src/bin/lttng-sessiond/action-executor.c

   1 /*
   2  * Copyright (C) 2020 Jérémie Galarneau <jeremie.galarneau@efficios.com>
   3  *
   4  * SPDX-License-Identifier: GPL-2.0-only
   5  *
   6  */
   7
   8 #include "action-executor.h"
   9 #include "cmd.h"
  10 #include "health-sessiond.h"
  11 #include "lttng-sessiond.h"
  12 #include "notification-thread-internal.h"
  13 #include "session.h"
  14 #include "thread.h"
  15 #include <common/macros.h>
  16 #include <common/optional.h>
  17 #include <lttng/action/action-internal.h>
  18 #include <lttng/action/group-internal.h>
  19 #include <lttng/action/group.h>
  20 #include <lttng/action/notify-internal.h>
  21 #include <lttng/action/notify.h>
  22 #include <lttng/action/rotate-session.h>
  23 #include <lttng/action/snapshot-session.h>
  24 #include <lttng/action/start-session.h>
  25 #include <lttng/action/stop-session.h>
  26 #include <lttng/condition/evaluation.h>
  27 #include <lttng/condition/on-event-internal.h>
  28 #include <lttng/lttng-error.h>
  29 #include <lttng/trigger/trigger-internal.h>
  30 #include <pthread.h>
  31 #include <stdbool.h>
  32 #include <stddef.h>
  33 #include <urcu/list.h>
  34
  35 #define THREAD_NAME "Action Executor"
  36 #define MAX_QUEUED_WORK_COUNT 8192
  37
  38 struct action_work_item {
  39         uint64_t id;
  40         struct lttng_trigger *trigger;
  41         struct lttng_evaluation *evaluation;
  42         struct notification_client_list *client_list;
  43         LTTNG_OPTIONAL(struct lttng_credentials) object_creds;
  44         struct cds_list_head list_node;
  45 };
  46
  47 struct action_executor {
  48         struct lttng_thread *thread;
  49         struct notification_thread_handle *notification_thread_handle;
  50         struct {
  51                 uint64_t pending_count;
  52                 struct cds_list_head list;
  53                 pthread_cond_t cond;
  54                 pthread_mutex_t lock;
  55         } work;
  56         bool should_quit;
  57         uint64_t next_work_item_id;
  58 };
  59
  60 /*
  61  * Only return non-zero on a fatal error that should shut down the action
  62  * executor.
  63  */
  64 typedef int (*action_executor_handler)(struct action_executor *executor,
  65                 const struct action_work_item *,
  66                 struct lttng_action *action);
  67
  68 static int action_executor_notify_handler(struct action_executor *executor,
  69                 const struct action_work_item *,
  70                 struct lttng_action *);
  71 static int action_executor_start_session_handler(
  72                 struct action_executor *executor,
  73                 const struct action_work_item *,
  74                 struct lttng_action *);
  75 static int action_executor_stop_session_handler(
  76                 struct action_executor *executor,
  77                 const struct action_work_item *,
  78                 struct lttng_action *);
  79 static int action_executor_rotate_session_handler(
  80                 struct action_executor *executor,
  81                 const struct action_work_item *,
  82                 struct lttng_action *);
  83 static int action_executor_snapshot_session_handler(
  84                 struct action_executor *executor,
  85                 const struct action_work_item *,
  86                 struct lttng_action *);
  87 static int action_executor_group_handler(struct action_executor *executor,
  88                 const struct action_work_item *,
  89                 struct lttng_action *);
  90 static int action_executor_generic_handler(struct action_executor *executor,
  91                 const struct action_work_item *,
  92                 struct lttng_action *);
  93
  94 static const action_executor_handler action_executors[] = {
  95         [LTTNG_ACTION_TYPE_NOTIFY] = action_executor_notify_handler,
  96         [LTTNG_ACTION_TYPE_START_SESSION] = action_executor_start_session_handler,
  97         [LTTNG_ACTION_TYPE_STOP_SESSION] = action_executor_stop_session_handler,
  98         [LTTNG_ACTION_TYPE_ROTATE_SESSION] = action_executor_rotate_session_handler,
  99         [LTTNG_ACTION_TYPE_SNAPSHOT_SESSION] = action_executor_snapshot_session_handler,
 100         [LTTNG_ACTION_TYPE_GROUP] = action_executor_group_handler,
 101 };
 102
 103 static const char *get_action_name(const struct lttng_action *action)
 104 {
 105         const enum lttng_action_type action_type = lttng_action_get_type(action);
 106
 107         assert(action_type != LTTNG_ACTION_TYPE_UNKNOWN);
 108
 109         return lttng_action_type_string(action_type);
 110 }
 111
 112 /* Check if this trigger allowed to interect with a given session. */
 113 static bool is_trigger_allowed_for_session(const struct lttng_trigger *trigger,
 114                 struct ltt_session *session)
 115 {
 116         bool is_allowed = false;
 117         const struct lttng_credentials session_creds = {
 118                 .uid = LTTNG_OPTIONAL_INIT_VALUE(session->uid),
 119                 .gid = LTTNG_OPTIONAL_INIT_VALUE(session->gid),
 120         };
 121         /* Can never be NULL. */
 122         const struct lttng_credentials *trigger_creds =
 123                         lttng_trigger_get_credentials(trigger);
 124
 125         is_allowed = (lttng_credentials_is_equal_uid(trigger_creds, &session_creds)) ||
 126                         (lttng_credentials_get_uid(trigger_creds) == 0);
 127         if (!is_allowed) {
 128                 WARN("Trigger is not allowed to interact with session `%s`: session uid = %ld, session gid = %ld, trigger uid = %ld",
 129                                 session->name,
 130                                 (long int) session->uid,
 131                                 (long int) session->gid,
 132                                 (long int) lttng_credentials_get_uid(trigger_creds));
 133         }
 134
 135         return is_allowed;
 136 }
 137
 138 static const char *get_trigger_name(const struct lttng_trigger *trigger)
 139 {
 140         const char *trigger_name;
 141         enum lttng_trigger_status trigger_status;
 142
 143         trigger_status = lttng_trigger_get_name(trigger, &trigger_name);
 144         assert(trigger_status == LTTNG_TRIGGER_STATUS_OK);
 145
 146         return trigger_name;
 147 }
 148
 149 static int client_handle_transmission_status(
 150                 struct notification_client *client,
 151                 enum client_transmission_status status,
 152                 void *user_data)
 153 {
 154         int ret = 0;
 155         struct action_executor *executor = user_data;
 156         bool update_communication = true;
 157
 158         switch (status) {
 159         case CLIENT_TRANSMISSION_STATUS_COMPLETE:
 160                 DBG("Successfully sent full notification to client, client_id = %" PRIu64,
 161                                 client->id);
 162                 update_communication = false;
 163                 break;
 164         case CLIENT_TRANSMISSION_STATUS_QUEUED:
 165                 DBG("Queued notification in client outgoing buffer, client_id = %" PRIu64,
 166                                 client->id);
 167                 break;
 168         case CLIENT_TRANSMISSION_STATUS_FAIL:
 169                 DBG("Communication error occurred while sending notification to client, client_id = %" PRIu64,
 170                                 client->id);
 171                 break;
 172         default:
 173                 ERR("Fatal error encoutered while sending notification to client, client_id = %" PRIu64,
 174                                 client->id);
 175                 ret = -1;
 176                 goto end;
 177         }
 178
 179         if (!update_communication) {
 180                 goto end;
 181         }
 182
 183         /* Safe to read client's id without locking as it is immutable. */
 184         ret = notification_thread_client_communication_update(
 185                         executor->notification_thread_handle, client->id,
 186                         status);
 187 end:
 188         return ret;
 189 }
 190
 191 static int action_executor_notify_handler(struct action_executor *executor,
 192                 const struct action_work_item *work_item,
 193                 struct lttng_action *action)
 194 {
 195         return notification_client_list_send_evaluation(work_item->client_list,
 196                         work_item->trigger,
 197                         work_item->evaluation,
 198                         work_item->object_creds.is_set ?
