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  * This program is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License, version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This program is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
  12  * more details.
  13  *
  14  * You should have received a copy of the GNU General Public License along with
  15  * this program; if not, write to the Free Software Foundation, Inc., 51
  16  * Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  17  */
  18
  19 #define _LGPL_SOURCE
  20 #include <lttng/trigger/trigger.h>
  21 #include <common/error.h>
  22 #include <common/config/session-config.h>
  23 #include <common/defaults.h>
  24 #include <common/utils.h>
  25 #include <common/futex.h>
  26 #include <common/align.h>
  27 #include <common/time.h>
  28 #include <common/hashtable/utils.h>
  29 #include <sys/eventfd.h>
  30 #include <sys/stat.h>
  31 #include <time.h>
  32 #include <signal.h>
  33 #include <inttypes.h>
  34
  35 #include <common/kernel-ctl/kernel-ctl.h>
  36 #include <lttng/notification/channel-internal.h>
  37 #include <lttng/rotate-internal.h>
  38
  39 #include "rotation-thread.h"
  40 #include "lttng-sessiond.h"
  41 #include "health-sessiond.h"
  42 #include "rotate.h"
  43 #include "cmd.h"
  44 #include "session.h"
  45 #include "timer.h"
  46 #include "notification-thread-commands.h"
  47 #include "utils.h"
  48 #include "thread.h"
  49
  50 #include <urcu.h>
  51 #include <urcu/list.h>
  52
  53 struct lttng_notification_channel *rotate_notification_channel = NULL;
  54
  55 struct rotation_thread {
  56         struct lttng_poll_event events;
  57 };
  58
  59 struct rotation_thread_job {
  60         enum rotation_thread_job_type type;
  61         struct ltt_session *session;
  62         /* List member in struct rotation_thread_timer_queue. */
  63         struct cds_list_head head;
  64 };
  65
  66 /*
  67  * The timer thread enqueues jobs and wakes up the rotation thread.
  68  * When the rotation thread wakes up, it empties the queue.
  69  */
  70 struct rotation_thread_timer_queue {
  71         struct lttng_pipe *event_pipe;
  72         struct cds_list_head list;
  73         pthread_mutex_t lock;
  74 };
  75
  76 struct rotation_thread_handle {
  77         struct rotation_thread_timer_queue *rotation_timer_queue;
  78         /* Access to the notification thread cmd_queue */
  79         struct notification_thread_handle *notification_thread_handle;
  80         /* Thread-specific quit pipe. */
  81         struct lttng_pipe *quit_pipe;
  82 };
  83
  84 static
  85 const char *get_job_type_str(enum rotation_thread_job_type job_type)
  86 {
  87         switch (job_type) {
  88         case ROTATION_THREAD_JOB_TYPE_CHECK_PENDING_ROTATION:
  89                 return "CHECK_PENDING_ROTATION";
  90         case ROTATION_THREAD_JOB_TYPE_SCHEDULED_ROTATION:
  91                 return "SCHEDULED_ROTATION";
  92         default:
  93                 abort();
  94         }
  95 }
  96
  97 struct rotation_thread_timer_queue *rotation_thread_timer_queue_create(void)
  98 {
  99         struct rotation_thread_timer_queue *queue = NULL;
 100
 101         queue = zmalloc(sizeof(*queue));
 102         if (!queue) {
 103                 PERROR("Failed to allocate timer rotate queue");
 104                 goto end;
 105         }
 106
 107         queue->event_pipe = lttng_pipe_open(FD_CLOEXEC | O_NONBLOCK);
 108         CDS_INIT_LIST_HEAD(&queue->list);
 109         pthread_mutex_init(&queue->lock, NULL);
 110 end:
 111         return queue;
 112 }
 113
 114 void log_job_destruction(const struct rotation_thread_job *job)
 115 {
 116         enum lttng_error_level log_level;
 117         const char *job_type_str = get_job_type_str(job->type);
 118
 119         switch (job->type) {
 120         case ROTATION_THREAD_JOB_TYPE_SCHEDULED_ROTATION:
 121                 /*
 122                  * Not a problem, the scheduled rotation is racing with the teardown
 123                  * of the daemon. In this case, the rotation will not happen, which
 124                  * is not a problem (or at least, not important enough to delay
 125                  * the shutdown of the session daemon).
 126                  */
 127                 log_level = PRINT_DBG;
 128                 break;
 129         case ROTATION_THREAD_JOB_TYPE_CHECK_PENDING_ROTATION:
 130                 /* This is not expected to happen; warn the user. */
 131                 log_level = PRINT_WARN;
 132                 break;
 133         default:
 134                 abort();
 135         }
 136
 137         LOG(log_level, "Rotation thread timer queue still contains job of type %s targeting session \"%s\" on destruction",
 138                         job_type_str, job->session->name);
 139 }
 140
 141 void rotation_thread_timer_queue_destroy(
 142                 struct rotation_thread_timer_queue *queue)
 143 {
 144         if (!queue) {
 145                 return;
 146         }
 147
 148         lttng_pipe_destroy(queue->event_pipe);
 149
 150         pthread_mutex_lock(&queue->lock);
 151         assert(cds_list_empty(&queue->list));
 152         pthread_mutex_unlock(&queue->lock);
 153         pthread_mutex_destroy(&queue->lock);
 154         free(queue);
 155 }
 156
 157 /*
 158  * Destroy the thread data previously created by the init function.
 159  */
 160 void rotation_thread_handle_destroy(
 161                 struct rotation_thread_handle *handle)
 162 {
 163         lttng_pipe_destroy(handle->quit_pipe);
 164         free(handle);
 165 }
 166
 167 struct rotation_thread_handle *rotation_thread_handle_create(
 168                 struct rotation_thread_timer_queue *rotation_timer_queue,
 169                 struct notification_thread_handle *notification_thread_handle)
 170 {
 171         struct rotation_thread_handle *handle;
 172
 173         handle = zmalloc(sizeof(*handle));
 174         if (!handle) {
 175                 goto end;
 176         }
 177
 178         handle->rotation_timer_queue = rotation_timer_queue;
 179         handle->notification_thread_handle = notification_thread_handle;
 180         handle->quit_pipe = lttng_pipe_open(FD_CLOEXEC);
 181         if (!handle->quit_pipe) {
 182                 goto error;
 183         }
 184
 185 end:
 186         return handle;
 187 error:
 188         rotation_thread_handle_destroy(handle);
 189         return NULL;
 190 }
 191
 192 /*
 193  * Called with the rotation_thread_timer_queue lock held.
 194  * Return true if the same timer job already exists in the queue, false if not.
 195  */
 196 static
 197 bool timer_job_exists(const struct rotation_thread_timer_queue *queue,
 198                 enum rotation_thread_job_type job_type,
 199                 struct ltt_session *session)
 200 {
 201         bool exists = false;
 202         struct rotation_thread_job *job;
 203
 204         cds_list_for_each_entry(job, &queue->list, head) {
 205                 if (job->session == session && job->type == job_type) {
 206                         exists = true;
 207                         goto end;
 208                 }
 209         }
 210 end:
 211         return exists;
 212 }
 213
 214 void rotation_thread_enqueue_job(struct rotation_thread_timer_queue *queue,
 215                 enum rotation_thread_job_type job_type,
 216                 struct ltt_session *session)
 217 {
 218         int ret;
 219         const char dummy = '!';
 220         struct rotation_thread_job *job = NULL;
 221         const char *job_type_str = get_job_type_str(job_type);
 222
 223         pthread_mutex_lock(&queue->lock);
 224         if (timer_job_exists(queue, job_type, session)) {
 225                 /*
 226                  * This timer job is already pending, we don't need to add
 227                  * it.
 228                  */
 229                 goto end;
 230         }
 231
 232         job = zmalloc(sizeof(struct rotation_thread_job));
 233         if (!job) {
 234                 PERROR("Failed to allocate rotation thread job of type \"%s\" for session \"%s\"",
 235                                 job_type_str, session->name);
 236                 goto end;
 237         }
 238         /* No reason for this to fail as the caller must hold a reference. */
 239         (void) session_get(session);
 240
 241         job->session = session;
 242         job->type = job_type;
 243         cds_list_add_tail(&job->head, &queue->list);
 244
 245         ret = lttng_write(lttng_pipe_get_writefd(queue->event_pipe), &dummy,
 246                         sizeof(dummy));
 247         if (ret < 0) {
 248                 /*
 249                  * We do not want to block in the timer handler, the job has
 250                  * been enqueued in the list, the wakeup pipe is probably full,
 251                  * the job will be processed when the rotation_thread catches
 252                  * up.
 253                  */
 254                 if (errno == EAGAIN || errno == EWOULDBLOCK) {
 255                         /*
 256                          * Not an error, but would be surprising and indicate
 257                          * that the rotation thread can't keep up with the
 258                          * current load.
 259                          */
 260                         DBG("Wake-up pipe of rotation thread job queue is full");
 261                         goto end;
 262                 }
 263                 PERROR("Failed to wake-up the rotation thread after pushing a job of type \"%s\" for session \"%s\"",
 264                                 job_type_str, session->name);
 265                 goto end;
 266         }
 267
 268 end:
 269         pthread_mutex_unlock(&queue->lock);
 270 }
 271
 272 static
 273 int init_poll_set(struct lttng_poll_event *poll_set,
 274                 struct rotation_thread_handle *handle)
 275 {
 276         int ret;
 277
 278         /*
 279          * Create pollset with size 3:
 280          *      - rotation thread quit pipe,
 281          *      - rotation thread timer queue pipe,
 282          *      - notification channel sock,
 283          */
 284         ret = lttng_poll_create(poll_set, 5, LTTNG_CLOEXEC);
 285         if (ret < 0) {
 286                 goto error;
 287         }
 288
 289         ret = lttng_poll_add(poll_set,
 290                         lttng_pipe_get_readfd(handle->quit_pipe),
 291                         LPOLLIN | LPOLLERR);
 292         if (ret < 0) {
 293                 ERR("[rotation-thread] Failed to add quit pipe read fd to poll set");
 294                 goto error;
 295         }
 296
 297         ret = lttng_poll_add(poll_set,
 298                         lttng_pipe_get_readfd(handle->rotation_timer_queue->event_pipe),
 299                         LPOLLIN | LPOLLERR);
 300         if (ret < 0) {
 301                 ERR("[rotation-thread] Failed to add rotate_pending fd to poll set");
 302                 goto error;
 303         }
 304
 305         return ret;
 306 error:
 307         lttng_poll_clean(poll_set);
 308         return ret;
 309 }
 310
 311 static
 312 void fini_thread_state(struct rotation_thread *state)
 313 {
 314         lttng_poll_clean(&state->events);
 315         if (rotate_notification_channel) {
 316                 lttng_notification_channel_destroy(rotate_notification_channel);
 317         }
 318 }
 319
 320 static
 321 int init_thread_state(struct rotation_thread_handle *handle,
 322                 struct rotation_thread *state)
 323 {
 324         int ret;
 325
 326         memset(state, 0, sizeof(*state));
 327         lttng_poll_init(&state->events);
 328
 329         ret = init_poll_set(&state->events, handle);
 330         if (ret) {
 331                 ERR("[rotation-thread] Failed to initialize rotation thread poll set");
 332                 goto end;
 333         }
 334
 335         rotate_notification_channel = lttng_notification_channel_create(
 336                         lttng_session_daemon_notification_endpoint);
 337         if (!rotate_notification_channel) {
 338                 ERR("[rotation-thread] Could not create notification channel");
 339                 ret = -1;
 340                 goto end;
 341         }
 342         ret = lttng_poll_add(&state->events, rotate_notification_channel->socket,
 343                         LPOLLIN | LPOLLERR);
 344         if (ret < 0) {
 345                 ERR("[rotation-thread] Failed to add notification fd to pollset");
 346                 goto end;
 347         }
 348
 349 end:
 350         return ret;
 351 }
 352
 353 static
 354 void check_session_rotation_pending_on_consumers(struct ltt_session *session,
 355                 bool *_rotation_completed)
 356 {
 357         int ret = 0;
 358         struct consumer_socket *socket;
 359         struct cds_lfht_iter iter;
 360         enum consumer_trace_chunk_exists_status exists_status;
 361         uint64_t relayd_id;
 362         bool chunk_exists_on_peer = false;
 363         enum lttng_trace_chunk_status chunk_status;
 364
 365         assert(session->chunk_being_archived);
 366
 367         /*
 368          * Check for a local pending rotation on all consumers (32-bit
 369          * user space, 64-bit user space, and kernel).
 370          */
 371         rcu_read_lock();
 372         if (!session->ust_session) {
 373                 goto skip_ust;
 374         }
 375         cds_lfht_for_each_entry(session->ust_session->consumer->socks->ht,
 376                         &iter, socket, node.node) {
 377                 relayd_id = session->ust_session->consumer->type == CONSUMER_DST_LOCAL ?
 378                                 -1ULL :
 379                                 session->ust_session->consumer->net_seq_index;
 380
 381                 pthread_mutex_lock(socket->lock);
 382                 ret = consumer_trace_chunk_exists(socket,
 383                                 relayd_id,
 384                                 session->id, session->chunk_being_archived,
 385                                 &exists_status);
 386                 if (ret) {
 387                         pthread_mutex_unlock(socket->lock);
 388                         ERR("Error occured while checking rotation status on consumer daemon");
 389                         goto end;
 390                 }
 391
 392                 if (exists_status != CONSUMER_TRACE_CHUNK_EXISTS_STATUS_UNKNOWN_CHUNK) {
 393                         pthread_mutex_unlock(socket->lock);
 394                         chunk_exists_on_peer = true;
 395                         goto end;
 396                 }
 397                 pthread_mutex_unlock(socket->lock);
 398         }
 399
 400 skip_ust:
 401         if (!session->kernel_session) {
 402                 goto skip_kernel;
 403         }
 404         cds_lfht_for_each_entry(session->kernel_session->consumer->socks->ht,
 405                                 &iter, socket, node.node) {
 406                 pthread_mutex_lock(socket->lock);
 407                 relayd_id = session->kernel_session->consumer->type == CONSUMER_DST_LOCAL ?
 408                                 -1ULL :
 409                                 session->kernel_session->consumer->net_seq_index;
 410
 411                 ret = consumer_trace_chunk_exists(socket,
 412                                 relayd_id,
 413                                 session->id, session->chunk_being_archived,
 414                                 &exists_status);
 415                 if (ret) {
 416                         pthread_mutex_unlock(socket->lock);
 417                         ERR("Error occured while checking rotation status on consumer daemon");
 418                         goto end;
 419                 }
 420
 421                 if (exists_status != CONSUMER_TRACE_CHUNK_EXISTS_STATUS_UNKNOWN_CHUNK) {
 422                         pthread_mutex_unlock(socket->lock);
 423                         chunk_exists_on_peer = true;
 424                         goto end;
 425                 }
 426                 pthread_mutex_unlock(socket->lock);
 427         }
 428 skip_kernel:
 429 end:
 430         rcu_read_unlock();
 431
 432         if (!chunk_exists_on_peer) {
 433                 uint64_t chunk_being_archived_id;
 434
 435                 chunk_status = lttng_trace_chunk_get_id(
 436                                 session->chunk_being_archived,
 437                                 &chunk_being_archived_id);
 438                 assert(chunk_status == LTTNG_TRACE_CHUNK_STATUS_OK);
 439                 DBG("[rotation-thread] Rotation of trace archive %" PRIu64 " of session \"%s\" is complete on all consumers",
 440                                 chunk_being_archived_id,
 441                                 session->name);
 442         }
 443         *_rotation_completed = !chunk_exists_on_peer;
 444         if (ret) {
 445                 ret = session_reset_rotation_state(session,
 446                                 LTTNG_ROTATION_STATE_ERROR);
 447                 if (ret) {
 448                         ERR("Failed to reset rotation state of session \"%s\"",
 449                                         session->name);
 450                 }
 451         }
 452 }
 453
 454 /*
 455  * Check if the last rotation was completed, called with session lock held.
 456  * Should only return non-zero in the event of a fatal error. Doing so will
 457  * shutdown the thread.
 458  */
 459 static
 460 int check_session_rotation_pending(struct ltt_session *session,
 461                 struct notification_thread_handle *notification_thread_handle)
 462 {
 463         int ret;
 464         struct lttng_trace_archive_location *location;
 465         enum lttng_trace_chunk_status chunk_status;
 466         bool rotation_completed = false;
 467         const char *archived_chunk_name;
 468         uint64_t chunk_being_archived_id;
 469
 470         if (!session->chunk_being_archived) {
 471                 ret = 0;
 472                 goto end;
 473         }
 474
 475         chunk_status = lttng_trace_chunk_get_id(session->chunk_being_archived,
 476                         &chunk_being_archived_id);
 477         assert(chunk_status == LTTNG_TRACE_CHUNK_STATUS_OK);
 478
 479         DBG("[rotation-thread] Checking for pending rotation on session \"%s\", trace archive %" PRIu64,
 480                         session->name, chunk_being_archived_id);
 481
 482         /*
 483          * The rotation-pending check timer of a session is launched in
 484          * one-shot mode. If the rotation is incomplete, the rotation
 485          * thread will re-enable the pending-check timer.
