743 lines
26 KiB
PHP
743 lines
26 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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* 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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/*
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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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namespace Symfony\Component\HttpKernel\HttpCache;
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use Symfony\Component\HttpFoundation\Exception\SuspiciousOperationException;
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use Symfony\Component\HttpFoundation\Request;
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use Symfony\Component\HttpFoundation\Response;
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use Symfony\Component\HttpKernel\HttpKernelInterface;
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use Symfony\Component\HttpKernel\TerminableInterface;
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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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class HttpCache implements HttpKernelInterface, TerminableInterface
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{
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public const BODY_EVAL_BOUNDARY_LENGTH = 24;
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private Request $request;
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private ?ResponseCacheStrategyInterface $surrogateCacheStrategy = null;
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private array $options = [];
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private array $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, exceptions are thrown when things go wrong. Otherwise, the cache
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* will try to carry on and deliver a meaningful response.
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*
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* * trace_level May be one of 'none', 'short' and 'full'. For 'short', a concise trace of the
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* main request will be added as an HTTP header. 'full' will add traces for all
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* requests (including ESI subrequests). (default: 'full' if in debug; 'none' otherwise)
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*
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* * trace_header Header name to use for traces. (default: X-Symfony-Cache)
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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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* * skip_response_headers Set of response headers that are never cached even if a response is cacheable (public).
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* (default: Set-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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public function __construct(
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private HttpKernelInterface $kernel,
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private StoreInterface $store,
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private ?SurrogateInterface $surrogate = null,
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array $options = [],
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) {
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// needed in case there is a fatal error because the backend is too slow to respond
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register_shutdown_function($this->store->cleanup(...));
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$this->options = array_merge([
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'debug' => false,
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'default_ttl' => 0,
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'private_headers' => ['Authorization', 'Cookie'],
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'skip_response_headers' => ['Set-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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'trace_level' => 'none',
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'trace_header' => 'X-Symfony-Cache',
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], $options);
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if (!isset($options['trace_level'])) {
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$this->options['trace_level'] = $this->options['debug'] ? 'full' : 'none';
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}
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}
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/**
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* Gets the current store.
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*/
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public function getStore(): StoreInterface
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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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public function getTraces(): array
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{
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return $this->traces;
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}
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private function addTraces(Response $response): void
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{
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$traceString = null;
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if ('full' === $this->options['trace_level']) {
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$traceString = $this->getLog();
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}
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if ('short' === $this->options['trace_level'] && $masterId = array_key_first($this->traces)) {
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$traceString = implode('/', $this->traces[$masterId]);
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}
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if (null !== $traceString) {
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$response->headers->add([$this->options['trace_header'] => $traceString]);
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}
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}
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/**
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* Returns a log message for the events of the last request processing.
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*/
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public function getLog(): string
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{
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$log = [];
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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 main request.
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*/
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public function getRequest(): Request
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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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public function getKernel(): HttpKernelInterface
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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 Surrogate instance.
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*
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* @throws \LogicException
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*/
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public function getSurrogate(): SurrogateInterface
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{
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return $this->surrogate;
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}
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public function handle(Request $request, int $type = HttpKernelInterface::MAIN_REQUEST, bool $catch = true): Response
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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::MAIN_REQUEST === $type) {
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$this->traces = [];
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// Keep a clone of the original request for surrogates so they can access it.
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// We must clone here to get a separate instance because the application will modify the request during
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// the application flow (we know it always does because we do ourselves by setting REMOTE_ADDR to 127.0.0.1
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// and adding the X-Forwarded-For header, see HttpCache::forward()).
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$this->request = clone $request;
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if (null !== $this->surrogate) {
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$this->surrogateCacheStrategy = $this->surrogate->createCacheStrategy();
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}
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}
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$this->traces[$this->getTraceKey($request)] = [];
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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') || !$request->isMethodCacheable()) {
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$response = $this->pass($request, $catch);
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} elseif ($this->options['allow_reload'] && $request->isNoCache()) {
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/*
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If allow_reload is configured and the client requests "Cache-Control: no-cache",
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reload the cache by fetching a fresh response and caching it (if possible).
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*/
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$this->record($request, 'reload');
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$response = $this->fetch($request, $catch);
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} else {
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$response = null;
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do {
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try {
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$response = $this->lookup($request, $catch);
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} catch (CacheWasLockedException) {
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}
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} while (null === $response);
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}
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$this->restoreResponseBody($request, $response);
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if (HttpKernelInterface::MAIN_REQUEST === $type) {
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$this->addTraces($response);
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}
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if (null !== $this->surrogate) {
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if (HttpKernelInterface::MAIN_REQUEST === $type) {
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$this->surrogateCacheStrategy->update($response);
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} else {
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$this->surrogateCacheStrategy->add($response);
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}
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}
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$response->prepare($request);
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if (HttpKernelInterface::MAIN_REQUEST === $type) {
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$response->isNotModified($request);
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}
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return $response;
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}
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public function terminate(Request $request, Response $response): void
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{
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// Do not call any listeners in case of a cache hit.
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// This ensures identical behavior as if you had a separate
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// reverse caching proxy such as Varnish and the like.
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if (\in_array('fresh', $this->traces[$this->getTraceKey($request)] ?? [], true)) {
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return;
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}
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if ($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 bool $catch Whether to process exceptions
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*/
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protected function pass(Request $request, bool $catch = false): Response
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{
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$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 bool $catch Whether to process exceptions
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*
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* @throws \Exception
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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, bool $catch = false): Response
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{
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$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);
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// As per the RFC, invalidate Location and Content-Location URLs if present
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foreach (['Location', 'Content-Location'] as $header) {
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if ($uri = $response->headers->get($header)) {
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$subRequest = Request::create($uri, 'get', [], [], [], $request->server->all());
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$this->store->invalidate($subRequest);
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}
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}
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$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 bool $catch Whether to process exceptions
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*
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* @throws \Exception
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*/
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protected function lookup(Request $request, bool $catch = false): Response
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{
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try {
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$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, $catch);
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}
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if ($entry->headers->hasCacheControlDirective('no-cache')) {
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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 bool $catch Whether to process exceptions
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*/
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protected function validate(Request $request, Response $entry, bool $catch = false): Response
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{
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$subRequest = clone $request;
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// send no head requests because we want content
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if ('HEAD' === $request->getMethod()) {
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$subRequest->setMethod('GET');
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}
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// add our cached last-modified validator
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if ($entry->headers->has('Last-Modified')) {
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$subRequest->headers->set('If-Modified-Since', $entry->headers->get('Last-Modified'));
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}
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// Add our cached etag validator to the environment.
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// We keep the etags from the client to handle the case when the client
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// has a different private valid entry which is not cached here.
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$cachedEtags = $entry->getEtag() ? [$entry->getEtag()] : [];
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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, $requestEtags, true) && !\in_array($etag, $cachedEtags, true)) {
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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 (['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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* Unconditionally fetches a fresh response from the backend and
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* stores it in the cache if is cacheable.
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*
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* @param bool $catch Whether to process exceptions
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*/
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protected function fetch(Request $request, bool $catch = false): Response
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{
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$subRequest = clone $request;
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// send no head requests because we want content
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if ('HEAD' === $request->getMethod()) {
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$subRequest->setMethod('GET');
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}
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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, $catch);
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if ($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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* All backend requests (cache passes, fetches, cache validations)
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* run through this method.
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*
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* @param bool $catch Whether to catch exceptions or not
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* @param Response|null $entry A Response instance (the stale entry if present, null otherwise)
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*/
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protected function forward(Request $request, bool $catch = false, ?Response $entry = null): Response
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{
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$this->surrogate?->addSurrogateCapability($request);
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// always a "master" request (as the real master request can be in cache)
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$response = SubRequestHandler::handle($this->kernel, $request, HttpKernelInterface::MAIN_REQUEST, $catch);
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/*
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* Support stale-if-error given on Responses or as a config option.