 199                                         &(work_item->object_creds.value) :
 200                                         NULL,
 201                         client_handle_transmission_status, executor);
 202 }
 203
 204 static int action_executor_start_session_handler(
 205                 struct action_executor *executor,
 206                 const struct action_work_item *work_item,
 207                 struct lttng_action *action)
 208 {
 209         int ret = 0;
 210         const char *session_name;
 211         enum lttng_action_status action_status;
 212         struct ltt_session *session;
 213         enum lttng_error_code cmd_ret;
 214
 215         action_status = lttng_action_start_session_get_session_name(
 216                         action, &session_name);
 217         if (action_status != LTTNG_ACTION_STATUS_OK) {
 218                 ERR("Failed to get session name from `%s` action",
 219                                 get_action_name(action));
 220                 ret = -1;
 221                 goto end;
 222         }
 223
 224         session_lock_list();
 225         session = session_find_by_name(session_name);
 226         if (!session) {
 227                 DBG("Failed to find session `%s` by name while executing `%s` action of trigger `%s`",
 228                                 session_name, get_action_name(action),
 229                                 get_trigger_name(work_item->trigger));
 230                 goto error_unlock_list;
 231         }
 232
 233         session_lock(session);
 234         if (!is_trigger_allowed_for_session(work_item->trigger, session)) {
 235                 goto error_dispose_session;
 236         }
 237
 238         cmd_ret = cmd_start_trace(session);
 239         switch (cmd_ret) {
 240         case LTTNG_OK:
 241                 DBG("Successfully started session `%s` on behalf of trigger `%s`",
 242                                 session_name, get_trigger_name(work_item->trigger));
 243                 break;
 244         case LTTNG_ERR_TRACE_ALREADY_STARTED:
 245                 DBG("Attempted to start session `%s` on behalf of trigger `%s` but it was already started",
 246                                 session_name, get_trigger_name(work_item->trigger));
 247                 break;
 248         default:
 249                 WARN("Failed to start session `%s` on behalf of trigger `%s`: %s",
 250                                 session_name, get_trigger_name(work_item->trigger),
 251                                 lttng_strerror(-cmd_ret));
 252                 lttng_action_increase_execution_failure_count(action);
 253                 break;
 254         }
 255
 256 error_dispose_session:
 257         session_unlock(session);
 258         session_put(session);
 259 error_unlock_list:
 260         session_unlock_list();
 261 end:
 262         return ret;
 263 }
 264
 265 static int action_executor_stop_session_handler(
 266                 struct action_executor *executor,
 267                 const struct action_work_item *work_item,
 268                 struct lttng_action *action)
 269 {
 270         int ret = 0;
 271         const char *session_name;
 272         enum lttng_action_status action_status;
 273         struct ltt_session *session;
 274         enum lttng_error_code cmd_ret;
 275
 276         action_status = lttng_action_stop_session_get_session_name(
 277                         action, &session_name);
 278         if (action_status != LTTNG_ACTION_STATUS_OK) {
 279                 ERR("Failed to get session name from `%s` action",
 280                                 get_action_name(action));
 281                 ret = -1;
 282                 goto end;
 283         }
 284
 285         session_lock_list();
 286         session = session_find_by_name(session_name);
 287         if (!session) {
 288                 DBG("Failed to find session `%s` by name while executing `%s` action of trigger `%s`",
 289                                 session_name, get_action_name(action),
 290                                 get_trigger_name(work_item->trigger));
 291                 lttng_action_increase_execution_failure_count(action);
 292                 goto error_unlock_list;
 293         }
 294
 295         session_lock(session);
 296         if (!is_trigger_allowed_for_session(work_item->trigger, session)) {
 297                 goto error_dispose_session;
 298         }
 299
