public static function check_cache(Request $request, Response $response, $etag = NULL)
{
if ($etag == NULL) {
$etag = $response->generate_etag();
}
$response->headers("etag", $etag);
if ($response->headers("cache-control")) {
$response->headers("cache-control", $response->headers("cache-control") . ", must-revalidate");
} else {
$response->headers("cache-control", "must-revalidate");
}
if ($request->headers("if-none-match") and (string) $request->headers("if-none-match") === $etag) {
throw HTTP_Exception::factory(304)->headers("etag", $etag);
}
return $response;
}
/**
* Checks the browser cache to see the response needs to be returned,
* execution will halt and a 304 Not Modified will be sent if the
* browser cache is up to date.
*
* @param Request $request Request
* @param Response $response Response
* @param string $etag Resource ETag
* @throws HTTP_Exception_304
* @return Response
*/
public static function check_cache(Request $request, Response $response, $etag = NULL)
{
// Generate an etag if necessary
if ($etag == NULL) {
$etag = $response->generate_etag();
}
// Set the ETag header
$response->headers('etag', $etag);
// Add the Cache-Control header if it is not already set
// This allows etags to be used with max-age, etc
if ($response->headers('cache-control')) {
$response->headers('cache-control', $response->headers('cache-control') . ', must-revalidate');
} else {
$response->headers('cache-control', 'must-revalidate');
}
// Check if we have a matching etag
if ($request->headers('if-none-match') and (string) $request->headers('if-none-match') === $etag) {
// No need to send data again
throw HTTP_Exception::factory(304)->headers('etag', $etag);
}
return $response;
}
