661 lines
22 KiB
PHP
661 lines
22 KiB
PHP
<?php
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/*
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* This file is part of the Symfony package.
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*
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* (c) Fabien Potencier <fabien@symfony.com>
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*
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* This code is partially based on the Rack-Cache library by Ryan Tomayko,
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* which is released under the MIT license.
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* (based on commit 02d2b48d75bcb63cf1c0c7149c077ad256542801)
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*
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* For the full copyright and license information, please view the LICENSE
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* file that was distributed with this source code.
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*/
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namespace Symfony\Component\HttpKernel\HttpCache;
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use Symfony\Component\HttpKernel\HttpKernelInterface;
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use Symfony\Component\HttpKernel\TerminableInterface;
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use Symfony\Component\HttpFoundation\Request;
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use Symfony\Component\HttpFoundation\Response;
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/**
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* Cache provides HTTP caching.
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*
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* @author Fabien Potencier <fabien@symfony.com>
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*
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* @api
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*/
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class HttpCache implements HttpKernelInterface, TerminableInterface
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{
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private $kernel;
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private $store;
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private $request;
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private $esi;
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private $esiCacheStrategy;
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private $traces;
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/**
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* Constructor.
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*
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* The available options are:
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*
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* * debug: If true, the traces are added as a HTTP header to ease debugging
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*
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* * default_ttl The number of seconds that a cache entry should be considered
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* fresh when no explicit freshness information is provided in
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* a response. Explicit Cache-Control or Expires headers
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* override this value. (default: 0)
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*
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* * private_headers Set of request headers that trigger "private" cache-control behavior
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* on responses that don't explicitly state whether the response is
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* public or private via a Cache-Control directive. (default: Authorization and Cookie)
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*
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* * allow_reload Specifies whether the client can force a cache reload by including a
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* Cache-Control "no-cache" directive in the request. Set it to ``true``
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* for compliance with RFC 2616. (default: false)
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*
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* * allow_revalidate Specifies whether the client can force a cache revalidate by including
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* a Cache-Control "max-age=0" directive in the request. Set it to ``true``
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* for compliance with RFC 2616. (default: false)
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*
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* * stale_while_revalidate Specifies the default number of seconds (the granularity is the second as the
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* Response TTL precision is a second) during which the cache can immediately return
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* a stale response while it revalidates it in the background (default: 2).
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* This setting is overridden by the stale-while-revalidate HTTP Cache-Control
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* extension (see RFC 5861).
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*
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* * stale_if_error Specifies the default number of seconds (the granularity is the second) during which
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* the cache can serve a stale response when an error is encountered (default: 60).
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* This setting is overridden by the stale-if-error HTTP Cache-Control extension
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* (see RFC 5861).
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*
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* @param HttpKernelInterface $kernel An HttpKernelInterface instance
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* @param StoreInterface $store A Store instance
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* @param Esi $esi An Esi instance
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* @param array $options An array of options
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*/
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public function __construct(HttpKernelInterface $kernel, StoreInterface $store, Esi $esi = null, array $options = array())
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{
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$this->store = $store;
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$this->kernel = $kernel;
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// needed in case there is a fatal error because the backend is too slow to respond
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register_shutdown_function(array($this->store, 'cleanup'));
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$this->options = array_merge(array(
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'debug' => false,
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'default_ttl' => 0,
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'private_headers' => array('Authorization', 'Cookie'),
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'allow_reload' => false,
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'allow_revalidate' => false,
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'stale_while_revalidate' => 2,
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'stale_if_error' => 60,
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), $options);
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$this->esi = $esi;
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$this->traces = array();
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}
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/**
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* Gets the current store.
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*
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* @return StoreInterface $store A StoreInterface instance
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*/
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public function getStore()
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{
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return $this->store;
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}
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/**
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* Returns an array of events that took place during processing of the last request.
