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[HttpKernel] Correctly merging cache directives in HttpCache/ResponseCacheStrategy

This commit is contained in:
Andreas Schempp 2018-03-14 17:46:26 +07:00 committed by Fabien Potencier
parent 3cfb558f03
commit 893118f978
2 changed files with 391 additions and 36 deletions
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198
src/Symfony/Component/HttpKernel/HttpCache/ResponseCacheStrategy.php
View File

@ -5,10 +5,6 @@
*
* (c) Fabien Potencier <fabien@symfony.com>
*
* This code is partially based on the Rack-Cache library by Ryan Tomayko,
* which is released under the MIT license.
* (based on commit 02d2b48d75bcb63cf1c0c7149c077ad256542801)
*
* For the full copyright and license information, please view the LICENSE
* file that was distributed with this source code.
*/
@ -28,30 +24,69 @@ use Symfony\Component\HttpFoundation\Response;
*/
class ResponseCacheStrategy implements ResponseCacheStrategyInterface
{
private $cacheable = true;
/**
* Cache-Control headers that are sent to the final response if they appear in ANY of the responses.
*/
private static $overrideDirectives = ['private', 'no-cache', 'no-store', 'no-transform', 'must-revalidate', 'proxy-revalidate'];
/**
* Cache-Control headers that are sent to the final response if they appear in ALL of the responses.
*/
private static $inheritDirectives = ['public', 'immutable'];
private $embeddedResponses = 0;
private $ttls = [];
private $maxAges = [];
private $isNotCacheableResponseEmbedded = false;
private $age = 0;
private $flagDirectives = [
'no-cache' => null,
'no-store' => null,
'no-transform' => null,
'must-revalidate' => null,
'proxy-revalidate' => null,
'public' => null,
'private' => null,
'immutable' => null,
];
private $ageDirectives = [
'max-age' => null,
's-maxage' => null,
'expires' => null,
];
/**
* {@inheritdoc}
*/
public function add(Response $response)
{
if (!$response->isFresh() || !$response->isCacheable()) {
$this->cacheable = false;
} else {
$maxAge = $response->getMaxAge();
$this->ttls[] = $response->getTtl();
$this->maxAges[] = $maxAge;
++$this->embeddedResponses;
if (null === $maxAge) {
$this->isNotCacheableResponseEmbedded = true;
foreach (self::$overrideDirectives as $directive) {
if ($response->headers->hasCacheControlDirective($directive)) {
$this->flagDirectives[$directive] = true;
}
}
++$this->embeddedResponses;
foreach (self::$inheritDirectives as $directive) {
if (false !== $this->flagDirectives[$directive]) {
$this->flagDirectives[$directive] = $response->headers->hasCacheControlDirective($directive);
}
}
$age = $response->getAge();
$this->age = max($this->age, $age);
if ($this->willMakeFinalResponseUncacheable($response)) {
$this->isNotCacheableResponseEmbedded = true;
return;
}
$this->storeRelativeAgeDirective('max-age', $response->headers->getCacheControlDirective('max-age'), $age);
$this->storeRelativeAgeDirective('s-maxage', $response->headers->getCacheControlDirective('s-maxage') ?: $response->headers->getCacheControlDirective('max-age'), $age);
$expires = $response->getExpires();
$expires = null !== $expires ? $expires->format('U') - $response->getDate()->format('U') : null;
$this->storeRelativeAgeDirective('expires', $expires >= 0 ? $expires : null, 0);
}
/**
@ -64,33 +99,124 @@ class ResponseCacheStrategy implements ResponseCacheStrategyInterface
return;
}
// Remove validation related headers in order to avoid browsers using
// their own cache, because some of the response content comes from
// at least one embedded response (which likely has a different caching strategy).
if ($response->isValidateable()) {
$response->setEtag(null);
$response->setLastModified(null);
}
// Remove validation related headers of the master response,
// because some of the response content comes from at least
// one embedded response (which likely has a different caching strategy).
