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         if (session->rotation_pending_local) {
 531                 /* Updates session->rotation_pending_local as needed. */
 532                 ret = check_session_rotation_pending_local(session);
 533                 if (ret) {
 534                         goto end;
 535                 }
 536
 537                 /*
 538                  * No need to check for a pending rotation on the relay
 539                  * since the rotation is not even completed locally yet.
 540                  */
 541                 if (session->rotation_pending_local) {
 542                         goto end;
 543                 }
 544         }
 545
 546         if (session->rotation_pending_relay) {
 547                 /* Updates session->rotation_pending_relay as needed. */
 548                 ret = check_session_rotation_pending_relay(session);
 549                 if (ret) {
 550                         goto end;
 551                 }
 552
 553                 if (session->rotation_pending_relay) {
 554                         goto end;
 555                 }
 556         }
 557
 558         DBG("[rotation-thread] Rotation of trace archive %" PRIu64 " completed for "
 559                         "session %s", session->current_archive_id - 1,
 560                         session->name);
 561
 562         /* Rename the completed trace archive's location. */
 563         now = time(NULL);
 564         if (now == (time_t) -1) {
 565                 ret = session_reset_rotation_state(session,
 566                                 LTTNG_ROTATION_STATE_ERROR);
 567                 if (ret) {
 568                         ERR("Failed to reset rotation state of session \"%s\"",
 569                                         session->name);
 570                 }
 571                 ret = LTTNG_ERR_UNK;
 572                 goto end;
 573         }
 574
 575         ret = rename_completed_chunk(session, now);
 576         if (ret < 0) {
 577                 ERR("Failed to rename completed rotation chunk");
 578                 goto end;
 579         }
 580         session->last_chunk_start_ts = session->current_chunk_start_ts;
 581
 582         /*
 583          * Now we can clear the "ONGOING" state in the session. New
 584          * rotations can start now.
 585          */
 586         session->rotation_state = LTTNG_ROTATION_STATE_COMPLETED;
 587
 588         /* Ownership of location is transferred. */
 589         location = session_get_trace_archive_location(session);
 590         ret = notification_thread_command_session_rotation_completed(
 591                         notification_thread_handle,
 592                         session->name,
 593                         session->uid,
 594                         session->gid,
 595                         session->current_archive_id,
 596                         location);
 597         if (ret != LTTNG_OK) {
 598                 ERR("[rotation-thread] Failed to notify notification thread of completed rotation for session %s",
 599                                 session->name);
 600         }
 601
 602         if (!session->active) {
 603                 /*
 604                  * A stop command was issued during the rotation, it is
 605                  * up to the rotation completion check to perform the
 606                  * renaming of the last chunk that was produced.
 607                  */
 608                 ret = notification_thread_command_session_rotation_ongoing(
 609                                 notification_thread_handle,
 610                                 session->name,
 611                                 session->uid,
 612                                 session->gid,
 613                                 session->current_archive_id);
 614                 if (ret != LTTNG_OK) {
 615                         ERR("[rotation-thread] Failed to notify notification thread of completed rotation for session %s",
 616                                         session->name);
 617                 }
 618
 619                 ret = rename_active_chunk(session);
 620                 if (ret < 0) {
 621                         ERR("[rotation-thread] Failed to rename active rotation chunk");
 622                         goto end;
 623                 }
 624
 625                 /* Ownership of location is transferred. */
 626                 location = session_get_trace_archive_location(session);
 627                 ret = notification_thread_command_session_rotation_completed(
 628                                 notification_thread_handle,
 629                                 session->name,
 630                                 session->uid,
 631                                 session->gid,
 632                                 session->current_archive_id,
 633                                 location);
 634                 if (ret != LTTNG_OK) {
 635                         ERR("[rotation-thread] Failed to notify notification thread of completed rotation for session %s",
 636                                         session->name);
 637                 }
 638         }
 639
 640         ret = 0;
 641 end:
 642         if (session->rotation_state == LTTNG_ROTATION_STATE_ONGOING) {
 643                 DBG("[rotation-thread] Rotation of trace archive %" PRIu64 " is still pending for session %s",
 644                                 session->current_archive_id - 1, session->name);
 645                 ret = timer_session_rotation_pending_check_start(session,
 646                                 DEFAULT_ROTATE_PENDING_TIMER);
 647                 if (ret) {
 648                         ERR("Re-enabling rotate pending timer");
 649                         ret = -1;
 650                         goto end;
 651                 }
 652         }
 653
 654         return ret;
 655 }
 656
 657 /* Call with the session and session_list locks held. */
 658 static
 659 int launch_session_rotation(struct ltt_session *session)
 660 {
 661         int ret;
 662         struct lttng_rotate_session_return rotation_return;
 663
 664         DBG("[rotation-thread] Launching scheduled time-based rotation on session \"%s\"",
 665                         session->name);
 666
 667         ret = cmd_rotate_session(session, &rotation_return);
 668         if (ret == LTTNG_OK) {
 669                 DBG("[rotation-thread] Scheduled time-based rotation successfully launched on session \"%s\"",
 670                                 session->name);
 671         } else {
 672                 /* Don't consider errors as fatal. */
 673                 DBG("[rotation-thread] Scheduled time-based rotation aborted for session %s: %s",
 674                                 session->name, lttng_strerror(ret));
 675         }
 676         return 0;
 677 }
 678
 679 static
 680 int run_job(struct rotation_thread_job *job, struct ltt_session *session,
 681                 struct notification_thread_handle *notification_thread_handle)
 682 {
 683         int ret;
 684
 685         switch (job->type) {
 686         case ROTATION_THREAD_JOB_TYPE_SCHEDULED_ROTATION:
 687                 ret = launch_session_rotation(session);
 688                 break;
 689         case ROTATION_THREAD_JOB_TYPE_CHECK_PENDING_ROTATION:
 690                 ret = check_session_rotation_pending(session,
 691                                 notification_thread_handle);
 692                 break;
 693         default:
 694                 abort();
 695         }
 696         return ret;
 697 }
 698
 699 static
 700 int handle_job_queue(struct rotation_thread_handle *handle,
 701                 struct rotation_thread *state,
 702                 struct rotation_thread_timer_queue *queue)
 703 {
 704         int ret = 0;
 705         int fd = lttng_pipe_get_readfd(queue->event_pipe);
 706         char buf;
 707
 708         ret = lttng_read(fd, &buf, 1);
 709         if (ret != 1) {
 710                 ERR("[rotation-thread] Failed to read from wakeup pipe (fd = %i)", fd);
 711                 ret = -1;
 712                 goto end;
 713         }
 714
 715         for (;;) {
 716                 struct ltt_session *session;
 717                 struct rotation_thread_job *job;
 718
 719                 /* Take the queue lock only to pop an element from the list. */
 720                 pthread_mutex_lock(&queue->lock);
 721                 if (cds_list_empty(&queue->list)) {
 722                         pthread_mutex_unlock(&queue->lock);
 723                         break;
 724                 }
 725                 job = cds_list_first_entry(&queue->list,
 726                                 typeof(*job), head);
 727                 cds_list_del(&job->head);
 728                 pthread_mutex_unlock(&queue->lock);
 729
 730                 session_lock_list();
 731                 session = job->session;
 732                 if (!session) {
 733                         DBG("[rotation-thread] Session \"%s\" not found",
 734                                         session->name);
 735                         /*
 736                          * This is a non-fatal error, and we cannot report it to
 737                          * the user (timer), so just print the error and
 738                          * continue the processing.
 739                          *
 740                          * While the timer thread will purge pending signals for
 741                          * a session on the session's destruction, it is
 742                          * possible for a job targeting that session to have
 743                          * already been queued before it was destroyed.
 744                          */
 745                         session_unlock_list();
 746                         free(job);
 747                         session_put(session);
 748                         continue;
 749                 }
 750
 751                 session_lock(session);
 752                 ret = run_job(job, session, handle->notification_thread_handle);
 753                 session_unlock(session);
 754                 session_put(session);
 755                 session_unlock_list();
 756                 free(job);
 757                 if (ret) {
 758                         goto end;
 759                 }
 760         }
 761
 762         ret = 0;
 763
 764 end:
 765         return ret;
 766 }
 767
 768 static
 769 int handle_condition(const struct lttng_condition *condition,
 770                 const struct lttng_evaluation *evaluation,
 771                 struct notification_thread_handle *notification_thread_handle)
 772 {
 773         int ret = 0;
 774         const char *condition_session_name = NULL;
 775         enum lttng_condition_type condition_type;
 776         enum lttng_condition_status condition_status;
 777         enum lttng_evaluation_status evaluation_status;
 778         uint64_t consumed;
 779         struct ltt_session *session;
 780
 781         condition_type = lttng_condition_get_type(condition);
 782
 783         if (condition_type != LTTNG_CONDITION_TYPE_SESSION_CONSUMED_SIZE) {
 784                 ret = -1;
 785                 ERR("[rotation-thread] Condition type and session usage type are not the same");
 786                 goto end;
 787         }
 788
 789         /* Fetch info to test */
 790         condition_status = lttng_condition_session_consumed_size_get_session_name(
 791                         condition, &condition_session_name);
 792         if (condition_status != LTTNG_CONDITION_STATUS_OK) {
 793                 ERR("[rotation-thread] Session name could not be fetched");
 794                 ret = -1;
 795                 goto end;
 796         }
 797         evaluation_status = lttng_evaluation_session_consumed_size_get_consumed_size(evaluation,
 798                         &consumed);
 799         if (evaluation_status != LTTNG_EVALUATION_STATUS_OK) {
 800                 ERR("[rotation-thread] Failed to get evaluation");
 801                 ret = -1;
 802                 goto end;
 803         }
 804
 805         session_lock_list();
 806         session = session_find_by_name(condition_session_name);
 807         if (!session) {
 808                 ret = -1;
 809                 session_unlock_list();
 810                 ERR("[rotation-thread] Session \"%s\" not found",
 811                                 condition_session_name);
 812                 goto end;
 813         }
 814         session_lock(session);
 815         session_unlock_list();
 816
 817         ret = unsubscribe_session_consumed_size_rotation(session,
 818                         notification_thread_handle);
 819         if (ret) {
 820                 goto end_unlock;
 821         }
 822
 823         ret = cmd_rotate_session(session, NULL);
 824         if (ret == -LTTNG_ERR_ROTATION_PENDING) {
 825                 DBG("Rotate already pending, subscribe to the next threshold value");
 826         } else if (ret != LTTNG_OK) {
 827                 ERR("[rotation-thread] Failed to rotate on size notification with error: %s",
 828                                 lttng_strerror(ret));
 829                 ret = -1;
 830                 goto end_unlock;
 831         }
 832         ret = subscribe_session_consumed_size_rotation(session,
 833                         consumed + session->rotate_size,
 834                         notification_thread_handle);
 835         if (ret) {
 836                 ERR("[rotation-thread] Failed to subscribe to session consumed size condition");
 837                 goto end_unlock;
 838         }
 839         ret = 0;
 840
 841 end_unlock:
 842         session_unlock(session);
 843         session_put(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 occurred 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 occurred 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 }