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*
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* @return array An array of events
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*/
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public function getTraces()
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{
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return $this->traces;
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}
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/**
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* Returns a log message for the events of the last request processing.
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*
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* @return string A log message
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*/
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public function getLog()
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{
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$log = array();
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foreach ($this->traces as $request => $traces) {
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$log[] = sprintf('%s: %s', $request, implode(', ', $traces));
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}
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return implode('; ', $log);
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}
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/**
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* Gets the Request instance associated with the master request.
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*
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* @return Symfony\Component\HttpFoundation\Request A Request instance
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*/
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public function getRequest()
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{
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return $this->request;
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}
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/**
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* Gets the Kernel instance
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*
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* @return Symfony\Component\HttpKernel\HttpKernelInterface An HttpKernelInterface instance
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*/
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public function getKernel()
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{
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return $this->kernel;
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}
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/**
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* Gets the Esi instance
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*
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* @return Symfony\Component\HttpKernel\HttpCache\Esi An Esi instance
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*/
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public function getEsi()
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{
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return $this->esi;
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}
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/**
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* {@inheritdoc}
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*
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* @api
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*/
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public function handle(Request $request, $type = HttpKernelInterface::MASTER_REQUEST, $catch = true)
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{
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// FIXME: catch exceptions and implement a 500 error page here? -> in Varnish, there is a built-in error page mechanism
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if (HttpKernelInterface::MASTER_REQUEST === $type) {
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$this->traces = array();
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$this->request = $request;
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if (null !== $this->esi) {
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$this->esiCacheStrategy = $this->esi->createCacheStrategy();
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}
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}
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$path = $request->getPathInfo();
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if ($qs = $request->getQueryString()) {
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$path .= '?'.$qs;
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}
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$this->traces[$request->getMethod().' '.$path] = array();
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if (!$request->isMethodSafe()) {
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$response = $this->invalidate($request, $catch);
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} elseif ($request->headers->has('expect')) {
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$response = $this->pass($request, $catch);
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} else {
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$response = $this->lookup($request, $catch);
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}
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$response->isNotModified($request);
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$this->restoreResponseBody($request, $response);
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$response->setDate(new \DateTime(null, new \DateTimeZone('UTC')));
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if (HttpKernelInterface::MASTER_REQUEST === $type && $this->options['debug']) {
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$response->headers->set('X-Symfony-Cache', $this->getLog());
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}
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if (null !== $this->esi) {
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$this->esiCacheStrategy->add($response);
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if (HttpKernelInterface::MASTER_REQUEST === $type) {
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$this->esiCacheStrategy->update($response);
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}
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}
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$response->prepare($request);
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return $response;
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}
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/**
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* {@inheritdoc}
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*
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* @api
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*/
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public function terminate(Request $request, Response $response)
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{
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if ($this->getKernel() instanceof TerminableInterface) {
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$this->getKernel()->terminate($request, $response);
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}
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}
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/**
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* Forwards the Request to the backend without storing the Response in the cache.
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*
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* @param Request $request A Request instance
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* @param Boolean $catch Whether to process exceptions
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*
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* @return Response A Response instance
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*/
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protected function pass(Request $request, $catch = false)
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{
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$this->record($request, 'pass');
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return $this->forward($request, $catch);
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}
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/**
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* Invalidates non-safe methods (like POST, PUT, and DELETE).
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*
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* @param Request $request A Request instance
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* @param Boolean $catch Whether to process exceptions
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*
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* @return Response A Response instance
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*
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* @see RFC2616 13.10
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*/
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protected function invalidate(Request $request, $catch = false)
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{
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$response = $this->pass($request, $catch);
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// invalidate only when the response is successful
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if ($response->isSuccessful() || $response->isRedirect()) {
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try {
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$this->store->invalidate($request, $catch);
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$this->record($request, 'invalidate');
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} catch (\Exception $e) {
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$this->record($request, 'invalidate-failed');
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if ($this->options['debug']) {
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throw $e;
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}
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}
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}
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return $response;
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}
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/**
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* Lookups a Response from the cache for the given Request.