$response->setEtag(null);
$response->setLastModified(null);
if (!$response->isFresh() || !$response->isCacheable()) {
$this->cacheable = false;
}
$this->add($response);
if (!$this->cacheable) {
$response->headers->set('Cache-Control', 'no-cache, must-revalidate');
$response->headers->set('Age', $this->age);
if ($this->isNotCacheableResponseEmbedded) {
$response->setExpires($response->getDate());
if ($this->flagDirectives['no-store']) {
$response->headers->set('Cache-Control', 'no-cache, no-store, must-revalidate');
} else {
$response->headers->set('Cache-Control', 'no-cache, must-revalidate');
}
return;
}
$this->ttls[] = $response->getTtl();
$this->maxAges[] = $response->getMaxAge();
$flags = array_filter($this->flagDirectives);
if ($this->isNotCacheableResponseEmbedded) {
$response->headers->removeCacheControlDirective('s-maxage');
} elseif (null !== $maxAge = min($this->maxAges)) {
$response->setSharedMaxAge($maxAge);
$response->headers->set('Age', $maxAge - min($this->ttls));
if (isset($flags['must-revalidate'])) {
$flags['no-cache'] = true;
}
$response->headers->set('Cache-Control', implode(', ', array_keys($flags)));
$maxAge = null;
$sMaxage = null;
if (\is_numeric($this->ageDirectives['max-age'])) {
$maxAge = $this->ageDirectives['max-age'] + $this->age;
$response->headers->addCacheControlDirective('max-age', $maxAge);
}
if (\is_numeric($this->ageDirectives['s-maxage'])) {
$sMaxage = $this->ageDirectives['s-maxage'] + $this->age;
if ($maxAge !== $sMaxage) {
$response->headers->addCacheControlDirective('s-maxage', $sMaxage);
}
}
if (\is_numeric($this->ageDirectives['expires'])) {
$date = clone $response->getDate();
$date->modify('+'.($this->ageDirectives['expires'] + $this->age).' seconds');
$response->setExpires($date);
}
}
/**
* RFC2616, Section 13.4.
*
* @see https://www.w3.org/Protocols/rfc2616/rfc2616-sec13.html#sec13.4
*
* @return bool
*/
private function willMakeFinalResponseUncacheable(Response $response)
{
// RFC2616: A response received with a status code of 200, 203, 300, 301 or 410
// MAY be stored by a cache […] unless a cache-control directive prohibits caching.
if ($response->headers->hasCacheControlDirective('no-cache')
|| $response->headers->getCacheControlDirective('no-store')
) {
return true;
}
// Last-Modified and Etag headers cannot be merged, they render the response uncacheable
// by default (except if the response also has max-age etc.).
if (\in_array($response->getStatusCode(), [200, 203, 300, 301, 410])
&& null === $response->getLastModified()
&& null === $response->getEtag()
) {
return false;
}
// RFC2616: A response received with any other status code (e.g. status codes 302 and 307)
// MUST NOT be returned in a reply to a subsequent request unless there are
// cache-control directives or another header(s) that explicitly allow it.
$cacheControl = ['max-age', 's-maxage', 'must-revalidate', 'proxy-revalidate', 'public', 'private'];
foreach ($cacheControl as $key) {
if ($response->headers->hasCacheControlDirective($key)) {
return false;
}
}
if ($response->headers->has('Expires')) {
return false;
}
return true;
}
/**
* Store lowest max-age/s-maxage/expires for the final response.
*
* The response might have been stored in cache a while ago. To keep things comparable,
* we have to subtract the age so that the value is normalized for an age of 0.
*
* If the value is lower than the currently stored value, we update the value, to keep a rolling
* minimal value of each instruction. If the value is NULL, the directive will not be set on the final response.
*
* @param string $directive
* @param int|null $value
* @param int $age
*/
private function storeRelativeAgeDirective($directive, $value, $age)
{
if (null === $value) {
$this->ageDirectives[$directive] = false;
}
if (false !== $this->ageDirectives[$directive]) {
$value = $value - $age;
$this->ageDirectives[$directive] = null !== $this->ageDirectives[$directive] ? min($this->ageDirectives[$directive], $value) : $value;
}
$response->setMaxAge(0);
}
}

229
src/Symfony/Component/HttpKernel/Tests/HttpCache/ResponseCacheStrategyTest.php
View File

@ -237,4 +237,233 @@ class ResponseCacheStrategyTest extends TestCase
$this->assertSame('60', $masterResponse->headers->getCacheControlDirective('s-maxage'));
$this->assertFalse($masterResponse->isValidateable());
}
/**
* @dataProvider cacheControlMergingProvider
*/
public function testCacheControlMerging(array $expects, array $master, array $surrogates)
{
$cacheStrategy = new ResponseCacheStrategy();
$buildResponse = function ($config) {
$response = new Response();
foreach ($config as $key => $value) {
switch ($key) {
case 'age':
