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
  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("[rotation-thread] 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("[rotation-thread] 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("[rotation-thread] 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("[rotation-thread] 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("[rotation-thread] 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-thread] 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("[rotation-thread] 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("[rotation-thread] 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                 uint64_t chunk_being_archived_id;
 501
 502                 chunk_status = lttng_trace_chunk_get_id(
 503                                 session->chunk_being_archived,
 504                                 &chunk_being_archived_id);
 505                 assert(chunk_status == LTTNG_TRACE_CHUNK_STATUS_OK);
 506
 507                 DBG("[rotation-thread] Rotation of trace archive %" PRIu64 " is still pending for session %s",
 508                                 chunk_being_archived_id, session->name);
 509                 ret = timer_session_rotation_pending_check_start(session,
 510                                 DEFAULT_ROTATE_PENDING_TIMER);
 511                 if (ret) {
 512                         ERR("Failed to re-enable rotation pending timer");
 513                         ret = -1;
 514                         goto end;
 515                 }
 516         }
 517
 518 end:
 519         return ret;
 520 }
 521
 522 /* Call with the session and session_list locks held. */
 523 static
 524 int launch_session_rotation(struct ltt_session *session)
 525 {
 526         int ret;
 527         struct lttng_rotate_session_return rotation_return;
 528
 529         DBG("[rotation-thread] Launching scheduled time-based rotation on session \"%s\"",
 530                         session->name);
 531
 532         ret = cmd_rotate_session(session, &rotation_return, false,
 533                 LTTNG_TRACE_CHUNK_COMMAND_TYPE_MOVE_TO_COMPLETED);
 534         if (ret == LTTNG_OK) {
 535                 DBG("[rotation-thread] Scheduled time-based rotation successfully launched on session \"%s\"",
 536                                 session->name);
 537         } else {
 538                 /* Don't consider errors as fatal. */
 539                 DBG("[rotation-thread] Scheduled time-based rotation aborted for session %s: %s",
 540                                 session->name, lttng_strerror(ret));
 541         }
 542         return 0;
 543 }
 544
 545 static
 546 int run_job(struct rotation_thread_job *job, struct ltt_session *session,
 547                 struct notification_thread_handle *notification_thread_handle)
 548 {
 549         int ret;
 550
 551         switch (job->type) {
 552         case ROTATION_THREAD_JOB_TYPE_SCHEDULED_ROTATION:
 553                 ret = launch_session_rotation(session);
 554                 break;
 555         case ROTATION_THREAD_JOB_TYPE_CHECK_PENDING_ROTATION:
 556                 ret = check_session_rotation_pending(session,
 557                                 notification_thread_handle);
 558                 break;
 559         default:
 560                 abort();
 561         }
 562         return ret;
 563 }
 564
 565 static
 566 int handle_job_queue(struct rotation_thread_handle *handle,
 567                 struct rotation_thread *state,
 568                 struct rotation_thread_timer_queue *queue)
 569 {
 570         int ret = 0;
 571
 572         for (;;) {
 573                 struct ltt_session *session;
 574                 struct rotation_thread_job *job;
 575
 576                 /* Take the queue lock only to pop an element from the list. */
 577                 pthread_mutex_lock(&queue->lock);
 578                 if (cds_list_empty(&queue->list)) {
 579                         pthread_mutex_unlock(&queue->lock);
 580                         break;
 581                 }
 582                 job = cds_list_first_entry(&queue->list,
 583                                 typeof(*job), head);
 584                 cds_list_del(&job->head);
 585                 pthread_mutex_unlock(&queue->lock);
 586
 587                 session_lock_list();
 588                 session = job->session;
 589                 if (!session) {
 590                         DBG("[rotation-thread] Session \"%s\" not found",
 591                                         session->name);
 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_put(session);
 604                         session_unlock_list();
 605                         continue;
 606                 }
 607
 608                 session_lock(session);
 609                 ret = run_job(job, session, handle->notification_thread_handle);
 610                 session_unlock(session);
 611                 /* Release reference held by the job. */
 612                 session_put(session);
 613                 session_unlock_list();
 614                 free(job);
 615                 if (ret) {
 616                         goto end;
 617                 }
 618         }
 619
 620         ret = 0;
 621
 622 end:
 623         return ret;
 624 }
 625
 626 static
 627 int handle_condition(const struct lttng_condition *condition,
 628                 const struct lttng_evaluation *evaluation,
 629                 struct notification_thread_handle *notification_thread_handle)
 630 {
 631         int ret = 0;
 632         const char *condition_session_name = NULL;
 633         enum lttng_condition_type condition_type;
 634         enum lttng_condition_status condition_status;
 635         enum lttng_evaluation_status evaluation_status;
 636         uint64_t consumed;
 637         struct ltt_session *session;
 638
 639         condition_type = lttng_condition_get_type(condition);
 640
 641         if (condition_type != LTTNG_CONDITION_TYPE_SESSION_CONSUMED_SIZE) {
 642                 ret = -1;
 643                 ERR("[rotation-thread] Condition type and session usage type are not the same");
 644                 goto end;
 645         }
 646
