function FinishResponseSubscriber::setResponseCacheable

Add Cache-Control and Expires headers to a cacheable response.

Parameters

\Symfony\Component\HttpFoundation\Response $response: A response object.

\Symfony\Component\HttpFoundation\Request $request: A request object.

File

core/lib/Drupal/Core/EventSubscriber/FinishResponseSubscriber.php, line 249

Class

FinishResponseSubscriber

Response subscriber to handle finished responses.

Namespace

Code

protected function setResponseCacheable(Response $response, Request $request) {
    // HTTP/1.0 proxies do not support the Vary header, so prevent any caching
    // by sending an Expires date in the past. HTTP/1.1 clients ignore the
    // Expires header if a Cache-Control: max-age directive is specified (see
    // RFC 2616, section 14.9.3).
    if (!$response->headers
        ->has('Expires')) {
        $this->setExpiresNoCache($response);
    }
    $max_age = $this->config
        ->get('cache.page.max_age');
    $response->headers
        ->set('Cache-Control', 'public, max-age=' . $max_age);
    // In order to support HTTP cache-revalidation, ensure that there is a
    // Last-Modified and an ETag header on the response.
    if (!$response->headers
        ->has('Last-Modified')) {
        $timestamp = REQUEST_TIME;
        $response->setLastModified(new \DateTime(gmdate(DateTimePlus::RFC7231, REQUEST_TIME)));
    }
    else {
        $timestamp = $response->getLastModified()
            ->getTimestamp();
    }
    $response->setEtag($timestamp);
    // Allow HTTP proxies to cache pages for anonymous users without a session
    // cookie. The Vary header is used to indicates the set of request-header
    // fields that fully determines whether a cache is permitted to use the
    // response to reply to a subsequent request for a given URL without
    // revalidation.
    if (!$response->hasVary() && !Settings::get('omit_vary_cookie')) {
        $response->setVary('Cookie', FALSE);
    }
}