DefaultRequestPolicy.php

<?php

namespace Drupal\Core\PageCache;

use Drupal\Core\PageCache\RequestPolicy\CommandLineOrUnsafeMethod;
use Drupal\Core\PageCache\RequestPolicy\NoSessionOpen;
use Drupal\Core\Session\SessionConfigurationInterface;

/**
 * The default page cache request policy.
 *
 * Delivery of cached pages is denied if either the application is running from
 * the command line or the request was not initiated with a safe method (GET or
 * HEAD). Also caching is only allowed for requests without a session cookie.
 */
class DefaultRequestPolicy extends ChainRequestPolicy {
    
    /**
     * Constructs the default page cache request policy.
     *
     * @param \Drupal\Core\Session\SessionConfigurationInterface $session_configuration
     *   The session configuration.
     */
    public function __construct(SessionConfigurationInterface $session_configuration) {
        $this->addPolicy(new CommandLineOrUnsafeMethod());
        $this->addPolicy(new NoSessionOpen($session_configuration));
    }

}