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 #include <lttng/location-internal.h>
  28 #include <lttng/condition/condition-internal.h>
  29 #include <lttng/notification/notification-internal.h>
  30
  31 #include "rotation-thread.h"
  32 #include "lttng-sessiond.h"
  33 #include "health-sessiond.h"
  34 #include "rotate.h"
  35 #include "cmd.h"
  36 #include "session.h"
  37 #include "timer.h"
  38 #include "notification-thread-commands.h"
  39 #include "utils.h"
  40 #include "thread.h"
  41
  42 #include <urcu.h>
  43 #include <urcu/list.h>
  44
  45 struct lttng_notification_channel *rotate_notification_channel = NULL;
  46
  47 struct rotation_thread {
  48         struct lttng_poll_event events;
  49 };
  50
  51 struct rotation_thread_job {
  52         enum rotation_thread_job_type type;
  53         struct ltt_session *session;
  54         /* List member in struct rotation_thread_timer_queue. */
  55         struct cds_list_head head;
  56 };
  57
  58 /*
  59  * The timer thread enqueues jobs and wakes up the rotation thread.
  60  * When the rotation thread wakes up, it empties the queue.
  61  */
  62 struct rotation_thread_timer_queue {
  63         struct lttng_pipe *event_pipe;
  64         struct cds_list_head list;
  65         pthread_mutex_t lock;
  66 };
  67
  68 struct rotation_thread_handle {
  69         struct rotation_thread_timer_queue *rotation_timer_queue;
  70         /* Access to the notification thread cmd_queue */
  71         struct notification_thread_handle *notification_thread_handle;
  72         /* Thread-specific quit pipe. */
  73         struct lttng_pipe *quit_pipe;
  74 };
  75
  76 static
  77 const char *get_job_type_str(enum rotation_thread_job_type job_type)
  78 {
  79         switch (job_type) {
  80         case ROTATION_THREAD_JOB_TYPE_CHECK_PENDING_ROTATION:
  81                 return "CHECK_PENDING_ROTATION";
  82         case ROTATION_THREAD_JOB_TYPE_SCHEDULED_ROTATION:
  83                 return "SCHEDULED_ROTATION";
  84         default:
  85                 abort();
  86         }
  87 }
  88
  89 struct rotation_thread_timer_queue *rotation_thread_timer_queue_create(void)
  90 {
  91         struct rotation_thread_timer_queue *queue = NULL;
  92
  93         queue = zmalloc(sizeof(*queue));
  94         if (!queue) {
  95                 PERROR("Failed to allocate timer rotate queue");
  96                 goto end;
  97         }
  98
  99         queue->event_pipe = lttng_pipe_open(FD_CLOEXEC | O_NONBLOCK);
 100         CDS_INIT_LIST_HEAD(&queue->list);
 101         pthread_mutex_init(&queue->lock, NULL);
 102 end:
 103         return queue;
 104 }
 105
 106 void rotation_thread_timer_queue_destroy(
 107                 struct rotation_thread_timer_queue *queue)
 108 {
 109         if (!queue) {
 110                 return;
 111         }
 112
 113         lttng_pipe_destroy(queue->event_pipe);
 114
 115         pthread_mutex_lock(&queue->lock);
 116         assert(cds_list_empty(&queue->list));
 117         pthread_mutex_unlock(&queue->lock);
 118         pthread_mutex_destroy(&queue->lock);
 119         free(queue);
 120 }
 121
 122 /*
 123  * Destroy the thread data previously created by the init function.
 124  */
 125 void rotation_thread_handle_destroy(
 126                 struct rotation_thread_handle *handle)
 127 {
 128         lttng_pipe_destroy(handle->quit_pipe);
 129         free(handle);
 130 }
 131
 132 struct rotation_thread_handle *rotation_thread_handle_create(
 133                 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(sizeof(*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 NULL;
 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
 162 bool timer_job_exists(const struct rotation_thread_timer_queue *queue,
 163                 enum rotation_thread_job_type job_type,
 164                 struct ltt_session *session)
 165 {
 166         bool exists = false;
 167         struct rotation_thread_job *job;
 168
 169         cds_list_for_each_entry(job, &queue->list, head) {
 170                 if (job->session == session && job->type == job_type) {
 171                         exists = true;
 172                         goto end;
 173                 }
 174         }
 175 end:
 176         return exists;
 177 }
 178
 179 void rotation_thread_enqueue_job(struct rotation_thread_timer_queue *queue,
 180                 enum rotation_thread_job_type job_type,
 181                 struct ltt_session *session)
 182 {
 183         int ret;
 184         const char dummy = '!';
 185         struct rotation_thread_job *job = NULL;
 186         const char *job_type_str = get_job_type_str(job_type);
 187
 188         pthread_mutex_lock(&queue->lock);
 189         if (timer_job_exists(queue, job_type, session)) {
 190                 /*
 191                  * This timer job is already pending, we don't need to add
 192                  * it.
 193                  */
 194                 goto end;
 195         }
 196
 197         job = zmalloc(sizeof(struct rotation_thread_job));
 198         if (!job) {
 199                 PERROR("Failed to allocate rotation thread job of type \"%s\" for session \"%s\"",
 200                                 job_type_str, 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,
 211                         sizeof(dummy));
 212         if (ret < 0) {
 213                 /*
 214                  * We do not want to block in the timer handler, the job has
 215                  * been enqueued in the list, the wakeup pipe is probably full,
 216                  * the job will be processed when the rotation_thread catches
 217                  * up.
 218                  */
 219                 if (errno == EAGAIN || errno == EWOULDBLOCK) {
 220                         /*
 221                          * Not an error, but would be surprising and indicate
 222                          * that the rotation thread can't keep up with the
 223                          * current load.
 224                          */
 225                         DBG("Wake-up pipe of rotation thread job queue is full");
 226                         goto end;
 227                 }
 228                 PERROR("Failed to wake-up the rotation thread after pushing a job of type \"%s\" for session \"%s\"",
 229                                 job_type_str, session->name);
 230                 goto end;
 231         }
 232
 233 end:
 234         pthread_mutex_unlock(&queue->lock);
 235 }
 236
 237 static
 238 int init_poll_set(struct lttng_poll_event *poll_set,
 239                 struct rotation_thread_handle *handle)
 240 {
 241         int ret;
 242
 243         /*
 244          * Create pollset with size 3:
 245          *      - rotation thread quit pipe,
 246          *      - rotation thread timer queue pipe,
 247          *      - notification channel sock,
 248          */
 249         ret = lttng_poll_create(poll_set, 5, LTTNG_CLOEXEC);
 250         if (ret < 0) {
 251                 goto error;
 252         }
 253
 254         ret = lttng_poll_add(poll_set,
 255                         lttng_pipe_get_readfd(handle->quit_pipe),
 256                         LPOLLIN | LPOLLERR);
 257         if (ret < 0) {
 258                 ERR("Failed to add quit pipe read fd to poll set");
 259                 goto error;
 260         }
 261
 262         ret = lttng_poll_add(poll_set,
 263                         lttng_pipe_get_readfd(handle->rotation_timer_queue->event_pipe),
 264                         LPOLLIN | LPOLLERR);
 265         if (ret < 0) {
 266                 ERR("Failed to add rotate_pending fd to poll set");
 267                 goto error;
 268         }
 269
 270         return ret;
 271 error:
 272         lttng_poll_clean(poll_set);
 273         return ret;
 274 }
 275
 276 static
 277 void fini_thread_state(struct rotation_thread *state)
 278 {
 279         lttng_poll_clean(&state->events);
 280         if (rotate_notification_channel) {
 281                 lttng_notification_channel_destroy(rotate_notification_channel);
 282         }
 283 }
 284
 285 static
 286 int init_thread_state(struct rotation_thread_handle *handle,
 287                 struct rotation_thread *state)
 288 {
 289         int ret;
 290
 291         memset(state, 0, sizeof(*state));
 292         lttng_poll_init(&state->events);
 293
 294         ret = init_poll_set(&state->events, handle);
 295         if (ret) {
 296                 ERR("Failed to initialize rotation thread poll set");
 297                 goto end;
 298         }
 299
 300         rotate_notification_channel = lttng_notification_channel_create(
 301                         lttng_session_daemon_notification_endpoint);
 302         if (!rotate_notification_channel) {
 303                 ERR("Could not create notification channel");
 304                 ret = -1;
 305                 goto end;
 306         }
 307         ret = lttng_poll_add(&state->events, rotate_notification_channel->socket,
 308                         LPOLLIN | LPOLLERR);
 309         if (ret < 0) {
 310                 ERR("Failed to add notification fd to pollset");
 311                 goto end;
 312         }
 313
 314 end:
 315         return ret;
 316 }
 317
 318 static
 319 void check_session_rotation_pending_on_consumers(struct ltt_session *session,
 320                 bool *_rotation_completed)
 321 {
 322         int ret = 0;
 323         struct consumer_socket *socket;
 324         struct cds_lfht_iter iter;
 325         enum consumer_trace_chunk_exists_status exists_status;
 326         uint64_t relayd_id;
 327         bool chunk_exists_on_peer = false;
 328         enum lttng_trace_chunk_status chunk_status;
 329
 330         assert(session->chunk_being_archived);
 331
 332         /*
 333          * Check for a local pending rotation on all consumers (32-bit
 334          * user space, 64-bit user space, and kernel).
 335          */
 336         rcu_read_lock();
 337         if (!session->ust_session) {
 338                 goto skip_ust;
 339         }
 340         cds_lfht_for_each_entry(session->ust_session->consumer->socks->ht,
 341                         &iter, socket, node.node) {
 342                 relayd_id = session->ust_session->consumer->type == CONSUMER_DST_LOCAL ?
 343                                 -1ULL :
 344                                 session->ust_session->consumer->net_seq_index;
 345
 346                 pthread_mutex_lock(socket->lock);
 347                 ret = consumer_trace_chunk_exists(socket,
 348                                 relayd_id,
 349                                 session->id, session->chunk_being_archived,
 350                                 &exists_status);
 351                 if (ret) {
 352                         pthread_mutex_unlock(socket->lock);
 353                         ERR("Error occurred while checking rotation status on consumer daemon");
 354                         goto end;
 355                 }
 356
 357                 if (exists_status != CONSUMER_TRACE_CHUNK_EXISTS_STATUS_UNKNOWN_CHUNK) {
 358                         pthread_mutex_unlock(socket->lock);
 359                         chunk_exists_on_peer = true;
 360                         goto end;
 361                 }
 362                 pthread_mutex_unlock(socket->lock);
 363         }
 364
 365 skip_ust:
 366         if (!session->kernel_session) {
 367                 goto skip_kernel;
 368         }
 369         cds_lfht_for_each_entry(session->kernel_session->consumer->socks->ht,
 370                                 &iter, socket, node.node) {
 371                 pthread_mutex_lock(socket->lock);
 372                 relayd_id = session->kernel_session->consumer->type == CONSUMER_DST_LOCAL ?