 300         cmd_ret = cmd_stop_trace(session);
 301         switch (cmd_ret) {
 302         case LTTNG_OK:
 303                 DBG("Successfully stopped session `%s` on behalf of trigger `%s`",
 304                                 session_name, get_trigger_name(work_item->trigger));
 305                 break;
 306         case LTTNG_ERR_TRACE_ALREADY_STOPPED:
 307                 DBG("Attempted to stop session `%s` on behalf of trigger `%s` but it was already stopped",
 308                                 session_name, get_trigger_name(work_item->trigger));
 309                 break;
 310         default:
 311                 WARN("Failed to stop session `%s` on behalf of trigger `%s`: %s",
 312                                 session_name, get_trigger_name(work_item->trigger),
 313                                 lttng_strerror(-cmd_ret));
 314                 lttng_action_increase_execution_failure_count(action);
 315                 break;
 316         }
 317
 318 error_dispose_session:
 319         session_unlock(session);
 320         session_put(session);
 321 error_unlock_list:
 322         session_unlock_list();
 323 end:
 324         return ret;
 325 }
 326
 327 static int action_executor_rotate_session_handler(
 328                 struct action_executor *executor,
 329                 const struct action_work_item *work_item,
 330                 struct lttng_action *action)
 331 {
 332         int ret = 0;
 333         const char *session_name;
 334         enum lttng_action_status action_status;
 335         struct ltt_session *session;
 336         enum lttng_error_code cmd_ret;
 337
 338         action_status = lttng_action_rotate_session_get_session_name(
 339                         action, &session_name);
 340         if (action_status != LTTNG_ACTION_STATUS_OK) {
 341                 ERR("Failed to get session name from `%s` action",
 342                                 get_action_name(action));
 343                 ret = -1;
 344                 goto end;
 345         }
 346
 347         session_lock_list();
 348         session = session_find_by_name(session_name);
 349         if (!session) {
 350                 DBG("Failed to find session `%s` by name while executing `%s` action of trigger `%s`",
 351                                 session_name, get_action_name(action),
 352                                 get_trigger_name(work_item->trigger));
 353                 lttng_action_increase_execution_failure_count(action);
 354                 goto error_unlock_list;
 355         }
 356
 357         session_lock(session);
 358         if (!is_trigger_allowed_for_session(work_item->trigger, session)) {
 359                 goto error_dispose_session;
 360         }
 361
 362         cmd_ret = cmd_rotate_session(session, NULL, false,
 363                         LTTNG_TRACE_CHUNK_COMMAND_TYPE_MOVE_TO_COMPLETED);
 364         switch (cmd_ret) {
 365         case LTTNG_OK:
 366                 DBG("Successfully started rotation of session `%s` on behalf of trigger `%s`",
 367                                 session_name, get_trigger_name(work_item->trigger));
 368                 break;
 369         case LTTNG_ERR_ROTATION_PENDING:
 370                 DBG("Attempted to start a rotation of session `%s` on behalf of trigger `%s` but a rotation is already ongoing",
 371                                 session_name, get_trigger_name(work_item->trigger));
 372                 lttng_action_increase_execution_failure_count(action);
 373                 break;
 374         case LTTNG_ERR_ROTATION_MULTIPLE_AFTER_STOP:
 375         case LTTNG_ERR_ROTATION_AFTER_STOP_CLEAR:
 376                 DBG("Attempted to start a rotation of session `%s` on behalf of trigger `%s` but a rotation has already been completed since the last stop or clear",
 377                                 session_name, get_trigger_name(work_item->trigger));
 378                 break;
 379         default:
 380                 WARN("Failed to start a rotation of session `%s` on behalf of trigger `%s`: %s",
 381                                 session_name, get_trigger_name(work_item->trigger),
 382                                 lttng_strerror(-cmd_ret));
 383                 lttng_action_increase_execution_failure_count(action);
 384                 break;
 385         }
 386
 387 error_dispose_session:
 388         session_unlock(session);
 389         session_put(session);
 390 error_unlock_list:
 391         session_unlock_list();
 392 end:
 393         return ret;
 394 }
 395
 396 static int action_executor_snapshot_session_handler(
 397                 struct action_executor *executor,
 398                 const struct action_work_item *work_item,
 399                 struct lttng_action *action)
 400 {
 401         int ret = 0;
 402         const char *session_name;
 403         enum lttng_action_status action_status;
 404         struct ltt_session *session;
 405         const struct lttng_snapshot_output default_snapshot_output = {
 406                 .max_size = UINT64_MAX,
 407         };
 408         const struct lttng_snapshot_output *snapshot_output =
 409                         &default_snapshot_output;
 410         enum lttng_error_code cmd_ret;
 411
 412         action_status = lttng_action_snapshot_session_get_session_name(
 413                         action, &session_name);
 414         if (action_status != LTTNG_ACTION_STATUS_OK) {
 415                 ERR("Failed to get session name from `%s` action",
 416                                 get_action_name(action));
 417                 ret = -1;
 418                 goto end;
 419         }
 420
 421         action_status = lttng_action_snapshot_session_get_output(
 422                         action, &snapshot_output);
 423         if (action_status != LTTNG_ACTION_STATUS_OK &&
 424                         action_status != LTTNG_ACTION_STATUS_UNSET) {
 425                 ERR("Failed to get output from `%s` action",
 426                                 get_action_name(action));
 427                 ret = -1;
 428                 goto end;
 429         }
 430
 431         session_lock_list();
 432         session = session_find_by_name(session_name);
 433         if (!session) {
 434                 DBG("Failed to find session `%s` by name while executing `%s` action of trigger `%s`",
 435                                 session_name, get_action_name(action),
 436                                 get_trigger_name(work_item->trigger));
 437                 lttng_action_increase_execution_failure_count(action);
 438                 goto error_unlock_list;
 439         }
 440
 441
 442         session_lock(session);
 443         if (!is_trigger_allowed_for_session(work_item->trigger, session)) {
 444                 goto error_dispose_session;
 445         }
 446
 447         cmd_ret = cmd_snapshot_record(session, snapshot_output, 0);
 448         switch (cmd_ret) {
 449         case LTTNG_OK:
 450                 DBG("Successfully recorded snapshot of session `%s` on behalf of trigger `%s`",
 451                                 session_name, get_trigger_name(work_item->trigger));
 452                 break;
 453         default:
 454                 WARN("Failed to record snapshot of session `%s` on behalf of trigger `%s`: %s",
 455                                 session_name, get_trigger_name(work_item->trigger),
 456                                 lttng_strerror(-cmd_ret));
 457                 lttng_action_increase_execution_failure_count(action);
 458                 break;
 459         }
 460
 461 error_dispose_session:
 462         session_unlock(session);
 463         session_put(session);
 464 error_unlock_list:
 465         session_unlock_list();
 466 end:
 467         return ret;
 468 }
 469
 470 static int action_executor_group_handler(struct action_executor *executor,
 471                 const struct action_work_item *work_item,
 472                 struct lttng_action *action_group)
 473 {
 474         int ret = 0;
 475         unsigned int i, count;
 476         enum lttng_action_status action_status;
 477
 478         action_status = lttng_action_group_get_count(action_group, &count);
 479         if (action_status != LTTNG_ACTION_STATUS_OK) {
 480                 /* Fatal error. */
 481                 ERR("Failed to get count of action in action group");
 482                 ret = -1;
 483                 goto end;
 484         }
 485
 486         DBG("Action group has %u action%s", count, count != 1 ? "s" : "");
 487         for (i = 0; i < count; i++) {
 488                 struct lttng_action *action =
 489                                 lttng_action_group_borrow_mutable_at_index(
 490                                                 action_group, i);
 491
 492                 ret = action_executor_generic_handler(
