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jayphajaypha
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Issue #224: Add task load metric
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‎classes/local/task_load/task_load_estimator.php‎

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<?php
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// This file is part of Moodle - http://moodle.org/
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//
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// Moodle is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// Moodle is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with Moodle. If not, see <http://www.gnu.org/licenses/>.
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namespace tool_cloudmetrics\local\task_load;
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use core\task\manager as taskmanager;
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/**
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* Base class for task load estimators.
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*
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* @package tool_cloudmetrics
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* @author Jason den Dulk <jasondendulk@catalyst-au.net>
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* @copyright 2026 Catalyst IT
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* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
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*/
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abstract class task_load_estimator {
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/**
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* Returns the object to calculate the task load estimates.
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* Which implementation is used depends on the availability of task statistics feature (MDL-85173).
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*
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* @return task_load_estimator
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*/
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public static function create(): task_load_estimator {
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if (class_exists('\core\task\stat_processor')) {
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return new task_load_from_stats();
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} else {
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return new task_load_from_log();
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}
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}
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/**
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* Generate task load estimates for the near future. The load is taken from the current
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* time determined with a DI clock.
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*
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* @param int $window The number of seconds into the future to look.
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* @return array Returns an array of task load estimates, indexed by classname. Each entry gives the count, total
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* time and average time estimates.
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*/
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abstract public function generate_load_estimates(int $window): array;
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/**
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* Main function for generating the load estimates array.
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*
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* @param array $scheduled
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* @param array $adhoc
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* @param int $start
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* @param int $finish
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* @return array
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*/
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protected function generate_load_estimates_inner(array $scheduled, array $adhoc, int $start, int $finish): array {
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// Loads will contain the estimates.
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$loads = [];
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foreach ($scheduled as $record) {
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$task = taskmanager::scheduled_task_from_record($record);
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$time = $start;
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$count = 0;
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$totalduration = 0;
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// If the task has already started, then we add the remaining time.
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if ($record->timestarted > 0) {
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$started = (int) $record->timestarted;
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$elapsed = max(0, $start - $started);
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$remaining = max(0.0, $record->mean - $elapsed);
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++$count;
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$totalduration += $remaining;
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// We do not want to include this in the loop below. So we get the next scheduled time.
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$time = $task->get_next_scheduled_time($record->timestarted);
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}
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$time = max($time, $record->nextruntime);
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// A scheduled task may run multiple times within the time window, so we add the mean time for each run.
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while ($time < $finish) {
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// If the task is expected to run past the window, then we add the remaining time,
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// otherwise we add the mean.
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++$count;
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if ($time + $record->mean > $finish) {
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$totalduration += ($finish - $time);
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} else {
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$totalduration += $record->mean;
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}
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$time = $task->get_next_scheduled_time($time);
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}
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$classname = taskmanager::get_canonical_class_name($task::class);
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$loads[$classname] = [
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'type' => 'scheduled',
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'classname' => $classname,
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'count' => $count,
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'totalduration' => $totalduration,
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'avgduration' => $totalduration / $count,
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];
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}
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foreach ($adhoc as $record) {
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$classname = taskmanager::get_canonical_class_name($record->classname);
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if (!isset($loads[$classname])) {
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$loads[$classname] = [
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'type' => 'adhoc',
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'classname' => $classname,
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'count' => 0,
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'totalduration' => 0,
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'avgduration' => 0,
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];
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}
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if ($record->timestarted > 0) {
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// Task has already started. Add remaining time.
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$started = (int) $record->timestarted;
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$elapsed = max(0, $start - $started);
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$remaining = max(0.0, $record->mean - $elapsed);
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$loads[$classname]['totalduration'] += $remaining;
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} else if ($record->nextruntime + $record->mean > $finish) {
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// Task will finish after window ends. Add time left in window.
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$loads[$classname]['totalduration'] += ($finish - $record->nextruntime);
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} else {
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// Task will run wholly within the window, so add the full mean.
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$loads[$classname]['totalduration'] += $record->mean;
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}
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++$loads[$classname]['count'];
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$loads[$classname]['avgduration'] = $loads[$classname]['totalduration'] / $loads[$classname]['count'];
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}
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// Order by queue then by estimated_seconds DESC to match the SQL ORDER BY.
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usort($loads, static function ($a, $b) {
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$q = strcmp($a['type'], $b['type']);
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if ($q !== 0) {
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return $q;
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}
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return $b['totalduration'] <=> $a['totalduration'];
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});
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return $loads;
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}
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}