 373                                 -1ULL :
 374                                 session->kernel_session->consumer->net_seq_index;
 375
 376                 ret = consumer_trace_chunk_exists(socket,
 377                                 relayd_id,
 378                                 session->id, session->chunk_being_archived,
 379                                 &exists_status);
 380                 if (ret) {
 381                         pthread_mutex_unlock(socket->lock);
 382                         ERR("Error occurred while checking rotation status on consumer daemon");
 383                         goto end;
 384                 }
 385
 386                 if (exists_status != CONSUMER_TRACE_CHUNK_EXISTS_STATUS_UNKNOWN_CHUNK) {
 387                         pthread_mutex_unlock(socket->lock);
 388                         chunk_exists_on_peer = true;
 389                         goto end;
 390                 }
 391                 pthread_mutex_unlock(socket->lock);
 392         }
 393 skip_kernel:
 394 end:
 395         rcu_read_unlock();
 396
 397         if (!chunk_exists_on_peer) {
 398                 uint64_t chunk_being_archived_id;
 399
 400                 chunk_status = lttng_trace_chunk_get_id(
 401                                 session->chunk_being_archived,
 402                                 &chunk_being_archived_id);
 403                 assert(chunk_status == LTTNG_TRACE_CHUNK_STATUS_OK);
 404                 DBG("Rotation of trace archive %" PRIu64 " of session \"%s\" is complete on all consumers",
 405                                 chunk_being_archived_id,
 406                                 session->name);
 407         }
 408         *_rotation_completed = !chunk_exists_on_peer;
 409         if (ret) {
 410                 ret = session_reset_rotation_state(session,
 411                                 LTTNG_ROTATION_STATE_ERROR);
 412                 if (ret) {
 413                         ERR("Failed to reset rotation state of session \"%s\"",
 414                                         session->name);
 415                 }
 416         }
 417 }
 418
 419 /*
 420  * Check if the last rotation was completed, called with session lock held.
 421  * Should only return non-zero in the event of a fatal error. Doing so will
 422  * shutdown the thread.
 423  */
 424 static
 425 int check_session_rotation_pending(struct ltt_session *session,
 426                 struct notification_thread_handle *notification_thread_handle)
 427 {
 428         int ret;
 429         struct lttng_trace_archive_location *location;
 430         enum lttng_trace_chunk_status chunk_status;
 431         bool rotation_completed = false;
 432         const char *archived_chunk_name;
 433         uint64_t chunk_being_archived_id;
 434
 435         if (!session->chunk_being_archived) {
 436                 ret = 0;
 437                 goto end;
 438         }
 439
 440         chunk_status = lttng_trace_chunk_get_id(session->chunk_being_archived,
 441                         &chunk_being_archived_id);
 442         assert(chunk_status == LTTNG_TRACE_CHUNK_STATUS_OK);
 443
 444         DBG("Checking for pending rotation on session \"%s\", trace archive %" PRIu64,
 445                         session->name, chunk_being_archived_id);
 446
 447         /*
 448          * The rotation-pending check timer of a session is launched in
 449          * one-shot mode. If the rotation is incomplete, the rotation
 450          * thread will re-enable the pending-check timer.
 451          *
 452          * The timer thread can't stop the timer itself since it is involved
 453          * in the check for the timer's quiescence.
 454          */
 455         ret = timer_session_rotation_pending_check_stop(session);
 456         if (ret) {
 457                 goto check_ongoing_rotation;
 458         }
 459
 460         check_session_rotation_pending_on_consumers(session,
 461                         &rotation_completed);
 462         if (!rotation_completed ||
 463                         session->rotation_state == LTTNG_ROTATION_STATE_ERROR) {
 464                 goto check_ongoing_rotation;
 465         }
 466
 467         /*
 468          * Now we can clear the "ONGOING" state in the session. New
 469          * rotations can start now.
