Chris@0: <?php
Chris@0: 
Chris@0: /*
Chris@0:  * This file is part of the Symfony package.
Chris@0:  *
Chris@0:  * (c) Fabien Potencier <fabien@symfony.com>
Chris@0:  *
Chris@0:  * This code is partially based on the Rack-Cache library by Ryan Tomayko,
Chris@0:  * which is released under the MIT license.
Chris@0:  * (based on commit 02d2b48d75bcb63cf1c0c7149c077ad256542801)
Chris@0:  *
Chris@0:  * For the full copyright and license information, please view the LICENSE
Chris@0:  * file that was distributed with this source code.
Chris@0:  */
Chris@0: 
Chris@0: namespace Symfony\Component\HttpKernel\HttpCache;
Chris@0: 
Chris@0: use Symfony\Component\HttpFoundation\Response;
Chris@0: 
Chris@0: /**
Chris@0:  * ResponseCacheStrategy knows how to compute the Response cache HTTP header
Chris@0:  * based on the different response cache headers.
Chris@0:  *
Chris@0:  * This implementation changes the master response TTL to the smallest TTL received
Chris@0:  * or force validation if one of the surrogates has validation cache strategy.
Chris@0:  *
Chris@0:  * @author Fabien Potencier <fabien@symfony.com>
Chris@0:  */
Chris@0: class ResponseCacheStrategy implements ResponseCacheStrategyInterface
Chris@0: {
Chris@0:     private $cacheable = true;
Chris@0:     private $embeddedResponses = 0;
Chris@0:     private $ttls = array();
Chris@0:     private $maxAges = array();
Chris@0:     private $isNotCacheableResponseEmbedded = false;
Chris@0: 
Chris@0:     /**
Chris@0:      * {@inheritdoc}
Chris@0:      */
Chris@0:     public function add(Response $response)
Chris@0:     {
Chris@0:         if ($response->isValidateable()) {
Chris@0:             $this->cacheable = false;
Chris@0:         } else {
Chris@0:             $maxAge = $response->getMaxAge();
Chris@0:             $this->ttls[] = $response->getTtl();
Chris@0:             $this->maxAges[] = $maxAge;
Chris@0: 
Chris@0:             if (null === $maxAge) {
Chris@0:                 $this->isNotCacheableResponseEmbedded = true;
Chris@0:             }
Chris@0:         }
Chris@0: 
Chris@0:         ++$this->embeddedResponses;
Chris@0:     }
Chris@0: 
Chris@0:     /**
Chris@0:      * {@inheritdoc}
Chris@0:      */
Chris@0:     public function update(Response $response)
Chris@0:     {
Chris@0:         // if we have no embedded Response, do nothing
Chris@0:         if (0 === $this->embeddedResponses) {
Chris@0:             return;
Chris@0:         }
Chris@0: 
Chris@0:         // Remove validation related headers in order to avoid browsers using
Chris@0:         // their own cache, because some of the response content comes from
Chris@0:         // at least one embedded response (which likely has a different caching strategy).
Chris@0:         if ($response->isValidateable()) {
Chris@0:             $response->setEtag(null);
Chris@0:             $response->setLastModified(null);
Chris@0:             $this->cacheable = false;
Chris@0:         }
Chris@0: 
Chris@0:         if (!$this->cacheable) {
Chris@0:             $response->headers->set('Cache-Control', 'no-cache, must-revalidate');
Chris@0: 
Chris@0:             return;
Chris@0:         }
Chris@0: 
Chris@0:         $this->ttls[] = $response->getTtl();
Chris@0:         $this->maxAges[] = $response->getMaxAge();
Chris@0: 
Chris@0:         if ($this->isNotCacheableResponseEmbedded) {
Chris@0:             $response->headers->removeCacheControlDirective('s-maxage');
Chris@0:         } elseif (null !== $maxAge = min($this->maxAges)) {
Chris@0:             $response->setSharedMaxAge($maxAge);
Chris@0:             $response->headers->set('Age', $maxAge - min($this->ttls));
Chris@0:         }
Chris@0:         $response->setMaxAge(0);
Chris@0:     }
Chris@0: }