"
  30 #include "health-sessiond.h"
  31 #include "rotate.h"
  32 #include "cmd.h"
  33 #include "session.h"
  34 #include "timer.h"
  35 #include "notification-thread-commands.h"
  36 #include "utils.h"
  37 #include "thread.h"
  38
  39 #include <urcu.h>
  40 #include <urcu/list.h>
  41
  42 struct lttng_notification_channel *rotate_notification_channel = NULL;
  43
  44 struct rotation_thread {
  45         struct lttng_poll_event events;
  46 };
  47
  48 struct rotation_thread_job {
  49         enum rotation_thread_job_type type;
  50         struct ltt_session *session;
  51         /* List member in struct rotation_thread_timer_queue. */
  52         struct cds_list_head head;
  53 };
  54
  55 /*
  56  * The timer thread enqueues jobs and wakes up the rotation thread.
  57  * When the rotation thread wakes up, it empties the queue.
  58  */
  59 struct rotation_thread_timer_queue {
  60         struct lttng_pipe *event_pipe;
  61         struct cds_list_head list;
  62         pthread_mutex_t lock;
  63 };
  64
  65 struct rotation_thread_handle {
  66         struct rotation_thread_timer_queue *rotation_timer_queue;
  67         /* Access to the notification thread cmd_queue */
  68         struct notification_thread_handle *notification_thread_handle;
  69         /* Thread-specific quit pipe. */
  70         struct lttng_pipe *quit_pipe;
  71 };
  72
  73 static
  74 const char *get_job_type_str(enum rotation_thread_job_type job_type)
  75 {
  76         switch (job_type) {
  77         case ROTATION_THREAD_JOB_TYPE_CHECK_PENDING_ROTATION:
  78                 return "CHECK_PENDING_ROTATION";
  79         case ROTATION_THREAD_JOB_TYPE_SCHEDULED_ROTATION:
  80                 return "SCHEDULED_ROTATION";
  81         default:
  82                 abort();
  83         }
  84 }
  85
  86 struct rotation_thread_timer_queue *rotation_thread_timer_queue_create(void)
  87 {
  88         struct rotation_thread_timer_queue *queue = NULL;
  89
  90         queue = zmalloc(sizeof(*queue));
  91         if (!queue) {
  92                 PERROR("Failed to allocate timer rotate queue");
  93                 goto end;
  94         }
  95
  96         queue->event_pipe = lttng_pipe_open(FD_CLOEXEC | O_NONBLOCK);
  97         CDS_INIT_LIST_HEAD(&queue->list);
  98         pthread_mutex_init(&queue->lock, NULL);
  99 end:
 100         return queue;
 101 }
 102
 103 void rotation_thread_timer_queue_destroy(
 104                 struct rotation_thread_timer_queue *queue)
 105 {
 106         if (!queue) {
 107                 return;
 108         }
 109
 110         lttng_pipe_destroy(queue->event_pipe);
 111
 112         pthread_mutex_lock(&queue->lock);
 113         assert(cds_list_empty(&queue->list));
 114         pthread_mutex_unlock(&queue->lock);
 115         pthread_mutex_destroy(&queue->lock);
 116         free(queue);
 117 }
 118
 119 /*
 120  * Destroy the thread data previously created by the init function.
 121  */
 122 void rotation_thread_handle_destroy(
 123                 struct rotation_thread_handle *handle)
 124 {
 125         lttng_pipe_destroy(handle->quit_pipe);
 126         free(handle);
 127 }
 128
 129 struct rotation_thread_handle *rotation_thread_handle_create(
 130                 struct rotation_thread_timer_queue *rotation_timer_queue,
 131                 struct notification_thread_handle *notification_thread_handle)
 132 {
 133         struct rotation_thread_handle *handle;
 134
 135         handle = zmalloc(sizeof(*handle));
 136         if (!handle) {
 137                 goto end;
 138         }
 139
 140         handle->rotation_timer_queue = rotation_timer_queue;
 141         handle->notification_thread_handle = notification_thread_handle;
 142         handle->quit_pipe = lttng_pipe_open(FD_CLOEXEC);
 143         if (!handle->quit_pipe) {
 144                 goto error;
 145         }
 146
 147 end:
 148         return handle;
 149 error:
 150         rotation_thread_handle_destroy(handle);
 151         return NULL;
 152 }
 153
 154 /*
 155  * Called with the rotation_thread_timer_queue lock held.
