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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   * Legacy log reader.
  19   *
  20   * @package    logstore_legacy
  21   * @copyright  2014 Petr Skoda {@link http://skodak.org}
  22   * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  23   */
  24  
  25  namespace logstore_legacy\task;
  26  
  27  defined('MOODLE_INTERNAL') || die();
  28  
  29  class cleanup_task extends \core\task\scheduled_task {
  30  
  31      /**
  32       * Get a descriptive name for this task (shown to admins).
  33       *
  34       * @return string
  35       */
  36      public function get_name() {
  37          return get_string('taskcleanup', 'logstore_legacy');
  38      }
  39  
  40      /**
  41       * Do the job.
  42       * Throw exceptions on errors (the job will be retried).
  43       */
  44      public function execute() {
  45          global $CFG, $DB;
  46  
  47          if (empty($CFG->loglifetime)) {
  48              return;
  49          }
  50  
  51          $loglifetime = time() - ($CFG->loglifetime * 3600 * 24); // Value in days.
  52          $lifetimep = array($loglifetime);
  53          $start = time();
  54  
  55          while ($min = $DB->get_field_select("log", "MIN(time)", "time < ?", $lifetimep)) {
  56              // Break this down into chunks to avoid transaction for too long and generally thrashing database.
  57              // Experiments suggest deleting one day takes up to a few seconds; probably a reasonable chunk size usually.
  58              // If the cleanup has just been enabled, it might take e.g a month to clean the years of logs.
  59              $params = array(min($min + 3600 * 24, $loglifetime));
  60              $DB->delete_records_select("log", "time < ?", $params);
  61              if (time() > $start + 300) {
  62                  // Do not churn on log deletion for too long each run.
  63                  break;
  64              }
  65          }
  66  
  67          mtrace(" Deleted old legacy log records");
  68      }
  69  }