 486          *
 487          * The timer thread can't stop the timer itself since it is involved
 488          * in the check for the timer's quiescence.
 489          */
 490         ret = timer_session_rotation_pending_check_stop(session);
 491         if (ret) {
 492                 goto check_ongoing_rotation;
 493         }
 494
 495         check_session_rotation_pending_on_consumers(session,
 496                         &rotation_completed);
 497         if (!rotation_completed ||
 498                         session->rotation_state == LTTNG_ROTATION_STATE_ERROR) {
 499                 goto check_ongoing_rotation;
 500         }
 501
 502         /*
 503          * Now we can clear the "ONGOING" state in the session. New
 504          * rotations can start now.
 505          */
 506         chunk_status = lttng_trace_chunk_get_name(session->chunk_being_archived,
 507                         &archived_chunk_name, NULL);
 508         assert(chunk_status == LTTNG_TRACE_CHUNK_STATUS_OK);
 509         free(session->last_archived_chunk_name);
 510         session->last_archived_chunk_name = strdup(archived_chunk_name);
 511         if (!session->last_archived_chunk_name) {
 512                 PERROR("Failed to duplicate archived chunk name");
 513         }
 514         session_reset_rotation_state(session, LTTNG_ROTATION_STATE_COMPLETED);
 515
 516         if (!session->quiet_rotation) {
 517                 location = session_get_trace_archive_location(session);
 518                 /* Ownership of location is transferred. */
 519                 ret = notification_thread_command_session_rotation_completed(
 520                                 notification_thread_handle,
 521                                 session->name,
 522                                 session->uid,
 523                                 session->gid,
 524                                 session->last_archived_chunk_id.value,
 525                                 location);
 526                 if (ret != LTTNG_OK) {
 527                         ERR("[rotation-thread] Failed to notify notification thread of completed rotation for session %s",
 528                                         session->name);
 529                 }
 530         }
 531
 532         if (!session->active && !session->quiet_rotation) {
 533                 /*
 534                  * A stop command was issued during the rotation, it is
 535                  * up to the rotation completion check to perform the
 536                  * renaming of the last chunk that was produced.
 537                  */
 538                 ret = notification_thread_command_session_rotation_ongoing(
 539                                 notification_thread_handle,
 540                                 session->name,
 541                                 session->uid,
 542                                 session->gid,
 543                                 session->most_recent_chunk_id.value);
 544                 if (ret != LTTNG_OK) {
 545                         ERR("[rotation-thread] Failed to notify notification thread of completed rotation for session %s",
 546                                         session->name);
 547                 }
 548
 549                 /* Ownership of location is transferred. */
 550                 location = session_get_trace_archive_location(session);
 551                 ret = notification_thread_command_session_rotation_completed(
 552                                 notification_thread_handle,
 553                                 session->name,
 554                                 session->uid,
 555                                 session->gid,
 556                                 session->most_recent_chunk_id.value,
 557                                 location);
 558                 if (ret != LTTNG_OK) {
 559                         ERR("[rotation-thread] Failed to notify notification thread of completed rotation for session %s",
 560                                         session->name);
 561                 }
 562         }
 563
 564         ret = 0;
 565 check_ongoing_rotation:
 566         if (session->rotation_state == LTTNG_ROTATION_STATE_ONGOING) {
 567                 uint64_t chunk_being_archived_id;
 568
 569                 chunk_status = lttng_trace_chunk_get_id(
 570                                 session->chunk_being_archived,
 571                                 &chunk_being_archived_id);
 572                 assert(chunk_status == LTTNG_TRACE_CHUNK_STATUS_OK);
 573
 574                 DBG("[rotation-thread] Rotation of trace archive %" PRIu64 " is still pending for session %s",
 575                                 chunk_being_archived_id, session->name);
 576                 ret = timer_session_rotation_pending_check_start(session,
 577                                 DEFAULT_ROTATE_PENDING_TIMER);
 578                 if (ret) {
 579                         ERR("Failed to re-enable rotation pending timer");
 580                         ret = -1;
 581                         goto end;
 582                 }
 583         }
 584
 585 end:
 586         return ret;
 587 }
 588
 589 /* Call with the session and session_list locks held. */
 590 static
 591 int launch_session_rotation(struct ltt_session *session)
 592 {
 593         int ret;
 594         struct lttng_rotate_session_return rotation_return;
 595
 596         DBG("[rotation-thread] Launching scheduled time-based rotation on session \"%s\"",
 597                         session->name);
 598
 599         ret = cmd_rotate_session(session, &rotation_return, false);
 600         if (ret == LTTNG_OK) {
 601                 DBG("[rotation-thread] Scheduled time-based rotation successfully launched on session \"%s\"",
 602                                 session->name);
 603         } else {
 604                 /* Don't consider errors as fatal. */
 605                 DBG("[rotation-thread] Scheduled time-based rotation aborted for session %s: %s",
 606                                 session->name, lttng_strerror(ret));
 607         }
 608         return 0;
 609 }
 610
 611 static
 612 int run_job(struct rotation_thread_job *job, struct ltt_session *session,
 613                 struct notification_thread_handle *notification_thread_handle)
 614 {
 615         int ret;
 616
 617         switch (job->type) {
 618         case ROTATION_THREAD_JOB_TYPE_SCHEDULED_ROTATION:
 619                 ret = launch_session_rotation(session);
 620                 break;
 621         case ROTATION_THREAD_JOB_TYPE_CHECK_PENDING_ROTATION:
 622                 ret = check_session_rotation_pending(session,
 623                                 notification_thread_handle);
 624                 break;
 625         default:
 626                 abort();
 627         }
 628         return ret;
 629 }
 630
 631 static
 632 int handle_job_queue(struct rotation_thread_handle *handle,
 633                 struct rotation_thread *state,
 634                 struct rotation_thread_timer_queue *queue)
 635 {
 636         int ret = 0;
 637
 638         for (;;) {
 639                 struct ltt_session *session;
 640                 struct rotation_thread_job *job;
 641
 642                 /* Take the queue lock only to pop an element from the list. */
 643                 pthread_mutex_lock(&queue->lock);
 644                 if (cds_list_empty(&queue->list)) {
 645                         pthread_mutex_unlock(&queue->lock);
 646                         break;
 647                 }
 648                 job = cds_list_first_entry(&queue->list,
 649                                 typeof(*job), head);
 650                 cds_list_del(&job->head);
 651                 pthread_mutex_unlock(&queue->lock);
 652
 653                 session_lock_list();
 654                 session = job->session;
 655                 if (!session) {
 656                         DBG("[rotation-thread] Session \"%s\" not found",
 657                                         session->name);
 658                         /*
 659                          * This is a non-fatal error, and we cannot report it to
 660                          * the user (timer), so just print the error and
 661                          * continue the processing.
 662                          *
 663                          * While the timer thread will purge pending signals for
 664                          * a session on the session's destruction, it is
 665                          * possible for a job targeting that session to have
 666                          * already been queued before it was destroyed.
 667                          */
 668                         free(job);
 669                         session_put(session);
 670                         session_unlock_list();
 671                         continue;
 672                 }
 673
 674                 session_lock(session);
 675                 ret = run_job(job, session, handle->notification_thread_handle);
 676                 session_unlock(session);
 677                 /* Release reference held by the job. */
 678                 session_put(session);
 679                 session_unlock_list();
 680                 free(job);
 681                 if (ret) {
 682                         goto end;
 683                 }
 684         }
 685
 686         ret = 0;
 687
 688 end:
 689         return ret;
 690 }
 691
 692 static
 693 int handle_condition(const struct lttng_condition *condition,
 694                 const struct lttng_evaluation *evaluation,
 695                 struct notification_thread_handle *notification_thread_handle)
 696 {
 697         int ret = 0;
 698         const char *condition_session_name = NULL;
 699         enum lttng_condition_type condition_type;
 700         enum lttng_condition_status condition_status;
 701         enum lttng_evaluation_status evaluation_status;
 702         uint64_t consumed;
 703         struct ltt_session *session;
 704
 705         condition_type = lttng_condition_get_type(condition);
 706
 707         if (condition_type != LTTNG_CONDITION_TYPE_SESSION_CONSUMED_SIZE) {
 708                 ret = -1;
 709                 ERR("[rotation-thread] Condition type and session usage type are not the same");
 710                 goto end;
 711         }
 712
 713         /* Fetch info to test */
 714         condition_status = lttng_condition_session_consumed_size_get_session_name(
 715                         condition, &condition_session_name);
 716         if (condition_status != LTTNG_CONDITION_STATUS_OK) {
 717                 ERR("[rotation-thread] Session name could not be fetched");
 718                 ret = -1;
 719                 goto end;
 720         }
 721         evaluation_status = lttng_evaluation_session_consumed_size_get_consumed_size(evaluation,
 722                         &consumed);
 723         if (evaluation_status != LTTNG_EVALUATION_STATUS_OK) {
 724                 ERR("[rotation-thread] Failed to get evaluation");
 725                 ret = -1;
 726                 goto end;