 647         /* Fetch info to test */
 648         condition_status = lttng_condition_session_consumed_size_get_session_name(
 649                         condition, &condition_session_name);
 650         if (condition_status != LTTNG_CONDITION_STATUS_OK) {
 651                 ERR("[rotation-thread] Session name could not be fetched");
 652                 ret = -1;
 653                 goto end;
 654         }
 655         evaluation_status = lttng_evaluation_session_consumed_size_get_consumed_size(evaluation,
 656                         &consumed);
 657         if (evaluation_status != LTTNG_EVALUATION_STATUS_OK) {
 658                 ERR("[rotation-thread] Failed to get evaluation");
 659                 ret = -1;
 660                 goto end;
 661         }
 662
 663         session_lock_list();
 664         session = session_find_by_name(condition_session_name);
 665         if (!session) {
 666                 DBG("[rotation-thread] Failed to find session while handling notification: session name = `%s`",
 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         ret = unsubscribe_session_consumed_size_rotation(session,
 679                         notification_thread_handle);
 680         if (ret) {
 681                 goto end_unlock;
 682         }
 683
 684         ret = cmd_rotate_session(session, NULL, false,
 685                 LTTNG_TRACE_CHUNK_COMMAND_TYPE_MOVE_TO_COMPLETED);
 686         if (ret == -LTTNG_ERR_ROTATION_PENDING) {
 687                 DBG("Rotate already pending, subscribe to the next threshold value");
 688         } else if (ret != LTTNG_OK) {
 689                 ERR("[rotation-thread] Failed to rotate on size notification with error: %s",
 690                                 lttng_strerror(ret));
 691                 ret = -1;
 692                 goto end_unlock;
 693         }
 694         ret = subscribe_session_consumed_size_rotation(session,
 695                         consumed + session->rotate_size,
 696                         notification_thread_handle);
 697         if (ret) {
 698                 ERR("[rotation-thread] Failed to subscribe to session consumed size condition");
 699                 goto end_unlock;
 700         }
 701         ret = 0;
 702
 703 end_unlock:
 704         session_unlock(session);
 705         session_put(session);
 706         session_unlock_list();
 707 end:
 708         return ret;
 709 }
 710
 711 static
 712 int handle_notification_channel(int fd,
 713                 struct rotation_thread_handle *handle,
 714                 struct rotation_thread *state)
 715 {
 716         int ret;
 717         bool notification_pending;
 718         struct lttng_notification *notification = NULL;
 719         enum lttng_notification_channel_status status;
 720         const struct lttng_evaluation *notification_evaluation;
 721         const struct lttng_condition *notification_condition;
 722
 723         status = lttng_notification_channel_has_pending_notification(
 724                         rotate_notification_channel, &notification_pending);
 725         if (status != LTTNG_NOTIFICATION_CHANNEL_STATUS_OK) {
 726                 ERR("[rotation-thread ]Error occurred while checking for pending notification");
 727                 ret = -1;
 728                 goto end;
 729         }
 730
 731         if (!notification_pending) {
 732                 ret = 0;
 733                 goto end;
 734         }
 735
 736         /* Receive the next notification. */
 737         status = lttng_notification_channel_get_next_notification(
 738                         rotate_notification_channel,
 739                         &notification);
 740
 741         switch (status) {
 742         case LTTNG_NOTIFICATION_CHANNEL_STATUS_OK:
 743                 break;
 744         case LTTNG_NOTIFICATION_CHANNEL_STATUS_NOTIFICATIONS_DROPPED:
 745                 /* Not an error, we will wait for the next one */
 746                 ret = 0;
 747                 goto end;;
 748         case LTTNG_NOTIFICATION_CHANNEL_STATUS_CLOSED:
 749                 ERR("Notification channel was closed");
 750                 ret = -1;
 751                 goto end;
 752         default:
 753                 /* Unhandled conditions / errors. */
 754                 ERR("Unknown notification channel status");
 755                 ret = -1;
 756                 goto end;
 757         }
 758
 759         notification_condition = lttng_notification_get_condition(notification);
 760         notification_evaluation = lttng_notification_get_evaluation(notification);
 761
 762         ret = handle_condition(notification_condition, notification_evaluation,
 763                         handle->notification_thread_handle);
 764
 765 end:
 766         lttng_notification_destroy(notification);
 767         return ret;
 768 }
 769
 770 static
 771 void *thread_rotation(void *data)
 772 {
 773         int ret;
 774         struct rotation_thread_handle *handle = data;
 775         struct rotation_thread thread;
 776         int queue_pipe_fd;
 777
 778         DBG("[rotation-thread] Started rotation thread");
 779         rcu_register_thread();
 780         rcu_thread_online();
 781         health_register(health_sessiond, HEALTH_SESSIOND_TYPE_ROTATION);
 782         health_code_update();
 783
 784         if (!handle) {
 785                 ERR("[rotation-thread] Invalid thread context provided");
 786                 goto end;
 787         }
 788
 789         queue_pipe_fd = lttng_pipe_get_readfd(
 790                         handle->rotation_timer_queue->event_pipe);
 791
 792
 793         ret = init_thread_state(handle, &thread);
 794         if (ret) {
 795                 goto error;
 796         }
 797
 798         while (true) {
 799                 int fd_count, i;
 800
 801                 health_poll_entry();
 802                 DBG("[rotation-thread] Entering poll wait");
 803                 ret = lttng_poll_wait(&thread.events, -1);
 804                 DBG("[rotation-thread] Poll wait returned (%i)", ret);
 805                 health_poll_exit();
 806                 if (ret < 0) {
 807                         /*
 808                          * Restart interrupted system call.
