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/eventfd.h>
  20 #include <sys/stat.h>
  21 #include <time.h>
  22 #include <signal.h>
  23 #include <inttypes.h>
  24
  25 #include <common/kernel-ctl/kernel-ctl.h>
  26 #include <lttng/notification/channel-internal.h>
  27 #include <lttng/rotate-internal.h>
  28 #include <lttng/location-internal.h>
  29 #include <lttng/condition/condition-internal.h>
  30 #include <lttng/notification/notification-internal.h>
  31
  32 #include "rotation-thread.h"
  33 #include "lttng-sessiond.h"
  34 #include "health-sessiond.h"
  35 #include "rotate.h"
  36 #include "cmd.h"
  37 #include "session.h"
  38 #include "timer.h"
  39 #include "notification-thread-commands.h"
  40 #include "utils.h"
  41 #include "thread.h"
  42
  43 #include <urcu.h>
  44 #include <urcu/list.h>
  45
  46 struct lttng_notification_channel *rotate_notification_channel = NULL;
  47
  48 struct rotation_thread {
  49         struct lttng_poll_event events;
  50 };
  51
  52 struct rotation_thread_job {
  53         enum rotation_thread_job_type type;
  54         struct ltt_session *session;
  55         /* List member in struct rotation_thread_timer_queue. */
  56         struct cds_list_head head;
  57 };
  58
  59 /*
  60  * The timer thread enqueues jobs and wakes up the rotation thread.
  61  * When the rotation thread wakes up, it empties the queue.
  62  */
  63 struct rotation_thread_timer_queue {
  64         struct lttng_pipe *event_pipe;
  65         struct cds_list_head list;
  66         pthread_mutex_t lock;
  67 };
  68
  69 struct rotation_thread_handle {
  70         struct rotation_thread_timer_queue *rotation_timer_queue;
  71         /* Access to the notification thread cmd_queue */
  72         struct notification_thread_handle *notification_thread_handle;
  73         /* Thread-specific quit pipe. */
  74         struct lttng_pipe *quit_pipe;
  75 };
  76
  77 static
  78 const char *get_job_type_str(enum rotation_thread_job_type job_type)
  79 {
  80         switch (job_type) {
  81         case ROTATION_THREAD_JOB_TYPE_CHECK_PENDING_ROTATION:
  82                 return "CHECK_PENDING_ROTATION";
  83         case ROTATION_THREAD_JOB_TYPE_SCHEDULED_ROTATION:
  84                 return "SCHEDULED_ROTATION";
  85         default:
  86                 abort();
  87         }
  88 }
  89
  90 struct rotation_thread_timer_queue *rotation_thread_timer_queue_create(void)
  91 {
  92         struct rotation_thread_timer_queue *queue = NULL;
  93
  94         queue = zmalloc(sizeof(*queue));
  95         if (!queue) {
  96                 PERROR("Failed to allocate timer rotate queue");
  97                 goto end;
  98         }
  99
 100         queue->event_pipe = lttng_pipe_open(FD_CLOEXEC | O_NONBLOCK);
 101         CDS_INIT_LIST_HEAD(&queue->list);
 102         pthread_mutex_init(&queue->lock, NULL);
 103 end:
 104         return queue;
 105 }
 106
 107 void rotation_thread_timer_queue_destroy(
 108                 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         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(
 127                 struct rotation_thread_handle *handle)
 128 {
 129         lttng_pipe_destroy(handle->quit_pipe);
 130         free(handle);
 131 }
 132
 133 struct rotation_thread_handle *rotation_thread_handle_create(
 134                 struct rotation_thread_timer_queue *rotation_timer_queue,
 135                 struct notification_thread_handle *notification_thread_handle)
 136 {
 137         struct rotation_thread_handle *handle;
 138
 139         handle = zmalloc(sizeof(*handle));
 140         if (!handle) {
 141                 goto end;
 142         }
 143
 144         handle->rotation_timer_queue = rotation_timer_queue;
 145         handle->notification_thread_handle = notification_thread_handle;
 146         handle->quit_pipe = lttng_pipe_open(FD_CLOEXEC);
 147         if (!handle->quit_pipe) {
 148                 goto error;
 149         }
 150
 151 end:
 152         return handle;
 153 error:
 154         rotation_thread_handle_destroy(handle);
 155         return NULL;
 156 }
 157
 158 /*
 159  * Called with the rotation_thread_timer_queue lock held.