$response->headers->set('Age', $value);
break;
case 'expires':
$expires = clone $response->getDate();
$expires->modify('+'.$value.' seconds');
$response->setExpires($expires);
break;
case 'max-age':
$response->setMaxAge($value);
break;
case 's-maxage':
$response->setSharedMaxAge($value);
break;
case 'private':
$response->setPrivate();
break;
case 'public':
$response->setPublic();
break;
default:
$response->headers->addCacheControlDirective($key, $value);
}
}
return $response;
};
foreach ($surrogates as $config) {
$cacheStrategy->add($buildResponse($config));
}
$response = $buildResponse($master);
$cacheStrategy->update($response);
foreach ($expects as $key => $value) {
if ('expires' === $key) {
$this->assertSame($value, $response->getExpires()->format('U') - $response->getDate()->format('U'));
} elseif ('age' === $key) {
$this->assertSame($value, $response->getAge());
} elseif (true === $value) {
$this->assertTrue($response->headers->hasCacheControlDirective($key), sprintf('Cache-Control header must have "%s" flag', $key));
} elseif (false === $value) {
$this->assertFalse(
$response->headers->hasCacheControlDirective($key),
sprintf('Cache-Control header must NOT have "%s" flag', $key)
);
} else {
$this->assertSame($value, $response->headers->getCacheControlDirective($key), sprintf('Cache-Control flag "%s" should be "%s"', $key, $value));
}
}
}
public function cacheControlMergingProvider()
{
yield 'result is public if all responses are public' => [
['private' => false, 'public' => true],
['public' => true],
[
['public' => true],
],
];
yield 'result is private by default' => [
['private' => true, 'public' => false],
['public' => true],
[
[],
],
];
yield 'combines public and private responses' => [
['must-revalidate' => false, 'private' => true, 'public' => false],
['public' => true],
[
['private' => true],
],
];
yield 'inherits no-cache from surrogates' => [
['no-cache' => true, 'public' => false],
['public' => true],
[
['no-cache' => true],
],
];
yield 'inherits no-store from surrogate' => [
['no-store' => true, 'public' => false],
['public' => true],
[
['no-store' => true],
],
];
yield 'resolve to lowest possible max-age' => [
['public' => false, 'private' => true, 's-maxage' => false, 'max-age' => '60'],
['public' => true, 'max-age' => 3600],
[
['private' => true, 'max-age' => 60],
],
];
yield 'resolves multiple max-age' => [
['public' => false, 'private' => true, 's-maxage' => false, 'max-age' => '60'],
['private' => true, 'max-age' => 100],
[
['private' => true, 'max-age' => 3600],
['public' => true, 'max-age' => 60, 's-maxage' => 60],
['private' => true, 'max-age' => 60],
],
];
yield 'merge max-age and s-maxage' => [
['public' => true, 's-maxage' => '60', 'max-age' => null],
['public' => true, 's-maxage' => 3600],
[
['public' => true, 'max-age' => 60],
],
];
yield 'result is private when combining private responses' => [
['no-cache' => false, 'must-revalidate' => false, 'private' => true],
['s-maxage' => 60, 'private' => true],
[
['s-maxage' => 60, 'private' => true],
],
];
yield 'result can have s-maxage and max-age' => [
['public' => true, 'private' => false, 's-maxage' => '60', 'max-age' => '30'],
['s-maxage' => 100, 'max-age' => 2000],
[
['s-maxage' => 1000, 'max-age' => 30],
['s-maxage' => 500, 'max-age' => 500],
['s-maxage' => 60, 'max-age' => 1000],
],
];
yield 'does not set headers without value' => [
['max-age' => null, 's-maxage' => null, 'public' => null],
['private' => true],
[
['private' => true],
],
];
yield 'max-age 0 is sent to the client' => [
['private' => true, 'max-age' => '0'],
['max-age' => 0, 'private' => true],
[
['max-age' => 60, 'private' => true],
],
];
yield 'max-age is relative to age' => [
['max-age' => '240', 'age' => 60],
['max-age' => 180],
[
['max-age' => 600, 'age' => 60],
],
];
yield 'retains lowest age of all responses' => [
['max-age' => '160', 'age' => 60],
['max-age' => 600, 'age' => 60],
[
['max-age' => 120, 'age' => 20],
],
];
yield 'max-age can be less than age, essentially expiring the response' => [
['age' => 120, 'max-age' => '90'],
['max-age' => 90, 'age' => 120],
[
['max-age' => 120, 'age' => 60],
],
];
yield 'max-age is 0 regardless of age' => [
['max-age' => '0'],
['max-age' => 60],
[
['max-age' => 0, 'age' => 60],
],
];
yield 'max-age is not negative' => [
['max-age' => '0'],
['max-age' => 0],
[
['max-age' => 0, 'age' => 60],
],
];
yield 'calculates lowest Expires header' => [
['expires' => 60],
['expires' => 60],
[
['expires' => 120],
],
];
yield 'calculates Expires header relative to age' => [
['expires' => 210, 'age' => 120],
['expires' => 90],
[
['expires' => 600, 'age' => '120'],
],
];
}
}