 493                                 executor, work_item, action);
 494                 if (ret) {
 495                         ERR("Stopping the execution of the action group of trigger `%s` following a fatal error",
 496                                         get_trigger_name(work_item->trigger));
 497                         goto end;
 498                 }
 499         }
 500 end:
 501         return ret;
 502 }
 503
 504 static int action_executor_generic_handler(struct action_executor *executor,
 505                 const struct action_work_item *work_item,
 506                 struct lttng_action *action)
 507 {
 508         int ret;
 509         const enum lttng_action_type action_type = lttng_action_get_type(action);
 510
 511         assert(action_type != LTTNG_ACTION_TYPE_UNKNOWN);
 512
 513         lttng_action_increase_execution_request_count(action);
 514         if (!lttng_action_should_execute(action)) {
 515                 DBG("Policy prevented execution of action `%s` of trigger `%s` action work item %" PRIu64,
 516                                 get_action_name(action),
 517                                 get_trigger_name(work_item->trigger),
 518                                 work_item->id);
 519                 ret = 0;
 520                 goto end;
 521         }
 522
 523         lttng_action_increase_execution_count(action);
 524         DBG("Executing action `%s` of trigger `%s` action work item %" PRIu64,
 525                         get_action_name(action),
 526                         get_trigger_name(work_item->trigger),
 527                         work_item->id);
 528         ret = action_executors[action_type](executor, work_item, action);
 529 end:
 530         return ret;
 531 }
 532
 533 static int action_work_item_execute(struct action_executor *executor,
 534                 struct action_work_item *work_item)
 535 {
 536         int ret;
 537         struct lttng_action *action =
 538                         lttng_trigger_get_action(work_item->trigger);
 539
 540         DBG("Starting execution of action work item %" PRIu64 " of trigger `%s`",
 541                         work_item->id, get_trigger_name(work_item->trigger));
 542         ret = action_executor_generic_handler(executor, work_item, action);
 543         DBG("Completed execution of action work item %" PRIu64 " of trigger `%s`",
 544                         work_item->id, get_trigger_name(work_item->trigger));
 545         return ret;
 546 }
 547
 548 static void action_work_item_destroy(struct action_work_item *work_item)
 549 {
 550         lttng_trigger_put(work_item->trigger);
 551         lttng_evaluation_destroy(work_item->evaluation);
 552         notification_client_list_put(work_item->client_list);
 553         free(work_item);
 554 }
 555
 556 static void *action_executor_thread(void *_data)
 557 {
 558         struct action_executor *executor = _data;
 559
 560         assert(executor);
 561
 562         health_register(the_health_sessiond,
 563                         HEALTH_SESSIOND_TYPE_ACTION_EXECUTOR);
 564
 565         rcu_register_thread();
 566         rcu_thread_online();
 567
 568         DBG("Entering work execution loop");
 569         pthread_mutex_lock(&executor->work.lock);
 570         while (!executor->should_quit) {
 571                 int ret;
 572                 struct action_work_item *work_item;
 573
 574                 health_code_update();
 575                 if (executor->work.pending_count == 0) {
 576                         health_poll_entry();
 577                         DBG("No work items enqueued, entering wait");
 578                         pthread_cond_wait(&executor->work.cond,
 579                                         &executor->work.lock);
 580                         DBG("Woke-up from wait");
 581                         health_poll_exit();
 582                         continue;
 583                 }
 584
 585                 /* Pop item from front of the list with work lock held. */
 586                 work_item = cds_list_first_entry(&executor->work.list,
 587                                 struct action_work_item, list_node);
 588                 cds_list_del(&work_item->list_node);
 589                 executor->work.pending_count--;
 590
 591                 /*
 592                  * Work can be performed without holding the work lock,
 593                  * allowing new items to be queued.