 470          */
 471         chunk_status = lttng_trace_chunk_get_name(session->chunk_being_archived,
 472                         &archived_chunk_name, NULL);
 473         assert(chunk_status == LTTNG_TRACE_CHUNK_STATUS_OK);
 474         free(session->last_archived_chunk_name);
 475         session->last_archived_chunk_name = strdup(archived_chunk_name);
 476         if (!session->last_archived_chunk_name) {
 477                 PERROR("Failed to duplicate archived chunk name");
 478         }
 479         session_reset_rotation_state(session, LTTNG_ROTATION_STATE_COMPLETED);
 480
 481         if (!session->quiet_rotation) {
 482                 location = session_get_trace_archive_location(session);
 483                 ret = notification_thread_command_session_rotation_completed(
 484                                 notification_thread_handle,
 485                                 session->name,
 486                                 session->uid,
 487                                 session->gid,
 488                                 session->last_archived_chunk_id.value,
 489                                 location);
 490                 lttng_trace_archive_location_put(location);
 491                 if (ret != LTTNG_OK) {
 492                         ERR("Failed to notify notification thread of completed rotation for session %s",
 493                                         session->name);
 494                 }
 495         }
 496
 497         ret = 0;
 498 check_ongoing_rotation:
 499         if (session->rotation_state == LTTNG_ROTATION_STATE_ONGOING) {
 500                 chunk_status = lttng_trace_chunk_get_id(
 501                                 session->chunk_being_archived,
 502                                 &chunk_being_archived_id);
 503                 assert(chunk_status == LTTNG_TRACE_CHUNK_STATUS_OK);
 504
 505                 DBG("Rotation of trace archive %" PRIu64 " is still pending for session %s",
 506                                 chunk_being_archived_id, session->name);
 507                 ret = timer_session_rotation_pending_check_start(session,
 508                                 DEFAULT_ROTATE_PENDING_TIMER);
 509                 if (ret) {
 510                         ERR("Failed to re-enable rotation pending timer");
 511                         ret = -1;
 512                         goto end;
 513                 }
 514         }
 515
 516 end:
 517         return ret;
 518 }
 519
 520 /* Call with the session and session_list locks held. */
 521 static
 522 int launch_session_rotation(struct ltt_session *session)
 523 {
 524         int ret;
 525         struct lttng_rotate_session_return rotation_return;
 526
 527         DBG("Launching scheduled time-based rotation on session \"%s\"",
 528                         session->name);
 529
 530         ret = cmd_rotate_session(session, &rotation_return, false,
 531                 LTTNG_TRACE_CHUNK_COMMAND_TYPE_MOVE_TO_COMPLETED);
 532         if (ret == LTTNG_OK) {
 533                 DBG("Scheduled time-based rotation successfully launched on session \"%s\"",
 534                                 session->name);
 535         } else {
 536                 /* Don't consider errors as fatal. */
 537                 DBG("Scheduled time-based rotation aborted for session %s: %s",
 538                                 session->name, lttng_strerror(ret));
 539         }
 540         return 0;
 541 }
 542
 543 static
 544 int run_job(struct rotation_thread_job *job, struct ltt_session *session,
 545                 struct notification_thread_handle *notification_thread_handle)
 546 {
 547         int ret;
 548
 549         switch (job->type) {
 550         case ROTATION_THREAD_JOB_TYPE_SCHEDULED_ROTATION:
 551                 ret = launch_session_rotation(session);
 552                 break;
 553         case ROTATION_THREAD_JOB_TYPE_CHECK_PENDING_ROTATION:
 554                 ret = check_session_rotation_pending(session,
 555                                 notification_thread_handle);
 556                 break;
 557         default:
 558                 abort();
 559         }
 560         return ret;
 561 }
 562
 563 static
 564 int handle_job_queue(struct rotation_thread_handle *handle,
 565                 struct rotation_thread *state,
 566                 struct rotation_thread_timer_queue *queue)
 567 {
 568         int ret = 0;
 569
 570         for (;;) {
 571                 struct ltt_session *session;
 572                 struct rotation_thread_job *job;
 573
 574                 /* Take the queue lock only to pop an element from the list. */
 575                 pthread_mutex_lock(&queue->lock);
 576                 if (cds_list_empty(&queue->list)) {
 577                         pthread_mutex_unlock(&queue->lock);
 578                         break;
 579                 }
 580                 job = cds_list_first_entry(&queue->list,
 581                                 typeof(*job), head);
 582                 cds_list_del(&job->head);
 583                 pthread_mutex_unlock(&queue->lock);
 584
 585                 session_lock_list();
 586                 session = job->session;
 587                 if (!session) {
 588                         /*
 589                          * This is a non-fatal error, and we cannot report it to
 590                          * the user (timer), so just print the error and
 591                          * continue the processing.
