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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   * Clean the tool_monitor_events table.
  19   *
  20   * @package    tool_monitor
  21   * @copyright  2014 Mark Nelson <markn@moodle.com>
  22   * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  23   */
  24  
  25  namespace tool_monitor\task;
  26  
  27  /**
  28   * Simple task to clean the tool_monitor_events table.
  29   */
  30  class clean_events extends \core\task\scheduled_task {
  31  
  32      /**
  33       * Get a descriptive name for this task.
  34       *
  35       * @return string
  36       */
  37      public function get_name() {
  38          return get_string('taskcleanevents', 'tool_monitor');
  39      }
  40  
  41      /**
  42       * Performs the cleaning of events.
  43       */
  44      public function execute() {
  45          global $DB;
  46  
  47          if (!get_config('tool_monitor', 'enablemonitor')) {
  48              return; // The tool is disabled. Nothing to do.
  49          }
  50  
  51          // Array to store which events have been triggered in which course.
  52          $courses = array();
  53  
  54          // Firstly, let's go through the site wide rules. There may be multiple rules for the site that rely on
  55          // the same event being triggered, so we only remove the events when they reach the max timewindow.
  56          if ($siterules = $DB->get_recordset('tool_monitor_rules', array('courseid' => 0), 'timewindow DESC')) {
  57              // Go through each rule and check if there are any events we can remove.
  58              foreach ($siterules as $rule) {
  59                  // Check if we have already processed this event.
  60                  if (isset($courses[$rule->courseid][$rule->eventname])) {
  61                      continue;
  62                  }
  63                  // Store the timewindow for this event.
  64                  $courses[$rule->courseid][$rule->eventname] = $rule->timewindow;
  65                  // Delete any events that may exist that have exceeded the timewindow.
  66                  $DB->delete_records_select('tool_monitor_events', 'eventname = :eventname AND
  67                      courseid = :courseid AND timecreated <= :timewindow',
  68                      array('eventname' => $rule->eventname, 'courseid' => $rule->courseid,
  69                          'timewindow' => time() - $rule->timewindow));
  70              }
  71              // Free resources.
  72              $siterules->close();
  73          }
  74  
  75          // Now, get the course rules. The same applies here - there may be multiple rules for the course that rely on
  76          // the same event being triggered, so we only remove the events when they reach the max timewindow.
  77          if ($rules = $DB->get_recordset_select('tool_monitor_rules', 'courseid != 0', array(), 'timewindow DESC')) {
  78              // Go through each rule and check if there are any events we can remove.
  79              foreach ($rules as $rule) {
  80                  // Check if we have already processed this event for this particular course.
  81                  if (isset($courses[$rule->courseid][$rule->eventname])) {
  82                      continue;
  83                  }
  84                  // Add the course and event to the list.
  85                  $courses[$rule->courseid][$rule->eventname] = $rule->timewindow;
  86                  // If there is a site wide rule listening for this event do not remove it unless the maximum
  87                  // timewindow between the two has exceeded.
  88                  $timewindow = $rule->timewindow;
  89                  if (isset($courses[0][$rule->eventname]) && ($courses[0][$rule->eventname] > $timewindow)) {
  90                      $timewindow = $courses[0][$rule->eventname];
  91                  }
  92                  // Delete any events that may exist that have exceeded the timewindow.
  93                  $DB->delete_records_select('tool_monitor_events', 'eventname = :eventname AND
  94                      courseid = :courseid AND timecreated <= :timewindow',
  95                          array('eventname' => $rule->eventname, 'courseid' => $rule->courseid,
  96                              'timewindow' => time() - $timewindow));
  97              }
  98              // Free resources.
  99              $rules->close();
 100          }
 101  
 102          if ($siterules || $rules) { // Check that there are rules present.
 103              // Get a list of all the events we have been through.
 104              $allevents = array();
 105              foreach ($courses as $key => $value) {
 106                  foreach ($courses[$key] as $event => $notused) {
 107                      $allevents[] = $event;
 108                  }
 109              }
 110              // Remove all the events in the table that are not applicable to any rule. There may be a rule in one course
 111              // listening for a certain event, but not in another course, so we can delete the event from the course
 112              // where there is no rule. We also have to consider site wide rules. We may have an event that is triggered
 113              // in a course we can't remove because there is a site wide rule for this event.
 114              if ($events = $DB->get_recordset('tool_monitor_events')) {
 115                  // Array to store which events we need to remove.
 116                  $eventstodelete = array();
 117                  // Store the current time.
 118                  $now = time();
 119                  foreach ($events as $event) {
 120                      // If the event is not required for a course rule and there is no site wide rule for it, or
 121                      // it has extended past or equal to the timewindow for the site rule - it can be deleted.
 122                      if (!isset($courses[$event->courseid][$event->eventname]) && (!isset($courses[0][$event->eventname])
 123                          || $courses[0][$event->eventname] <= ($now - $event->timecreated))) {
 124                          $eventstodelete[] = $event->id;
 125                      }
 126                  }
 127                  // Free resources.
 128                  $events->close();
 129  
 130                  // Remove the events.
 131                  if (!empty($eventstodelete)) {
 132                      list($eventidsql, $params) = $DB->get_in_or_equal($eventstodelete);
 133                      $DB->delete_records_select('tool_monitor_events', "id $eventidsql", $params);
 134                  }
 135              }
 136  
 137              // Remove all the events in the table that are not used by any rule.
 138              if (!empty($allevents)) {
 139                  list($eventnamesql, $params) = $DB->get_in_or_equal($allevents, SQL_PARAMS_QM, 'param', false);
 140                  $DB->delete_records_select('tool_monitor_events', "eventname $eventnamesql", $params);
 141              }
 142          } else { // No rules, just remove everything.
 143              $DB->delete_records('tool_monitor_events');
 144          }
 145      }
 146  }