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<?php |
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namespace Http\Client\Plugin; |
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use Http\Client\Tools\Promise\FulfilledPromise; |
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use Http\Message\StreamFactory; |
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use Psr\Cache\CacheItemPoolInterface; |
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use Psr\Http\Message\RequestInterface; |
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use Psr\Http\Message\ResponseInterface; |
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use Symfony\Component\OptionsResolver\OptionsResolver; |
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/** |
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* Allow for caching a response. |
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* |
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* @author Tobias Nyholm <[email protected]> |
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*/ |
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class CachePlugin implements Plugin |
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{ |
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/** |
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* @var CacheItemPoolInterface |
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*/ |
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private $pool; |
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/** |
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* @var StreamFactory |
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*/ |
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private $streamFactory; |
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private $config = [ |
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'default_ttl' => null, |
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'respect_cache_headers' => true |
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]; |
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/** |
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* @param CacheItemPoolInterface $pool |
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* @param StreamFactory $streamFactory |
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* @param array $config |
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*/ |
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public function __construct(CacheItemPoolInterface $pool, StreamFactory $streamFactory, array $config = []) |
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{ |
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$this->pool = $pool; |
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$this->streamFactory = $streamFactory; |
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$this->config = $this->configure($config); |
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} |
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/** |
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* {@inheritdoc} |
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*/ |
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public function handleRequest(RequestInterface $request, callable $next, callable $first) |
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{ |
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$method = strtoupper($request->getMethod()); |
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// if the request not is cachable, move to $next |
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if ($method !== 'GET' && $method !== 'HEAD') { |
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return $next($request); |
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} |
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// If we can cache the request |
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$key = $this->createCacheKey($request); |
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$cacheItem = $this->pool->getItem($key); |
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if ($cacheItem->isHit()) { |
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// return cached response |
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$data = $cacheItem->get(); |
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$response = $data['response']; |
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$response = $response->withBody($this->streamFactory->createStream($data['body'])); |
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return new FulfilledPromise($response); |
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} |
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return $next($request)->then(function (ResponseInterface $response) use ($cacheItem) { |
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if ($this->isCacheable($response)) { |
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$cacheItem->set(['response' => $response, 'body' => $response->getBody()->__toString()]) |
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->expiresAfter($this->getMaxAge($response)); |
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$this->pool->save($cacheItem); |
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} |
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return $response; |
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}); |
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} |
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/** |
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* Verify that we can cache this response. |
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* |
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* @param ResponseInterface $response |
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* |
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* @return bool |
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*/ |
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protected function isCacheable(ResponseInterface $response) |
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{ |
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$cachableCodes = [200, 203, 300, 301, 302, 404, 410]; |
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$privateHeaders = $this->getCacheControlDirective($response, 'no-store') || $this->getCacheControlDirective($response, 'private'); |
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// If http status code is cachable and if we respect the headers, make sure there is no private cache headers. |
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return in_array($response->getStatusCode(), $cachableCodes) && !($this->respectCacheHeaders && $privateHeaders); |
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} |
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/** |
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* Returns the value of a parameter in the cache control header. If not found we return false. If found with no |
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* value return true. |
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* |
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* @param ResponseInterface $response |
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* @param string $name |
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* |
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* @return bool|string |
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*/ |
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private function getCacheControlDirective(ResponseInterface $response, $name) |
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{ |
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$headers = $response->getHeader('Cache-Control'); |
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foreach ($headers as $header) { |
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if (preg_match(sprintf('|%s=?([0-9]+)?|i', $name), $header, $matches)) { |
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// return the value for $name if it exists |
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if (isset($matches[1])) { |
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return $matches[1]; |
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} |
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return true; |
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} |
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} |
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return false; |
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} |
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/** |
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* @param RequestInterface $request |
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* |
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* @return string |
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*/ |
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private function createCacheKey(RequestInterface $request) |
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{ |
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return md5($request->getMethod().' '.$request->getUri()); |
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} |
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/** |
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* Get a ttl in seconds. It could return null if we do not respect cache headers and got no defaultTtl. |
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* |
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* @param ResponseInterface $response |
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* |
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* @return int|null |
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*/ |
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private function getMaxAge(ResponseInterface $response) |
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{ |
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if (!$this->config['respect_cache_headers']) { |
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return $this->config['default_ttl']; |
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} |
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// check for max age in the Cache-Control header |
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$maxAge = $this->getCacheControlDirective($response, 'max-age'); |
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if (!is_bool($maxAge)) { |
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$ageHeaders = $response->getHeader('Age'); |
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foreach ($ageHeaders as $age) { |
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return $maxAge - ((int) $age); |
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} |
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return $maxAge; |
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} |
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// check for ttl in the Expires header |
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$headers = $response->getHeader('Expires'); |
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foreach ($headers as $header) { |
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return (new \DateTime($header))->getTimestamp() - (new \DateTime())->getTimestamp(); |
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} |
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return $this->config['default_ttl']; |
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} |
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/** |
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* @param array $config |
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* |
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* @return array |
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*/ |
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protected function configure(array $config = []) |
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{ |
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$resolver = new OptionsResolver(); |
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$resolver->setDefaults($this->config); |
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$resolver->setAllowedTypes('default_ttl', 'int'); |
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$resolver->setAllowedTypes('respect_cache_headers', 'bool'); |
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return $resolver->resolve($config); |
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} |
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} |
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In PHP it is possible to write to properties without declaring them. For example, the following is perfectly valid PHP code:
Generally, it is a good practice to explictly declare properties to avoid accidental typos and provide IDE auto-completion: