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

   1 /*
   2  * Copyright (C) 2017 Julien Desfossez <jdesfossez@efficios.com>
   3  * Copyright (C) 2018 Jérémie Galarneau <jeremie.galarneau@efficios.com>
   4  *
   5  * SPDX-License-Identifier: GPL-2.0-only
   6  *
   7  */
   8
   9 #define _LGPL_SOURCE
  10 #include <lttng/trigger/trigger.h>
  11 #include <common/error.h>
  12 #include <common/config/session-config.h>
  13 #include <common/defaults.h>
  14 #include <common/utils.h>
  15 #include <common/futex.h>
  16 #include <common/align.h>
  17 #include <common/time.h>
  18 #include <common/hashtable/utils.h>
  19 #include <sys/stat.h>
  20 #include <time.h>
  21 #include <signal.h>
  22 #include <inttypes.h>
  23
  24 #include <common/kernel-ctl/kernel-ctl.h>
  25 #include <lttng/notification/channel-internal.h>
  26 #include <lttng/rotate-internal.h>
  27
  28 #include "rotation-thread.h"
  29 #include "lttng-sessiond.h"
  30 #include "health-sessiond.h"
  31 #include "rotate.h"
  32 #include "cmd.h"
  33 #include "session.h"
  34 #include "timer.h"
  35 #include "notification-thread-commands.h"
  36 #include "utils.h"
  37 #include "thread.h"
  38
  39 #include <urcu.h>
  40 #include <urcu/list.h>
  41
  42 struct lttng_notification_channel *rotate_notification_channel = NULL;
  43
  44 struct rotation_thread {
  45         struct lttng_poll_event events;
  46 };
  47
  48 struct rotation_thread_job {
  49         enum rotation_thread_job_type type;
  50         struct ltt_session *session;
  51         /* List member in struct rotation_thread_timer_queue. */
  52         struct cds_list_head head;
  53 };
  54
  55 /*
  56  * The timer thread enqueues jobs and wakes up the rotation thread.
  57  * When the rotation thread wakes up, it empties the queue.
  58  */
  59 struct rotation_thread_timer_queue {
  60         struct lttng_pipe *event_pipe;
  61         struct cds_list_head list;
  62         pthread_mutex_t lock;
  63 };
  64
  65 struct rotation_thread_handle {
  66         struct rotation_thread_timer_queue *rotation_timer_queue;
  67         /* Access to the notification thread cmd_queue */
  68         struct notification_thread_handle *notification_thread_handle;
  69         /* Thread-specific quit pipe. */
  70         struct lttng_pipe *quit_pipe;
  71 };
  72
  73 static
  74 const char *get_job_type_str(enum rotation_thread_job_type job_type)
  75 {
  76         switch (job_type) {
  77         case ROTATION_THREAD_JOB_TYPE_CHECK_PENDING_ROTATION:
  78                 return "CHECK_PENDING_ROTATION";
  79         case ROTATION_THREAD_JOB_TYPE_SCHEDULED_ROTATION:
  80                 return "SCHEDULED_ROTATION";
  81         default:
  82                 abort();
  83         }
  84 }
  85
  86 struct rotation_thread_timer_queue *rotation_thread_timer_queue_create(void)
  87 {
  88         struct rotation_thread_timer_queue *queue = NULL;
  89
  90         queue = zmalloc(sizeof(*queue));
  91         if (!queue) {
  92                 PERROR("Failed to allocate timer rotate queue");
  93                 goto end;
  94         }
  95
  96         queue->event_pipe = lttng_pipe_open(FD_CLOEXEC | O_NONBLOCK);
  97         CDS_INIT_LIST_HEAD(&queue->list);
  98         pthread_mutex_init(&queue->lock, NULL);
  99 end:
 100         return queue;
 101 }
 102
 103 void rotation_thread_timer_queue_destroy(
 104                 struct rotation_thread_timer_queue *queue)
 105 {
 106         if (!queue) {
 107                 return;
 108         }
 109
 110         lttng_pipe_destroy(queue->event_pipe);
 111
 112         pthread_mutex_lock(&queue->lock);
 113         assert(cds_list_empty(&queue->list));
 114         pthread_mutex_unlock(&queue->lock);
 115         pthread_mutex_destroy(&queue->lock);
 116         free(queue);
 117 }
 118
 119 /*
 120  * Destroy the thread data previously created by the init function.
 121  */
 122 void rotation_thread_handle_destroy(
 123                 struct rotation_thread_handle *handle)
 124 {
 125         lttng_pipe_destroy(handle->quit_pipe);
 126         free(handle);
 127 }
 128
 129 struct rotation_thread_handle *rotation_thread_handle_create(
 130                 struct rotation_thread_timer_queue *rotation_timer_queue,
 131                 struct notification_thread_handle *notification_thread_handle)
 132 {
 133         struct rotation_thread_handle *handle;
 134
 135         handle = zmalloc(sizeof(*handle));
 136         if (!handle) {
 137                 goto end;
 138         }
 139
 140         handle->rotation_timer_queue = rotation_timer_queue;
 141         handle->notification_thread_handle = notification_thread_handle;
 142         handle->quit_pipe = lttng_pipe_open(FD_CLOEXEC);
 143         if (!handle->quit_pipe) {
 144                 goto error;
 145         }
 146
 147 end:
 148         return handle;
 149 error:
 150         rotation_thread_handle_destroy(handle);
 151         return NULL;
 152 }
 153
 154 /*
 155  * Called with the rotation_thread_timer_queue lock held.
 156  * Return true if the same timer job already exists in the queue, false if not.
 157  */
 158 static
 159 bool timer_job_exists(const struct rotation_thread_timer_queue *queue,
 160                 enum rotation_thread_job_type job_type,
 161                 struct ltt_session *session)
 162 {
 163         bool exists = false;
 164         struct rotation_thread_job *job;
 165
 166         cds_list_for_each_entry(job, &queue->list, head) {
 167                 if (job->session == session && job->type == job_type) {
 168                         exists = true;
 169                         goto end;
 170                 }
 171         }
 172 end:
 173         return exists;
 174 }
 175
 176 void rotation_thread_enqueue_job(struct rotation_thread_timer_queue *queue,
 177                 enum rotation_thread_job_type job_type,
 178                 struct ltt_session *session)
 179 {
 180         int ret;
 181         const char dummy = '!';
 182         struct rotation_thread_job *job = NULL;
 183         const char *job_type_str = get_job_type_str(job_type);
 184
 185         pthread_mutex_lock(&queue->lock);
 186         if (timer_job_exists(queue, job_type, session)) {
 187                 /*
 188                  * This timer job is already pending, we don't need to add
 189                  * it.
 190                  */
 191                 goto end;
 192         }
 193
 194         job = zmalloc(sizeof(struct rotation_thread_job));
 195         if (!job) {
 196                 PERROR("Failed to allocate rotation thread job of type \"%s\" for session \"%s\"",
 197                                 job_type_str, session->name);
 198                 goto end;
 199         }
 200         /* No reason for this to fail as the caller must hold a reference. */
 201         (void) session_get(session);
 202
 203         job->session = session;
 204         job->type = job_type;
 205         cds_list_add_tail(&job->head, &queue->list);
 206
 207         ret = lttng_write(lttng_pipe_get_writefd(queue->event_pipe), &dummy,
 208                         sizeof(dummy));
 209         if (ret < 0) {
 210                 /*
 211                  * We do not want to block in the timer handler, the job has
 212                  * been enqueued in the list, the wakeup pipe is probably full,
 213                  * the job will be processed when the rotation_thread catches
 214                  * up.
 215                  */
 216                 if (errno == EAGAIN || errno == EWOULDBLOCK) {
 217                         /*
 218                          * Not an error, but would be surprising and indicate
 219                          * that the rotation thread can't keep up with the
 220                          * current load.