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* RFC 7234 summarizes in Section 4.2.4 (but also mentions with the individual
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* Cache-Control directives) that
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*
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* A cache MUST NOT generate a stale response if it is prohibited by an
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* explicit in-protocol directive (e.g., by a "no-store" or "no-cache"
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* cache directive, a "must-revalidate" cache-response-directive, or an
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* applicable "s-maxage" or "proxy-revalidate" cache-response-directive;
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* see Section 5.2.2).
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*
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* https://tools.ietf.org/html/rfc7234#section-4.2.4
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*
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* We deviate from this in one detail, namely that we *do* serve entries in the
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* stale-if-error case even if they have a `s-maxage` Cache-Control directive.
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*/
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if (null !== $entry
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&& \in_array($response->getStatusCode(), [500, 502, 503, 504])
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&& !$entry->headers->hasCacheControlDirective('no-cache')
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&& !$entry->mustRevalidate()
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) {
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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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/*
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* stale-if-error gives the (extra) time that the Response may be used *after* it has become stale.
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* So we compare the time the $entry has been sitting in the cache already with the
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* time it was fresh plus the allowed grace period.
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*/
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if ($entry->getAge() <= $entry->getMaxAge() + $age) {
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$this->record($request, 'stale-if-error');
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return $entry;
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}
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}
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/*
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RFC 7231 Sect. 7.1.1.2 says that a server that does not have a reasonably accurate
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clock MUST NOT send a "Date" header, although it MUST send one in most other cases
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except for 1xx or 5xx responses where it MAY do so.
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Anyway, a client that received a message without a "Date" header MUST add it.
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*/
|
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if (!$response->headers->has('Date')) {
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$response->setDate(\DateTimeImmutable::createFromFormat('U', time()));
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}
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$this->processResponseBody($request, $response);
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if ($this->isPrivateRequest($request) && !$response->headers->hasCacheControlDirective('public')) {
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$response->setPrivate();
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} elseif ($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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return $response;
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}
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/**
|
|
* Checks whether the cache entry is "fresh enough" to satisfy the Request.
|
|
*/
|
|
protected function isFreshEnough(Request $request, Response $entry): bool
|
|
{
|
|
if (!$entry->isFresh()) {
|
|
return $this->lock($request, $entry);
|
|
}
|
|
|
|
if ($this->options['allow_revalidate'] && null !== $maxAge = $request->headers->getCacheControlDirective('max-age')) {
|
|
return $maxAge > 0 && $maxAge >= $entry->getAge();
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
/**
|
|
* Locks a Request during the call to the backend.
|
|
*
|
|
* @return bool true if the cache entry can be returned even if it is staled, false otherwise
|
|
*/
|
|
protected function lock(Request $request, Response $entry): bool
|
|
{
|
|
// try to acquire a lock to call the backend
|
|
$lock = $this->store->lock($request);
|
|
|
|
if (true === $lock) {
|
|
// we have the lock, call the backend
|
|
return false;
|
|
}
|
|
|
|
// there is already another process calling the backend
|
|
|
|
// May we serve a stale response?
|
|
if ($this->mayServeStaleWhileRevalidate($entry)) {
|
|
$this->record($request, 'stale-while-revalidate');
|
|
|
|
return true;
|
|
}
|
|
|
|
// wait for the lock to be released
|
|
if ($this->waitForLock($request)) {
|
|
throw new CacheWasLockedException(); // unwind back to handle(), try again
|
|
} else {
|
|
// backend is slow as hell, send a 503 response (to avoid the dog pile effect)
|
|
$entry->setStatusCode(503);
|
|
$entry->setContent('503 Service Unavailable');
|
|
$entry->headers->set('Retry-After', 10);
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
/**
|
|
* Writes the Response to the cache.
|
|
*
|
|
* @throws \Exception
|
|
*/
|
|
protected function store(Request $request, Response $response): void
|
|
{
|
|
try {
|
|
$restoreHeaders = [];
|
|
foreach ($this->options['skip_response_headers'] as $header) {
|
|
if (!$response->headers->has($header)) {
|
|
continue;
|
|
}
|
|
|
|
$restoreHeaders[$header] = $response->headers->all($header);
|
|
$response->headers->remove($header);
|
|
}
|
|
|
|
$this->store->write($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 $e;
|
|
}
|
|
} finally {
|
|
foreach ($restoreHeaders as $header => $values) {
|
|
$response->headers->set($header, $values);
|
|
}
|
|
}
|
|
|
|
// now that the response is cached, release the lock
|
|
$this->store->unlock($request);
|
|
}
|
|
|
|
/**
|
|
* Restores the Response body.