‎classes/local/task_load/task_load_from_log.php‎

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<?php
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// This file is part of Moodle - http://moodle.org/
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//
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// Moodle is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// Moodle is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with Moodle. If not, see <http://www.gnu.org/licenses/>.
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namespace tool_cloudmetrics\local\task_load;
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/**
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* Generates task load estimates from the task log. Useful for versions of Modoel prior to
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* the introduction of task statistics.
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*
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* @package tool_cloudmetrics
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* @author Jason den Dulk <jasondendulk@catalyst-au.net>
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* @copyright 2026 Catalyst IT
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* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
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*/
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class task_load_from_log extends task_load_estimator {
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/**
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* Time cutoff for log aggregation.
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*/
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const AVG_CUTOFF = 7243600; // 83.837 days
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/**
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* Generate task load estimates for the near future. The load is taken from the current
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* time determined with a DI clock.
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*
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* @param int $window The number of seconds into the future to look.
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* @return array Returns an array of task load estimates, indexed by classname. Each entry gives the count, total
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* time and average time estimates.
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*/
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public function generate_load_estimates(int $window): array {
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global $DB;
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$clock = \core\di::get(\core\clock::class);
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$now = $clock->time();
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$finish = $now + $window;
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// Timecutoff for log aggregation (matches original SQL: last 7,243,600 seconds).
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$cutoff = $now - self::AVG_CUTOFF;
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// Per-class average durations from task_log.
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$sql = "SELECT classname, AVG(timeend - timestart) AS avg_duration
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FROM {task_log}
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WHERE timestart >= ?
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GROUP BY classname";
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$avgtimes = $DB->get_records_sql_menu($sql, [$cutoff]);
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// Global average (fallback), defaulting to 10 if no data.
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$globalsql = "SELECT COALESCE(AVG(avg_duration), 10)
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FROM (
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SELECT AVG(timeend - timestart) AS avg_duration
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FROM {task_log}
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WHERE timestart >= ?
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GROUP BY classname
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) AS t";
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$globalavg = (float) $DB->get_field_sql($globalsql, [$cutoff]);
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// Count scheduled tasks in the next $window seconds.
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$scheduled = $DB->get_records_sql(
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"SELECT {task_scheduled}.*
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FROM {task_scheduled}
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WHERE {task_scheduled}.nextruntime < :finish",
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['finish' => $finish, 'globalavg' => $globalavg]
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);
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foreach ($scheduled as $record) {
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$record->mean = (float) ($avgtimes[ltrim($record->classname, '\\')] ?? $globalavg);
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}
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$adhoc = $DB->get_records_sql(
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"SELECT {task_adhoc}.*
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FROM {task_adhoc}
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WHERE {task_adhoc}.nextruntime < :finish",
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['finish' => $finish]
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);
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foreach ($adhoc as $record) {
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$record->mean = (float) ($avgtimes[ltrim($record->classname, '\\')] ?? $globalavg);
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}
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return $this->generate_load_estimates_inner($scheduled, $adhoc, $now, $finish);
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}
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}

‎classes/local/task_load/task_load_from_stats.php‎

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<?php
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// This file is part of Moodle - http://moodle.org/
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//
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// Moodle is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// 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.
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//
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// You should have received a copy of the GNU General Public License
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// along with Moodle. If not, see <http://www.gnu.org/licenses/>.
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namespace tool_cloudmetrics\local\task_load;
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/**
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* Generates task load estimates from the task stats table.
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*
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* @package tool_cloudmetrics
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* @author Jason den Dulk <jasondendulk@catalyst-au.net>
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* @copyright 2026 Catalyst IT
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* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
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*/
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class task_load_from_stats extends task_load_estimator {
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/**
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* Generate task load estimates for the near future. The load is taken from the current
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* time determined with a DI clock.
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*
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* @param int $window The number of seconds into the future to look.
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* @return array Returns an array of task load estimates, indexed by classname. Each entry gives the count, total
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* time and average time estimates.
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*/
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public function generate_load_estimates(int $window): array {
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global $DB;
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$clock = \core\di::get(\core\clock::class);
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$now = $clock->time();
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$finish = $now + $window;
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$sql = "SELECT COALESCE(AVG(mean), 10) AS avg_duration FROM {task_stats};";
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$globalavg = (float)$DB->get_field_sql($sql);
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// Get scheduled tasks, along with averages, that will run before the time window ends.
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$scheduled = $DB->get_records_sql(
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"SELECT {task_scheduled}.*, COALESCE({task_stats}.mean, :globalavg) AS mean
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FROM {task_scheduled}
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RIGHT JOIN {task_stats} ON {task_stats}.classname = {task_scheduled}.classname
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WHERE {task_scheduled}.nextruntime < :finish",
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['finish' => $finish, 'globalavg' => $globalavg]
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);
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// Get adhoc tasks, along with averages, that will run before the time window ends.
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$adhoc = $DB->get_records_sql(
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"SELECT {task_adhoc}.*, COALESCE({task_stats}.mean, :globalavg) AS mean
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FROM {task_adhoc}
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LEFT JOIN {task_stats} ON {task_stats}.classname = {task_adhoc}.classname
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WHERE {task_adhoc}.nextruntime < :finish",
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['finish' => $finish, 'globalavg' => $globalavg]
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);
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return $this->generate_load_estimates_inner($scheduled, $adhoc, $now, $finish);
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}
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}

‎classes/metric/manager.php‎

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@@ -85,6 +85,8 @@ public static function get_frequency_labels(): array {
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'onlineusers' => self::FREQ_5MIN,
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'dailyusers' => self::FREQ_DAY,
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'yearlyactiveusers' => self::FREQ_DAY,
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'currenttaskcount' => self::FREQ_5MIN,
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'estimatedtaskload' => self::FREQ_5MIN,
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];
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/**
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'dailyusers' => new daily_users_metric(),
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'yearlyactiveusers' => new yearly_active_users_metric(),
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'currenttaskcount' => new current_task_count_metric(),
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'estimatedtaskload' => new task_load_metric(),
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];
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if (!empty(PHPUNIT_TEST)) {
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// Add testing metrics to the list.

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