HoldTestSubscriber.php

<?php

namespace Drupal\hold_test\EventSubscriber;

use Symfony\Component\HttpKernel\KernelEvents;
use Symfony\Component\EventDispatcher\EventSubscriberInterface;

/**
 * Response subscriber to test hold.
 */
class HoldTestSubscriber implements EventSubscriberInterface {
    const HOLD_REQUEST = 'request';
    const HOLD_RESPONSE = 'response';
    
    /**
     * Time in microseconds to wait for before checking if the file is updated.
     *
     * @var int
     */
    const WAIT = 100000;
    
    /**
     * The site path.
     *
     * @var string
     */
    protected $sitePath;
    
    /**
     * HoldTestSubscriber constructor.
     *
     * @param string $site_path
     *   The site path.
     */
    public function __construct(string $site_path) {
        $this->sitePath = $site_path;
    }
    
    /**
     * Request hold.
     */
    public function onRequest() {
        $this->hold(static::HOLD_REQUEST);
    }
    
    /**
     * Response hold.
     */
    public function onRespond() {
        $this->hold(static::HOLD_RESPONSE);
    }
    
    /**
     * Hold process by type.
     *
     * @param string $type
     *   Type of hold.
     */
    protected function hold($type) {
        $path = "{$this->sitePath}/hold_test_{$type}.txt";
        while ((bool) file_get_contents($path)) {
            usleep(static::WAIT);
        }
    }
    
    /**
     * {@inheritdoc}
     */
    public static function getSubscribedEvents() : array {
        $events[KernelEvents::REQUEST][] = [
            'onRequest',
        ];
        $events[KernelEvents::RESPONSE][] = [
            'onRespond',
        ];
        return $events;
    }

}