 727         }
 728
 729         session_lock_list();
 730         session = session_find_by_name(condition_session_name);
 731         if (!session) {
 732                 ret = -1;
 733                 session_unlock_list();
 734                 ERR("[rotation-thread] Session \"%s\" not found",
 735                                 condition_session_name);
 736                 goto end;
 737         }
 738         session_lock(session);
 739
 740         ret = unsubscribe_session_consumed_size_rotation(session,
 741                         notification_thread_handle);
 742         if (ret) {
 743                 goto end_unlock;
 744         }
 745
 746         ret = cmd_rotate_session(session, NULL, false);
 747         if (ret == -LTTNG_ERR_ROTATION_PENDING) {
 748                 DBG("Rotate already pending, subscribe to the next threshold value");
 749         } else if (ret != LTTNG_OK) {
 750                 ERR("[rotation-thread] Failed to rotate on size notification with error: %s",
 751                                 lttng_strerror(ret));
 752                 ret = -1;
 753                 goto end_unlock;
 754         }
 755         ret = subscribe_session_consumed_size_rotation(session,
 756                         consumed + session->rotate_size,
 757                         notification_thread_handle);
 758         if (ret) {
 759                 ERR("[rotation-thread] Failed to subscribe to session consumed size condition");
 760                 goto end_unlock;
 761         }
 762         ret = 0;
 763
 764 end_unlock:
 765         session_unlock(session);
 766         session_put(session);
 767         session_unlock_list();
 768 end:
 769         return ret;
 770 }
 771
 772 static
 773 int handle_notification_channel(int fd,
 774                 struct rotation_thread_handle *handle,
 775                 struct rotation_thread *state)
 776 {
 777         int ret;
 778         bool notification_pending;
 779         struct lttng_notification *notification = NULL;
 780         enum lttng_notification_channel_status status;
 781         const struct lttng_evaluation *notification_evaluation;
 782         const struct lttng_condition *notification_condition;
 783
 784         status = lttng_notification_channel_has_pending_notification(
 785                         rotate_notification_channel, &notification_pending);
 786         if (status != LTTNG_NOTIFICATION_CHANNEL_STATUS_OK) {
 787                 ERR("[rotation-thread ]Error occurred while checking for pending notification");
 788                 ret = -1;
 789                 goto end;
 790         }
 791
 792         if (!notification_pending) {
 793                 ret = 0;
 794                 goto end;
 795         }
 796
 797         /* Receive the next notification. */
 798         status = lttng_notification_channel_get_next_notification(
 799                         rotate_notification_channel,
 800                         &notification);
 801
 802         switch (status) {
 803         case LTTNG_NOTIFICATION_CHANNEL_STATUS_OK:
 804                 break;
 805         case LTTNG_NOTIFICATION_CHANNEL_STATUS_NOTIFICATIONS_DROPPED:
 806                 /* Not an error, we will wait for the next one */
 807                 ret = 0;
 808                 goto end;;
 809         case LTTNG_NOTIFICATION_CHANNEL_STATUS_CLOSED:
 810                 ERR("Notification channel was closed");
 811                 ret = -1;
 812                 goto end;
 813         default:
 814                 /* Unhandled conditions / errors. */
 815                 ERR("Unknown notification channel status");
 816                 ret = -1;
 817                 goto end;
 818         }
 819
 820         notification_condition = lttng_notification_get_condition(notification);
 821         notification_evaluation = lttng_notification_get_evaluation(notification);
 822
 823         ret = handle_condition(notification_condition, notification_evaluation,
 824                         handle->notification_thread_handle);
 825
 826 end:
 827         lttng_notification_destroy(notification);
 828         return ret;
 829 }
 830
 831 void *thread_rotation(void *data)
 832 {
 833         int ret;
 834         struct rotation_thread_handle *handle = data;
 835         struct rotation_thread thread;
 836         int queue_pipe_fd;
 837
 838         DBG("[rotation-thread] Started rotation thread");
 839
 840         if (!handle) {
 841                 ERR("[rotation-thread] Invalid thread context provided");
 842                 goto end;
 843         }
 844
 845         queue_pipe_fd = lttng_pipe_get_readfd(
 846                         handle->rotation_timer_queue->event_pipe);
 847
 848         rcu_register_thread();
 849         rcu_thread_online();
 850
 851         health_register(health_sessiond, HEALTH_SESSIOND_TYPE_ROTATION);
 852         health_code_update();
 853
 854         ret = init_thread_state(handle, &thread);
 855         if (ret) {
 856                 goto error;
 857         }
 858
 859         while (true) {
 860                 int fd_count, i;
 861
 862                 health_poll_entry();
 863                 DBG("[rotation-thread] Entering poll wait");
 864                 ret = lttng_poll_wait(&thread.events, -1);
 865                 DBG("[rotation-thread] Poll wait returned (%i)", ret);
 866                 health_poll_exit();
 867                 if (ret < 0) {
 868                         /*
 869                          * Restart interrupted system call.