 160  * Return true if the same timer job already exists in the queue, false if not.
 161  */
 162 static
 163 bool timer_job_exists(const struct rotation_thread_timer_queue *queue,
 164                 enum rotation_thread_job_type job_type,
 165                 struct ltt_session *session)
 166 {
 167         bool exists = false;
 168         struct rotation_thread_job *job;
 169
 170         cds_list_for_each_entry(job, &queue->list, head) {
 171                 if (job->session == session && job->type == job_type) {
 172                         exists = true;
 173                         goto end;
 174                 }
 175         }
 176 end:
 177         return exists;
 178 }
 179
 180 void rotation_thread_enqueue_job(struct rotation_thread_timer_queue *queue,
 181                 enum rotation_thread_job_type job_type,
 182                 struct ltt_session *session)
 183 {
 184         int ret;
 185         const char dummy = '!';
 186         struct rotation_thread_job *job = NULL;
 187         const char *job_type_str = get_job_type_str(job_type);
 188
 189         pthread_mutex_lock(&queue->lock);
 190         if (timer_job_exists(queue, job_type, session)) {
 191                 /*
 192                  * This timer job is already pending, we don't need to add
 193                  * it.
 194                  */
 195                 goto end;
 196         }
 197
 198         job = zmalloc(sizeof(struct rotation_thread_job));
 199         if (!job) {
 200                 PERROR("Failed to allocate rotation thread job of type \"%s\" for session \"%s\"",
 201                                 job_type_str, session->name);
 202                 goto end;
 203         }
 204         /* No reason for this to fail as the caller must hold a reference. */
 205         (void) session_get(session);
 206
 207         job->session = session;
 208         job->type = job_type;
 209         cds_list_add_tail(&job->head, &queue->list);
 210
 211         ret = lttng_write(lttng_pipe_get_writefd(queue->event_pipe), &dummy,
 212                         sizeof(dummy));
 213         if (ret < 0) {
 214                 /*
 215                  * We do not want to block in the timer handler, the job has
 216                  * been enqueued in the list, the wakeup pipe is probably full,
 217                  * the job will be processed when the rotation_thread catches
 218                  * up.
 219                  */
 220                 if (errno == EAGAIN || errno == EWOULDBLOCK) {
 221                         /*
 222                          * Not an error, but would be surprising and indicate
 223                          * that the rotation thread can't keep up with the
 224                          * current load.
 225                          */
 226                         DBG("Wake-up pipe of rotation thread job queue is full");
 227                         goto end;
 228                 }
 229                 PERROR("Failed to wake-up the rotation thread after pushing a job of type \"%s\" for session \"%s\"",
 230                                 job_type_str, session->name);
 231                 goto end;
 232         }
 233
 234 end:
 235         pthread_mutex_unlock(&queue->lock);
 236 }
 237
 238 static
 239 int init_poll_set(struct lttng_poll_event *poll_set,
 240                 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,
 256                         lttng_pipe_get_readfd(handle->quit_pipe),
 257                         LPOLLIN | LPOLLERR);
 258         if (ret < 0) {
 259                 ERR("[rotation-thread] Failed to add quit pipe read fd to poll set");
 260                 goto error;
 261         }
 262
 263         ret = lttng_poll_add(poll_set,
 264                         lttng_pipe_get_readfd(handle->rotation_timer_queue->event_pipe),
 265                         LPOLLIN | LPOLLERR);
 266         if (ret < 0) {
 267                 ERR("[rotation-thread] Failed to add rotate_pending fd to poll set");
 268                 goto error;
 269         }
 270
 271         return ret;
 272 error:
 273         lttng_poll_clean(poll_set);
 274         return ret;
 275 }
 276
 277 static
 278 void fini_thread_state(struct rotation_thread *state)
 279 {
 280         lttng_poll_clean(&state->events);
 281         if (rotate_notification_channel) {
 282                 lttng_notification_channel_destroy(rotate_notification_channel);
 283         }
 284 }
 285
 286 static
 287 int init_thread_state(struct rotation_thread_handle *handle,
 288                 struct rotation_thread *state)
 289 {
 290         int ret;
 291
 292         memset(state, 0, sizeof(*state));
 293         lttng_poll_init(&state->events);
 294
 295         ret = init_poll_set(&state->events, handle);
 296         if (ret) {
 297                 ERR("[rotation-thread] Failed to initialize rotation thread poll set");
 298                 goto end;
 299         }
 300
 301         rotate_notification_channel = lttng_notification_channel_create(
 302                         lttng_session_daemon_notification_endpoint);
 303         if (!rotate_notification_channel) {
 304                 ERR("[rotation-thread] Could not create notification channel");
 305                 ret = -1;
 306                 goto end;
 307         }
 308         ret = lttng_poll_add(&state->events, rotate_notification_channel->socket,
 309                         LPOLLIN | LPOLLERR);
 310         if (ret < 0) {
 311                 ERR("[rotation-thread] Failed to add notification fd to pollset");
 312                 goto end;
 313         }
 314
 315 end:
 316         return ret;
 317 }
 318
 319 static
 320 void check_session_rotation_pending_on_consumers(struct ltt_session *session,
 321                 bool *_rotation_completed)
 322 {
 323         int ret = 0;
 324         struct consumer_socket *socket;
 325         struct cds_lfht_iter iter;
 326         enum consumer_trace_chunk_exists_status exists_status;
 327         uint64_t relayd_id;
 328         bool chunk_exists_on_peer = false;
 329         enum lttng_trace_chunk_status chunk_status;
 330
 331         assert(session->chunk_being_archived);
 332
 333         /*
 334          * Check for a local pending rotation on all consumers (32-bit
 335          * user space, 64-bit user space, and kernel).
 336          */
 337         rcu_read_lock();
 338         if (!session->ust_session) {
 339                 goto skip_ust;
 340         }
 341         cds_lfht_for_each_entry(session->ust_session->consumer->socks->ht,
 342                         &iter, socket, node.node) {
 343                 relayd_id = session->ust_session->consumer->type == CONSUMER_DST_LOCAL ?
 344                                 -1ULL :
 345                                 session->ust_session->consumer->net_seq_index;
 346
 347                 pthread_mutex_lock(socket->lock);
 348                 ret = consumer_trace_chunk_exists(socket,
 349                                 relayd_id,
 350                                 session->id, session->chunk_being_archived,
 351                                 &exists_status);
 352                 if (ret) {
 353                         pthread_mutex_unlock(socket->lock);
 354                         ERR("Error occurred while checking rotation status on consumer daemon");
 355                         goto end;
 356                 }
 357
 358                 if (exists_status != CONSUMER_TRACE_CHUNK_EXISTS_STATUS_UNKNOWN_CHUNK) {
 359                         pthread_mutex_unlock(socket->lock);
 360                         chunk_exists_on_peer = true;
 361                         goto end;
 362                 }
 363                 pthread_mutex_unlock(socket->lock);
 364         }
 365
 366 skip_ust:
 367         if (!session->kernel_session) {
 368                 goto skip_kernel;
 369         }
 370         cds_lfht_for_each_entry(session->kernel_session->consumer->socks->ht,
 371                                 &iter, socket, node.node) {
 372                 pthread_mutex_lock(socket->lock);
 373                 relayd_id = session->kernel_session->consumer->type == CONSUMER_DST_LOCAL ?
 374                                 -1ULL :
 375                                 session->kernel_session->consumer->net_seq_index;
 376
 377                 ret = consumer_trace_chunk_exists(socket,
 378                                 relayd_id,
 379                                 session->id, session->chunk_being_archived,
 380                                 &exists_status);
 381                 if (ret) {
 382                         pthread_mutex_unlock(socket->lock);
 383                         ERR("Error occurred while checking rotation status on consumer daemon");
 384                         goto end;
 385                 }
 386
 387                 if (exists_status != CONSUMER_TRACE_CHUNK_EXISTS_STATUS_UNKNOWN_CHUNK) {
 388                         pthread_mutex_unlock(socket->lock);
 389                         chunk_exists_on_peer = true;
 390                         goto end;
 391                 }
 392                 pthread_mutex_unlock(socket->lock);
 393         }
 394 skip_kernel:
 395 end:
 396         rcu_read_unlock();
 397
 398         if (!chunk_exists_on_peer) {
 399                 uint64_t chunk_being_archived_id;
 400
 401                 chunk_status = lttng_trace_chunk_get_id(
 402                                 session->chunk_being_archived,
 403                                 &chunk_being_archived_id);
 404                 assert(chunk_status == LTTNG_TRACE_CHUNK_STATUS_OK);
 405                 DBG("[rotation-thread] Rotation of trace archive %" PRIu64 " of session \"%s\" is complete on all consumers",
 406                                 chunk_being_archived_id,
 407                                 session->name);
 408         }
 409         *_rotation_completed = !chunk_exists_on_peer;
 410         if (ret) {
 411                 ret = session_reset_rotation_state(session,
 412                                 LTTNG_ROTATION_STATE_ERROR);
 413                 if (ret) {
 414                         ERR("Failed to reset rotation state of session \"%s\"",
 415                                         session->name);
 416                 }
 417         }
 418 }
 419
 420 /*
 421  * Check if the last rotation was completed, called with session lock held.
 422  * Should only return non-zero in the event of a fatal error. Doing so will
 423  * shutdown the thread.
 424  */
 425 static
 426 int check_session_rotation_pending(struct ltt_session *session,
 427                 struct notification_thread_handle *notification_thread_handle)
 428 {
 429         int ret;
 430         struct lttng_trace_archive_location *location;
 431         enum lttng_trace_chunk_status chunk_status;
 432         bool rotation_completed = false;
 433         const char *archived_chunk_name;
 434         uint64_t chunk_being_archived_id;
 435
 436         if (!session->chunk_being_archived) {
 437                 ret = 0;
 438                 goto end;
 439         }
 440
 441         chunk_status = lttng_trace_chunk_get_id(session->chunk_being_archived,
 442                         &chunk_being_archived_id);
 443         assert(chunk_status == LTTNG_TRACE_CHUNK_STATUS_OK);
 444
 445         DBG("[rotation-thread] Checking for pending rotation on session \"%s\", trace archive %" PRIu64,
 446                         session->name, chunk_being_archived_id);
 447
 448         /*
 449          * The rotation-pending check timer of a session is launched in
 450          * one-shot mode. If the rotation is incomplete, the rotation
 451          * thread will re-enable the pending-check timer.
 452          *
 453          * The timer thread can't stop the timer itself since it is involved
 454          * in the check for the timer's quiescence.
 455          */
 456         ret = timer_session_rotation_pending_check_stop(session);
 457         if (ret) {
 458                 goto check_ongoing_rotation;
 459         }
 460
 461         check_session_rotation_pending_on_consumers(session,
 462                         &rotation_completed);
 463         if (!rotation_completed ||
 464                         session->rotation_state == LTTNG_ROTATION_STATE_ERROR) {
 465                 goto check_ongoing_rotation;
 466         }
 467
 468         /*
 469          * Now we can clear the "ONGOING" state in the session. New
 470          * rotations can start now.
 471          */
 472         chunk_status = lttng_trace_chunk_get_name(session->chunk_being_archived,
 473                         &archived_chunk_name, NULL);
 474         assert(chunk_status == LTTNG_TRACE_CHUNK_STATUS_OK);
 475         free(session->last_archived_chunk_name);
 476         session->last_archived_chunk_name = strdup(archived_chunk_name);
 477         if (!session->last_archived_chunk_name) {
 478                 PERROR("Failed to duplicate archived chunk name");
 479         }
 480         session_reset_rotation_state(session, LTTNG_ROTATION_STATE_COMPLETED);
 481
 482         if (!session->quiet_rotation) {
 483                 location = session_get_trace_archive_location(session);
 484                 ret = notification_thread_command_session_rotation_completed(
 485                                 notification_thread_handle,
 486                                 session->name,
 487                                 session->uid,
 488                                 session->gid,
 489                                 session->last_archived_chunk_id.value,
 490                                 location);
 491                 lttng_trace_archive_location_put(location);
 492                 if (ret != LTTNG_OK) {
 493                         ERR("[rotation-thread] Failed to notify notification thread of completed rotation for session %s",
 494                                         session->name);
 495                 }
 496         }
 497
 498         ret = 0;
 499 check_ongoing_rotation:
 500         if (session->rotation_state == LTTNG_ROTATION_STATE_ONGOING) {
 501                 uint64_t chunk_being_archived_id;
 502
 503                 chunk_status = lttng_trace_chunk_get_id(
 504                                 session->chunk_being_archived,
 505                                 &chunk_being_archived_id);
 506                 assert(chunk_status == LTTNG_TRACE_CHUNK_STATUS_OK);
 507
 508                 DBG("[rotation-thread] Rotation of trace archive %" PRIu64 " is still pending for session %s",
 509                                 chunk_being_archived_id, session->name);
 510                 ret = timer_session_rotation_pending_check_start(session,
 511                                 DEFAULT_ROTATE_PENDING_TIMER);
 512                 if (ret) {
 513                         ERR("Failed to re-enable rotation pending timer");
 514                         ret = -1;
 515                         goto end;
 516                 }
 517         }
 518
 519 end:
 520         return ret;
 521 }
 522
 523 /* Call with the session and session_list locks held. */
 524 static
 525 int launch_session_rotation(struct ltt_session *session)
 526 {
 527         int ret;
 528         struct lttng_rotate_session_return rotation_return;
 529
 530         DBG("[rotation-thread] Launching scheduled time-based rotation on session \"%s\"",
 531                         session->name);
 532
 533         ret = cmd_rotate_session(session, &rotation_return, false,
 534                 LTTNG_TRACE_CHUNK_COMMAND_TYPE_MOVE_TO_COMPLETED);
 535         if (ret == LTTNG_OK) {
 536                 DBG("[rotation-thread] Scheduled time-based rotation successfully launched on session \"%s\"",
 537                                 session->name);
 538         } else {
 539                 /* Don't consider errors as fatal. */
 540                 DBG("[rotation-thread] Scheduled time-based rotation aborted for session %s: %s",
 541                                 session->name, lttng_strerror(ret));
 542         }
 543         return 0;
 544 }
 545
 546 static
 547 int run_job(struct rotation_thread_job *job, struct ltt_session *session,
 548                 struct notification_thread_handle *notification_thread_handle)
 549 {
 550         int ret;
 551
 552         switch (job->type) {
 553         case ROTATION_THREAD_JOB_TYPE_SCHEDULED_ROTATION:
 554                 ret = launch_session_rotation(session);
 555                 break;
 556         case ROTATION_THREAD_JOB_TYPE_CHECK_PENDING_ROTATION:
 557                 ret = check_session_rotation_pending(session,
 558                                 notification_thread_handle);
 559                 break;
 560         default:
 561                 abort();
 562         }
 563         return ret;
 564 }
 565
 566 static
 567 int handle_job_queue(struct rotation_thread_handle *handle,
 568                 struct rotation_thread *state,
 569                 struct rotation_thread_timer_queue *queue)
 570 {
 571         int ret = 0;
 572
 573         for (;;) {
 574                 struct ltt_session *session;
 575                 struct rotation_thread_job *job;
 576
 577                 /* Take the queue lock only to pop an element from the list. */
 578                 pthread_mutex_lock(&queue->lock);
 579                 if (cds_list_empty(&queue->list)) {
 580                         pthread_mutex_unlock(&queue->lock);
 581                         break;
 582                 }
 583                 job = cds_list_first_entry(&queue->list,
 584                                 typeof(*job), head);
 585                 cds_list_del(&job->head);
 586                 pthread_mutex_unlock(&queue->lock);
 587
 588                 session_lock_list();
 589                 session = job->session;
 590                 if (!session) {
 591                         DBG("[rotation-thread] Session not found");
 592                         /*
 593                          * This is a non-fatal error, and we cannot report it to
 594                          * the user (timer), so just print the error and
 595                          * continue the processing.