 156  * Return true if the same timer job already exists in the queue, false if not.
 157  */
 158 static
 159 bool timer_job_exists(const struct rotation_thread_timer_queue *queue,
 160                 enum rotation_thread_job_type job_type,
 161                 struct ltt_session *session)
 162 {
 163         bool exists = false;
 164         struct rotation_thread_job *job;
 165
 166         cds_list_for_each_entry(job, &queue->list, head) {
 167                 if (job->session == session && job->type == job_type) {
 168                         exists = true;
 169                         goto end;
 170                 }
 171         }
 172 end:
 173         return exists;
 174 }
 175
 176 void rotation_thread_enqueue_job(struct rotation_thread_timer_queue *queue,
 177                 enum rotation_thread_job_type job_type,
 178                 struct ltt_session *session)
 179 {
 180         int ret;
 181         const char dummy = '!';
 182         struct rotation_thread_job *job = NULL;
 183         const char *job_type_str = get_job_type_str(job_type);
 184
 185         pthread_mutex_lock(&queue->lock);
 186         if (timer_job_exists(queue, job_type, session)) {
 187                 /*
 188                  * This timer job is already pending, we don't need to add
 189                  * it.
 190                  */
 191                 goto end;
 192         }
 193
 194         job = zmalloc(sizeof(struct rotation_thread_job));
 195         if (!job) {
 196                 PERROR("Failed to allocate rotation thread job of type \"%s\" for session \"%s\"",
 197                                 job_type_str, session->name);
 198                 goto end;
 199         }
 200         /* No reason for this to fail as the caller must hold a reference. */
 201         (void) session_get(session);
 202
 203         job->session = session;
 204         job->type = job_type;
 205         cds_list_add_tail(&job->head, &queue->list);
 206
 207         ret = lttng_write(lttng_pipe_get_writefd(queue->event_pipe), &dummy,
 208                         sizeof(dummy));
 209         if (ret < 0) {
 210                 /*
 211                  * We do not want to block in the timer handler, the job has
 212                  * been enqueued in the list, the wakeup pipe is probably full,
 213                  * the job will be processed when the rotation_thread catches
 214                  * up.
 215                  */
 216                 if (errno == EAGAIN || errno == EWOULDBLOCK) {
 217                         /*
 218                          * Not an error, but would be surprising and indicate
 219                          * that the rotation thread can't keep up with the
 220                          * current load.
 221                          */
 222                         DBG("Wake-up pipe of rotation thread job queue is full");
 223                         goto end;
 224                 }
 225                 PERROR("Failed to wake-up the rotation thread after pushing a job of type \"%s\" for session \"%s\"",
 226                                 job_type_str, session->name);
 227                 goto end;
 228         }
 229
 230 end:
 231         pthread_mutex_unlock(&queue->lock);
 232 }
 233
 234 static
 235 int init_poll_set(struct lttng_poll_event *poll_set,
 236                 struct rotation_thread_handle *handle)
 237 {
 238         int ret;
 239
 240         /*
 241          * Create pollset with size 3:
 242          *      - rotation thread quit pipe,
 243          *      - rotation thread timer queue pipe,
 244          *      - notification channel sock,
 245          */
 246         ret = lttng_poll_create(poll_set, 5, LTTNG_CLOEXEC);
 247         if (ret < 0) {
 248                 goto error;
 249         }
 250
 251         ret = lttng_poll_add(poll_set,
 252                         lttng_pipe_get_readfd(handle->quit_pipe),
 253                         LPOLLIN | LPOLLERR);
 254         if (ret < 0) {
 255                 ERR("[rotation-thread] Failed to add quit pipe read fd to poll set");
 256                 goto error;
 257         }
 258
 259         ret = lttng_poll_add(poll_set,
 260                         lttng_pipe_get_readfd(handle->rotation_timer_queue->event_pipe),
 261                         LPOLLIN | LPOLLERR);
 262         if (ret < 0) {
 263                 ERR("[rotation-thread] Failed to add rotate_pending fd to poll set");
 264                 goto error;
 265         }
 266
 267         return ret;
 268 error:
 269         lttng_poll_clean(poll_set);
 270         return ret;
 271 }
 272
 273 static
 274 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
 283 int init_thread_state(struct rotation_thread_handle *handle,
 284                 struct rotation_thread *state)
 285 {
 286         int ret;
 287
 288         memset(state, 0, sizeof(*state));
 289         lttng_poll_init(&state->events);
 290
 291         ret = init_poll_set(&state->events, handle);
 292         if (ret) {
 293                 ERR("[rotation-thread] Failed to initialize rotation thread poll set");
 294                 goto end;
 295         }
 296
 297         rotate_notification_channel = lttng_notification_channel_create(
 298                         lttng_session_daemon_notification_endpoint);
 299         if (!rotate_notification_channel) {
 300                 ERR("[rotation-thread] Could not create notification channel");
 301                 ret = -1;
 302                 goto end;
 303         }
 304         ret = lttng_poll_add(&state->events, rotate_notification_channel->socket,
 305                         LPOLLIN | LPOLLERR);
 306         if (ret < 0) {
 307                 ERR("[rotation-thread] Failed to add notification fd to pollset");
 308                 goto end;
 309         }
 310
 311 end:
 312         return ret;
 313 }
 314
 315 static
 316 void check_session_rotation_pending_on_consumers(struct ltt_session *session,
 317                 bool *_rotation_completed)
 318 {
 319         int ret = 0;
 320         struct consumer_socket *socket;
 321         struct cds_lfht_iter iter;
 322         enum consumer_trace_chunk_exists_status exists_status;
 323         uint64_t relayd_id;
 324         bool chunk_exists_on_peer = false;
 325         enum lttng_trace_chunk_status chunk_status;
 326
 327         assert(session->chunk_being_archived);
 328
 329         /*
 330          * Check for a local pending rotation on all consumers (32-bit
 331          * user space, 64-bit user space, and kernel).
 332          */
 333         rcu_read_lock();
 334         if (!session->ust_session) {
 335                 goto skip_ust;
 336         }
 337         cds_lfht_for_each_entry(session->ust_session->consumer->socks->ht,
 338                         &iter, socket, node.node) {
 339                 relayd_id = session->ust_session->consumer->type == CONSUMER_DST_LOCAL ?
 340                                 -1ULL :
 341                                 session->ust_session->consumer->net_seq_index;
 342
 343                 pthread_mutex_lock(socket->lock);
 344                 ret = consumer_trace_chunk_exists(socket,
 345                                 relayd_id,
 346                                 session->id, session->chunk_being_archived,
 347                                 &exists_status);
 348                 if (ret) {
 349                         pthread_mutex_unlock(socket->lock);
 350                         ERR("Error occurred while checking rotation status on consumer daemon");
 351                         goto end;
 352                 }
 353
 354                 if (exists_status != CONSUMER_TRACE_CHUNK_EXISTS_STATUS_UNKNOWN_CHUNK) {
 355                         pthread_mutex_unlock(socket->lock);
 356                         chunk_exists_on_peer = true;
 357                         goto end;
 358                 }
 359                 pthread_mutex_unlock(socket->lock);
 360         }
 361
 362 skip_ust:
 363         if (!session->kernel_session) {
 364                 goto skip_kernel;
 365         }
 366         cds_lfht_for_each_entry(session->kernel_session->consumer->socks->ht,
 367                                 &iter, socket, node.node) {
 368                 pthread_mutex_lock(socket->lock);
 369                 relayd_id = session->kernel_session->consumer->type == CONSUMER_DST_LOCAL ?
 370                                 -1ULL :
 371                                 session->kernel_session->consumer->net_seq_index;
 372
 373                 ret = consumer_trace_chunk_exists(socket,
 374                                 relayd_id,
 375                                 session->id, session->chunk_being_archived,
 376                                 &exists_status);
 377                 if (ret) {
 378                         pthread_mutex_unlock(socket->lock);
 379                         ERR("Error occurred while checking rotation status on consumer daemon");
 380                         goto end;
 381                 }
 382
 383                 if (exists_status != CONSUMER_TRACE_CHUNK_EXISTS_STATUS_UNKNOWN_CHUNK) {
 384                         pthread_mutex_unlock(socket->lock);
 385                         chunk_exists_on_peer = true;
 386                         goto end;
 387                 }
 388                 pthread_mutex_unlock(socket->lock);
 389         }
 390 skip_kernel:
 391 end:
 392         rcu_read_unlock();
 393
 394         if (!chunk_exists_on_peer) {
 395                 uint64_t chunk_being_archived_id;
 396
 397                 chunk_status = lttng_trace_chunk_get_id(
 398                                 session->chunk_being_archived,
 399                                 &chunk_being_archived_id);
 400                 assert(chunk_status == LTTNG_TRACE_CHUNK_STATUS_OK);
 401                 DBG("[rotation-thread] Rotation of trace archive %" PRIu64 " of session \"%s\" is complete on all consumers",
 402                                 chunk_being_archived_id,
 403                                 session->name);
 404         }
 405         *_rotation_completed = !chunk_exists_on_peer;
 406         if (ret) {
 407                 ret = session_reset_rotation_state(session,
 408                                 LTTNG_ROTATION_STATE_ERROR);
 409                 if (ret) {
 410                         ERR("Failed to reset rotation state of session \"%s\"",
 411                                         session->name);
 412                 }
 413         }
 414 }
 415
 416 /*
 417  * Check if the last rotation was completed, called with session lock held.
 418  * Should only return non-zero in the event of a fatal error. Doing so will
 419  * shutdown the thread.
 420  */
 421 static
 422 int check_session_rotation_pending(struct ltt_session *session,
 423                 struct notification_thread_handle *notification_thread_handle)
 424 {
 425         int ret;
 426         struct lttng_trace_archive_location *location;
 427         enum lttng_trace_chunk_status chunk_status;
 428         bool rotation_completed = false;
 429         const char *archived_chunk_name;
 430         uint64_t chunk_being_archived_id;
 431
 432         if (!session->chunk_being_archived) {
 433                 ret = 0;
 434                 goto end;
 435         }
 436
 437         chunk_status = lttng_trace_chunk_get_id(session->chunk_being_archived,
 438                         &chunk_being_archived_id);
 439         assert(chunk_status == LTTNG_TRACE_CHUNK_STATUS_OK);
 440
 441         DBG("[rotation-thread] Checking for pending rotation on session \"%s\", trace archive %" PRIu64,
 442                         session->name, chunk_being_archived_id);
 443
 444         /*
 445          * The rotation-pending check timer of a session is launched in
 446          * one-shot mode. If the rotation is incomplete, the rotation
 447          * thread will re-enable the pending-check timer.
 448          *
 449          * The timer thread can't stop the timer itself since it is involved
 450          * in the check for the timer's quiescence.
 451          */
 452         ret = timer_session_rotation_pending_check_stop(session);
 453         if (ret) {
 454                 goto check_ongoing_rotation;
 455         }
 456
 457         check_session_rotation_pending_on_consumers(session,
 458                         &rotation_completed);
 459         if (!rotation_completed ||
 460                         session->rotation_state == LTTNG_ROTATION_STATE_ERROR) {
 461                 goto check_ongoing_rotation;
 462         }
 463
 464         /*
 465          * Now we can clear the "ONGOING" state in the session. New
 466          * rotations can start now.