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*
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* When a matching cache entry is found and is fresh, it uses it as the
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* response without forwarding any request to the backend. When a matching
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* cache entry is found but is stale, it attempts to "validate" the entry with
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* the backend using conditional GET. When no matching cache entry is found,
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* it triggers "miss" processing.
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*
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* @param Request $request A Request instance
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* @param Boolean $catch whether to process exceptions
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*
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* @return Response A Response instance
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*/
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protected function lookup(Request $request, $catch = false)
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{
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// if allow_reload and no-cache Cache-Control, allow a cache reload
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if ($this->options['allow_reload'] && $request->isNoCache()) {
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$this->record($request, 'reload');
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return $this->fetch($request);
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}
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try {
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$entry = $this->store->lookup($request);
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} catch (\Exception $e) {
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$this->record($request, 'lookup-failed');
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if ($this->options['debug']) {
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throw $e;
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}
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return $this->pass($request, $catch);
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}
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if (null === $entry) {
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$this->record($request, 'miss');
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return $this->fetch($request, $catch);
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}
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if (!$this->isFreshEnough($request, $entry)) {
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$this->record($request, 'stale');
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return $this->validate($request, $entry, $catch);
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}
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$this->record($request, 'fresh');
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$entry->headers->set('Age', $entry->getAge());
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return $entry;
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}
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/**
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* Validates that a cache entry is fresh.
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*
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* The original request is used as a template for a conditional
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* GET request with the backend.
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*
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* @param Request $request A Request instance
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* @param Response $entry A Response instance to validate
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* @param Boolean $catch Whether to process exceptions
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*
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* @return Response A Response instance
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*/
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protected function validate(Request $request, Response $entry, $catch = false)
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{
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$subRequest = clone $request;
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// send no head requests because we want content
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$subRequest->setMethod('GET');
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// add our cached last-modified validator
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$subRequest->headers->set('if_modified_since', $entry->headers->get('Last-Modified'));
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// Add our cached etag validator to the environment.
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// We keep the etags from the client to handle the case when the client
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// has a different private valid entry which is not cached here.
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$cachedEtags = $entry->getEtag() ? array($entry->getEtag()) : array();
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$requestEtags = $request->getEtags();
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if ($etags = array_unique(array_merge($cachedEtags, $requestEtags))) {
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$subRequest->headers->set('if_none_match', implode(', ', $etags));
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}
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$response = $this->forward($subRequest, $catch, $entry);
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if (304 == $response->getStatusCode()) {
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$this->record($request, 'valid');
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// return the response and not the cache entry if the response is valid but not cached
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$etag = $response->getEtag();
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if ($etag && in_array($etag, $requestEtags) && !in_array($etag, $cachedEtags)) {
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return $response;
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}
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$entry = clone $entry;
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$entry->headers->remove('Date');
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foreach (array('Date', 'Expires', 'Cache-Control', 'ETag', 'Last-Modified') as $name) {
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if ($response->headers->has($name)) {
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$entry->headers->set($name, $response->headers->get($name));
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}
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}
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$response = $entry;
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} else {
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$this->record($request, 'invalid');
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}
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if ($response->isCacheable()) {
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$this->store($request, $response);
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}
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return $response;
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}
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/**
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* Forwards the Request to the backend and determines whether the response should be stored.
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*
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* This methods is triggered when the cache missed or a reload is required.
