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<?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/>.
namespace cachestore_redis\task;
/**
* Task deletes old data from Redis caches with TTL set.
*
* @package cachestore_redis
* @copyright 2021 The Open University
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
class ttl extends \core\task\scheduled_task {
/** @var int Only display memory savings of at least 100 KB */
const MIN_MEMORY_SIZE = 100 * 1024;
/**
* Gets the name of this task.
*
* @return string Task name
*/
public function get_name(): string {
return get_string('task_ttl', 'cachestore_redis');
}
/**
* Executes the scheduled task.
*/
public function execute(): void {
// Find all Redis cache stores.
$factory = \cache_factory::instance();
$config = $factory->create_config_instance();
$stores = $config->get_all_stores();
$doneanything = false;
foreach ($stores as $storename => $storeconfig) {
if ($storeconfig['plugin'] !== 'redis') {
continue;
}
// For each definition in the cache store, do TTL expiry if needed.
$definitions = $config->get_definitions_by_store($storename);
foreach ($definitions as $definition) {
if (empty($definition['ttl'])) {
continue;
}
if (!empty($definition['requireidentifiers'])) {
// We can't make cache below if it requires identifiers.
continue;
}
$doneanything = true;
$definitionname = $definition['component'] . '/' . $definition['area'];
mtrace($definitionname, ': ');
\cache::make($definition['component'], $definition['area']);
$definition = $factory->create_definition($definition['component'], $definition['area']);
$stores = $factory->get_store_instances_in_use($definition);
foreach ($stores as $store) {
// These were all definitions using a Redis store but one definition may
// potentially have multiple stores, we need to process the Redis ones only.
if (!($store instanceof \cachestore_redis)) {
continue;
}
$info = $store->expire_ttl();
$infotext = 'Deleted ' . $info['keys'] . ' key(s) in ' .
sprintf('%0.2f', $info['time']) . 's';
// Only report memory information if available, positive, and reasonably large.
// Otherwise the real information is hard to see amongst random variation etc.
if (!empty($info['memory']) && $info['memory'] > self::MIN_MEMORY_SIZE) {
$infotext .= ' - reported saving ' . display_size($info['memory']);
}
mtrace($infotext);
}
}
}
if (!$doneanything) {
mtrace('No TTL caches assigned to a Redis store; nothing to do.');
}
}
/**
* Checks if this task is allowed to run - this makes it show the 'Run now' link (or not).
*
* @return bool True if task can run
*/
public function can_run(): bool {
// The default implementation of this function checks the plugin is enabled, which doesn't
// seem to work (probably because cachestore plugins can't be enabled).
// We could check if there is a Redis store configured, but it would have to do the exact
// same logic as already in the first part of 'execute', so it's probably OK to just return
// true.
return true;
}
}