 594                  */
 595                 pthread_mutex_unlock(&executor->work.lock);
 596
 597                 /* Execute item only if a trigger is registered. */
 598                 lttng_trigger_lock(work_item->trigger);
 599                 if (!lttng_trigger_is_registered(work_item->trigger)) {
 600                         const char *trigger_name = NULL;
 601                         uid_t trigger_owner_uid;
 602                         enum lttng_trigger_status trigger_status;
 603
 604                         trigger_status = lttng_trigger_get_name(
 605                                         work_item->trigger, &trigger_name);
 606                         switch (trigger_status) {
 607                         case LTTNG_TRIGGER_STATUS_OK:
 608                                 break;
 609                         case LTTNG_TRIGGER_STATUS_UNSET:
 610                                 trigger_name = "(unset)";
 611                                 break;
 612                         default:
 613                                 abort();
 614                         }
 615
 616                         trigger_status = lttng_trigger_get_owner_uid(
 617                                         work_item->trigger, &trigger_owner_uid);
 618                         assert(trigger_status == LTTNG_TRIGGER_STATUS_OK);
 619
 620                         DBG("Work item skipped since the associated trigger is no longer registered: work item id = %" PRIu64 ", trigger name = '%s', trigger owner uid = %d",
 621                                         work_item->id, trigger_name,
 622                                         (int) trigger_owner_uid);
 623                         ret = 0;
 624                         goto skip_execute;
 625                 }
 626
 627                 ret = action_work_item_execute(executor, work_item);
 628
 629         skip_execute:
 630                 lttng_trigger_unlock(work_item->trigger);
 631                 action_work_item_destroy(work_item);
 632                 if (ret) {
 633                         /* Fatal error. */
 634                         break;
 635                 }
 636
 637                 health_code_update();
 638                 pthread_mutex_lock(&executor->work.lock);
 639         }
 640
 641         if (executor->should_quit) {
 642                 pthread_mutex_unlock(&executor->work.lock);
 643         }
 644         DBG("Left work execution loop");
 645
 646         health_code_update();
 647
 648         rcu_thread_offline();
 649         rcu_unregister_thread();
 650         health_unregister(the_health_sessiond);
 651
 652         return NULL;
 653 }
 654
 655 static bool shutdown_action_executor_thread(void *_data)
 656 {
 657         struct action_executor *executor = _data;
 658
 659         pthread_mutex_lock(&executor->work.lock);
 660         executor->should_quit = true;
 661         pthread_cond_signal(&executor->work.cond);
 662         pthread_mutex_unlock(&executor->work.lock);
 663         return true;
 664 }
 665
 666 static void clean_up_action_executor_thread(void *_data)
 667 {
 668         struct action_executor *executor = _data;
 669
 670         assert(cds_list_empty(&executor->work.list));
 671
 672         pthread_mutex_destroy(&executor->work.lock);
 673         pthread_cond_destroy(&executor->work.cond);
 674         free(executor);
 675 }
 676
 677 struct action_executor *action_executor_create(
 678                 struct notification_thread_handle *handle)
 679 {
 680         struct action_executor *executor = zmalloc(sizeof(*executor));
 681
 682         if (!executor) {
 683                 goto end;
 684         }
 685
 686         CDS_INIT_LIST_HEAD(&executor->work.list);
 687         pthread_cond_init(&executor->work.cond, NULL);
 688         pthread_mutex_init(&executor->work.lock, NULL);
 689         executor->notification_thread_handle = handle;
 690
 691         executor->thread = lttng_thread_create(THREAD_NAME,
 692                         action_executor_thread, shutdown_action_executor_thread,
 693                         clean_up_action_executor_thread, executor);
 694 end:
 695         return executor;
 696 }
 697
 698 void action_executor_destroy(struct action_executor *executor)
 699 {
 700         struct action_work_item *work_item, *tmp;
 701
 702         /* TODO Wait for work list to drain? */