 592                          *
 593                          * While the timer thread will purge pending signals for
 594                          * a session on the session's destruction, it is
 595                          * possible for a job targeting that session to have
 596                          * already been queued before it was destroyed.
 597                          */
 598                         free(job);
 599                         session_put(session);
 600                         session_unlock_list();
 601                         continue;
 602                 }
 603
 604                 session_lock(session);
 605                 ret = run_job(job, session, handle->notification_thread_handle);
 606                 session_unlock(session);
 607                 /* Release reference held by the job. */
 608                 session_put(session);
 609                 session_unlock_list();
 610                 free(job);
 611                 if (ret) {
 612                         goto end;
 613                 }
 614         }
 615
 616         ret = 0;
 617
 618 end:
 619         return ret;
 620 }
 621
 622 static
 623 int handle_condition(const struct lttng_notification *notification,
 624                 struct notification_thread_handle *notification_thread_handle)
 625 {
 626         int ret = 0;
 627         const char *condition_session_name = NULL;
 628         enum lttng_condition_type condition_type;
 629         enum lttng_condition_status condition_status;
 630         enum lttng_evaluation_status evaluation_status;
 631         uint64_t consumed;
 632         struct ltt_session *session;
 633         const struct lttng_condition *condition =
 634                         lttng_notification_get_const_condition(notification);
 635         const struct lttng_evaluation *evaluation =
 636                         lttng_notification_get_const_evaluation(notification);
 637
 638         condition_type = lttng_condition_get_type(condition);
 639
 640         if (condition_type != LTTNG_CONDITION_TYPE_SESSION_CONSUMED_SIZE) {
 641                 ret = -1;
 642                 ERR("Condition type and session usage type are not the same");
 643                 goto end;
 644         }
 645
 646         /* Fetch info to test */
 647         condition_status = lttng_condition_session_consumed_size_get_session_name(
 648                         condition, &condition_session_name);
 649         if (condition_status != LTTNG_CONDITION_STATUS_OK) {
 650                 ERR("Session name could not be fetched");
 651                 ret = -1;
 652                 goto end;
 653         }
 654         evaluation_status = lttng_evaluation_session_consumed_size_get_consumed_size(evaluation,
 655                         &consumed);
 656         if (evaluation_status != LTTNG_EVALUATION_STATUS_OK) {
 657                 ERR("Failed to get evaluation");
 658                 ret = -1;
 659                 goto end;
 660         }
 661
 662         session_lock_list();
 663         session = session_find_by_name(condition_session_name);
 664         if (!session) {
 665                 DBG("Failed to find session while handling notification: notification type = %s, session name = `%s`",
 666                                 lttng_condition_type_str(condition_type),
 667                                 condition_session_name);
 668                 /*
 669                  * Not a fatal error: a session can be destroyed before we get
 670                  * the chance to handle the notification.
