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