 467          */
 468         chunk_status = lttng_trace_chunk_get_name(session->chunk_being_archived,
 469                         &archived_chunk_name, NULL);
 470         assert(chunk_status == LTTNG_TRACE_CHUNK_STATUS_OK);
 471         free(session->last_archived_chunk_name);
 472         session->last_archived_chunk_name = strdup(archived_chunk_name);
 473         if (!session->last_archived_chunk_name) {
 474                 PERROR("Failed to duplicate archived chunk name");
 475         }
 476         session_reset_rotation_state(session, LTTNG_ROTATION_STATE_COMPLETED);
 477
 478         if (!session->quiet_rotation) {
 479                 location = session_get_trace_archive_location(session);
 480                 /* Ownership of location is transferred. */
 481                 ret = notification_thread_command_session_rotation_completed(
 482                                 notification_thread_handle,
 483                                 session->name,
 484                                 session->uid,
 485                                 session->gid,
 486                                 session->last_archived_chunk_id.value,
 487                                 location);
 488                 if (ret != LTTNG_OK) {
 489                         ERR("[rotation-thread] Failed to notify notification thread of completed rotation for session %s",
 490                                         session->name);
 491                 }
 492         }
 493
 494         ret = 0;
 495 check_ongoing_rotation:
 496         if (session->rotation_state == LTTNG_ROTATION_STATE_ONGOING) {
 497                 uint64_t chunk_being_archived_id;
 498
 499                 chunk_status = lttng_trace_chunk_get_id(
 500                                 session->chunk_being_archived,
 501                                 &chunk_being_archived_id);
 502                 assert(chunk_status == LTTNG_TRACE_CHUNK_STATUS_OK);
 503
 504                 DBG("[rotation-thread] Rotation of trace archive %" PRIu64 " is still pending for session %s",
 505                                 chunk_being_archived_id, session->name);
 506                 ret = timer_session_rotation_pending_check_start(session,
 507                                 DEFAULT_ROTATE_PENDING_TIMER);
 508                 if (ret) {
 509                         ERR("Failed to re-enable rotation pending timer");
 510                         ret = -1;
 511                         goto end;
 512                 }
 513         }
 514
 515 end:
 516         return ret;
 517 }
 518
 519 /* Call with the session and session_list locks held. */
 520 static
 521 int launch_session_rotation(struct ltt_session *session)
 522 {
 523         int ret;
 524         struct lttng_rotate_session_return rotation_return;
 525
 526         DBG("[rotation-thread] Launching scheduled time-based rotation on session \"%s\"",
 527                         session->name);
 528
 529         ret = cmd_rotate_session(session, &rotation_return, false,
 530                 LTTNG_TRACE_CHUNK_COMMAND_TYPE_MOVE_TO_COMPLETED);
 531         if (ret == LTTNG_OK) {
 532                 DBG("[rotation-thread] Scheduled time-based rotation successfully launched on session \"%s\"",
 533                                 session->name);
 534         } else {
 535                 /* Don't consider errors as fatal. */
 536                 DBG("[rotation-thread] Scheduled time-based rotation aborted for session %s: %s",
 537                                 session->name, lttng_strerror(ret));
 538         }
 539         return 0;
 540 }
 541
 542 static
 543 int run_job(struct rotation_thread_job *job, struct ltt_session *session,
 544                 struct notification_thread_handle *notification_thread_handle)
 545 {
 546         int ret;
 547
 548         switch (job->type) {
 549         case ROTATION_THREAD_JOB_TYPE_SCHEDULED_ROTATION:
 550                 ret = launch_session_rotation(session);
 551                 break;
 552         case ROTATION_THREAD_JOB_TYPE_CHECK_PENDING_ROTATION:
 553                 ret = check_session_rotation_pending(session,
 554                                 notification_thread_handle);
 555                 break;
 556         default:
 557                 abort();
 558         }
 559         return ret;
 560 }
 561
 562 static
 563 int handle_job_queue(struct rotation_thread_handle *handle,
 564                 struct rotation_thread *state,
 565                 struct rotation_thread_timer_queue *queue)
 566 {
 567         int ret = 0;
 568
 569         for (;;) {
 570                 struct ltt_session *session;
 571                 struct rotation_thread_job *job;
 572
 573                 /* Take the queue lock only to pop an element from the list. */
 574                 pthread_mutex_lock(&queue->lock);
 575                 if (cds_list_empty(&queue->list)) {
 576                         pthread_mutex_unlock(&queue->lock);
 577                         break;
 578                 }
 579                 job = cds_list_first_entry(&queue->list,
 580                                 typeof(*job), head);
 581                 cds_list_del(&job->head);
 582                 pthread_mutex_unlock(&queue->lock);
 583
 584                 session_lock_list();
 585                 session = job->session;
 586                 if (!session) {
 587                         DBG("[rotation-thread] Session \"%s\" not found",
 588                                         session->name);
 589                         /*
 590                          * This is a non-fatal error, and we cannot report it to
 591                          * the user (timer), so just print the error and
 592                          * continue the processing.