 221                          */
 222                         DBG("Wake-up pipe of rotation thread job queue is full");
 223                         goto end;
 224                 }
 225                 PERROR("Failed to wake-up the rotation thread after pushing a job of type \"%s\" for session \"%s\"",
 226                                 job_type_str, session->name);
 227                 goto end;
 228         }
 229
 230 end:
 231         pthread_mutex_unlock(&queue->lock);
 232 }
 233
 234 static
 235 int init_poll_set(struct lttng_poll_event *poll_set,
 236                 struct rotation_thread_handle *handle)
 237 {
 238         int ret;
 239
 240         /*
 241          * Create pollset with size 3:
 242          *      - rotation thread quit pipe,
 243          *      - rotation thread timer queue pipe,
 244          *      - notification channel sock,
 245          */
 246         ret = lttng_poll_create(poll_set, 5, LTTNG_CLOEXEC);
 247         if (ret < 0) {
 248                 goto error;
 249         }
 250
 251         ret = lttng_poll_add(poll_set,
 252                         lttng_pipe_get_readfd(handle->quit_pipe),
 253                         LPOLLIN | LPOLLERR);
 254         if (ret < 0) {
 255                 ERR("Failed to add quit pipe read fd to poll set");
 256                 goto error;
 257         }
 258
 259         ret = lttng_poll_add(poll_set,
 260                         lttng_pipe_get_readfd(handle->rotation_timer_queue->event_pipe),
 261                         LPOLLIN | LPOLLERR);
 262         if (ret < 0) {
 263                 ERR("Failed to add rotate_pending fd to poll set");
 264                 goto error;
 265         }
 266
 267         return ret;
 268 error:
 269         lttng_poll_clean(poll_set);
 270         return ret;
 271 }
 272
 273 static
 274 void fini_thread_state(struct rotation_thread *state)
 275 {
 276         lttng_poll_clean(&state->events);
 277         if (rotate_notification_channel) {
 278                 lttng_notification_channel_destroy(rotate_notification_channel);
 279         }
 280 }
 281
 282 static
 283 int init_thread_state(struct rotation_thread_handle *handle,
 284                 struct rotation_thread *state)
 285 {
 286         int ret;
 287
 288         memset(state, 0, sizeof(*state));
 289         lttng_poll_init(&state->events);
 290
 291         ret = init_poll_set(&state->events, handle);
 292         if (ret) {
 293                 ERR("Failed to initialize rotation thread poll set");
 294                 goto end;
 295         }
 296
 297         rotate_notification_channel = lttng_notification_channel_create(
 298                         lttng_session_daemon_notification_endpoint);
 299         if (!rotate_notification_channel) {
 300                 ERR("Could not create notification channel");
 301                 ret = -1;
 302                 goto end;
 303         }
 304         ret = lttng_poll_add(&state->events, rotate_notification_channel->socket,
 305                         LPOLLIN | LPOLLERR);
 306         if (ret < 0) {
 307                 ERR("Failed to add notification fd to pollset");
 308                 goto end;
 309         }
 310
 311 end:
 312         return ret;
 313 }
 314
 315 static
 316 void check_session_rotation_pending_on_consumers(struct ltt_session *session,
 317                 bool *_rotation_completed)
 318 {
 319         int ret = 0;
 320         struct consumer_socket *socket;
 321         struct cds_lfht_iter iter;
 322         enum consumer_trace_chunk_exists_status exists_status;
 323         uint64_t relayd_id;
 324         bool chunk_exists_on_peer = false;
 325         enum lttng_trace_chunk_status chunk_status;
 326
 327         assert(session->chunk_being_archived);
 328
 329         /*
 330          * Check for a local pending rotation on all consumers (32-bit
 331          * user space, 64-bit user space, and kernel).
 332          */
 333         rcu_read_lock();
 334         if (!session->ust_session) {
 335                 goto skip_ust;
 336         }
 337         cds_lfht_for_each_entry(session->ust_session->consumer->socks->ht,
 338                         &iter, socket, node.node) {
 339                 relayd_id = session->ust_session->consumer->type == CONSUMER_DST_LOCAL ?
 340                                 -1ULL :
 341                                 session->ust_session->consumer->net_seq_index;
 342
 343                 pthread_mutex_lock(socket->lock);
 344                 ret = consumer_trace_chunk_exists(socket,
 345                                 relayd_id,
 346                                 session->id, session->chunk_being_archived,
 347                                 &exists_status);
 348                 if (ret) {
 349                         pthread_mutex_unlock(socket->lock);
 350                         ERR("Error occurred while checking rotation status on consumer daemon");
 351                         goto end;
 352                 }
 353
 354                 if (exists_status != CONSUMER_TRACE_CHUNK_EXISTS_STATUS_UNKNOWN_CHUNK) {
 355                         pthread_mutex_unlock(socket->lock);
 356                         chunk_exists_on_peer = true;
 357                         goto end;
 358                 }
 359                 pthread_mutex_unlock(socket->lock);
 360         }
 361
 362 skip_ust:
 363         if (!session->kernel_session) {
 364                 goto skip_kernel;
 365         }
 366         cds_lfht_for_each_entry(session->kernel_session->consumer->socks->ht,
 367                                 &iter, socket, node.node) {
 368                 pthread_mutex_lock(socket->lock);
 369                 relayd_id = session->kernel_session->consumer->type == CONSUMER_DST_LOCAL ?
 370                                 -1ULL :
 371                                 session->kernel_session->consumer->net_seq_index;
 372
 373                 ret = consumer_trace_chunk_exists(socket,
 374                                 relayd_id,
 375                                 session->id, session->chunk_being_archived,
 376                                 &exists_status);
 377                 if (ret) {
 378                         pthread_mutex_unlock(socket->lock);
 379                         ERR("Error occurred while checking rotation status on consumer daemon");
 380                         goto end;
 381                 }
 382
 383                 if (exists_status != CONSUMER_TRACE_CHUNK_EXISTS_STATUS_UNKNOWN_CHUNK) {
 384                         pthread_mutex_unlock(socket->lock);
 385                         chunk_exists_on_peer = true;
 386                         goto end;
 387                 }
 388                 pthread_mutex_unlock(socket->lock);
 389         }
 390 skip_kernel:
 391 end:
 392         rcu_read_unlock();
 393
 394         if (!chunk_exists_on_peer) {
 395                 uint64_t chunk_being_archived_id;
 396
 397                 chunk_status = lttng_trace_chunk_get_id(
 398                                 session->chunk_being_archived,
 399                                 &chunk_being_archived_id);
 400                 assert(chunk_status == LTTNG_TRACE_CHUNK_STATUS_OK);
 401                 DBG("Rotation of trace archive %" PRIu64 " of session \"%s\" is complete on all consumers",
 402                                 chunk_being_archived_id,
 403                                 session->name);
 404         }
 405         *_rotation_completed = !chunk_exists_on_peer;
 406         if (ret) {
 407                 ret = session_reset_rotation_state(session,
 408                                 LTTNG_ROTATION_STATE_ERROR);
 409                 if (ret) {
 410                         ERR("Failed to reset rotation state of session \"%s\"",
 411                                         session->name);
 412                 }
 413         }
 414 }
 415
 416 /*
 417  * Check if the last rotation was completed, called with session lock held.
 418  * Should only return non-zero in the event of a fatal error. Doing so will
 419  * shutdown the thread.
 420  */
 421 static
 422 int check_session_rotation_pending(struct ltt_session *session,
 423                 struct notification_thread_handle *notification_thread_handle)
 424 {
 425         int ret;
 426         struct lttng_trace_archive_location *location;
 427         enum lttng_trace_chunk_status chunk_status;
 428         bool rotation_completed = false;
 429         const char *archived_chunk_name;
 430         uint64_t chunk_being_archived_id;
 431
 432         if (!session->chunk_being_archived) {
 433                 ret = 0;
 434                 goto end;
 435         }
 436
 437         chunk_status = lttng_trace_chunk_get_id(session->chunk_being_archived,
 438                         &chunk_being_archived_id);
 439         assert(chunk_status == LTTNG_TRACE_CHUNK_STATUS_OK);
 440
 441         DBG("Checking for pending rotation on session \"%s\", trace archive %" PRIu64,
 442                         session->name, chunk_being_archived_id);
 443
 444         /*
 445          * The rotation-pending check timer of a session is launched in
 446          * one-shot mode. If the rotation is incomplete, the rotation
 447          * thread will re-enable the pending-check timer.
