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<?php |
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namespace CybozuHttp\Subscriber; |
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use CybozuHttp\Subscriber\Cache\CacheStorage; |
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use GuzzleHttp\Event\HasEmitterInterface; |
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use GuzzleHttp\Event\BeforeEvent; |
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use GuzzleHttp\Event\CompleteEvent; |
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use GuzzleHttp\Event\RequestEvents; |
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use GuzzleHttp\Event\SubscriberInterface; |
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use GuzzleHttp\Message\RequestInterface; |
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use GuzzleHttp\Message\ResponseInterface; |
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/** |
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* @author ochi51 <[email protected]> |
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*/ |
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class CacheSubscriber implements SubscriberInterface |
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{ |
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/** @var CacheStorage $cache Object used to cache responses */ |
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protected $storage; |
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/** |
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* @param CacheStorage $cache Cache storage |
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*/ |
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public function __construct(CacheStorage $cache) |
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{ |
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$this->storage = $cache; |
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} |
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/** |
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* @param HasEmitterInterface $subject |
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* @param CacheStorage|null $storage |
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* @return array |
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*/ |
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public static function attach(HasEmitterInterface $subject, CacheStorage $storage) |
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{ |
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$emitter = $subject->getEmitter(); |
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$cache = new self($storage); |
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$emitter->attach($cache); |
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return ['subscriber' => $cache, 'storage' => $storage]; |
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} |
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/** |
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* @return array |
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*/ |
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public function getEvents() |
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{ |
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return [ |
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'before' => ['onBefore', RequestEvents::LATE], |
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'complete' => ['onComplete', RequestEvents::EARLY] |
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]; |
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} |
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/** |
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* Checks if a request can be cached, and if so, intercepts with a cached |
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* response is available. |
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*/ |
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public function onBefore(BeforeEvent $event) |
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{ |
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$request = $event->getRequest(); |
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if (!($response = $this->storage->fetch($request))) { |
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$this->cacheMiss($request); |
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return; |
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} |
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$request->getConfig()->set('cache_lookup', 'HIT'); |
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$request->getConfig()->set('cache_hit', true); |
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$event->intercept($response); |
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} |
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/** |
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* Checks if the request and response can be cached, and if so, store it |
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*/ |
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public function onComplete(CompleteEvent $event) |
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{ |
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$request = $event->getRequest(); |
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$response = $event->getResponse(); |
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// Cache the response if it can be cached and isn't already |
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if ($request->getConfig()->get('cache_lookup') === 'MISS') { |
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$this->storage->cache($request, $response); |
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} |
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$this->addResponseHeaders($request, $response); |
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} |
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private function cacheMiss(RequestInterface $request) |
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{ |
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$request->getConfig()->set('cache_lookup', 'MISS'); |
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} |
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private function addResponseHeaders(RequestInterface $request, ResponseInterface $response) |
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{ |
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$params = $request->getConfig(); |
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$lookup = $params['cache_lookup'] . ' from GuzzleCache'; |
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$response->addHeader('X-Cache-Lookup', $lookup); |
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if ($params['cache_hit'] === true) { |
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$response->addHeader('X-Cache', 'HIT from GuzzleCache'); |
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} else { |
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$response->addHeader('X-Cache', 'MISS from GuzzleCache'); |
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} |
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} |
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} |
Unless you are absolutely sure that the expression can never be null because of other conditions, we strongly recommend to add an additional type check to your code: