AutomatedCron.php

<?php

namespace Drupal\automated_cron\EventSubscriber;

use Drupal\Core\Config\ConfigFactoryInterface;
use Drupal\Core\CronInterface;
use Drupal\Core\State\StateInterface;
use Symfony\Component\EventDispatcher\EventSubscriberInterface;
use Symfony\Component\HttpKernel\Event\TerminateEvent;
use Symfony\Component\HttpKernel\KernelEvents;

/**
 * A subscriber running cron after a response is sent.
 */
class AutomatedCron implements EventSubscriberInterface {
    
    /**
     * The cron service.
     *
     * @var \Drupal\Core\CronInterface
     */
    protected $cron;
    
    /**
     * The cron configuration.
     *
     * @var \Drupal\Core\Config\Config
     */
    protected $config;
    
    /**
     * The state key value store.
     *
     * @var \Drupal\Core\State\StateInterface
     */
    protected $state;
    
    /**
     * Constructs a new automated cron runner.
     *
     * @param \Drupal\Core\CronInterface $cron
     *   The cron service.
     * @param \Drupal\Core\Config\ConfigFactoryInterface $config_factory
     *   The config factory.
     * @param \Drupal\Core\State\StateInterface $state
     *   The state key-value store service.
     */
    public function __construct(CronInterface $cron, ConfigFactoryInterface $config_factory, StateInterface $state) {
        $this->cron = $cron;
        $this->config = $config_factory->get('automated_cron.settings');
        $this->state = $state;
    }
    
    /**
     * Run the automated cron if enabled.
     *
     * @param \Symfony\Component\HttpKernel\Event\TerminateEvent $event
     *   The Event to process.
     */
    public function onTerminate(TerminateEvent $event) {
        $interval = $this->config
            ->get('interval');
        if ($interval > 0) {
            $cron_next = $this->state
                ->get('system.cron_last', 0) + $interval;
            if ((int) $event->getRequest()->server
                ->get('REQUEST_TIME') > $cron_next) {
                $this->cron
                    ->run();
            }
        }
    }
    
    /**
     * Registers the methods in this class that should be listeners.
     *
     * @return array
     *   An array of event listener definitions.
     */
    public static function getSubscribedEvents() : array {
        return [
            KernelEvents::TERMINATE => [
                [
                    'onTerminate',
                    100,
                ],
            ],
        ];
    }

}