 448          *
 449          * The timer thread can't stop the timer itself since it is involved
 450          * in the check for the timer's quiescence.
 451          */
 452         ret = timer_session_rotation_pending_check_stop(session);
 453         if (ret) {
 454                 goto check_ongoing_rotation;
 455         }
 456
 457         check_session_rotation_pending_on_consumers(session,
 458                         &rotation_completed);
 459         if (!rotation_completed ||
 460                         session->rotation_state == LTTNG_ROTATION_STATE_ERROR) {
 461                 goto check_ongoing_rotation;
 462         }
 463
 464         /*
 465          * Now we can clear the "ONGOING" state in the session. New
 466          * rotations can start now.
 467          */
 468         chunk_status = lttng_trace_chunk_get_name(session->chunk_being_archived,
 469                         &archived_chunk_name, NULL);
 470         assert(chunk_status == LTTNG_TRACE_CHUNK_STATUS_OK);
 471         free(session->last_archived_chunk_name);
 472         session->last_archived_chunk_name = strdup(archived_chunk_name);
 473         if (!session->last_archived_chunk_name) {
 474                 PERROR("Failed to duplicate archived chunk name");
 475         }
 476         session_reset_rotation_state(session, LTTNG_ROTATION_STATE_COMPLETED);
 477
 478         if (!session->quiet_rotation) {
 479                 location = session_get_trace_archive_location(session);
 480                 /* Ownership of location is transferred. */
 481                 ret = notification_thread_command_session_rotation_completed(
 482                                 notification_thread_handle,
 483                                 session->name,
 484                                 session->uid,
 485                                 session->gid,
 486                                 session->last_archived_chunk_id.value,
 487                                 location);
 488                 if (ret != LTTNG_OK) {
 489                         ERR("Failed to notify notification thread of completed rotation for session %s",
 490                                         session->name);
 491                 }
 492         }
 493
 494         ret = 0;
 495 check_ongoing_rotation:
 496         if (session->rotation_state == LTTNG_ROTATION_STATE_ONGOING) {
 497                 chunk_status = lttng_trace_chunk_get_id(
 498                                 session->chunk_being_archived,
 499                                 &chunk_being_archived_id);
 500                 assert(chunk_status == LTTNG_TRACE_CHUNK_STATUS_OK);
 501
 502                 DBG("Rotation of trace archive %" PRIu64 " is still pending for session %s",
 503                                 chunk_being_archived_id, session->name);
 504                 ret = timer_session_rotation_pending_check_start(session,
 505                                 DEFAULT_ROTATE_PENDING_TIMER);
 506                 if (ret) {
 507                         ERR("Failed to re-enable rotation pending timer");
 508                         ret = -1;
 509                         goto end;
 510                 }
 511         }
 512
 513 end:
 514         return ret;
 515 }
 516
 517 /* Call with the session and session_list locks held. */
 518 static
 519 int launch_session_rotation(struct ltt_session *session)
 520 {
 521         int ret;
 522         struct lttng_rotate_session_return rotation_return;
 523
 524         DBG("Launching scheduled time-based rotation on session \"%s\"",
 525                         session->name);
 526
 527         ret = cmd_rotate_session(session, &rotation_return, false,
 528                 LTTNG_TRACE_CHUNK_COMMAND_TYPE_MOVE_TO_COMPLETED);
 529         if (ret == LTTNG_OK) {
 530                 DBG("Scheduled time-based rotation successfully launched on session \"%s\"",
 531                                 session->name);
 532         } else {
 533                 /* Don't consider errors as fatal. */
 534                 DBG("Scheduled time-based rotation aborted for session %s: %s",
 535                                 session->name, lttng_strerror(ret));
 536         }
 537         return 0;
 538 }
 539
 540 static
 541 int run_job(struct rotation_thread_job *job, struct ltt_session *session,
 542                 struct notification_thread_handle *notification_thread_handle)
 543 {
 544         int ret;
 545
 546         switch (job->type) {
 547         case ROTATION_THREAD_JOB_TYPE_SCHEDULED_ROTATION:
 548                 ret = launch_session_rotation(session);
 549                 break;
 550         case ROTATION_THREAD_JOB_TYPE_CHECK_PENDING_ROTATION:
 551                 ret = check_session_rotation_pending(session,
 552                                 notification_thread_handle);
 553                 break;
 554         default:
 555                 abort();
 556         }
 557         return ret;
 558 }
 559
 560 static
 561 int handle_job_queue(struct rotation_thread_handle *handle,
 562                 struct rotation_thread *state,
 563                 struct rotation_thread_timer_queue *queue)
 564 {
 565         int ret = 0;
 566
 567         for (;;) {
 568                 struct ltt_session *session;
 569                 struct rotation_thread_job *job;
 570
 571                 /* Take the queue lock only to pop an element from the list. */
 572                 pthread_mutex_lock(&queue->lock);
 573                 if (cds_list_empty(&queue->list)) {
 574                         pthread_mutex_unlock(&queue->lock);
 575                         break;
 576                 }
 577                 job = cds_list_first_entry(&queue->list,
 578                                 typeof(*job), head);
 579                 cds_list_del(&job->head);
 580                 pthread_mutex_unlock(&queue->lock);
 581
 582                 session_lock_list();
 583                 session = job->session;
 584                 if (!session) {
 585                         DBG("Session \"%s\" not found",
 586                                         session->name);
 587                         /*
 588                          * This is a non-fatal error, and we cannot report it to
 589                          * the user (timer), so just print the error and
 590                          * continue the processing.
 591                          *
 592                          * While the timer thread will purge pending signals for
 593                          * a session on the session's destruction, it is
 594                          * possible for a job targeting that session to have
 595                          * already been queued before it was destroyed.
 596                          */
 597                         free(job);
 598                         session_put(session);
 599                         session_unlock_list();
 600                         continue;
 601                 }
 602
 603                 session_lock(session);
 604                 ret = run_job(job, session, handle->notification_thread_handle);
 605                 session_unlock(session);
 606                 /* Release reference held by the job. */
 607                 session_put(session);
 608                 session_unlock_list();
 609                 free(job);
 610                 if (ret) {
 611                         goto end;
 612                 }
 613         }
 614
 615         ret = 0;
 616
 617 end:
 618         return ret;
 619 }
 620
 621 static
 622 int handle_condition(const struct lttng_condition *condition,
 623                 const struct lttng_evaluation *evaluation,
 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
 634         condition_type = lttng_condition_get_type(condition);
 635
 636         if (condition_type != LTTNG_CONDITION_TYPE_SESSION_CONSUMED_SIZE) {
 637                 ret = -1;
 638                 ERR("Condition type and session usage type are not the same");
 639                 goto end;
 640         }
 641
 642         /* Fetch info to test */
 643         condition_status = lttng_condition_session_consumed_size_get_session_name(
 644                         condition, &condition_session_name);
 645         if (condition_status != LTTNG_CONDITION_STATUS_OK) {
 646                 ERR("Session name could not be fetched");
 647                 ret = -1;
 648                 goto end;
 649         }
 650         evaluation_status = lttng_evaluation_session_consumed_size_get_consumed_size(evaluation,
 651                         &consumed);
 652         if (evaluation_status != LTTNG_EVALUATION_STATUS_OK) {
 653                 ERR("Failed to get evaluation");
 654                 ret = -1;
 655                 goto end;
 656         }
 657
 658         session_lock_list();
 659         session = session_find_by_name(condition_session_name);
 660         if (!session) {
 661                 ret = -1;
 662                 session_unlock_list();
 663                 ERR("Session \"%s\" not found",
 664                                 condition_session_name);
 665                 goto end;
 666         }
 667         session_lock(session);
 668
 669         ret = unsubscribe_session_consumed_size_rotation(session,
 670                         notification_thread_handle);
 671         if (ret) {
 672                 goto end_unlock;
 673         }
 674
 675         ret = cmd_rotate_session(session, NULL, false,
