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
  48 #include <urcu.h>
  49 #include <urcu/list.h>
  50
  51 struct lttng_notification_channel *rotate_notification_channel = NULL;
  52
  53 struct rotation_thread {
  54         struct lttng_poll_event events;
  55 };
  56
  57 struct rotation_thread_job {
  58         enum rotation_thread_job_type type;
  59         struct ltt_session *session;
  60         /* List member in struct rotation_thread_timer_queue. */
  61         struct cds_list_head head;
  62 };
  63
  64 /*
  65  * The timer thread enqueues jobs and wakes up the rotation thread.
  66  * When the rotation thread wakes up, it empties the queue.
  67  */
  68 struct rotation_thread_timer_queue {
  69         struct lttng_pipe *event_pipe;
  70         struct cds_list_head list;
  71         pthread_mutex_t lock;
  72 };
  73
  74 struct rotation_thread_handle {
  75         struct rotation_thread_timer_queue *rotation_timer_queue;
  76         /* Access to the notification thread cmd_queue */
  77         struct notification_thread_handle *notification_thread_handle;
  78 };
  79
  80 static
  81 const char *get_job_type_str(enum rotation_thread_job_type job_type)
  82 {
  83         switch (job_type) {
  84         case ROTATION_THREAD_JOB_TYPE_CHECK_PENDING_ROTATION:
  85                 return "CHECK_PENDING_ROTATION";
  86         case ROTATION_THREAD_JOB_TYPE_SCHEDULED_ROTATION:
  87                 return "SCHEDULED_ROTATION";
  88         default:
  89                 abort();
  90         }
  91 }
  92
  93 struct rotation_thread_timer_queue *rotation_thread_timer_queue_create(void)
  94 {
  95         struct rotation_thread_timer_queue *queue = NULL;
  96
  97         queue = zmalloc(sizeof(*queue));
  98         if (!queue) {
  99                 PERROR("Failed to allocate timer rotate queue");
 100                 goto end;
 101         }
 102
 103         queue->event_pipe = lttng_pipe_open(FD_CLOEXEC | O_NONBLOCK);
 104         CDS_INIT_LIST_HEAD(&queue->list);
 105         pthread_mutex_init(&queue->lock, NULL);
 106 end:
 107         return queue;
 108 }
 109
 110 void log_job_destruction(const struct rotation_thread_job *job)
 111 {
 112         enum lttng_error_level log_level;
 113         const char *job_type_str = get_job_type_str(job->type);
 114
 115         switch (job->type) {
 116         case ROTATION_THREAD_JOB_TYPE_SCHEDULED_ROTATION:
 117                 /*
 118                  * Not a problem, the scheduled rotation is racing with the teardown
 119                  * of the daemon. In this case, the rotation will not happen, which
 120                  * is not a problem (or at least, not important enough to delay
 121                  * the shutdown of the session daemon).
 122                  */
 123                 log_level = PRINT_DBG;
 124                 break;
 125         case ROTATION_THREAD_JOB_TYPE_CHECK_PENDING_ROTATION:
 126                 /* This is not expected to happen; warn the user. */
 127                 log_level = PRINT_WARN;
 128                 break;
 129         default:
 130                 abort();
 131         }
 132
 133         LOG(log_level, "Rotation thread timer queue still contains job of type %s targeting session \"%s\" on destruction",
 134                         job_type_str, job->session->name);
 135 }
 136
 137 void rotation_thread_timer_queue_destroy(
 138                 struct rotation_thread_timer_queue *queue)
 139 {
 140         struct rotation_thread_job *job, *tmp_job;
 141
 142         if (!queue) {
 143                 return;
 144         }
 145
 146         lttng_pipe_destroy(queue->event_pipe);
 147
 148         pthread_mutex_lock(&queue->lock);
 149         /* Empty wait queue. */
 150         cds_list_for_each_entry_safe(job, tmp_job, &queue->list, head) {
 151                 log_job_destruction(job);
 152                 cds_list_del(&job->head);
 153                 free(job);
 154         }
 155         pthread_mutex_unlock(&queue->lock);
 156         pthread_mutex_destroy(&queue->lock);
 157         free(queue);
 158 }
 159
 160 /*
 161  * Destroy the thread data previously created by the init function.
