/**
* Check if a cache response satisfies a request's caching constraints
*
* @param RequestInterface $request Request to validate
* @param Response $response Response to validate
*
* @return bool
*/
public function canResponseSatisfyRequest(RequestInterface $request, Response $response)
{
$responseAge = $response->getAge();
// Check the request's max-age header against the age of the response
if ($request->hasCacheControlDirective('max-age') && $responseAge > $request->getCacheControlDirective('max-age')) {
return false;
}
// Check the response's max-age header
if ($response->isFresh() === false) {
$maxStale = $request->getCacheControlDirective('max-stale');
if (null !== $maxStale) {
if ($maxStale !== true && $response->getFreshness() < -1 * $maxStale) {
return false;
}
} elseif ($response->hasCacheControlDirective('max-age') && $responseAge > $response->getCacheControlDirective('max-age')) {
return false;
}
}
// Only revalidate GET requests
if ($request->getMethod() == RequestInterface::GET) {
// Check if the response must be validated against the origin server
if ($request->getHeader('Pragma') == 'no-cache' || $request->hasCacheControlDirective('no-cache') || $request->hasCacheControlDirective('must-revalidate') || $response->hasCacheControlDirective('must-revalidate') || $response->hasCacheControlDirective('no-cache')) {
// no-cache: When no parameters are present, always revalidate
// When parameters are present in no-cache and the request includes those same parameters, then the
// response must re-validate. I'll need an example of what fields look like in order to implement a
// smarter version of no-cache
// Requests can decline to revalidate against the origin server by setting the cache.revalidate param:
// - never - To never revalidate and always contact the origin server
// - skip - To skip revalidation and just use what is in cache
switch ($request->getParams()->get('cache.revalidate')) {
case 'never':
return false;
case 'skip':
return true;
default:
return $this->revalidation->revalidate($request, $response);
}
}
}
return true;
}
