Same name in other branches

1. 9 core/modules/page_cache/src/StackMiddleware/PageCache.php \Drupal\page_cache\StackMiddleware\PageCache::lookup()
2. 8.9.x core/modules/page_cache/src/StackMiddleware/PageCache.php \Drupal\page_cache\StackMiddleware\PageCache::lookup()
3. 10 core/modules/page_cache/src/StackMiddleware/PageCache.php \Drupal\page_cache\StackMiddleware\PageCache::lookup()

Retrieves a response from the cache or fetches it from the backend.

Parameters

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

int $type: The type of the request (one of HttpKernelInterface::MAIN_REQUEST or HttpKernelInterface::SUB_REQUEST)

bool $catch: Whether to catch exceptions or not

Return value

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

1 call to PageCache::lookup()

PageCache::handle in core/modules/page_cache/src/StackMiddleware/PageCache.php

File

core/modules/page_cache/src/StackMiddleware/PageCache.php, line 123

Class

PageCache

Executes the page caching before the main kernel takes over the request.

Namespace

Drupal\page_cache\StackMiddleware

Code

protected function lookup(Request $request, $type = self::MAIN_REQUEST, $catch = TRUE) {
    if ($response = $this->get($request)) {
        $response->headers
            ->set('X-Drupal-Cache', 'HIT');
    }
    else {
        $response = $this->fetch($request, $type, $catch);
    }
    // Only allow caching in the browser and prevent that the response is stored
    // by an external proxy server when the following conditions apply:
    // 1. There is a session cookie on the request.
    // 2. The Vary: Cookie header is on the response.
    // 3. The Cache-Control header does not contain the no-cache directive.
    if ($request->cookies
        ->has(session_name()) && in_array('Cookie', $response->getVary()) && !$response->headers
        ->hasCacheControlDirective('no-cache')) {
        $response->setPrivate();
    }
    // Perform HTTP revalidation.
    // @todo Use Response::isNotModified() as
    //   per https://www.drupal.org/node/2259489.
    $last_modified = $response->getLastModified();
    if ($last_modified) {
        // See if the client has provided the required HTTP headers.
        $if_modified_since = $request->server
            ->has('HTTP_IF_MODIFIED_SINCE') ? strtotime($request->server
            ->get('HTTP_IF_MODIFIED_SINCE')) : FALSE;
        $if_none_match = $request->server
            ->has('HTTP_IF_NONE_MATCH') ? stripslashes($request->server
            ->get('HTTP_IF_NONE_MATCH')) : FALSE;
        if ($if_modified_since && $if_none_match && $if_none_match == $response->getEtag() && $if_modified_since == $last_modified->getTimestamp()) {
            $response->setStatusCode(304);
            $response->setContent(NULL);
            // In the case of a 304 response, certain headers must be sent, and the
            // remaining may not (see RFC 2616, section 10.3.5).
            foreach (array_keys($response->headers
                ->all()) as $name) {
                if (!in_array($name, [
                    'content-location',
                    'expires',
                    'cache-control',
                    'vary',
                ])) {
                    $response->headers
                        ->remove($name);
                }
            }
        }
    }
    return $response;
}

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