8000 [HttpKernel] Be smarter when merging cache directives in HttpCache/ResponseCacheStrategy by nicolas-grekas · Pull Request #26352 · symfony/symfony · GitHub
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[HttpKernel] Be smarter when merging cache directives in HttpCache/ResponseCacheStrategy #26352

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[HttpKernel] Be smarter when merging cache directives in HttpCache/ResponseCacheStrategy #26352

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a243bca
[HttpKernel] Be smarter when merging cache directives in HttpCache/Re…
nicolas-grekas Mar 1, 2018
4392826
Added various unit tests to validate the ResponseCacheStrategy
aschempp Mar 1, 2018
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27 changes: 20 additions & 7 deletions src/Symfony/Component/HttpKernel/HttpCache/ResponseCacheStrategy.php
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Original file line number Diff line number Diff line change
Expand Up @@ -30,6 +30,13 @@ class ResponseCacheStrategy implements ResponseCacheStrategyInterface
{
private $cacheable = true;
private $embeddedResponses = 0;
private $cacheDirectives = array(
'no-cache' => false,
'no-store' => false,
'must-revalidate' => false,
'private' => false,
'proxy-revalidate' => false,
);
private $ttls = array();
private $maxAges = array();
private $isNotCacheableResponseEmbedded = false;
Expand All @@ -41,6 +48,17 @@ public function add(Response $response)
{
if (!$response->isFresh() || !$response->isCacheable()) {
$this->cacheable = false;

$hasCacheDirective = $response->headers->hasCacheControlDirective('public');
foreach ($this->cacheDirectives as $directive => $status) {
if ($response->headers->hasCacheControlDirective($directive)) {
$this->cacheDirectives[$directive] = $hasCacheDirective = true;
}
}

if (!$hasCacheDirective || !$response->isFresh()) {
$this->cacheDirectives['no-cache'] = $this->cacheDirectives['must-revalidate'] = true;
}
} else {
$maxAge = $response->getMaxAge();
$this->ttls[] = $response->getTtl();
Expand Down Expand Up @@ -72,19 +90,14 @@ public function update(Response $response)
$response->setLastModified(null);
}

if (!$response->isFresh()) {
$this->cacheable = false;
}
$this->add($response);

if (!$this->cacheable) {
$response->headers->set('Cache-Control', 'no-cache, must-revalidate');
$response->headers->set('Cache-Control', implode(', ', array_keys(array_filter($this->cacheDirectives))));
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what about the max age allowing client-side caching ?

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let's say we don't care, we don't have to be that smart?

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well, allowing private caching without telling the browser how long it can cache it is broken: it won't allow caching in well-behaving browsers (and may allow infinite caching if a crappy browser treats the absence of age on the response as an invitation to cache forever instead of for 0s).

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client side caching can have 2 modes: expiration-based (caching for a timestamp) and validation-based (asking whether the last-modified or the etag they have is still the right one).
When using ESI or SSI (which this code is about), we don't send an Etag or LastModified (which this class is handling) because we cannot build them properly when the final response is built based on embedded responses. So this only leaves the expiration-based caching client-side. If you don't care about it, close your PR as it brings nothing.

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I'm about to create unit tests to validate that case so we can implement the re 10000 quired checks.

we don't send an Etag or LastModified (which this class is handling) because we cannot build them properly when the final response is built based on embedded responses.

Actually we could do that by generating an ETag based on the complete response. Something like a hash of the whole content. But I think that's for another PR if we want to add that at all.

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see nicolas-grekas#13

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not helpful, as we could still not use Etag validation of the different sub-requests as we would not have Etags for each of them (unless we build the final Etag as a reversible combination of info about each response), and so we could not perform Etag validation in the controllers generating each subresponse.


return;
}

$this->ttls[] = $response->getTtl();
$this->maxAges[] = $response->getMaxAge();

if ($this->isNotCacheableResponseEmbedded) {
$response->headers->removeCacheControlDirective('s-maxage');
} elseif (null !== $maxAge = min($this->maxAges)) {
Expand Down
20 changes: 20 additions & 0 deletions src/Symfony/Component/HttpKernel/Tests/HttpCache/ResponseCacheStrategyTest.php
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Expand Up @@ -219,4 +219,24 @@ public function testResponseIsExpirableButNotValidateableWhenMasterResponseCombi
$this->assertSame('60', $masterResponse->headers->getCacheControlDirective('s-maxage'));
$this->assertFalse($masterResponse->isValidateable());
}

public function testResponseIsPrivateWhenCombiningPrivateResponses()
{
$cacheStrategy = new ResponseCacheStrategy();

$masterResponse = new Response();
$masterResponse->setSharedMaxAge(60);
$masterResponse->setPrivate();

$embeddedResponse = new Response();
$embeddedResponse->setSharedMaxAge(60);
$embeddedResponse->setPrivate();

$cacheStrategy->add($embeddedResponse);
$cacheStrategy->update($masterResponse);

$this->assertFalse($masterResponse->headers->hasCacheControlDirective('no-cache'));
$this->assertFalse($masterResponse->headers->hasCacheControlDirective('must-revalidate'));
$this->assertTrue($masterResponse->headers->hasCacheControlDirective('private'));
}
}
0