Adds cache metadata information as headers in the response.

If a header exceeds the maximum response header length, the data will be split across multiple header lines with the same header name. By default, Apache uses the header merge strategy that merges and glues all the lines into one with ', ' separating them. Nginx will send separate headers lines with the same name.

Parameters

string $header: The response header name.

list<string> $values: The list of either cache tags or contexts.

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

File

core/lib/Drupal/Core/EventSubscriber/FinishResponseSubscriber.php, line 318

Class

FinishResponseSubscriber

Response subscriber to handle finished responses.

Namespace

Drupal\Core\EventSubscriber

Code

protected function addDebugCacheHeaders(string $header, array $values, Response $response) : void {
  sort($values);
  $values_as_string = implode(static::RESPONSE_HEADER_CACHE_ITEM_SEPARATOR, $values);
  $headers = explode("\n", wordwrap($values_as_string, static::RESPONSE_HEADER_LINE_MAX_LENGTH));
  $response->headers
    ->set($header, $headers);
}

---