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*
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* @param Request $request A Request instance
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* @param Boolean $catch whether to process exceptions
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*
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* @return Response A Response instance
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*/
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protected function fetch(Request $request, $catch = false)
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{
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$subRequest = clone $request;
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// send no head requests because we want content
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$subRequest->setMethod('GET');
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// avoid that the backend sends no content
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$subRequest->headers->remove('if_modified_since');
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$subRequest->headers->remove('if_none_match');
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$response = $this->forward($subRequest, $catch);
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if ($this->isPrivateRequest($request) && !$response->headers->hasCacheControlDirective('public')) {
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$response->setPrivate(true);
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} elseif ($this->options['default_ttl'] > 0 && null === $response->getTtl() && !$response->headers->getCacheControlDirective('must-revalidate')) {
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$response->setTtl($this->options['default_ttl']);
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}
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if ($response->isCacheable()) {
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$this->store($request, $response);
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}
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return $response;
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}
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/**
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* Forwards the Request to the backend and returns the Response.
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*
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* @param Request $request A Request instance
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* @param Boolean $catch Whether to catch exceptions or not
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* @param Response $entry A Response instance (the stale entry if present, null otherwise)
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*
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* @return Response A Response instance
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*/
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protected function forward(Request $request, $catch = false, Response $entry = null)
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{
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if ($this->esi) {
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$this->esi->addSurrogateEsiCapability($request);
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}
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// always a "master" request (as the real master request can be in cache)
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$response = $this->kernel->handle($request, HttpKernelInterface::MASTER_REQUEST, $catch);
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// FIXME: we probably need to also catch exceptions if raw === true
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// we don't implement the stale-if-error on Requests, which is nonetheless part of the RFC
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if (null !== $entry && in_array($response->getStatusCode(), array(500, 502, 503, 504))) {
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if (null === $age = $entry->headers->getCacheControlDirective('stale-if-error')) {
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$age = $this->options['stale_if_error'];
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}
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if (abs($entry->getTtl()) < $age) {
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$this->record($request, 'stale-if-error');
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return $entry;
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}
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}
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$this->processResponseBody($request, $response);
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return $response;
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}
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/**
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* Checks whether the cache entry is "fresh enough" to satisfy the Request.
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*
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* @param Request $request A Request instance
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* @param Response $entry A Response instance
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*
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* @return Boolean true if the cache entry if fresh enough, false otherwise
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*/
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protected function isFreshEnough(Request $request, Response $entry)
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{
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if (!$entry->isFresh()) {
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return $this->lock($request, $entry);
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}
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if ($this->options['allow_revalidate'] && null !== $maxAge = $request->headers->getCacheControlDirective('max-age')) {
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return $maxAge > 0 && $maxAge >= $entry->getAge();
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}
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return true;
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}
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/**
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* Locks a Request during the call to the backend.
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*
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* @param Request $request A Request instance
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* @param Response $entry A Response instance
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*
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* @return Boolean true if the cache entry can be returned even if it is staled, false otherwise
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*/
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protected function lock(Request $request, Response $entry)
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{
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// try to acquire a lock to call the backend
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$lock = $this->store->lock($request, $entry);
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// there is already another process calling the backend
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if (true !== $lock) {
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// check if we can serve the stale entry
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if (null === $age = $entry->headers->getCacheControlDirective('stale-while-revalidate')) {
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$age = $this->options['stale_while_revalidate'];
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}
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if (abs($entry->getTtl()) < $age) {
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$this->record($request, 'stale-while-revalidate');
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// server the stale response while there is a revalidation
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return true;
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}
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// wait for the lock to be released
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$wait = 0;
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while (is_file($lock) && $wait < 5000000) {
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usleep(50000);
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$wait += 50000;
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}
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if ($wait < 2000000) {
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// replace the current entry with the fresh one
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$new = $this->lookup($request);
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$entry->headers = $new->headers;
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$entry->setContent($new->getContent());
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$entry->setStatusCode($new->getStatusCode());
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$entry->setProtocolVersion($new->getProtocolVersion());
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foreach ($new->headers->getCookies() as $cookie) {
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$entry->headers->setCookie($cookie);
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}
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} else {
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// backend is slow as hell, send a 503 response (to avoid the dog pile effect)
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$entry->setStatusCode(503);
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$entry->setContent('503 Service Unavailable');
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$entry->headers->set('Retry-After', 10);
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}
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return true;
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}
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// we have the lock, call the backend
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return false;
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}
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/**
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* Writes the Response to the cache.
