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   1  <?php
   2  // This file is part of Moodle - http://moodle.org/
   3  //
   4  // Moodle is free software: you can redistribute it and/or modify
   5  // it under the terms of the GNU General Public License as published by
   6  // the Free Software Foundation, either version 3 of the License, or
   7  // (at your option) any later version.
   8  //
   9  // Moodle is distributed in the hope that it will be useful,
  10  // but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  // GNU General Public License for more details.
  13  //
  14  // You should have received a copy of the GNU General Public License
  15  // along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
  16  
  17  /**
  18   * Task to cleanup old question previews.
  19   *
  20   * @package    core
  21   * @copyright  2013 onwards Martin Dougiamas  http://dougiamas.com
  22   * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  23   */
  24  namespace core\task;
  25  
  26  /**
  27   * A task to cleanup old question previews.
  28   *
  29   * @copyright  2013 onwards Martin Dougiamas  http://dougiamas.com
  30   * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  31   */
  32  class question_preview_cleanup_task extends scheduled_task {
  33  
  34      /**
  35       * Get a descriptive name for this task (shown to admins).
  36       *
  37       * @return string
  38       */
  39      public function get_name() {
  40          return get_string('taskquestioncron', 'admin');
  41      }
  42  
  43      /**
  44       * Do the job.
  45       * Throw exceptions on errors (the job will be retried).
  46       */
  47      public function execute() {
  48          global $CFG;
  49          require_once($CFG->dirroot . '/question/engine/lib.php');
  50  
  51          // We delete previews that have not been touched for 24 hours.
  52          $lastmodifiedcutoff = time() - DAYSECS;
  53  
  54          mtrace("\n  Cleaning up old question previews...", '');
  55          $oldpreviews = new \qubaid_join('{question_usages} quba', 'quba.id',
  56              'quba.component = :qubacomponent
  57                      AND NOT EXISTS (
  58                          SELECT 1
  59                            FROM {question_attempts}      subq_qa
  60                            JOIN {question_attempt_steps} subq_qas ON subq_qas.questionattemptid = subq_qa.id
  61                            JOIN {question_usages}        subq_qu  ON subq_qu.id = subq_qa.questionusageid
  62                           WHERE subq_qa.questionusageid = quba.id
  63                             AND subq_qu.component = :qubacomponent2
  64                             AND (subq_qa.timemodified > :qamodifiedcutoff
  65                                      OR subq_qas.timecreated > :stepcreatedcutoff)
  66                      )
  67              ',
  68              ['qubacomponent' => 'core_question_preview', 'qubacomponent2' => 'core_question_preview',
  69                  'qamodifiedcutoff' => $lastmodifiedcutoff, 'stepcreatedcutoff' => $lastmodifiedcutoff]);
  70  
  71          \question_engine::delete_questions_usage_by_activities($oldpreviews);
  72          mtrace('done.');
  73      }
  74  
  75  }