 703         lttng_thread_shutdown(executor->thread);
 704         pthread_mutex_lock(&executor->work.lock);
 705         if (executor->work.pending_count != 0) {
 706                 WARN("%" PRIu64
 707                         " trigger action%s still queued for execution and will be discarded",
 708                                 executor->work.pending_count,
 709                                 executor->work.pending_count == 1 ? " is" :
 710                                                                     "s are");
 711         }
 712
 713         cds_list_for_each_entry_safe (
 714                         work_item, tmp, &executor->work.list, list_node) {
 715                 WARN("Discarding action work item %" PRIu64
 716                                 " associated to trigger `%s`",
 717                                 work_item->id, get_trigger_name(work_item->trigger));
 718                 cds_list_del(&work_item->list_node);
 719                 action_work_item_destroy(work_item);
 720         }
 721         pthread_mutex_unlock(&executor->work.lock);
 722         lttng_thread_put(executor->thread);
 723 }
 724
 725 /* RCU read-lock must be held by the caller. */
 726 enum action_executor_status action_executor_enqueue(
 727                 struct action_executor *executor,
 728                 struct lttng_trigger *trigger,
 729                 struct lttng_evaluation *evaluation,
 730                 const struct lttng_credentials *object_creds,
 731                 struct notification_client_list *client_list)
 732 {
 733         enum action_executor_status executor_status = ACTION_EXECUTOR_STATUS_OK;
 734         const uint64_t work_item_id = executor->next_work_item_id++;
 735         struct action_work_item *work_item;
 736         bool signal = false;
 737
 738         pthread_mutex_lock(&executor->work.lock);
 739         /* Check for queue overflow. */
 740         if (executor->work.pending_count >= MAX_QUEUED_WORK_COUNT) {
 741                 /* Most likely spammy, remove if it is the case. */
 742                 DBG("Refusing to enqueue action for trigger `%s` as work item %" PRIu64
 743                         " (overflow)", get_trigger_name(trigger), work_item_id);
 744                 executor_status = ACTION_EXECUTOR_STATUS_OVERFLOW;
 745                 goto error_unlock;
 746         }
 747
 748         work_item = zmalloc(sizeof(*work_item));
 749         if (!work_item) {
 750                 PERROR("Failed to allocate action executor work item on behalf of trigger `%s`",
 751                                 get_trigger_name(trigger));
 752                 executor_status = ACTION_EXECUTOR_STATUS_ERROR;
 753                 goto error_unlock;
 754         }
 755
 756         lttng_trigger_get(trigger);
 757         if (client_list) {
 758                 const bool reference_acquired =
 759                                 notification_client_list_get(client_list);
 760
 761                 assert(reference_acquired);
 762         }
 763
 764         *work_item = (typeof(*work_item)){
 765                         .id = work_item_id,
 766                         .trigger = trigger,
 767                         /* Ownership transferred to the work item. */
 768                         .evaluation = evaluation,
 769                         .object_creds = {
 770                                 .is_set = !!object_creds,
 771                                 .value = object_creds ? *object_creds :
 772                                         (typeof(work_item->object_creds.value)) {},
 773                         },
 774                         .client_list = client_list,
 775                         .list_node = CDS_LIST_HEAD_INIT(work_item->list_node),
 776         };
 777
 778         evaluation = NULL;
 779         cds_list_add_tail(&work_item->list_node, &executor->work.list);
 780         executor->work.pending_count++;
 781         DBG("Enqueued action for trigger `%s` as work item #%" PRIu64,
 782                         get_trigger_name(trigger), work_item_id);
 783         signal = true;
 784
 785 error_unlock:
 786         if (signal) {
 787                 pthread_cond_signal(&executor->work.cond);
 788         }
 789         pthread_mutex_unlock(&executor->work.lock);
 790
 791         lttng_evaluation_destroy(evaluation);
 792         return executor_status;
 793 }