 809                          */
 810                         if (errno == EINTR) {
 811                                 continue;
 812                         }
 813                         ERR("[rotation-thread] Error encountered during lttng_poll_wait (%i)", ret);
 814                         goto error;
 815                 }
 816
 817                 fd_count = ret;
 818                 for (i = 0; i < fd_count; i++) {
 819                         int fd = LTTNG_POLL_GETFD(&thread.events, i);
 820                         uint32_t revents = LTTNG_POLL_GETEV(&thread.events, i);
 821
 822                         DBG("[rotation-thread] Handling fd (%i) activity (%u)",
 823                                         fd, revents);
 824
 825                         if (revents & LPOLLERR) {
 826                                 ERR("[rotation-thread] Polling returned an error on fd %i", fd);
 827                                 goto error;
 828                         }
 829
 830                         if (fd == rotate_notification_channel->socket) {
 831                                 ret = handle_notification_channel(fd, handle,
 832                                                 &thread);
 833                                 if (ret) {
 834                                         ERR("[rotation-thread] Error occurred while handling activity on notification channel socket");
 835                                         goto error;
 836                                 }
 837                         } else {
 838                                 /* Job queue or quit pipe activity. */
 839
 840                                 /*
 841                                  * The job queue is serviced if there is
 842                                  * activity on the quit pipe to ensure it is
 843                                  * flushed and all references held in the queue
 844                                  * are released.
 845                                  */
 846                                 ret = handle_job_queue(handle, &thread,
 847                                                 handle->rotation_timer_queue);
 848                                 if (ret) {
 849                                         ERR("[rotation-thread] Failed to handle rotation timer pipe event");
 850                                         goto error;
 851                                 }
 852
 853                                 if (fd == queue_pipe_fd) {
 854                                         char buf;
 855
 856                                         ret = lttng_read(fd, &buf, 1);
 857                                         if (ret != 1) {
 858                                                 ERR("[rotation-thread] Failed to read from wakeup pipe (fd = %i)", fd);
 859                                                 goto error;
 860                                         }
 861                                 } else {
 862                                         DBG("[rotation-thread] Quit pipe activity");
 863                                         goto exit;
 864                                 }
 865                         }
 866                 }
 867         }
 868 exit:
 869 error:
 870         DBG("[rotation-thread] Exit");
 871         fini_thread_state(&thread);
 872 end:
 873         health_unregister(health_sessiond);
 874         rcu_thread_offline();
 875         rcu_unregister_thread();
 876         return NULL;
 877 }
 878
 879 static
 880 bool shutdown_rotation_thread(void *thread_data)
 881 {
 882         struct rotation_thread_handle *handle = thread_data;
 883         const int write_fd = lttng_pipe_get_writefd(handle->quit_pipe);
 884
 885         return notify_thread_pipe(write_fd) == 1;
 886 }
 887
 888 bool launch_rotation_thread(struct rotation_thread_handle *handle)
 889 {
 890         struct lttng_thread *thread;
 891
 892         thread = lttng_thread_create("Rotation",
 893                         thread_rotation,
 894                         shutdown_rotation_thread,
 895                         NULL,
 896                         handle);
 897         if (!thread) {
 898                 goto error;
 899         }
 900         lttng_thread_put(thread);
 901         return true;
 902 error:
 903         return false;
 904 }