class CronForm

system.routing.yml in drupal/core/modules/system/system.routing.yml

drupal/core/modules/system/system.routing.yml

class CronForm extends SystemConfigFormBase {

  /**
   * Stores the state storage service.
   *
   * @var \Drupal\Core\KeyValueStore\KeyValueStoreInterface
   */
  protected $state;

  /**
   * Constructs a CronForm object.
   *
   * @param \Drupal\Core\Config\ConfigFactory $config_factory
   *   The factory for configuration objects.
   * @param \Drupal\Core\Config\Context\ContextInterface $context
   *   The configuration context used for this configuration object.
   * @param \Drupal\Core\KeyValueStore\KeyValueStoreInterface $state
   *   The state key value store.
   */
  public function __construct(ConfigFactory $config_factory, ContextInterface $context, KeyValueFactory $key_value_factory) {
    parent::__construct($config_factory, $context);
    $this->state = $key_value_factory
      ->get('state');
  }

  /**
   * {@inheritdoc}
   */
  public static function create(ContainerInterface $container) {
    return new static($container
      ->get('config.factory'), $container
      ->get('config.context.free'), $container
      ->get('keyvalue'));
  }

  /**
   * {@inheritdoc}
   */
  public function getFormID() {
    return 'system_cron_settings';
  }

  /**
   * {@inheritdoc}
   */
  public function buildForm(array $form, array &$form_state) {
    $config = $this->configFactory
      ->get('system.cron');
    $form['description'] = array(
      '#markup' => '<p>' . t('Cron takes care of running periodic tasks like checking for updates and indexing content for search.') . '</p>',
    );
    $form['run'] = array(
      '#type' => 'submit',
      '#value' => t('Run cron'),
      '#submit' => array(
        array(
          $this,
          'submitCron',
        ),
      ),
    );
    $status = '<p>' . t('Last run: %cron-last ago.', array(
      '%cron-last' => format_interval(REQUEST_TIME - $this->state
        ->get('system.cron_last')),
    )) . '</p>';
    $form['status'] = array(
      '#markup' => $status,
    );
    $form['cron_url'] = array(
      '#markup' => '<p>' . t('To run cron from outside the site, go to <a href="!cron">!cron</a>', array(
        '!cron' => url('cron/' . $this->state
          ->get('system.cron_key'), array(
          'absolute' => TRUE,
        )),
      )) . '</p>',
    );
    $form['cron'] = array(
      '#type' => 'details',
    );
    $form['cron']['cron_safe_threshold'] = array(
      '#type' => 'select',
      '#title' => t('Run cron every'),
      '#default_value' => $config
        ->get('threshold.autorun'),
      '#options' => array(
        0 => t('Never'),
      ) + drupal_map_assoc(array(
        3600,
        10800,
        21600,
        43200,
        86400,
        604800,
      ), 'format_interval'),
    );
    return parent::buildForm($form, $form_state);
  }

  /**
   * {@inheritdoc}
   */
  public function submitForm(array &$form, array &$form_state) {
    $this->configFactory
      ->get('system.cron')
      ->set('threshold.autorun', $form_state['values']['cron_safe_threshold'])
      ->save();
    parent::submitForm($form, $form_state);
  }

  /**
   * Runs cron and reloads the page.
   */
  public function submitCron(array &$form, array &$form_state) {

    // Run cron manually from Cron form.
    if (drupal_cron_run()) {
      drupal_set_message(t('Cron run successfully.'));
    }
    else {
      drupal_set_message(t('Cron run failed.'), 'error');
    }
    return new RedirectResponse(url('admin/config/system/cron', array(
      'absolute' => TRUE,
    )));
  }

}