 596                          *
 597                          * While the timer thread will purge pending signals for
 598                          * a session on the session's destruction, it is
 599                          * possible for a job targeting that session to have
 600                          * already been queued before it was destroyed.
 601                          */
 602                         free(job);
 603                         session_unlock_list();
 604                         continue;
 605                 }
 606
 607                 session_lock(session);
 608                 ret = run_job(job, session, handle->notification_thread_handle);
 609                 session_unlock(session);
 610                 /* Release reference held by the job. */
 611                 session_put(session);
 612                 session_unlock_list();
 613                 free(job);
 614                 if (ret) {
 615                         goto end;
 616                 }
 617         }
 618
 619         ret = 0;
 620
 621 end:
 622         return ret;
 623 }
 624
 625 static
 626 int handle_condition(const struct lttng_notification *notification,
 627                 struct notification_thread_handle *notification_thread_handle)
 628 {
 629         int ret = 0;
 630         const char *condition_session_name = NULL;
 631         enum lttng_condition_type condition_type;
 632         enum lttng_condition_status condition_status;
 633         enum lttng_evaluation_status evaluation_status;
 634         uint64_t consumed;
 635         struct ltt_session *session;
 636         const struct lttng_condition *condition =
 637                         lttng_notification_get_const_condition(notification);
 638         const struct lttng_evaluation *evaluation =
 639                         lttng_notification_get_const_evaluation(notification);
 640
 641         condition_type = lttng_condition_get_type(condition);
 642
 643         if (condition_type != LTTNG_CONDITION_TYPE_SESSION_CONSUMED_SIZE) {
 644                 ret = -1;
 645                 ERR("[rotation-thread] Condition type and session usage type are not the same");
 646                 goto end;
 647         }
 648
 649         /* Fetch info to test */
 650         condition_status = lttng_condition_session_consumed_size_get_session_name(
 651                         condition, &condition_session_name);
 652         if (condition_status != LTTNG_CONDITION_STATUS_OK) {
 653                 ERR("[rotation-thread] Session name could not be fetched");
 654                 ret = -1;
 655                 goto end;
 656         }
 657         evaluation_status = lttng_evaluation_session_consumed_size_get_consumed_size(evaluation,
 658                         &consumed);
 659         if (evaluation_status != LTTNG_EVALUATION_STATUS_OK) {
 660                 ERR("[rotation-thread] Failed to get evaluation");
 661                 ret = -1;
 662                 goto end;
 663         }
 664
 665         session_lock_list();
 666         session = session_find_by_name(condition_session_name);
 667         if (!session) {
 668                 DBG("[rotation-thread] Failed to find session while handling notification: session name = `%s`",
 669                                 condition_session_name);
 670                 /*
 671                  * Not a fatal error: a session can be destroyed before we get
 672                  * the chance to handle the notification.