 593                          *
 594                          * While the timer thread will purge pending signals for
 595                          * a session on the session's destruction, it is
 596                          * possible for a job targeting that session to have
 597                          * already been queued before it was destroyed.
 598                          */
 599                         free(job);
 600                         session_put(session);
 601                         session_unlock_list();
 602                         continue;
 603                 }
 604
 605                 session_lock(session);
 606                 ret = run_job(job, session, handle->notification_thread_handle);
 607                 session_unlock(session);
 608                 /* Release reference held by the job. */
 609                 session_put(session);
 610                 session_unlock_list();
 611                 free(job);
 612                 if (ret) {
 613                         goto end;
 614                 }
 615         }
 616
 617         ret = 0;
 618
 619 end:
 620         return ret;
 621 }
 622
 623 static
 624 int handle_condition(const struct lttng_condition *condition,
 625                 const struct lttng_evaluation *evaluation,
 626                 struct notification_thread_handle *notification_thread_handle)
 627 {
 628         int ret = 0;
 629         const char *condition_session_name = NULL;
 630         enum lttng_condition_type condition_type;
 631         enum lttng_condition_status condition_status;
 632         enum lttng_evaluation_status evaluation_status;
 633         uint64_t consumed;
 634         struct ltt_session *session;
 635
 636         condition_type = lttng_condition_get_type(condition);
 637
 638         if (condition_type != LTTNG_CONDITION_TYPE_SESSION_CONSUMED_SIZE) {
 639                 ret = -1;
 640                 ERR("[rotation-thread] Condition type and session usage type are not the same");
 641                 goto end;
 642         }
 643
 644         /* Fetch info to test */
 645         condition_status = lttng_condition_session_consumed_size_get_session_name(
 646                         condition, &condition_session_name);
 647         if (condition_status != LTTNG_CONDITION_STATUS_OK) {
 648                 ERR("[rotation-thread] Session name could not be fetched");
 649                 ret = -1;
 650                 goto end;
 651         }
 652         evaluation_status = lttng_evaluation_session_consumed_size_get_consumed_size(evaluation,
 653                         &consumed);
 654         if (evaluation_status != LTTNG_EVALUATION_STATUS_OK) {
 655                 ERR("[rotation-thread] Failed to get evaluation");
 656                 ret = -1;
 657                 goto end;
 658         }
 659
 660         session_lock_list();
 661         session = session_find_by_name(condition_session_name);
 662         if (!session) {
 663                 ret = -1;
 664                 session_unlock_list();
 665                 ERR("[rotation-thread] Session \"%s\" not found",
 666                                 condition_session_name);
 667                 goto end;
 668         }
 669         session_lock(session);
 670
 671         ret = unsubscribe_session_consumed_size_rotation(session,
 672                         notification_thread_handle);
 673         if (ret) {
 674                 goto end_unlock;
 675         }
 676
 677         ret = cmd_rotate_session(session, NULL, false,
 678                 LTTNG_TRACE_CHUNK_COMMAND_TYPE_MOVE_TO_COMPLETED);
 679         if (ret == -LTTNG_ERR_ROTATION_PENDING) {
 680                 DBG("Rotate already pending, subscribe to the next threshold value");
 681         } else if (ret != LTTNG_OK) {
 682                 ERR("[rotation-thread] Failed to rotate on size notification with error: %s",
 683                                 lttng_strerror(ret));
 684                 ret = -1;
 685                 goto end_unlock;
 686         }
 687         ret = subscribe_session_consumed_size_rotation(session,
 688                         consumed + session->rotate_size,
 689                         notification_thread_handle);