|
|
*/
|
|
private function restoreResponseBody(Request $request, Response $response): void
|
|
{
|
|
if ($response->headers->has('X-Body-Eval')) {
|
|
\assert(self::BODY_EVAL_BOUNDARY_LENGTH === 24);
|
|
|
|
ob_start();
|
|
|
|
$content = $response->getContent();
|
|
$boundary = substr($content, 0, 24);
|
|
$j = strpos($content, $boundary, 24);
|
|
echo substr($content, 24, $j - 24);
|
|
$i = $j + 24;
|
|
|
|
while (false !== $j = strpos($content, $boundary, $i)) {
|
|
[$uri, $alt, $ignoreErrors, $part] = explode("\n", substr($content, $i, $j - $i), 4);
|
|
$i = $j + 24;
|
|
|
|
echo $this->surrogate->handle($this, $uri, $alt, $ignoreErrors);
|
|
echo $part;
|
|
}
|
|
|
|
$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 ($response->headers->has('X-Body-File')) {
|
|
// Response does not include possibly dynamic content (ESI, SSI), so we need
|
|
// not handle the content for HEAD requests
|
|
if (!$request->isMethod('HEAD')) {
|
|
$response->setContent(file_get_contents($response->headers->get('X-Body-File')));
|
|
}
|
|
} else {
|
|
return;
|
|
}
|
|
|
|
$response->headers->remove('X-Body-File');
|
|
}
|
|
|
|
protected function processResponseBody(Request $request, Response $response): void
|
|
{
|
|
if ($this->surrogate?->needsParsing($response)) {
|
|
$this->surrogate->process($request, $response);
|
|
}
|
|
}
|
|
|
|
/**
|
|
* Checks if the Request includes authorization or other sensitive information
|
|
* that should cause the Response to be considered private by default.
|
|
*/
|
|
private function isPrivateRequest(Request $request): bool
|
|
{
|
|
foreach ($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.
|
|
*/
|
|
private function record(Request $request, string $event): void
|
|
{
|
|
$this->traces[$this->getTraceKey($request)][] = $event;
|
|
}
|
|
|
|
/**
|
|
* Calculates the key we use in the "trace" array for a given request.
|
|
*/
|
|
private function getTraceKey(Request $request): string
|
|
{
|
|
$path = $request->getPathInfo();
|
|
if ($qs = $request->getQueryString()) {
|
|
$path .= '?'.$qs;
|
|
}
|
|
|
|
try {
|
|
return $request->getMethod().' '.$path;
|
|
} catch (SuspiciousOperationException) {
|
|
return '_BAD_METHOD_ '.$path;
|
|
}
|
|
}
|
|
|
|
/**
|
|
* Checks whether the given (cached) response may be served as "stale" when a revalidation
|
|
* is currently in progress.
|
|
*/
|
|
private function mayServeStaleWhileRevalidate(Response $entry): bool
|
|
{
|
|
$timeout = $entry->headers->getCacheControlDirective('stale-while-revalidate');
|
|
$timeout ??= $this->options['stale_while_revalidate'];
|
|
|
|
$age = $entry->getAge();
|
|
$maxAge = $entry->getMaxAge() ?? 0;
|
|
$ttl = $maxAge - $age;
|
|
|
|
return abs($ttl) < $timeout;
|
|
}
|
|
|
|
/**
|
|
* Waits for the store to release a locked entry.
|
|
*/
|
|
private function waitForLock(Request $request): bool
|
|
{
|
|
$wait = 0;
|
|
while ($this->store->isLocked($request) && $wait < 100) {
|
|
usleep(50000);
|
|
++$wait;
|
|
}
|
|
|
|
return $wait < 100;
|
|
}
|
|
}
|