 870                          */
 871                         if (errno == EINTR) {
 872                                 continue;
 873                         }
 874                         ERR("[rotation-thread] Error encountered during lttng_poll_wait (%i)", ret);
 875                         goto error;
 876                 }
 877
 878                 fd_count = ret;
 879                 for (i = 0; i < fd_count; i++) {
 880                         int fd = LTTNG_POLL_GETFD(&thread.events, i);
 881                         uint32_t revents = LTTNG_POLL_GETEV(&thread.events, i);
 882
 883                         DBG("[rotation-thread] Handling fd (%i) activity (%u)",
 884                                         fd, revents);
 885
 886                         if (revents & LPOLLERR) {
 887                                 ERR("[rotation-thread] Polling returned an error on fd %i", fd);
 888                                 goto error;
 889                         }
 890
 891                         if (fd == rotate_notification_channel->socket) {
 892                                 ret = handle_notification_channel(fd, handle,
 893                                                 &thread);
 894                                 if (ret) {
 895                                         ERR("[rotation-thread] Error occurred while handling activity on notification channel socket");
 896                                         goto error;
 897                                 }
 898                         } else {
 899                                 /* Job queue or quit pipe activity. */
 900
 901                                 /*
 902                                  * The job queue is serviced if there is
 903                                  * activity on the quit pipe to ensure it is
 904                                  * flushed and all references held in the queue
 905                                  * are released.
 906                                  */
 907                                 ret = handle_job_queue(handle, &thread,
 908                                                 handle->rotation_timer_queue);
 909                                 if (ret) {
 910                                         ERR("[rotation-thread] Failed to handle rotation timer pipe event");
 911                                         goto error;
 912                                 }
 913
 914                                 if (fd == queue_pipe_fd) {
 915                                         char buf;
 916
 917                                         ret = lttng_read(fd, &buf, 1);
 918                                         if (ret != 1) {
 919                                                 ERR("[rotation-thread] Failed to read from wakeup pipe (fd = %i)", fd);
 920                                                 goto error;
 921                                         }
 922                                 } else {
 923                                         DBG("[rotation-thread] Quit pipe activity");
 924                                         goto exit;
 925                                 }
 926                         }
 927                 }
 928         }
 929 exit:
 930 error:
 931         DBG("[rotation-thread] Exit");
 932         fini_thread_state(&thread);
 933         health_unregister(health_sessiond);
 934         rcu_thread_offline();
 935         rcu_unregister_thread();
 936 end:
 937         return NULL;
 938 }
 939
 940 static
 941 bool shutdown_rotation_thread(void *thread_data)
 942 {
 943         struct rotation_thread_handle *handle = thread_data;
 944         const int write_fd = lttng_pipe_get_writefd(handle->quit_pipe);
 945
 946         return notify_thread_pipe(write_fd) == 1;
 947 }
 948
 949 bool launch_rotation_thread(struct rotation_thread_handle *handle)
 950 {
 951         struct lttng_thread *thread;
 952
 953         thread = lttng_thread_create("Rotation",
 954                         thread_rotation,
 955                         shutdown_rotation_thread,
 956                         NULL,
 957                         handle);
 958         if (!thread) {
 959                 goto error;
 960         }
 961         lttng_thread_put(thread);
 962         return true;
 963 error:
 964         return false;
 965 }