 690         if (ret) {
 691                 ERR("[rotation-thread] Failed to subscribe to session consumed size condition");
 692                 goto end_unlock;
 693         }
 694         ret = 0;
 695
 696 end_unlock:
 697         session_unlock(session);
 698         session_put(session);
 699         session_unlock_list();
 700 end:
 701         return ret;
 702 }
 703
 704 static
 705 int handle_notification_channel(int fd,
 706                 struct rotation_thread_handle *handle,
 707                 struct rotation_thread *state)
 708 {
 709         int ret;
 710         bool notification_pending;
 711         struct lttng_notification *notification = NULL;
 712         enum lttng_notification_channel_status status;
 713         const struct lttng_evaluation *notification_evaluation;
 714         const struct lttng_condition *notification_condition;
 715
 716         status = lttng_notification_channel_has_pending_notification(
 717                         rotate_notification_channel, &notification_pending);
 718         if (status != LTTNG_NOTIFICATION_CHANNEL_STATUS_OK) {
 719                 ERR("[rotation-thread] Error occurred while checking for pending notification");
 720                 ret = -1;
 721                 goto end;
 722         }
 723
 724         if (!notification_pending) {
 725                 ret = 0;
 726                 goto end;
 727         }
 728
 729         /* Receive the next notification. */
 730         status = lttng_notification_channel_get_next_notification(
 731                         rotate_notification_channel,
 732                         &notification);
 733
 734         switch (status) {
 735         case LTTNG_NOTIFICATION_CHANNEL_STATUS_OK:
 736                 break;
 737         case LTTNG_NOTIFICATION_CHANNEL_STATUS_NOTIFICATIONS_DROPPED:
 738                 /* Not an error, we will wait for the next one */
 739                 ret = 0;
 740                 goto end;;
 741         case LTTNG_NOTIFICATION_CHANNEL_STATUS_CLOSED:
 742                 ERR("Notification channel was closed");
 743                 ret = -1;
 744                 goto end;
 745         default:
 746                 /* Unhandled conditions / errors. */
 747                 ERR("Unknown notification channel status");
 748                 ret = -1;
 749                 goto end;
 750         }
 751
 752         notification_condition = lttng_notification_get_condition(notification);
 753         notification_evaluation = lttng_notification_get_evaluation(notification);
 754
 755         ret = handle_condition(notification_condition, notification_evaluation,
 756                         handle->notification_thread_handle);
 757
 758 end:
 759         lttng_notification_destroy(notification);
 760         return ret;
 761 }
 762
 763 static
 764 void *thread_rotation(void *data)
 765 {
 766         int ret;
 767         struct rotation_thread_handle *handle = data;
 768         struct rotation_thread thread;
 769         int queue_pipe_fd;
 770
 771         DBG("[rotation-thread] Started rotation thread");
 772         rcu_register_thread();
 773         rcu_thread_online();
 774         health_register(health_sessiond, HEALTH_SESSIOND_TYPE_ROTATION);
 775         health_code_update();
 776
 777         if (!handle) {
 778                 ERR("[rotation-thread] Invalid thread context provided");
 779                 goto end;
 780         }
 781
 782         queue_pipe_fd = lttng_pipe_get_readfd(
 783                         handle->rotation_timer_queue->event_pipe);
 784
 785
 786         ret = init_thread_state(handle, &thread);
 787         if (ret) {
 788                 goto error;
 789         }
 790
 791         while (true) {
 792                 int fd_count, i;
 793
 794                 health_poll_entry();
 795                 DBG("[rotation-thread] Entering poll wait");
 796                 ret = lttng_poll_wait(&thread.events, -1);
 797                 DBG("[rotation-thread] Poll wait returned (%i)", ret);
 798                 health_poll_exit();
 799                 if (ret < 0) {
 800                         /*
 801                          * Restart interrupted system call.
