lib/eventslib.php

   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  * Library of functions for events manipulation.
  19  *
  20  * The public API is all at the end of this file.
  21  *
  22  * @package core
  23  * @copyright 1999 onwards Martin Dougiamas  {@link http://moodle.com}
  24  * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  25  */
  26
  27 defined('MOODLE_INTERNAL') || die();
  28
  29 /**
  30  * Gets the capabilities that have been cached in the database for this
  31  * component.
  32  *
  33  * @access protected To be used from eventslib only
  34  *
  35  * @param string $component examples: 'moodle', 'mod_forum', 'block_quiz_results'
  36  * @return array of events
  37  */
  38 function events_get_cached($component) {
  39     global $DB;
  40
  41     $cachedhandlers = array();
  42
  43     if ($storedhandlers = $DB->get_records('events_handlers', array('component'=>$component))) {
  44         foreach ($storedhandlers as $handler) {
  45             $cachedhandlers[$handler->eventname] = array (
  46                 'id'              => $handler->id,
  47                 'handlerfile'     => $handler->handlerfile,
  48                 'handlerfunction' => $handler->handlerfunction,
  49                 'schedule'        => $handler->schedule,
  50                 'internal'        => $handler->internal);
  51         }
  52     }
  53
  54     return $cachedhandlers;
  55 }
  56
  57 /**
  58  * Remove all event handlers and queued events
  59  *
  60  * @category event
  61  * @param string $component examples: 'moodle', 'mod_forum', 'block_quiz_results'
  62  */
  63 function events_uninstall($component) {
  64     $cachedhandlers = events_get_cached($component);
  65     events_cleanup($component, $cachedhandlers);
  66
  67     events_get_handlers('reset');
  68 }
  69
  70 /**
  71  * Deletes cached events that are no longer needed by the component.
  72  *
  73  * @access protected To be used from eventslib only
  74  *
  75  * @param string $component examples: 'moodle', 'mod_forum', 'block_quiz_results'
  76  * @param array $cachedhandlers array of the cached events definitions that will be
  77  * @return int number of unused handlers that have been removed
  78  */
  79 function events_cleanup($component, $cachedhandlers) {
  80     global $DB;
  81
  82     $deletecount = 0;
  83     foreach ($cachedhandlers as $eventname => $cachedhandler) {
  84         if ($qhandlers = $DB->get_records('events_queue_handlers', array('handlerid'=>$cachedhandler['id']))) {
  85             //debugging("Removing pending events from queue before deleting of event handler: $component - $eventname");
  86             foreach ($qhandlers as $qhandler) {
  87                 events_dequeue($qhandler);
  88             }
  89         }
  90         $DB->delete_records('events_handlers', array('eventname'=>$eventname, 'component'=>$component));
  91         $deletecount++;
  92     }
  93
  94     return $deletecount;
  95 }
  96
  97 /**
  98  * Removes this queued handler from the events_queued_handler table
  99  *
 100  * Removes events_queue record from events_queue if no more references to this event object exists
 101  *
 102  * @access protected To be used from eventslib only
 103  *
 104  * @param stdClass $qhandler A row from the events_queued_handler table
 105  */
 106 function events_dequeue($qhandler) {
 107     global $DB;
 108
 109     // first delete the queue handler
 110     $DB->delete_records('events_queue_handlers', array('id'=>$qhandler->id));
 111
 112     // if no more queued handler is pointing to the same event - delete the event too
 113     if (!$DB->record_exists('events_queue_handlers', array('queuedeventid'=>$qhandler->queuedeventid))) {
 114         $DB->delete_records('events_queue', array('id'=>$qhandler->queuedeventid));
 115     }
 116 }
 117
 118 /**
 119  * Returns handlers for given event. Uses caching for better perf.
 120  *
 121  * @access protected To be used from eventslib only
 122  *
 123  * @staticvar array $handlers
 124  * @param string $eventname name of event or 'reset'
 125  * @return array|false array of handlers or false otherwise
 126  */
 127 function events_get_handlers($eventname) {
 128     global $DB;
 129     static $handlers = array();
 130
 131     if ($eventname === 'reset') {
 132         $handlers = array();
 133         return false;
 134     }
 135
 136     if (!array_key_exists($eventname, $handlers)) {
 137         $handlers[$eventname] = $DB->get_records('events_handlers', array('eventname'=>$eventname));
 138     }
 139
 140     return $handlers[$eventname];
 141 }