 673                  */
 674                 ret = 0;
 675                 session_unlock_list();
 676                 goto end;
 677         }
 678         session_lock(session);
 679
 680         if (!lttng_trigger_is_equal(session->rotate_trigger,
 681                         lttng_notification_get_const_trigger(notification))) {
 682                 /* Notification does not originate from our rotation trigger. */
 683                 ret = 0;
 684                 goto end_unlock;
 685         }
 686
 687         ret = unsubscribe_session_consumed_size_rotation(session,
 688                         notification_thread_handle);
 689         if (ret) {
 690                 goto end_unlock;
 691         }
 692
 693         ret = cmd_rotate_session(session, NULL, false,
 694                 LTTNG_TRACE_CHUNK_COMMAND_TYPE_MOVE_TO_COMPLETED);
 695         if (ret == -LTTNG_ERR_ROTATION_PENDING) {
 696                 DBG("Rotate already pending, subscribe to the next threshold value");
 697         } else if (ret != LTTNG_OK) {
 698                 ERR("[rotation-thread] Failed to rotate on size notification with error: %s",
 699                                 lttng_strerror(ret));
 700                 ret = -1;
 701                 goto end_unlock;
 702         }
 703         ret = subscribe_session_consumed_size_rotation(session,
 704                         consumed + session->rotate_size,
 705                         notification_thread_handle);
 706         if (ret) {
 707                 ERR("[rotation-thread] Failed to subscribe to session consumed size condition");
 708                 goto end_unlock;
 709         }
 710         ret = 0;
 711
 712 end_unlock:
 713         session_unlock(session);
 714         session_put(session);
 715         session_unlock_list();
 716 end:
 717         return ret;
 718 }
 719
 720 static
 721 int handle_notification_channel(int fd,
 722                 struct rotation_thread_handle *handle,
 723                 struct rotation_thread *state)
 724 {
 725         int ret;
 726         bool notification_pending;
 727         struct lttng_notification *notification = NULL;
 728         enum lttng_notification_channel_status status;
 729
 730         status = lttng_notification_channel_has_pending_notification(
 731                         rotate_notification_channel, &notification_pending);
 732         if (status != LTTNG_NOTIFICATION_CHANNEL_STATUS_OK) {
 733                 ERR("[rotation-thread ]Error occurred while checking for pending notification");
 734                 ret = -1;
 735                 goto end;
 736         }
 737
 738         if (!notification_pending) {
 739                 ret = 0;
 740                 goto end;
 741         }
 742
 743         /* Receive the next notification. */
 744         status = lttng_notification_channel_get_next_notification(
 745                         rotate_notification_channel,
 746                         &notification);
 747
 748         switch (status) {
 749         case LTTNG_NOTIFICATION_CHANNEL_STATUS_OK:
 750                 break;
 751         case LTTNG_NOTIFICATION_CHANNEL_STATUS_NOTIFICATIONS_DROPPED:
 752                 /* Not an error, we will wait for the next one */
 753                 ret = 0;
 754                 goto end;;
 755         case LTTNG_NOTIFICATION_CHANNEL_STATUS_CLOSED:
 756                 ERR("Notification channel was closed");
 757                 ret = -1;
 758                 goto end;
 759         default:
 760                 /* Unhandled conditions / errors. */
 761                 ERR("Unknown notification channel status");
 762                 ret = -1;
 763                 goto end;
 764         }
 765
 766         ret = handle_condition(notification,
 767                         handle->notification_thread_handle);
 768
 769 end:
 770         lttng_notification_destroy(notification);
 771         return ret;
 772 }
 773
 774 static
 775 void *thread_rotation(void *data)
 776 {
 777         int ret;
 778         struct rotation_thread_handle *handle = data;
 779         struct rotation_thread thread;
 780         int queue_pipe_fd;
 781
 782         DBG("[rotation-thread] Started rotation thread");
 783         rcu_register_thread();
 784         rcu_thread_online();
 785         health_register(health_sessiond, HEALTH_SESSIOND_TYPE_ROTATION);
 786         health_code_update();
 787
 788         if (!handle) {
 789                 ERR("[rotation-thread] Invalid thread context provided");
 790                 goto end;
 791         }
 792
 793         queue_pipe_fd = lttng_pipe_get_readfd(
 794                         handle->rotation_timer_queue->event_pipe);
 795
 796
 797         ret = init_thread_state(handle, &thread);
 798         if (ret) {
 799                 goto error;
 800         }
 801
 802         while (true) {
 803                 int fd_count, i;
 804
 805                 health_poll_entry();
 806                 DBG("[rotation-thread] Entering poll wait");
 807                 ret = lttng_poll_wait(&thread.events, -1);
 808                 DBG("[rotation-thread] Poll wait returned (%i)", ret);
 809                 health_poll_exit();
 810                 if (ret < 0) {
 811                         /*
 812                          * Restart interrupted system call.