 802                          */
 803                         if (errno == EINTR) {
 804                                 continue;
 805                         }
 806                         ERR("[rotation-thread] Error encountered during lttng_poll_wait (%i)", ret);
 807                         goto error;
 808                 }
 809
 810                 fd_count = ret;
 811                 for (i = 0; i < fd_count; i++) {
 812                         int fd = LTTNG_POLL_GETFD(&thread.events, i);
 813                         uint32_t revents = LTTNG_POLL_GETEV(&thread.events, i);
 814
 815                         DBG("[rotation-thread] Handling fd (%i) activity (%u)",
 816                                         fd, revents);
 817
 818                         if (revents & LPOLLERR) {
 819                                 ERR("[rotation-thread] Polling returned an error on fd %i", fd);
 820                                 goto error;
 821                         }
 822
 823                         if (fd == rotate_notification_channel->socket) {
 824                                 ret = handle_notification_channel(fd, handle,
 825                                                 &thread);
 826                                 if (ret) {
 827                                         ERR("[rotation-thread] Error occurred while handling activity on notification channel socket");
 828                                         goto error;
 829                                 }
 830                         } else {
 831                                 /* Job queue or quit pipe activity. */
 832
 833                                 /*
 834                                  * The job queue is serviced if there is
 835                                  * activity on the quit pipe to ensure it is
 836                                  * flushed and all references held in the queue
 837                                  * are released.
 838                                  */
 839                                 ret = handle_job_queue(handle, &thread,
 840                                                 handle->rotation_timer_queue);
 841                                 if (ret) {
 842                                         ERR("[rotation-thread] Failed to handle rotation timer pipe event");
 843                                         goto error;
 844                                 }
 845
 846                                 if (fd == queue_pipe_fd) {
 847                                         char buf;
 848
 849                                         ret = lttng_read(fd, &buf, 1);
 850                                         if (ret != 1) {
 851                                                 ERR("[rotation-thread] Failed to read from wakeup pipe (fd = %i)", fd);
 852                                                 goto error;
 853                                         }
 854                                 } else {
 855                                         DBG("[rotation-thread] Quit pipe activity");
 856                                         goto exit;
 857                                 }
 858                         }
 859                 }
 860         }
 861 exit:
 862 error:
 863         DBG("[rotation-thread] Exit");
 864         fini_thread_state(&thread);
 865 end:
 866         health_unregister(health_sessiond);
 867         rcu_thread_offline();
 868         rcu_unregister_thread();
 869         return NULL;
 870 }
 871
 872 static
 873 bool shutdown_rotation_thread(void *thread_data)
 874 {
 875         struct rotation_thread_handle *handle = thread_data;
 876         const int write_fd = lttng_pipe_get_writefd(handle->quit_pipe);
 877
 878         return notify_thread_pipe(write_fd) == 1;
 879 }
 880
 881 bool launch_rotation_thread(struct rotation_thread_handle *handle)
 882 {
 883         struct lttng_thread *thread;
 884
 885         thread = lttng_thread_create("Rotation",
 886                         thread_rotation,
 887                         shutdown_rotation_thread,
 888                         NULL,
 889                         handle);
 890         if (!thread) {
 891                 goto error;
 892         }
 893         lttng_thread_put(thread);
 894         return true;
 895 error:
 896         return false;
 897 }