1 <?php

     2 

     3 /*

     4  * This file is part of the Symfony package.

     5  *

     6  * (c) Fabien Potencier <fabien@symfony.com>

     7  *

     8  * This code is partially based on the Rack-Cache library by Ryan Tomayko,

     9  * which is released under the MIT license.

    10  * (based on commit 02d2b48d75bcb63cf1c0c7149c077ad256542801)

    11  *

    12  * For the full copyright and license information, please view the LICENSE

    13  * file that was distributed with this source code.

    14  */

    15 

    16 namespace Symfony\Component\HttpKernel\HttpCache;

    17 

    18 use Symfony\Component\HttpFoundation\Response;

    19 

    20 /**

    21  * EsiResponseCacheStrategy knows how to compute the Response cache HTTP header

    22  * based on the different ESI response cache headers.

    23  *

    24  * This implementation changes the master response TTL to the smallest TTL received

    25  * or force validation if one of the ESI has validation cache strategy.

    26  *

    27  * @author Fabien Potencier <fabien@symfony.com>

    28  */

    29 class EsiResponseCacheStrategy implements EsiResponseCacheStrategyInterface

    30 {

    31     private $cacheable = true;

    32     private $ttls = array();

    33     private $maxAges = array();

    34 

    35     /**

    36      * Adds a Response.

    37      *

    38      * @param Response $response

    39      */

    40     public function add(Response $response)

    41     {

    42         if ($response->isValidateable()) {

    43             $this->cacheable = false;

    44         } else {

    45             $this->ttls[] = $response->getTtl();

    46             $this->maxAges[] = $response->getMaxAge();

    47         }

    48     }

    49 

    50     /**

    51      * Updates the Response HTTP headers based on the embedded Responses.

    52      *

    53      * @param Response $response

    54      */

    55     public function update(Response $response)

    56     {

    57         // if we only have one Response, do nothing

    58         if (1 === count($this->ttls)) {

    59             return;

    60         }

    61 

    62         if (!$this->cacheable) {

    63             $response->headers->set('Cache-Control', 'no-cache, must-revalidate');

    64 

    65             return;

    66         }

    67 

    68         if (null !== $maxAge = min($this->maxAges)) {

    69             $response->setSharedMaxAge($maxAge);

    70             $response->headers->set('Age', $maxAge - min($this->ttls));

    71         }

    72         $response->setMaxAge(0);

    73     }

    74 }