 813                          */
 814                         if (errno == EINTR) {
 815                                 continue;
 816                         }
 817                         ERR("[rotation-thread] Error encountered during lttng_poll_wait (%i)", ret);
 818                         goto error;
 819                 }
 820
 821                 fd_count = ret;
 822                 for (i = 0; i < fd_count; i++) {
 823                         int fd = LTTNG_POLL_GETFD(&thread.events, i);
 824                         uint32_t revents = LTTNG_POLL_GETEV(&thread.events, i);
 825
 826                         DBG("[rotation-thread] Handling fd (%i) activity (%u)",
 827                                         fd, revents);
 828
 829                         if (revents & LPOLLERR) {
 830                                 ERR("[rotation-thread] Polling returned an error on fd %i", fd);
 831                                 goto error;
 832                         }
 833
 834                         if (fd == rotate_notification_channel->socket) {
 835                                 ret = handle_notification_channel(fd, handle,
 836                                                 &thread);
 837                                 if (ret) {
 838                                         ERR("[rotation-thread] Error occurred while handling activity on notification channel socket");
 839                                         goto error;
 840                                 }
 841                         } else {
 842                                 /* Job queue or quit pipe activity. */
 843
 844                                 /*
 845                                  * The job queue is serviced if there is
 846                                  * activity on the quit pipe to ensure it is
 847                                  * flushed and all references held in the queue
 848                                  * are released.
 849                                  */
 850                                 ret = handle_job_queue(handle, &thread,
 851                                                 handle->rotation_timer_queue);
 852                                 if (ret) {
 853                                         ERR("[rotation-thread] Failed to handle rotation timer pipe event");
 854                                         goto error;
 855                                 }
 856
 857                                 if (fd == queue_pipe_fd) {
 858                                         char buf;
 859
 860                                         ret = lttng_read(fd, &buf, 1);
 861                                         if (ret != 1) {
 862                                                 ERR("[rotation-thread] Failed to read from wakeup pipe (fd = %i)", fd);
 863                                                 goto error;
 864                                         }
 865                                 } else {
 866                                         DBG("[rotation-thread] Quit pipe activity");
 867                                         goto exit;
 868                                 }
 869                         }
 870                 }
 871         }
 872 exit:
 873 error:
 874         DBG("[rotation-thread] Exit");
 875         fini_thread_state(&thread);
 876 end:
 877         health_unregister(health_sessiond);
 878         rcu_thread_offline();
 879         rcu_unregister_thread();
 880         return NULL;
 881 }
 882
 883 static
 884 bool shutdown_rotation_thread(void *thread_data)
 885 {
 886         struct rotation_thread_handle *handle = thread_data;
 887         const int write_fd = lttng_pipe_get_writefd(handle->quit_pipe);
 888
 889         return notify_thread_pipe(write_fd) == 1;
 890 }
 891
 892 bool launch_rotation_thread(struct rotation_thread_handle *handle)
 893 {
 894         struct lttng_thread *thread;
 895
 896         thread = lttng_thread_create("Rotation",
 897                         thread_rotation,
 898                         shutdown_rotation_thread,
 899                         NULL,
 900                         handle);
 901         if (!thread) {
 902                 goto error;
 903         }
 904         lttng_thread_put(thread);
 905         return true;
 906 error:
 907         return false;
 908 }