 162  */
 163 void rotation_thread_handle_destroy(
 164                 struct rotation_thread_handle *handle)
 165 {
 166         free(handle);
 167 }
 168
 169 struct rotation_thread_handle *rotation_thread_handle_create(
 170                 struct rotation_thread_timer_queue *rotation_timer_queue,
 171                 struct notification_thread_handle *notification_thread_handle)
 172 {
 173         struct rotation_thread_handle *handle;
 174
 175         handle = zmalloc(sizeof(*handle));
 176         if (!handle) {
 177                 goto end;
 178         }
 179
 180         handle->rotation_timer_queue = rotation_timer_queue;
 181         handle->notification_thread_handle = notification_thread_handle;
 182
 183 end:
 184         return handle;
 185 }
 186
 187 /*
 188  * Called with the rotation_thread_timer_queue lock held.
 189  * Return true if the same timer job already exists in the queue, false if not.
 190  */
 191 static
 192 bool timer_job_exists(const struct rotation_thread_timer_queue *queue,
 193                 enum rotation_thread_job_type job_type,
 194                 struct ltt_session *session)
 195 {
 196         bool exists = false;
 197         struct rotation_thread_job *job;
 198
 199         cds_list_for_each_entry(job, &queue->list, head) {
 200                 if (job->session == session && job->type == job_type) {
 201                         exists = true;
 202                         goto end;
 203                 }
 204         }
 205 end:
 206         return exists;
 207 }
 208
 209 void rotation_thread_enqueue_job(struct rotation_thread_timer_queue *queue,
 210                 enum rotation_thread_job_type job_type,
 211                 struct ltt_session *session)
 212 {
 213         int ret;
 214         const char * const dummy = "!";
 215         struct rotation_thread_job *job = NULL;
 216         const char *job_type_str = get_job_type_str(job_type);
 217
 218         pthread_mutex_lock(&queue->lock);
 219         if (timer_job_exists(queue, job_type, session)) {
 220                 /*
 221                  * This timer job is already pending, we don't need to add
 222                  * it.
 223                  */
 224                 goto end;
 225         }
 226
 227         job = zmalloc(sizeof(struct rotation_thread_job));
 228         if (!job) {
 229                 PERROR("Failed to allocate rotation thread job of type \"%s\" for session \"%s\"",
 230                                 job_type_str, session->name);
 231                 goto end;
 232         }
 233         /* No reason for this to fail as the caller must hold a reference. */
 234         (void) session_get(session);
 235
 236         job->session = session;
 237         job->type = job_type;
 238         cds_list_add_tail(&job->head, &queue->list);
 239
 240         ret = lttng_write(lttng_pipe_get_writefd(queue->event_pipe), dummy,
 241                         1);
 242         if (ret < 0) {
 243                 /*
 244                  * We do not want to block in the timer handler, the job has
 245                  * been enqueued in the list, the wakeup pipe is probably full,
 246                  * the job will be processed when the rotation_thread catches
 247                  * up.
 248                  */
 249                 if (errno == EAGAIN || errno == EWOULDBLOCK) {
 250                         /*
 251                          * Not an error, but would be surprising and indicate
 252                          * that the rotation thread can't keep up with the
 253                          * current load.
 254                          */
 255                         DBG("Wake-up pipe of rotation thread job queue is full");
 256                         goto end;
 257                 }
 258                 PERROR("Failed to wake-up the rotation thread after pushing a job of type \"%s\" for session \"%s\"",
 259                                 job_type_str, session->name);
 260                 goto end;
 261         }
 262
 263 end:
 264         pthread_mutex_unlock(&queue->lock);
 265 }
 266
 267 static
 268 int init_poll_set(struct lttng_poll_event *poll_set,
 269                 struct rotation_thread_handle *handle)
 270 {
 271         int ret;
 272
 273         /*
 274          * Create pollset with size 2:
 275          *      - quit pipe,
 276          *      - rotation thread timer queue pipe,
 277          */
 278         ret = sessiond_set_thread_pollset(poll_set, 2);
 279         if (ret) {
 280                 goto error;
 281         }
 282         ret = lttng_poll_add(poll_set,
 283                         lttng_pipe_get_readfd(handle->rotation_timer_queue->event_pipe),
 284                         LPOLLIN | LPOLLERR);
 285         if (ret < 0) {
 286                 ERR("[rotation-thread] Failed to add rotate_pending fd to pollset");
 287                 goto error;
 288         }
 289
 290         return ret;
 291 error:
 292         lttng_poll_clean(poll_set);
 293         return ret;
 294 }
 295
 296 static
 297 void fini_thread_state(struct rotation_thread *state)
 298 {
 299         lttng_poll_clean(&state->events);
 300         if (rotate_notification_channel) {
 301                 lttng_notification_channel_destroy(rotate_notification_channel);
 302         }
 303 }
 304
 305 static
 306 int init_thread_state(struct rotation_thread_handle *handle,
 307                 struct rotation_thread *state)
 308 {
 309         int ret;
 310
 311         memset(state, 0, sizeof(*state));
 312         lttng_poll_init(&state->events);
 313
 314         ret = init_poll_set(&state->events, handle);
 315         if (ret) {
 316                 ERR("[rotation-thread] Failed to initialize rotation thread poll set");
 317                 goto end;
 318         }
 319
 320         rotate_notification_channel = lttng_notification_channel_create(
 321                         lttng_session_daemon_notification_endpoint);
 322         if (!rotate_notification_channel) {
 323                 ERR("[rotation-thread] Could not create notification channel");
 324                 ret = -1;
 325                 goto end;
 326         }
 327         ret = lttng_poll_add(&state->events, rotate_notification_channel->socket,
 328                         LPOLLIN | LPOLLERR);
 329         if (ret < 0) {
 330                 ERR("[rotation-thread] Failed to add notification fd to pollset");
 331                 goto end;
 332         }
 333
 334 end:
 335         return ret;
 336 }
 337
 338 static
 339 int check_session_rotation_pending_local_on_consumer(
 340                 const struct ltt_session *session,
 341                 struct consumer_socket *socket, bool *rotation_completed)
 342 {
 343         int ret;
 344
 345         pthread_mutex_lock(socket->lock);
 346         DBG("[rotation-thread] Checking for locally pending rotation on the %s consumer for session %s",
 347                         lttng_consumer_type_str(socket->type),
 348                         session->name);
 349         ret = consumer_check_rotation_pending_local(socket,
 350                         session->id,
 351                         session->current_archive_id - 1);
 352         pthread_mutex_unlock(socket->lock);
 353
 354         if (ret == 0) {
 355                 /* Rotation was completed on this consumer. */
 356                 DBG("[rotation-thread] Local rotation of trace archive %" PRIu64 " of session \"%s\" was completed on the %s consumer",
 357                                 session->current_archive_id - 1,
 358                                 session->name,
 359                                 lttng_consumer_type_str(socket->type));
 360                 *rotation_completed = true;
 361         } else if (ret == 1) {
 362                 /* Rotation pending on this consumer. */
 363                 DBG("[rotation-thread] Local rotation of trace archive %" PRIu64 " of session \"%s\" is pending on the %s consumer",
 364                                 session->current_archive_id - 1,
 365                                 session->name,
 366                                 lttng_consumer_type_str(socket->type));
 367                 *rotation_completed = false;
 368                 ret = 0;
 369         } else {
 370                 /* Not a fatal error. */
 371                 ERR("[rotation-thread] Encountered an error when checking if local rotation of trace archive %" PRIu64 " of session \"%s\" is pending on the %s consumer",
 372                                 session->current_archive_id - 1,
 373                                 session->name,
 374                                 lttng_consumer_type_str(socket->type));
 375                 *rotation_completed = false;
 376         }
 377         return ret;
 378 }
 379
 380 static
 381 int check_session_rotation_pending_local(struct ltt_session *session)
 382 {
 383         int ret = 0;
 384         struct consumer_socket *socket;
 385         struct cds_lfht_iter iter;
 386         bool rotation_completed = true;
 387
 388         /*
 389          * Check for a local pending rotation on all consumers (32-bit
 390          * user space, 64-bit user space, and kernel).
 391          */
 392         DBG("[rotation-thread] Checking for pending local rotation on session \"%s\", trace archive %" PRIu64,
 393                         session->name, session->current_archive_id - 1);
 394
 395         rcu_read_lock();
 396         if (!session->ust_session) {
 397                 goto skip_ust;
 398         }
 399         cds_lfht_for_each_entry(session->ust_session->consumer->socks->ht,
 400                         &iter, socket, node.node) {
 401                 ret = check_session_rotation_pending_local_on_consumer(session,
 402                                 socket, &rotation_completed);
 403                 if (ret || !rotation_completed) {
 404                         goto end;
 405                 }
 406         }
 407
 408 skip_ust:
 409         if (!session->kernel_session) {
 410                 goto skip_kernel;
 411         }
 412         cds_lfht_for_each_entry(session->kernel_session->consumer->socks->ht,
 413                                 &iter, socket, node.node) {
 414                 ret = check_session_rotation_pending_local_on_consumer(session,
 415                                 socket, &rotation_completed);
 416                 if (ret || !rotation_completed) {
 417                         goto end;
 418                 }
 419         }
 420 skip_kernel:
 421 end:
 422         rcu_read_unlock();
 423
 424         if (rotation_completed) {
 425                 DBG("[rotation-thread] Local rotation of trace archive %" PRIu64 " of session \"%s\" is complete on all consumers",
 426                                 session->current_archive_id - 1,
 427                                 session->name);
 428                 session->rotation_pending_local = false;
 429         }
 430         if (ret) {
 431                 ret = session_reset_rotation_state(session,
 432                                 LTTNG_ROTATION_STATE_ERROR);
 433                 if (ret) {
 434                         ERR("Failed to reset rotation state of session \"%s\"",
 435                                         session->name);
 436                 }
 437         }
 438         return 0;
 439 }
 440
 441 static
 442 int check_session_rotation_pending_relay(struct ltt_session *session)
 443 {
 444         int ret;
 445         struct consumer_socket *socket;
 446         struct cds_lfht_iter iter;
 447         bool rotation_completed = true;
 448         const struct consumer_output *output;
 449
 450         /*
 451          * Check for a pending rotation on any consumer as we only use
 452          * it as a "tunnel" to the relayd.
 453          */
 454
 455         rcu_read_lock();
 456         if (session->ust_session) {
 457                 cds_lfht_first(session->ust_session->consumer->socks->ht,
 458                                 &iter);
 459                 output = session->ust_session->consumer;
 460         } else {
 461                 cds_lfht_first(session->kernel_session->consumer->socks->ht,
 462                                 &iter);
 463                 output = session->kernel_session->consumer;
 464         }
 465         assert(cds_lfht_iter_get_node(&iter));
 466
 467         socket = caa_container_of(cds_lfht_iter_get_node(&iter),
 468                         typeof(*socket), node.node);
 469
 470         pthread_mutex_lock(socket->lock);
 471         DBG("[rotation-thread] Checking for pending relay rotation on session \"%s\", trace archive %" PRIu64 " through the %s consumer",
 472                         session->name, session->current_archive_id - 1,
 473                         lttng_consumer_type_str(socket->type));
 474         ret = consumer_check_rotation_pending_relay(socket,
 475                         output,
 476                         session->id,
 477                         session->current_archive_id - 1);
 478         pthread_mutex_unlock(socket->lock);
 479
 480         if (ret == 0) {
 481                 /* Rotation was completed on the relay. */
 482                 DBG("[rotation-thread] Relay rotation of trace archive %" PRIu64 " of session \"%s\" was completed",
 483                                 session->current_archive_id - 1,
 484                                 session->name);
 485         } else if (ret == 1) {
 486                 /* Rotation pending on relay. */
 487                 DBG("[rotation-thread] Relay rotation of trace archive %" PRIu64 " of session \"%s\" is pending",
 488                                 session->current_archive_id - 1,
 489                                 session->name);
 490                 rotation_completed = false;
 491         } else {
 492                 /* Not a fatal error. */
 493                 ERR("[rotation-thread] Encountered an error when checking if rotation of trace archive %" PRIu64 " of session \"%s\" is pending on the relay",
 494                                 session->current_archive_id - 1,
 495                                 session->name);
 496                 ret = session_reset_rotation_state(session,
 497                                 LTTNG_ROTATION_STATE_ERROR);
 498                 if (ret) {
 499                         ERR("Failed to reset rotation state of session \"%s\"",
 500                                         session->name);
 501                 }
 502                 rotation_completed = false;
 503         }
 504
 505         rcu_read_unlock();
 506
 507         if (rotation_completed) {
 508                 DBG("[rotation-thread] Rotation of trace archive %" PRIu64 " of session \"%s\" is complete on the relay",
 509                                 session->current_archive_id - 1,
 510                                 session->name);
 511                 session->rotation_pending_relay = false;
 512         }
 513         return 0;
 514 }
 515
 516 /*
 517  * Check if the last rotation was completed, called with session lock held.
 518  */
 519 static
 520 int check_session_rotation_pending(struct ltt_session *session,
 521                 struct notification_thread_handle *notification_thread_handle)
 522 {
 523         int ret;
 524         struct lttng_trace_archive_location *location;
 525         time_t now;
 526
 527         DBG("[rotation-thread] Checking for pending rotation on session \"%s\", trace archive %" PRIu64,
 528                         session->name, session->current_archive_id - 1);
 529
 530         /*
 531          * The rotation-pending check timer of a session is launched in
 532          * one-shot mode. If the rotation is incomplete, the rotation
 533          * thread will re-enable the pending-check timer.
 534          *
 535          * The timer thread can't stop the timer itself since it is involved
 536          * in the check for the timer's quiescence.
 537          */
 538         ret = timer_session_rotation_pending_check_stop(session);
 539         if (ret) {
 540                 goto end;
 541         }
 542
 543         if (session->rotation_pending_local) {
 544                 /* Updates session->rotation_pending_local as needed. */
 545                 ret = check_session_rotation_pending_local(session);
 546                 if (ret) {
 547                         goto end;
 548                 }
 549
 550                 /*
 551                  * No need to check for a pending rotation on the relay
 552                  * since the rotation is not even completed locally yet.
 553                  */
 554                 if (session->rotation_pending_local) {
 555                         goto end;
 556                 }
 557         }
 558
 559         if (session->rotation_pending_relay) {
 560                 /* Updates session->rotation_pending_relay as needed. */
 561                 ret = check_session_rotation_pending_relay(session);
 562                 if (ret) {
 563                         goto end;
 564                 }
 565
 566                 if (session->rotation_pending_relay) {
 567                         goto end;
 568                 }
 569         }
 570
 571         DBG("[rotation-thread] Rotation of trace archive %" PRIu64 " completed for "
 572                         "session %s", session->current_archive_id - 1,
 573                         session->name);
 574
 575         /* Rename the completed trace archive's location. */
 576         now = time(NULL);
 577         if (now == (time_t) -1) {
 578                 ret = session_reset_rotation_state(session,
 579                                 LTTNG_ROTATION_STATE_ERROR);
 580                 if (ret) {
 581                         ERR("Failed to reset rotation state of session \"%s\"",
 582                                         session->name);
 583                 }
 584                 ret = LTTNG_ERR_UNK;
 585                 goto end;
 586         }
 587
 588         ret = rename_completed_chunk(session, now);
 589         if (ret < 0) {
 590                 ERR("Failed to rename completed rotation chunk");
 591                 goto end;
 592         }
 593         session->last_chunk_start_ts = session->current_chunk_start_ts;
 594
 595         /*
 596          * Now we can clear the "ONGOING" state in the session. New
 597          * rotations can start now.
 598          */
 599         session->rotation_state = LTTNG_ROTATION_STATE_COMPLETED;
 600
 601         /* Ownership of location is transferred. */
 602         location = session_get_trace_archive_location(session);
 603         ret = notification_thread_command_session_rotation_completed(
 604                         notification_thread_handle,
 605                         session->name,
 606                         session->uid,
 607                         session->gid,
 608                         session->current_archive_id,
 609                         location);
 610         if (ret != LTTNG_OK) {
 611                 ERR("[rotation-thread] Failed to notify notification thread of completed rotation for session %s",
 612                                 session->name);
 613         }
 614
 615         if (!session->active) {
 616                 /*
 617                  * A stop command was issued during the rotation, it is
 618                  * up to the rotation completion check to perform the
 619                  * renaming of the last chunk that was produced.
 620                  */
 621                 ret = notification_thread_command_session_rotation_ongoing(
 622                                 notification_thread_handle,
 623                                 session->name,
 624                                 session->uid,
 625                                 session->gid,
 626                                 session->current_archive_id);
 627                 if (ret != LTTNG_OK) {
 628                         ERR("[rotation-thread] Failed to notify notification thread of completed rotation for session %s",
 629                                         session->name);
 630                 }
 631
 632                 ret = rename_active_chunk(session);
 633                 if (ret < 0) {
 634                         ERR("[rotation-thread] Failed to rename active rotation chunk");
 635                         goto end;
 636                 }
 637
 638                 /* Ownership of location is transferred. */
 639                 location = session_get_trace_archive_location(session);
 640                 ret = notification_thread_command_session_rotation_completed(
 641                                 notification_thread_handle,
 642                                 session->name,
 643                                 session->uid,
 644                                 session->gid,
 645                                 session->current_archive_id,
 646                                 location);
 647                 if (ret != LTTNG_OK) {
 648                         ERR("[rotation-thread] Failed to notify notification thread of completed rotation for session %s",
 649                                         session->name);
 650                 }
 651         }
 652
 653         ret = 0;
 654 end:
 655         if (session->rotation_state == LTTNG_ROTATION_STATE_ONGOING) {
 656                 DBG("[rotation-thread] Rotation of trace archive %" PRIu64 " is still pending for session %s",
 657                                 session->current_archive_id - 1, session->name);
 658                 ret = timer_session_rotation_pending_check_start(session,
 659                                 DEFAULT_ROTATE_PENDING_TIMER);
 660                 if (ret) {
 661                         ERR("Re-enabling rotate pending timer");
 662                         ret = -1;
 663                         goto end;
 664                 }
 665         }
 666
 667         return ret;
 668 }
 669
 670 /* Call with the session and session_list locks held. */
 671 static
 672 int launch_session_rotation(struct ltt_session *session)
 673 {
 674         int ret;
 675         struct lttng_rotate_session_return rotation_return;
 676
 677         DBG("[rotation-thread] Launching scheduled time-based rotation on session \"%s\"",
 678                         session->name);
 679
 680         ret = cmd_rotate_session(session, &rotation_return);
 681         if (ret == LTTNG_OK) {
 682                 DBG("[rotation-thread] Scheduled time-based rotation successfully launched on session \"%s\"",
 683                                 session->name);
 684         } else {
 685                 /* Don't consider errors as fatal. */
 686                 DBG("[rotation-thread] Scheduled time-based rotation aborted for session %s: %s",
 687                                 session->name, lttng_strerror(ret));
 688         }
 689         return 0;
 690 }
 691
 692 static
 693 int run_job(struct rotation_thread_job *job, struct ltt_session *session,
 694                 struct notification_thread_handle *notification_thread_handle)
 695 {
 696         int ret;
 697
 698         switch (job->type) {
 699         case ROTATION_THREAD_JOB_TYPE_SCHEDULED_ROTATION:
 700                 ret = launch_session_rotation(session);
 701                 break;
 702         case ROTATION_THREAD_JOB_TYPE_CHECK_PENDING_ROTATION:
 703                 ret = check_session_rotation_pending(session,
 704                                 notification_thread_handle);
 705                 break;
 706         default:
 707                 abort();
 708         }
 709         return ret;
 710 }
 711
 712 static
 713 int handle_job_queue(struct rotation_thread_handle *handle,
 714                 struct rotation_thread *state,
 715                 struct rotation_thread_timer_queue *queue)
 716 {
 717         int ret = 0;
 718
 719         for (;;) {
 720                 struct ltt_session *session;
 721                 struct rotation_thread_job *job;
 722
 723                 /* Take the queue lock only to pop an element from the list. */
 724                 pthread_mutex_lock(&queue->lock);
 725                 if (cds_list_empty(&queue->list)) {
 726                         pthread_mutex_unlock(&queue->lock);
 727                         break;
 728                 }
 729                 job = cds_list_first_entry(&queue->list,
 730                                 typeof(*job), head);
 731                 cds_list_del(&job->head);
 732                 pthread_mutex_unlock(&queue->lock);
 733
 734                 session_lock_list();
 735                 session = job->session;
 736                 if (!session) {
 737                         DBG("[rotation-thread] Session \"%s\" not found",
 738                                         session->name);
 739                         /*
 740                          * This is a non-fatal error, and we cannot report it to
 741                          * the user (timer), so just print the error and
 742                          * continue the processing.
 743                          *
 744                          * While the timer thread will purge pending signals for
 745                          * a session on the session's destruction, it is
 746                          * possible for a job targeting that session to have
 747                          * already been queued before it was destroyed.
 748                          */
 749                         session_unlock_list();
 750                         free(job);
 751                         session_put(session);
 752                         continue;
 753                 }
 754
 755                 session_lock(session);
 756                 ret = run_job(job, session, handle->notification_thread_handle);
 757                 session_unlock(session);
 758                 /* Release reference held by the job. */
 759                 session_put(session);
 760                 session_unlock_list();
 761                 free(job);
 762                 if (ret) {
 763                         goto end;
 764                 }
 765         }
 766
 767         ret = 0;
 768
 769 end:
 770         return ret;
 771 }
 772
 773 static
 774 int handle_condition(const struct lttng_condition *condition,
 775                 const struct lttng_evaluation *evaluation,
 776                 struct notification_thread_handle *notification_thread_handle)
 777 {
 778         int ret = 0;
 779         const char *condition_session_name = NULL;
 780         enum lttng_condition_type condition_type;
 781         enum lttng_condition_status condition_status;
 782         enum lttng_evaluation_status evaluation_status;
 783         uint64_t consumed;
 784         struct ltt_session *session;
 785
 786         condition_type = lttng_condition_get_type(condition);
 787
 788         if (condition_type != LTTNG_CONDITION_TYPE_SESSION_CONSUMED_SIZE) {
 789                 ret = -1;
 790                 ERR("[rotation-thread] Condition type and session usage type are not the same");
 791                 goto end;
 792         }
 793
 794         /* Fetch info to test */
 795         condition_status = lttng_condition_session_consumed_size_get_session_name(
 796                         condition, &condition_session_name);
 797         if (condition_status != LTTNG_CONDITION_STATUS_OK) {
 798                 ERR("[rotation-thread] Session name could not be fetched");
 799                 ret = -1;
 800                 goto end;
 801         }
 802         evaluation_status = lttng_evaluation_session_consumed_size_get_consumed_size(evaluation,
 803                         &consumed);
 804         if (evaluation_status != LTTNG_EVALUATION_STATUS_OK) {
 805                 ERR("[rotation-thread] Failed to get evaluation");
 806                 ret = -1;
 807                 goto end;
 808         }
 809
 810         session_lock_list();
 811         session = session_find_by_name(condition_session_name);
 812         if (!session) {
 813                 ret = -1;
 814                 session_unlock_list();
 815                 ERR("[rotation-thread] Session \"%s\" not found",
 816                                 condition_session_name);
 817                 goto end;
 818         }
 819         session_lock(session);
 820         session_unlock_list();
 821
 822         ret = unsubscribe_session_consumed_size_rotation(session,
 823                         notification_thread_handle);
 824         if (ret) {
 825                 goto end_unlock;
 826         }
 827
 828         ret = cmd_rotate_session(session, NULL);
 829         if (ret == -LTTNG_ERR_ROTATION_PENDING) {
 830                 DBG("Rotate already pending, subscribe to the next threshold value");
 831         } else if (ret != LTTNG_OK) {
 832                 ERR("[rotation-thread] Failed to rotate on size notification with error: %s",
 833                                 lttng_strerror(ret));
 834                 ret = -1;
 835                 goto end_unlock;
 836         }
 837         ret = subscribe_session_consumed_size_rotation(session,
 838                         consumed + session->rotate_size,
 839                         notification_thread_handle);
 840         if (ret) {
 841                 ERR("[rotation-thread] Failed to subscribe to session consumed size condition");
 842                 goto end_unlock;
 843         }
 844         ret = 0;
 845
 846 end_unlock:
 847         session_unlock(session);
 848         session_put(session);
 849 end:
 850         return ret;
 851 }
 852
 853 static
 854 int handle_notification_channel(int fd,
 855                 struct rotation_thread_handle *handle,
 856                 struct rotation_thread *state)
 857 {
 858         int ret;
 859         bool notification_pending;
 860         struct lttng_notification *notification = NULL;
 861         enum lttng_notification_channel_status status;
 862         const struct lttng_evaluation *notification_evaluation;
 863         const struct lttng_condition *notification_condition;
 864
 865         status = lttng_notification_channel_has_pending_notification(
 866                         rotate_notification_channel, &notification_pending);
 867         if (status != LTTNG_NOTIFICATION_CHANNEL_STATUS_OK) {
 868                 ERR("[rotation-thread ]Error occurred while checking for pending notification");
 869                 ret = -1;
 870                 goto end;
 871         }
 872
 873         if (!notification_pending) {
 874                 ret = 0;
 875                 goto end;
 876         }
 877
 878         /* Receive the next notification. */
 879         status = lttng_notification_channel_get_next_notification(
 880                         rotate_notification_channel,
 881                         &notification);
 882
 883         switch (status) {
 884         case LTTNG_NOTIFICATION_CHANNEL_STATUS_OK:
 885                 break;
 886         case LTTNG_NOTIFICATION_CHANNEL_STATUS_NOTIFICATIONS_DROPPED:
 887                 /* Not an error, we will wait for the next one */
 888                 ret = 0;
 889                 goto end;;
 890         case LTTNG_NOTIFICATION_CHANNEL_STATUS_CLOSED:
 891                 ERR("Notification channel was closed");
 892                 ret = -1;
 893                 goto end;
 894         default:
 895                 /* Unhandled conditions / errors. */
 896                 ERR("Unknown notification channel status");
 897                 ret = -1;
 898                 goto end;
 899         }
 900
 901         notification_condition = lttng_notification_get_condition(notification);
 902         notification_evaluation = lttng_notification_get_evaluation(notification);
 903
 904         ret = handle_condition(notification_condition, notification_evaluation,
 905                         handle->notification_thread_handle);
 906
 907 end:
 908         lttng_notification_destroy(notification);
 909         return ret;
 910 }
 911
 912 void *thread_rotation(void *data)
 913 {
 914         int ret;
 915         struct rotation_thread_handle *handle = data;
 916         struct rotation_thread thread;
 917
 918         DBG("[rotation-thread] Started rotation thread");
 919
 920         if (!handle) {
 921                 ERR("[rotation-thread] Invalid thread context provided");
 922                 goto end;
 923         }
 924
 925         rcu_register_thread();
 926         rcu_thread_online();
 927
 928         health_register(health_sessiond, HEALTH_SESSIOND_TYPE_ROTATION);
 929         health_code_update();
 930
 931         ret = init_thread_state(handle, &thread);
 932         if (ret) {
 933                 goto error;
 934         }
 935
 936         /* Ready to handle client connections. */
 937         sessiond_notify_ready();
 938
 939         while (true) {
 940                 int fd_count, i;
 941
 942                 health_poll_entry();
 943                 DBG("[rotation-thread] Entering poll wait");
 944                 ret = lttng_poll_wait(&thread.events, -1);
 945                 DBG("[rotation-thread] Poll wait returned (%i)", ret);
 946                 health_poll_exit();
 947                 if (ret < 0) {
 948                         /*
 949                          * Restart interrupted system call.
 950                          */
 951                         if (errno == EINTR) {
 952                                 continue;
 953                         }
 954                         ERR("[rotation-thread] Error encountered during lttng_poll_wait (%i)", ret);
 955                         goto error;
 956                 }
 957
 958                 fd_count = ret;
 959                 for (i = 0; i < fd_count; i++) {
 960                         int fd = LTTNG_POLL_GETFD(&thread.events, i);
 961                         uint32_t revents = LTTNG_POLL_GETEV(&thread.events, i);
 962
 963                         DBG("[rotation-thread] Handling fd (%i) activity (%u)",
 964                                         fd, revents);
 965
 966                         if (revents & LPOLLERR) {
 967                                 ERR("[rotation-thread] Polling returned an error on fd %i", fd);
 968                                 goto error;
 969                         }
 970
 971                         if (fd == rotate_notification_channel->socket) {
 972                                 ret = handle_notification_channel(fd, handle,
 973                                                 &thread);
 974                                 if (ret) {
 975                                         ERR("[rotation-thread] Error occurred while handling activity on notification channel socket");
 976                                         goto error;
 977                                 }
 978                         } else {
 979                                 /* Job queue or quit pipe activity. */
 980                                 if (fd == lttng_pipe_get_readfd(
 981                                                 handle->rotation_timer_queue->event_pipe)) {
 982                                         char buf;
 983
 984                                         ret = lttng_read(fd, &buf, 1);
 985                                         if (ret != 1) {
 986                                                 ERR("[rotation-thread] Failed to read from wakeup pipe (fd = %i)", fd);
 987                                                 ret = -1;
 988                                                 goto error;
 989                                         }
 990                                 }
 991
 992                                 /*
 993                                  * The job queue is serviced if there is
 994                                  * activity on the quit pipe to ensure it is
 995                                  * flushed and all references held in the queue
 996                                  * are released.
 997                                  */
 998                                 ret = handle_job_queue(handle, &thread,
 999                                                 handle->rotation_timer_queue);
1000                                 if (ret) {
1001                                         ERR("[rotation-thread] Failed to handle rotation timer pipe event");
1002                                         goto error;
1003                                 }
1004
1005                                 if (sessiond_check_thread_quit_pipe(fd, revents)) {
1006                                         DBG("[rotation-thread] Quit pipe activity");
1007                                         goto exit;
1008                                 }
1009                         }
1010                 }
1011         }
1012 exit:
1013 error:
1014         DBG("[rotation-thread] Exit");
1015         fini_thread_state(&thread);
1016         health_unregister(health_sessiond);
1017         rcu_thread_offline();
1018         rcu_unregister_thread();
1019 end:
1020         return NULL;
1021 }