 676                 LTTNG_TRACE_CHUNK_COMMAND_TYPE_MOVE_TO_COMPLETED);
 677         if (ret == -LTTNG_ERR_ROTATION_PENDING) {
 678                 DBG("Rotate already pending, subscribe to the next threshold value");
 679         } else if (ret != LTTNG_OK) {
 680                 ERR("Failed to rotate on size notification with error: %s",
 681                                 lttng_strerror(ret));
 682                 ret = -1;
 683                 goto end_unlock;
 684         }
 685         ret = subscribe_session_consumed_size_rotation(session,
 686                         consumed + session->rotate_size,
 687                         notification_thread_handle);
 688         if (ret) {
 689                 ERR("Failed to subscribe to session consumed size condition");
 690                 goto end_unlock;
 691         }
 692         ret = 0;
 693
 694 end_unlock:
 695         session_unlock(session);
 696         session_put(session);
 697         session_unlock_list();
 698 end:
 699         return ret;
 700 }
 701
 702 static
 703 int handle_notification_channel(int fd,
 704                 struct rotation_thread_handle *handle,
 705                 struct rotation_thread *state)
 706 {
 707         int ret;
 708         bool notification_pending;
 709         struct lttng_notification *notification = NULL;
 710         enum lttng_notification_channel_status status;
 711         const struct lttng_evaluation *notification_evaluation;
 712         const struct lttng_condition *notification_condition;
 713
 714         status = lttng_notification_channel_has_pending_notification(
 715                         rotate_notification_channel, &notification_pending);
 716         if (status != LTTNG_NOTIFICATION_CHANNEL_STATUS_OK) {
 717                 ERR("Error occurred while checking for pending notification");
 718                 ret = -1;
 719                 goto end;
 720         }
 721
 722         if (!notification_pending) {
 723                 ret = 0;
 724                 goto end;
 725         }
 726
 727         /* Receive the next notification. */
 728         status = lttng_notification_channel_get_next_notification(
 729                         rotate_notification_channel,
 730                         &notification);
 731
 732         switch (status) {
 733         case LTTNG_NOTIFICATION_CHANNEL_STATUS_OK:
 734                 break;
 735         case LTTNG_NOTIFICATION_CHANNEL_STATUS_NOTIFICATIONS_DROPPED:
 736                 /* Not an error, we will wait for the next one */
 737                 ret = 0;
 738                 goto end;;
 739         case LTTNG_NOTIFICATION_CHANNEL_STATUS_CLOSED:
 740                 ERR("Notification channel was closed");
 741                 ret = -1;
 742                 goto end;
 743         default:
 744                 /* Unhandled conditions / errors. */
 745                 ERR("Unknown notification channel status");
 746                 ret = -1;
 747                 goto end;
 748         }
 749
 750         notification_condition = lttng_notification_get_condition(notification);
 751         notification_evaluation = lttng_notification_get_evaluation(notification);
 752
 753         ret = handle_condition(notification_condition, notification_evaluation,
 754                         handle->notification_thread_handle);
 755
 756 end:
 757         lttng_notification_destroy(notification);
 758         return ret;
 759 }
 760
 761 static
 762 void *thread_rotation(void *data)
 763 {
 764         int ret;
 765         struct rotation_thread_handle *handle = data;
 766         struct rotation_thread thread;
 767         int queue_pipe_fd;
 768
 769         DBG("Started rotation thread");
 770         rcu_register_thread();
 771         rcu_thread_online();
 772         health_register(the_health_sessiond, HEALTH_SESSIOND_TYPE_ROTATION);
 773         health_code_update();
 774
 775         if (!handle) {
 776                 ERR("Invalid thread context provided");
 777                 goto end;
 778         }
 779
 780         queue_pipe_fd = lttng_pipe_get_readfd(
 781                         handle->rotation_timer_queue->event_pipe);
 782
 783
 784         ret = init_thread_state(handle, &thread);
 785         if (ret) {
 786                 goto error;
 787         }
 788
 789         while (true) {
 790                 int fd_count, i;
 791
 792                 health_poll_entry();
 793                 DBG("Entering poll wait");
 794                 ret = lttng_poll_wait(&thread.events, -1);
 795                 DBG("Poll wait returned (%i)", ret);
 796                 health_poll_exit();
 797                 if (ret < 0) {
 798                         /*
 799                          * Restart interrupted system call.