 671                  */
 672                 ret = 0;
 673                 session_unlock_list();
 674                 goto end;
 675         }
 676         session_lock(session);
 677
 678         if (!lttng_trigger_is_equal(session->rotate_trigger,
 679                         lttng_notification_get_const_trigger(notification))) {
 680                 /* Notification does not originate from our rotation trigger. */
 681                 ret = 0;
 682                 goto end_unlock;
 683         }
 684
 685         ret = unsubscribe_session_consumed_size_rotation(session,
 686                         notification_thread_handle);
 687         if (ret) {
 688                 goto end_unlock;
 689         }
 690
 691         ret = cmd_rotate_session(
 692                         session, NULL, false, LTTNG_TRACE_CHUNK_COMMAND_TYPE_MOVE_TO_COMPLETED);
 693         switch (ret) {
 694         case LTTNG_OK:
 695                 break;
 696         case -LTTNG_ERR_ROTATION_PENDING:
 697                 DBG("Rotate already pending, subscribe to the next threshold value");
 698                 break;
 699         case -LTTNG_ERR_ROTATION_MULTIPLE_AFTER_STOP:
 700                 DBG("Rotation already happened since last stop, subscribe to the next threshold value");
 701                 break;
 702         case -LTTNG_ERR_ROTATION_AFTER_STOP_CLEAR:
 703                 DBG("Rotation already happened since last stop and clear, subscribe to the next threshold value");
 704                 break;
 705         default:
 706                 ERR("Failed to rotate on size notification with error: %s", lttng_strerror(ret));
 707                 ret = -1;
 708                 goto end_unlock;
 709         }
 710
 711         ret = subscribe_session_consumed_size_rotation(
 712                         session, consumed + session->rotate_size, notification_thread_handle);
 713         if (ret) {
 714                 ERR("Failed to subscribe to session consumed size condition");
 715                 goto end_unlock;
 716         }
 717         ret = 0;
 718
 719 end_unlock:
 720         session_unlock(session);
 721         session_put(session);
 722         session_unlock_list();
 723 end:
 724         return ret;
 725 }
 726
 727 static
 728 int handle_notification_channel(int fd,
 729                 struct rotation_thread_handle *handle,
 730                 struct rotation_thread *state)
 731 {
 732         int ret;
 733         bool notification_pending;
 734         struct lttng_notification *notification = NULL;
 735         enum lttng_notification_channel_status status;
 736
 737         status = lttng_notification_channel_has_pending_notification(
 738                         rotate_notification_channel, &notification_pending);
 739         if (status != LTTNG_NOTIFICATION_CHANNEL_STATUS_OK) {
 740                 ERR("Error occurred while checking for pending notification");
 741                 ret = -1;
 742                 goto end;
 743         }
 744
 745         if (!notification_pending) {
 746                 ret = 0;
 747                 goto end;
 748         }
 749
 750         /* Receive the next notification. */
 751         status = lttng_notification_channel_get_next_notification(
 752                         rotate_notification_channel,
 753                         &notification);
 754
 755         switch (status) {
 756         case LTTNG_NOTIFICATION_CHANNEL_STATUS_OK:
 757                 break;
 758         case LTTNG_NOTIFICATION_CHANNEL_STATUS_NOTIFICATIONS_DROPPED:
 759                 /* Not an error, we will wait for the next one */
 760                 ret = 0;
 761                 goto end;;
 762         case LTTNG_NOTIFICATION_CHANNEL_STATUS_CLOSED:
 763                 ERR("Notification channel was closed");
 764                 ret = -1;
 765                 goto end;
 766         default:
 767                 /* Unhandled conditions / errors. */
 768                 ERR("Unknown notification channel status");
 769                 ret = -1;
 770                 goto end;
 771         }
 772
 773         ret = handle_condition(notification,
 774                         handle->notification_thread_handle);
 775
 776 end:
 777         lttng_notification_destroy(notification);
 778         return ret;
 779 }
 780
 781 static
 782 void *thread_rotation(void *data)
 783 {
 784         int ret;
 785         struct rotation_thread_handle *handle = data;
 786         struct rotation_thread thread;
 787         int queue_pipe_fd;
 788
 789         DBG("Started rotation thread");
 790         rcu_register_thread();
 791         rcu_thread_online();
 792         health_register(the_health_sessiond, HEALTH_SESSIOND_TYPE_ROTATION);
 793         health_code_update();
 794
 795         if (!handle) {
 796                 ERR("Invalid thread context provided");
 797                 goto end;
 798         }
 799
 800         queue_pipe_fd = lttng_pipe_get_readfd(
 801                         handle->rotation_timer_queue->event_pipe);
 802
 803
 804         ret = init_thread_state(handle, &thread);
 805         if (ret) {
 806                 goto error;
 807         }
 808
 809         while (true) {
 810                 int fd_count, i;
 811
 812                 health_poll_entry();
 813                 DBG("Entering poll wait");
 814                 ret = lttng_poll_wait(&thread.events, -1);
 815                 DBG("Poll wait returned (%i)", ret);
 816                 health_poll_exit();
 817                 if (ret < 0) {
 818                         /*
 819                          * Restart interrupted system call.