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*
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* @param Request $request A Request instance
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* @param Response $response A Response instance
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*/
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protected function store(Request $request, Response $response)
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{
|
|
try {
|
|
$this->store->write($request, $response);
|
|
|
|
$this->record($request, 'store');
|
|
|
|
$response->headers->set('Age', $response->getAge());
|
|
} catch (\Exception $e) {
|
|
$this->record($request, 'store-failed');
|
|
|
|
if ($this->options['debug']) {
|
|
throw $e;
|
|
}
|
|
}
|
|
|
|
// now that the response is cached, release the lock
|
|
$this->store->unlock($request);
|
|
}
|
|
|
|
/**
|
|
* Restores the Response body.
|
|
*
|
|
* @param Request $request A Request instance
|
|
* @param Response $response A Response instance
|
|
*
|
|
* @return Response A Response instance
|
|
*/
|
|
private function restoreResponseBody(Request $request, Response $response)
|
|
{
|
|
if ('HEAD' === $request->getMethod() || 304 === $response->getStatusCode()) {
|
|
$response->setContent(null);
|
|
$response->headers->remove('X-Body-Eval');
|
|
$response->headers->remove('X-Body-File');
|
|
|
|
return;
|
|
}
|
|
|
|
if ($response->headers->has('X-Body-Eval')) {
|
|
ob_start();
|
|
|
|
if ($response->headers->has('X-Body-File')) {
|
|
include $response->headers->get('X-Body-File');
|
|
} else {
|
|
eval('; ?>'.$response->getContent().'<?php ;');
|
|
}
|
|
|
|
$response->setContent(ob_get_clean());
|
|
$response->headers->remove('X-Body-Eval');
|
|
if (!$response->headers->has('Transfer-Encoding')) {
|
|
$response->headers->set('Content-Length', strlen($response->getContent()));
|
|
}
|
|
} elseif ($response->headers->has('X-Body-File')) {
|
|
$response->setContent(file_get_contents($response->headers->get('X-Body-File')));
|
|
} else {
|
|
return;
|
|
}
|
|
|
|
$response->headers->remove('X-Body-File');
|
|
}
|
|
|
|
protected function processResponseBody(Request $request, Response $response)
|
|
{
|
|
if (null !== $this->esi && $this->esi->needsEsiParsing($response)) {
|
|
$this->esi->process($request, $response);
|
|
}
|
|
}
|
|
|
|
/**
|
|
* Checks if the Request includes authorization or other sensitive information
|
|
* that should cause the Response to be considered private by default.
|
|
*
|
|
* @param Request $request A Request instance
|
|
*
|
|
* @return Boolean true if the Request is private, false otherwise
|
|
*/
|
|
private function isPrivateRequest(Request $request)
|
|
{
|
|
foreach ($this->options['private_headers'] as $key) {
|
|
$key = strtolower(str_replace('HTTP_', '', $key));
|
|
|
|
if ('cookie' === $key) {
|
|
if (count($request->cookies->all())) {
|
|
return true;
|
|
}
|
|
} elseif ($request->headers->has($key)) {
|
|
return true;
|
|
}
|
|
}
|
|
|
|
return false;
|
|
}
|
|
|
|
/**
|
|
* Records that an event took place.
|
|
*
|
|
* @param Request $request A Request instance
|
|
* @param string $event The event name
|
|
*/
|
|
private function record(Request $request, $event)
|
|
{
|
|
$path = $request->getPathInfo();
|
|
if ($qs = $request->getQueryString()) {
|
|
$path .= '?'.$qs;
|
|
}
|
|
$this->traces[$request->getMethod().' '.$path][] = $event;
|
|
}
|
|
}
|