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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   * Functions common to the question usage statistics code.
  19   *
  20   * @package    moodlecore
  21   * @subpackage questionbank
  22   * @copyright  2013 The Open University
  23   * @author     Jamie Pratt <me@jamiep.org>
  24   * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  25   */
  26  
  27  defined('MOODLE_INTERNAL') || die();
  28  
  29  /**
  30   * Question statistics cron code. Deletes cached stats more than a certain age.
  31   */
  32  function question_usage_statistics_cron() {
  33      global $DB;
  34  
  35      $expiretime = time() - 5 * HOURSECS;
  36  
  37      mtrace("\n  Cleaning up old question statistics cache records...", '');
  38  
  39      $DB->delete_records_select('question_statistics', 'timemodified < ?', array($expiretime));
  40      $responseanlysisids = $DB->get_records_select_menu('question_response_analysis',
  41                                                             'timemodified < ?',
  42                                                             array($expiretime),
  43                                                             'id',
  44                                                             'id, id AS id2');
  45  
  46      $DB->delete_records_list('question_response_analysis', 'id', $responseanlysisids);
  47      $DB->delete_records_list('question_response_count', 'analysisid', $responseanlysisids);
  48  
  49      mtrace('done.');
  50      return true;
  51  }