[HttpKernel] Fix stale-if-error behavior, add tests
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@ -649,7 +649,7 @@ class Response
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}
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/**
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* Returns true if the response must be revalidated by caches.
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* Returns true if the response must be revalidated by shared caches once it has become stale.
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*
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* This method indicates that the response must not be served stale by a
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* cache in any circumstance without first revalidating with the origin.
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@ -452,13 +452,37 @@ class HttpCache implements HttpKernelInterface, TerminableInterface
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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::MASTER_REQUEST, $catch);
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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(), [500, 502, 503, 504])) {
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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 = $this->options['stale_if_error'];
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}
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if (abs($entry->getTtl()) < $age) {
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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 $entry;
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@ -1523,6 +1523,168 @@ class HttpCacheTest extends HttpCacheTestCase
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// Surrogate request
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$cache->handle($request, HttpKernelInterface::SUB_REQUEST);
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}
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public function testStaleIfErrorMustNotResetLifetime()
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{
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// Make sure we don't accidentally treat the response as fresh (revalidated) again
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// when stale-if-error handling kicks in.
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$responses = [
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[
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'status' => 200,
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'body' => 'OK',
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// This is cacheable and can be used in stale-if-error cases:
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'headers' => ['Cache-Control' => 'public, max-age=10', 'ETag' => 'some-etag'],
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],
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[
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'status' => 500,
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'body' => 'FAIL',
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'headers' => [],
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],
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[
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'status' => 500,
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'body' => 'FAIL',
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'headers' => [],
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],
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];
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$this->setNextResponses($responses);
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$this->cacheConfig['stale_if_error'] = 10;
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$this->request('GET', '/'); // warm cache
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sleep(15); // now the entry is stale, but still within the grace period (10s max-age + 10s stale-if-error)
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$this->request('GET', '/'); // hit backend error
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$this->assertEquals(200, $this->response->getStatusCode()); // stale-if-error saved the day
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$this->assertEquals(15, $this->response->getAge());
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sleep(10); // now we're outside the grace period
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$this->request('GET', '/'); // hit backend error
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$this->assertEquals(500, $this->response->getStatusCode()); // fail
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}
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/**
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* @dataProvider getResponseDataThatMayBeServedStaleIfError
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*/
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public function testResponsesThatMayBeUsedStaleIfError($responseHeaders, $sleepBetweenRequests = null)
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{
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$responses = [
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[
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'status' => 200,
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'body' => 'OK',
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'headers' => $responseHeaders,
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],
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[
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'status' => 500,
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'body' => 'FAIL',
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'headers' => [],
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],
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];
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$this->setNextResponses($responses);
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$this->cacheConfig['stale_if_error'] = 10; // after stale, may be served for 10s
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$this->request('GET', '/'); // warm cache
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if ($sleepBetweenRequests) {
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sleep($sleepBetweenRequests);
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}
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$this->request('GET', '/'); // hit backend error
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$this->assertEquals(200, $this->response->getStatusCode());
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$this->assertEquals('OK', $this->response->getContent());
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$this->assertTraceContains('stale-if-error');
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}
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public function getResponseDataThatMayBeServedStaleIfError()
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{
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// All data sets assume that a 10s stale-if-error grace period has been configured
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yield 'public, max-age expired' => [['Cache-Control' => 'public, max-age=60'], 65];
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yield 'public, validateable with ETag, no TTL' => [['Cache-Control' => 'public', 'ETag' => 'some-etag'], 5];
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yield 'public, validateable with Last-Modified, no TTL' => [['Cache-Control' => 'public', 'Last-Modified' => 'yesterday'], 5];
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yield 'public, s-maxage will be served stale-if-error, even if the RFC mandates otherwise' => [['Cache-Control' => 'public, s-maxage=20'], 25];
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}
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/**
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* @dataProvider getResponseDataThatMustNotBeServedStaleIfError
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*/
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public function testResponsesThatMustNotBeUsedStaleIfError($responseHeaders, $sleepBetweenRequests = null)
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{
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$responses = [
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[
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'status' => 200,
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'body' => 'OK',
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'headers' => $responseHeaders,
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],
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[
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'status' => 500,
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'body' => 'FAIL',
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'headers' => [],
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],
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];
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$this->setNextResponses($responses);
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$this->cacheConfig['stale_if_error'] = 10; // after stale, may be served for 10s
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$this->cacheConfig['strict_smaxage'] = true; // full RFC compliance for this feature
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$this->request('GET', '/'); // warm cache
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if ($sleepBetweenRequests) {
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sleep($sleepBetweenRequests);
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}
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$this->request('GET', '/'); // hit backend error
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$this->assertEquals(500, $this->response->getStatusCode());
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}
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public function getResponseDataThatMustNotBeServedStaleIfError()
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{
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// All data sets assume that a 10s stale-if-error grace period has been configured
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yield 'public, no TTL but beyond grace period' => [['Cache-Control' => 'public'], 15];
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yield 'public, validateable with ETag, no TTL but beyond grace period' => [['Cache-Control' => 'public', 'ETag' => 'some-etag'], 15];
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yield 'public, validateable with Last-Modified, no TTL but beyond grace period' => [['Cache-Control' => 'public', 'Last-Modified' => 'yesterday'], 15];
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yield 'public, stale beyond grace period' => [['Cache-Control' => 'public, max-age=10'], 30];
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// Cache-control values that prohibit serving stale responses or responses without positive validation -
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// see https://tools.ietf.org/html/rfc7234#section-4.2.4 and
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// https://tools.ietf.org/html/rfc7234#section-5.2.2
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yield 'no-cache requires positive validation' => [['Cache-Control' => 'public, no-cache', 'ETag' => 'some-etag']];
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yield 'no-cache requires positive validation, even if fresh' => [['Cache-Control' => 'public, no-cache, max-age=10']];
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yield 'must-revalidate requires positive validation once stale' => [['Cache-Control' => 'public, max-age=10, must-revalidate'], 15];
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yield 'proxy-revalidate requires positive validation once stale' => [['Cache-Control' => 'public, max-age=10, proxy-revalidate'], 15];
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}
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public function testStaleIfErrorWhenStrictSmaxageDisabled()
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{
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$responses = [
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[
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'status' => 200,
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'body' => 'OK',
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'headers' => ['Cache-Control' => 'public, s-maxage=20'],
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],
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[
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'status' => 500,
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'body' => 'FAIL',
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'headers' => [],
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],
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];
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$this->setNextResponses($responses);
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$this->cacheConfig['stale_if_error'] = 10;
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$this->cacheConfig['strict_smaxage'] = false;
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$this->request('GET', '/'); // warm cache
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sleep(25);
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$this->request('GET', '/'); // hit backend error
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$this->assertEquals(200, $this->response->getStatusCode());
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$this->assertEquals('OK', $this->response->getContent());
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$this->assertTraceContains('stale-if-error');
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}
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}
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class TestKernel implements HttpKernelInterface
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