 820                          */
 821                         if (errno == EINTR) {
 822                                 continue;
 823                         }
 824                         ERR("Error encountered during lttng_poll_wait (%i)", ret);
 825                         goto error;
 826                 }
 827
 828                 fd_count = ret;
 829                 for (i = 0; i < fd_count; i++) {
 830                         int fd = LTTNG_POLL_GETFD(&thread.events, i);
 831                         uint32_t revents = LTTNG_POLL_GETEV(&thread.events, i);
 832
 833                         DBG("Handling fd (%i) activity (%u)",
 834                                         fd, revents);
 835
 836                         if (revents & LPOLLERR) {
 837                                 ERR("Polling returned an error on fd %i", fd);
 838                                 goto error;
 839                         }
 840
 841                         if (fd == rotate_notification_channel->socket) {
 842                                 ret = handle_notification_channel(fd, handle,
 843                                                 &thread);
 844                                 if (ret) {
 845                                         ERR("Error occurred while handling activity on notification channel socket");
 846                                         goto error;
 847                                 }
 848                         } else {
 849                                 /* Job queue or quit pipe activity. */
 850
 851                                 /*
 852                                  * The job queue is serviced if there is
 853                                  * activity on the quit pipe to ensure it is
 854                                  * flushed and all references held in the queue
 855                                  * are released.
 856                                  */
 857                                 ret = handle_job_queue(handle, &thread,
 858                                                 handle->rotation_timer_queue);
 859                                 if (ret) {
 860                                         ERR("Failed to handle rotation timer pipe event");
 861                                         goto error;
 862                                 }
 863
 864                                 if (fd == queue_pipe_fd) {
 865                                         char buf;
 866
 867                                         ret = lttng_read(fd, &buf, 1);
 868                                         if (ret != 1) {
 869                                                 ERR("Failed to read from wakeup pipe (fd = %i)", fd);
 870                                                 goto error;
 871                                         }
 872                                 } else {
 873                                         DBG("Quit pipe activity");
 874                                         goto exit;
 875                                 }
 876                         }
 877                 }
 878         }
 879 exit:
 880 error:
 881         DBG("Thread exit");
 882         fini_thread_state(&thread);
 883 end:
 884         health_unregister(the_health_sessiond);
 885         rcu_thread_offline();
 886         rcu_unregister_thread();
 887         return NULL;
 888 }
 889
 890 static
 891 bool shutdown_rotation_thread(void *thread_data)
 892 {
 893         struct rotation_thread_handle *handle = thread_data;
 894         const int write_fd = lttng_pipe_get_writefd(handle->quit_pipe);
 895
 896         return notify_thread_pipe(write_fd) == 1;
 897 }
 898
 899 bool launch_rotation_thread(struct rotation_thread_handle *handle)
 900 {
 901         struct lttng_thread *thread;
 902
 903         thread = lttng_thread_create("Rotation",
 904                         thread_rotation,
 905                         shutdown_rotation_thread,
 906                         NULL,
 907                         handle);
 908         if (!thread) {
 909                 goto error;
 910         }
 911         lttng_thread_put(thread);
 912         return true;
 913 error:
 914         return false;
 915 }