 800                          */
 801                         if (errno == EINTR) {
 802                                 continue;
 803                         }
 804                         ERR("Error encountered during lttng_poll_wait (%i)", ret);
 805                         goto error;
 806                 }
 807
 808                 fd_count = ret;
 809                 for (i = 0; i < fd_count; i++) {
 810                         int fd = LTTNG_POLL_GETFD(&thread.events, i);
 811                         uint32_t revents = LTTNG_POLL_GETEV(&thread.events, i);
 812
 813                         DBG("Handling fd (%i) activity (%u)",
 814                                         fd, revents);
 815
 816                         if (revents & LPOLLERR) {
 817                                 ERR("Polling returned an error on fd %i", fd);
 818                                 goto error;
 819                         }
 820
 821                         if (fd == rotate_notification_channel->socket) {
 822                                 ret = handle_notification_channel(fd, handle,
 823                                                 &thread);
 824                                 if (ret) {
 825                                         ERR("Error occurred while handling activity on notification channel socket");
 826                                         goto error;
 827                                 }
 828                         } else {
 829                                 /* Job queue or quit pipe activity. */
 830
 831                                 /*
 832                                  * The job queue is serviced if there is
 833                                  * activity on the quit pipe to ensure it is
 834                                  * flushed and all references held in the queue
 835                                  * are released.
 836                                  */
 837                                 ret = handle_job_queue(handle, &thread,
 838                                                 handle->rotation_timer_queue);
 839                                 if (ret) {
 840                                         ERR("Failed to handle rotation timer pipe event");
 841                                         goto error;
 842                                 }
 843
 844                                 if (fd == queue_pipe_fd) {
 845                                         char buf;
 846
 847                                         ret = lttng_read(fd, &buf, 1);
 848                                         if (ret != 1) {
 849                                                 ERR("Failed to read from wakeup pipe (fd = %i)", fd);
 850                                                 goto error;
 851                                         }
 852                                 } else {
 853                                         DBG("Quit pipe activity");
 854                                         goto exit;
 855                                 }
 856                         }
 857                 }
 858         }
 859 exit:
 860 error:
 861         DBG("Thread exit");
 862         fini_thread_state(&thread);
 863 end:
 864         health_unregister(the_health_sessiond);
 865         rcu_thread_offline();
 866         rcu_unregister_thread();
 867         return NULL;
 868 }
 869
 870 static
 871 bool shutdown_rotation_thread(void *thread_data)
 872 {
 873         struct rotation_thread_handle *handle = thread_data;
 874         const int write_fd = lttng_pipe_get_writefd(handle->quit_pipe);
 875
 876         return notify_thread_pipe(write_fd) == 1;
 877 }
 878
 879 bool launch_rotation_thread(struct rotation_thread_handle *handle)
 880 {
 881         struct lttng_thread *thread;
 882
 883         thread = lttng_thread_create("Rotation",
 884                         thread_rotation,
 885                         shutdown_rotation_thread,
 886                         NULL,
 887                         handle);
 888         if (!thread) {
 889                 goto error;
 890         }
 891         lttng_thread_put(thread);
 892         return true;
 893 error:
 894         return false;
 895 }