diff --git a/admin/tool/monitor/classes/task/clean_events.php b/admin/tool/monitor/classes/task/clean_events.php
new file mode 100644
index 00000000000..9efb360e898
--- /dev/null
+++ b/admin/tool/monitor/classes/task/clean_events.php
@@ -0,0 +1,142 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle. If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * Clean the tool_monitor_events table.
+ *
+ * @package tool_monitor
+ * @copyright 2014 Mark Nelson <markn@moodle.com>
+ * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace tool_monitor\task;
+
+/**
+ * Simple task to clean the tool_monitor_events table.
+ */
+class clean_events extends \core\task\scheduled_task {
+
+ /**
+ * Get a descriptive name for this task.
+ *
+ * @return string
+ */
+ public function get_name() {
+ return get_string('taskcleanevents', 'tool_monitor');
+ }
+
+ /**
+ * Performs the cleaning of events.
+ */
+ public function execute() {
+ global $DB;
+
+ // Array to store which events have been triggered in which course.
+ $courses = array();
+
+ // Firstly, let's go through the site wide rules. There may be multiple rules for the site that rely on
+ // the same event being triggered, so we only remove the events when they reach the max timewindow.
+ if ($siterules = $DB->get_recordset('tool_monitor_rules', array('courseid' => 0), 'timewindow DESC')) {
+ // Go through each rule and check if there are any events we can remove.
+ foreach ($siterules as $rule) {
+ // Check if we have already processed this event.
+ if (isset($courses[$rule->courseid][$rule->eventname])) {
+ continue;
+ }
+ // Store the timewindow for this event.
+ $courses[$rule->courseid][$rule->eventname] = $rule->timewindow;
+ // Delete any events that may exist that have exceeded the timewindow.
+ $DB->delete_records_select('tool_monitor_events', 'eventname = :eventname AND
+ courseid = :courseid AND timecreated <= :timewindow',
+ array('eventname' => $rule->eventname, 'courseid' => $rule->courseid,
+ 'timewindow' => time() - $rule->timewindow));
+ }
+ // Free resources.
+ $siterules->close();
+ }
+
+ // Now, get the course rules. The same applies here - there may be multiple rules for the course that rely on
+ // the same event being triggered, so we only remove the events when they reach the max timewindow.
+ if ($rules = $DB->get_recordset_select('tool_monitor_rules', 'courseid != 0', array(), 'timewindow DESC')) {
+ // Go through each rule and check if there are any events we can remove.
+ foreach ($rules as $rule) {
+ // Check if we have already processed this event for this particular course.
+ if (isset($courses[$rule->courseid][$rule->eventname])) {
+ continue;
+ }
+ // Add the course and event to the list.
+ $courses[$rule->courseid][$rule->eventname] = $rule->timewindow;
+ // If there is a site wide rule listening for this event do not remove it unless the maximum
+ // timewindow between the two has exceeded.
+ $timewindow = $rule->timewindow;
+ if (isset($courses[0][$rule->eventname]) && ($courses[0][$rule->eventname] > $timewindow)) {
+ $timewindow = $courses[0][$rule->eventname];
+ }
+ // Delete any events that may exist that have exceeded the timewindow.
+ $DB->delete_records_select('tool_monitor_events', 'eventname = :eventname AND
+ courseid = :courseid AND timecreated <= :timewindow',
+ array('eventname' => $rule->eventname, 'courseid' => $rule->courseid,
+ 'timewindow' => time() - $timewindow));
+ }
+ // Free resources.
+ $rules->close();
+ }
+
+ if ($siterules || $rules) { // Check that there are rules present.
+ // Get a list of all the events we have been through.
+ $allevents = array();
+ foreach ($courses as $key => $value) {
+ foreach ($courses[$key] as $event => $notused) {
+ $allevents[] = $event;
+ }
+ }
+ // Remove all the events in the table that are not applicable to any rule. There may be a rule in one course
+ // listening for a certain event, but not in another course, so we can delete the event from the course
+ // where there is no rule. We also have to consider site wide rules. We may have an event that is triggered
+ // in a course we can't remove because there is a site wide rule for this event.
+ if ($events = $DB->get_recordset('tool_monitor_events')) {
+ // Array to store which events we need to remove.
+ $eventstodelete = array();
+ // Store the current time.
+ $now = time();
+ foreach ($events as $event) {
+ // If the event is not required for a course rule and there is no site wide rule for it, or
+ // it has extended past or equal to the timewindow for the site rule - it can be deleted.
+ if (!isset($courses[$event->courseid][$event->eventname]) && (!isset($courses[0][$event->eventname])
+ || $courses[0][$event->eventname] <= ($now - $event->timecreated))) {
+ $eventstodelete[] = $event->id;
+ }
+ }
+ // Free resources.
+ $events->close();
+
+ // Remove the events.
+ if (!empty($eventstodelete)) {
+ list($eventidsql, $params) = $DB->get_in_or_equal($eventstodelete);
+ $DB->delete_records_select('tool_monitor_events', "id $eventidsql", $params);
+ }
+ }
+
+ // Remove all the events in the table that are not used by any rule.
+ if (!empty($allevents)) {
+ list($eventnamesql, $params) = $DB->get_in_or_equal($allevents, SQL_PARAMS_QM, 'param', false);
+ $DB->delete_records_select('tool_monitor_events', "eventname $eventnamesql", $params);
+ }
+ } else { // No rules, just remove everything.
+ $DB->delete_records('tool_monitor_events');
+ }
+ }
+}
diff --git a/admin/tool/monitor/db/tasks.php b/admin/tool/monitor/db/tasks.php
new file mode 100644
index 00000000000..e70c3448110
--- /dev/null
+++ b/admin/tool/monitor/db/tasks.php
@@ -0,0 +1,36 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle. If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * This file defines tasks performed by the tool.
+ *
+ * @package tool_monitor
+ * @copyright 2014 Mark Nelson <markn@moodle.com>
+ * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+// List of tasks.
+$tasks = array(
+ array(
+ 'classname' => 'tool_monitor\task\clean_events',
+ 'blocking' => 0,
+ 'minute' => '*',
+ 'hour' => '*',
+ 'day' => '*',
+ 'dayofweek' => '*',
+ 'month' => '*'
+ )
+);
diff --git a/admin/tool/monitor/lang/en/tool_monitor.php b/admin/tool/monitor/lang/en/tool_monitor.php
index bfac7998977..0d39eeb6e6f 100644
--- a/admin/tool/monitor/lang/en/tool_monitor.php
+++ b/admin/tool/monitor/lang/en/tool_monitor.php
@@ -84,6 +84,7 @@ $string['subcreatesuccess'] = "Subscription successfully created";
$string['subdeletesuccess'] = "Subscription successfully removed";
$string['subhelp'] = 'Subscription details';
$string['subhelp_help'] = 'This subscription listens for when the event \'{$a->eventname}\' has been triggered in \'{$a->moduleinstance}\' {$a->frequency} time(s) in {$a->minutes} minute(s).';
+$string['taskcleanevents'] = 'Removes any unnecessary event monitor events';
$string['title'] = '{$a->coursename} : {$a->reportname}';
$string['monitor:managerules'] = 'Manage event monitor rules';
$string['monitor:subscribe'] = 'Subscribe to event monitor rules';