mirror of
https://github.com/moodle/moodle.git
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484 lines
17 KiB
PHP
Executable File
484 lines
17 KiB
PHP
Executable File
<?php
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/**
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* Library of functions for events manipulation.
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*
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* @author Martin Dougiamas and many others
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* @version $Id$
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* @license http://www.gnu.org/copyleft/gpl.html GNU Public License
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* @package moodlecore
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*/
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/**
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* Loads the events definitions for the component (from file). If no
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* events are defined for the component, we simply return an empty array.
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* @param $component - examples: 'moodle', 'mod/forum', 'block/quiz_results'
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* @return array of capabilities or empty array if not exists
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*
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* INTERNAL - to be used from eventslib only
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*/
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function events_load_def($component) {
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global $CFG;
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if ($component == 'moodle') {
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$defpath = $CFG->libdir.'/db/events.php';
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} else if ($component == 'unittest') {
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$defpath = $CFG->libdir.'/simpletest/fixtures/events.php';
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} else {
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$compparts = explode('/', $component);
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if ($compparts[0] == 'block') {
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// Blocks are an exception. Blocks directory is 'blocks', and not
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// 'block'. So we need to jump through hoops.
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$defpath = $CFG->dirroot.'/blocks/'.$compparts[1].'/db/events.php';
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} else if ($compparts[0] == 'format') {
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// Similar to the above, course formats are 'format' while they
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// are stored in 'course/format'.
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$defpath = $CFG->dirroot.'/course/format/'.$compparts[1].'/db/events.php';
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} else if ($compparts[0] == 'gradeimport') {
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$defpath = $CFG->dirroot.'/grade/import/'.$compparts[1].'/db/events.php';
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} else if ($compparts[0] == 'gradeexport') {
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$defpath = $CFG->dirroot.'/grade/export/'.$compparts[1].'/db/events.php';
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} else if ($compparts[0] == 'gradereport') {
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$defpath = $CFG->dirroot.'/grade/report/'.$compparts[1].'/db/events.php';
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} else {
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$defpath = $CFG->dirroot.'/'.$component.'/db/events.php';
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}
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}
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$handlers = array();
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if (file_exists($defpath)) {
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require($defpath);
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}
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return $handlers;
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}
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/**
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* Gets the capabilities that have been cached in the database for this
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* component.
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* @param $component - examples: 'moodle', 'mod/forum', 'block/quiz_results'
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* @return array of events
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*
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* INTERNAL - to be used from eventslib only
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*/
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function events_get_cached($component) {
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$cachedhandlers = array();
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if ($storedhandlers = get_records('events_handlers', 'handlermodule', $component)) {
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foreach ($storedhandlers as $handler) {
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$cachedhandlers[$handler->eventname] = array (
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'id' => $handler->id,
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'handlerfile' => $handler->handlerfile,
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'handlerfunction' => $handler->handlerfunction,
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'schedule' => $handler->schedule);
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}
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}
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return $cachedhandlers;
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}
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/**
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* We can not removed all event handlers in table, then add them again
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* because event handlers could be referenced by queued items
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*
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* Note that the absence of the db/events.php event definition file
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* will cause any queued events for the component to be removed from
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* the database.
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*
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* @param $component - examples: 'moodle', 'mod/forum', 'block/quiz_results'
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* @return boolean
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*/
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function events_update_definition($component='moodle') {
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// load event definition from events.php
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$filehandlers = events_load_def($component);
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// load event definitions from db tables
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// if we detect an event being already stored, we discard from this array later
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// the remaining needs to be removed
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$cachedhandlers = events_get_cached($component);
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foreach ($filehandlers as $eventname => $filehandler) {
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if (!empty($cachedhandlers[$eventname])) {
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if ($cachedhandlers[$eventname]['handlerfile'] == $filehandler['handlerfile'] &&
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$cachedhandlers[$eventname]['handlerfunction'] == serialize($filehandler['handlerfunction']) &&
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$cachedhandlers[$eventname]['schedule'] == $filehandler['schedule']) {
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// exact same event handler already present in db, ignore this entry
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unset($cachedhandlers[$eventname]);
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continue;
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} else {
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// same event name matches, this event has been updated, update the datebase
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$handler = new object();
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$handler->id = $cachedhandlers[$eventname]['id'];
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$handler->handlerfile = $filehandler['handlerfile'];
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$handler->handlerfunction = serialize($filehandler['handlerfunction']); // static class methods stored as array
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$handler->schedule = $filehandler['schedule'];
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update_record('events_handlers', $handler);
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unset($cachedhandlers[$eventname]);
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continue;
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}
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} else {
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// if we are here, this event handler is not present in db (new)
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// add it
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$handler = new object();
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$handler->eventname = $eventname;
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$handler->handlermodule = $component;
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$handler->handlerfile = $filehandler['handlerfile'];
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$handler->handlerfunction = serialize($filehandler['handlerfunction']); // static class methods stored as array
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$handler->schedule = $filehandler['schedule'];
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insert_record('events_handlers', $handler);
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}
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}
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// clean up the left overs, the entries in cachedevents array at this points are deprecated event handlers
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// and should be removed, delete from db
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events_cleanup($component, $cachedhandlers);
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return true;
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}
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/**
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* Remove all event handlers and queued events
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* @param $component - examples: 'moodle', 'mod/forum', 'block/quiz_results'
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*/
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function events_uninstall($component) {
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$cachedhandlers = events_get_cached($component);
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events_cleanup($component, $cachedhandlers);
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}
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/**
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* Deletes cached events that are no longer needed by the component.
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* @param $component - examples: 'moodle', 'mod/forum', 'block/quiz_results'
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* @param $chachedevents - array of the cached events definitions that will be
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* @return int - number of deprecated capabilities that have been removed
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*
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* INTERNAL - to be used from eventslib only
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*/
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function events_cleanup($component, $cachedhandlers) {
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$deletecount = 0;
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foreach ($cachedhandlers as $eventname => $cachedhandler) {
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if ($qhandlers = get_records('events_queue_handlers', 'handlerid', $cachedhandler['id'])) {
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debugging("Removing pending events from queue before deleting of event handler: $component - $eventname");
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foreach ($qhandlers as $qhandler) {
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events_dequeue($qhandler);
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}
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}
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if (delete_records('events_handlers', 'eventname', $eventname, 'handlermodule', $component)) {
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$deletecount++;
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}
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}
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return $deletecount;
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}
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/****************** End of Events handler Definition code *******************/
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/**
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* puts a handler on queue
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* @param object handler - event handler object from db
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* @param object eventdata - event data object
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* @return id number of new queue handler
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*
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* INTERNAL - to be used from eventslib only
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*/
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function events_queue_handler($handler, $event, $errormessage) {
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if ($qhandler = get_record('events_queue_handlers', 'queuedeventid', $event->id, 'handlerid', $handler->id)) {
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debugging("Please check code: Event id $event->id is already queued in handler id $qhandler->id");
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return $qhandler->id;
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}
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// make a new queue handler
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$qhandler = new object();
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$qhandler->queuedeventid = $event->id;
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$qhandler->handlerid = $handler->id;
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$qhandler->errormessage = addslashes($errormessage);
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$qhandler->timemodified = time();
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if ($handler->schedule == 'instant' and $handler->status == 1) {
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$qhandler->status = 1; //already one failed attempt to dispatch this event
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} else {
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$qhandler->status = 0;
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}
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return insert_record('events_queue_handlers', $qhandler);
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}
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/**
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* trigger a single event with a specified handler
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* @param handler - hander object from db
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* @param eventdata - event dataobject
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* @param errormessage - error message indicating problem
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* @return bool - success or fail
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*
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* INTERNAL - to be used from eventslib only
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*/
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function events_dispatch($handler, $eventdata, &$errormessage) {
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global $CFG;
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$function = unserialize($handler->handlerfunction);
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if (is_callable($function)) {
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// oki, no need for includes
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} else if (file_exists($CFG->dirroot.$handler->handlerfile)) {
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include_once($CFG->dirroot.$handler->handlerfile);
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} else {
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$errormessage = "Handler file of component $handler->handlermodule: $handler->handlerfile can not be found!";
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return false;
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}
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// checks for handler validity
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if (is_callable($function)) {
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return call_user_func($function, $eventdata);
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} else {
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$errormessage = "Handler function of component $handler->handlermodule: $handler->handlerfunction not callable function or class method!";
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return false;
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}
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}
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/**
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* given a queued handler, call the respective event handler to process the event
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* @param object qhandler - events_queued_handler object from db
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* @return boolean meaning success, or NULL on fatal failure
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*
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* INTERNAL - to be used from eventslib only
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*/
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function events_process_queued_handler($qhandler) {
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global $CFG;
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// get handler
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if (!$handler = get_record('events_handlers', 'id', $qhandler->handlerid)) {
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debugging("Error processing queue handler $qhandler->id, missing handler id: $qhandler->handlerid");
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//irrecoverable error, remove broken queue handler
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events_dequeue($qhandler);
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return NULL;
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}
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// get event object
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if (!$event = get_record('events_queue', 'id', $qhandler->queuedeventid)) {
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// can't proceed with no event object - might happen when two crons running at the same time
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debugging("Error processing queue handler $qhandler->id, missing event id: $qhandler->queuedeventid");
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//irrecoverable error, remove broken queue handler
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events_dequeue($qhandler);
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return NULL;
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}
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// call the function specified by the handler
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$errormessage = 'Unknown error';
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if (events_dispatch($handler, unserialize($event->eventdata), $errormessage)) {
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//everything ok
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events_dequeue($qhandler);
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return true;
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} else {
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//dispatching failed
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$qh = new object();
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$qh->id = $qhandler->id;
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$qh->errormessage = addslashes($errormessage);
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$qh->timemodified = time();
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$qh->status = $qhandler->status + 1;
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update_record('events_queue_handlers', $qh);
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return false;
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}
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}
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/**
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* removes this queued handler from the events_queued_handler table
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* removes events_queue record from events_queue if no more references to this event object exists
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* @param object qhandler - events_queued_handler object from db
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*
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* INTERNAL - to be used from eventslib only
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*/
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function events_dequeue($qhandler) {
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// first delete the queue handler
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delete_records('events_queue_handlers', 'id', $qhandler->id);
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// if no more queued handler is pointing to the same event - delete the event too
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if (!record_exists('events_queue_handlers', 'queuedeventid', $qhandler->queuedeventid)) {
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delete_records('events_queue', 'id', $qhandler->queuedeventid);
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}
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}
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/****** Public events API starts here, do not use functions above in 3rd party code ******/
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/**
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* Events cron will try to empty the events queue by processing all the queued events handlers
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* @param string eventname - empty means all
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* @return number of dispatched+removed broken events
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*
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* PUBLIC
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*/
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function events_cron($eventname='') {
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global $CFG;
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$failed = array();
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$processed = 0;
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if ($eventname) {
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$sql = "SELECT qh.* FROM {$CFG->prefix}events_queue_handlers qh, {$CFG->prefix}events_handlers h
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WHERE qh.handlerid = h.id AND h.eventname='$eventname'
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ORDER BY qh.id";
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} else {
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$sql = "SELECT * FROM {$CFG->prefix}events_queue_handlers
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ORDER BY id";
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}
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if ($rs = get_recordset_sql($sql)) {
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if ($rs->RecordCount() > 0) {
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while ($qhandler = rs_fetch_next_record($rs)) {
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if (in_array($qhandler->handlerid, $failed)) {
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// do not try to dispatch any later events when one already failed
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continue;
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}
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$status = events_process_queued_handler($qhandler);
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if ($status === false) {
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$failed[] = $qhandler->handlerid;
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} else {
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$processed++;
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}
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}
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}
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rs_close($rs);
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}
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return $processed;
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}
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/**
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* Function to call all eventhandlers when triggering an event
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* @param eventname - name of the event
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* @param eventdata - event data object
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* @return number of failed events
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*
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* PUBLIC
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*/
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function events_trigger($eventname, $eventdata) {
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global $CFG, $USER;
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$failedcount = 0; // number of failed events.
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$event = false;
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// pull out all registered event handlers
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if ($handlers = get_records('events_handlers', 'eventname', $eventname)) {
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foreach ($handlers as $handler) {
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$errormessage = '';
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if ($handler->schedule == 'instant') {
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if ($handler->status) {
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//check if previous pending events processed
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if (!record_exists('events_queue_handlers', 'handlerid', $handler->id)) {
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// ok, queue is empty, lets reset the status back to 0 == ok
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$handler->status = 0;
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set_field('events_handlers', 'status', 0, 'id', $handler->id);
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}
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}
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// dispatch the event only if instant schedule and status ok
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if (!$handler->status) {
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$errormessage = 'Unknown error';;
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if (events_dispatch($handler, $eventdata, $errormessage)) {
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continue;
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}
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// set error count to 1 == send next instant into cron queue
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set_field('events_handlers', 'status', 1, 'id', $handler->id);
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} else {
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// increment the error status counter
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$handler->status++;
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set_field('events_handlers', 'status', $handler->status, 'id', $handler->id);
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}
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// update the failed counter
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$failedcount ++;
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} else if ($handler->schedule == 'cron') {
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//ok - use queuing of events only
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} else {
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// unknown schedule - fallback to cron type
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debugging("Unknown handler schedule type: $handler->schedule");
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}
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// if even type is not instant, or dispatch failed, queue it
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if ($event === false) {
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$event = new object();
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$event->userid = $USER->id;
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$event->eventdata = serialize($eventdata);
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$event->timecreated = time();
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if (debugging()) {
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$dump = '';
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$callers = debug_backtrace();
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foreach ($callers as $caller) {
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$dump .= 'line ' . $caller['line'] . ' of ' . substr($caller['file'], strlen($CFG->dirroot) + 1);
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if (isset($caller['function'])) {
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$dump .= ': call to ';
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if (isset($caller['class'])) {
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$dump .= $caller['class'] . $caller['type'];
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}
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$dump .= $caller['function'] . '()';
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}
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$dump .= "\n";
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}
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$event->stackdump = addslashes($dump);
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} else {
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$event->stackdump = '';
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}
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$event->id = insert_record('events_queue', $event);
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}
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events_queue_handler($handler, $event, $errormessage);
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}
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} else {
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//debugging("No handler found for event: $eventname");
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}
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return $failedcount;
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}
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/**
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* checks if an event is registered for this component
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* @param string eventname - name of the event
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* @param string component - component name, can be mod/data or moodle
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* @return bool
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*
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* PUBLIC
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*/
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function events_is_registered($eventname, $component) {
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return record_exists('events_handlers', 'handlermodule', $component, 'eventname', $eventname);
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}
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/**
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* checks if an event is queued for processing - either cron handlers attached or failed instant handlers
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* @param string eventname - name of the event
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* @return int number of queued events
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*
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* PUBLIC
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*/
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function events_pending_count($eventname) {
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global $CFG;
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$sql = "SELECT COUNT(*) FROM {$CFG->prefix}events_queue_handlers qh, {$CFG->prefix}events_handlers h
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WHERE qh.handlerid = h.id AND h.eventname='$eventname'";
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return count_records_sql($sql);
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}
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?>
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