/usr/share/php/Symfony/Component/HttpKernel/HttpCache/EsiResponseCacheStrategy.php is in php-symfony-http-kernel 2.3.21+dfsg-4+deb8u3.
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/*
* This file is part of the Symfony package.
*
* (c) Fabien Potencier <fabien@symfony.com>
*
* This code is partially based on the Rack-Cache library by Ryan Tomayko,
* which is released under the MIT license.
* (based on commit 02d2b48d75bcb63cf1c0c7149c077ad256542801)
*
* For the full copyright and license information, please view the LICENSE
* file that was distributed with this source code.
*/
namespace Symfony\Component\HttpKernel\HttpCache;
use Symfony\Component\HttpFoundation\Response;
/**
* EsiResponseCacheStrategy knows how to compute the Response cache HTTP header
* based on the different ESI response cache headers.
*
* This implementation changes the master response TTL to the smallest TTL received
* or force validation if one of the ESI has validation cache strategy.
*
* @author Fabien Potencier <fabien@symfony.com>
*/
class EsiResponseCacheStrategy implements EsiResponseCacheStrategyInterface
{
private $cacheable = true;
private $embeddedResponses = 0;
private $ttls = array();
private $maxAges = array();
/**
* {@inheritdoc}
*/
public function add(Response $response)
{
if ($response->isValidateable()) {
$this->cacheable = false;
} else {
$this->ttls[] = $response->getTtl();
$this->maxAges[] = $response->getMaxAge();
}
$this->embeddedResponses++;
}
/**
* {@inheritdoc}
*/
public function update(Response $response)
{
// if we have no embedded Response, do nothing
if (0 === $this->embeddedResponses) {
return;
}
// Remove validation related headers in order to avoid browsers using
// their own cache, because some of the response content comes from
// at least one embedded response (which likely has a different caching strategy).
if ($response->isValidateable()) {
$response->setEtag(null);
$response->setLastModified(null);
$this->cacheable = false;
}
if (!$this->cacheable) {
$response->headers->set('Cache-Control', 'no-cache, must-revalidate');
return;
}
$this->ttls[] = $response->getTtl();
$this->maxAges[] = $response->getMaxAge();
if (null !== $maxAge = min($this->maxAges)) {
$response->setSharedMaxAge($maxAge);
$response->headers->set('Age', $maxAge - min($this->ttls));
}
$response->setMaxAge(0);
}
}
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