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<?php |
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namespace VDB\Spider\Downloader; |
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use VDB\Spider\Downloader\DownloaderInterface; |
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use Symfony\Component\EventDispatcher\Event; |
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use Symfony\Component\EventDispatcher\EventDispatcher; |
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use Symfony\Component\EventDispatcher\EventDispatcherInterface; |
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use Symfony\Component\EventDispatcher\GenericEvent; |
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use VDB\Spider\Event\SpiderEvents; |
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use VDB\Spider\PersistenceHandler\MemoryPersistenceHandler; |
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use VDB\Spider\PersistenceHandler\PersistenceHandlerInterface; |
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use VDB\Spider\RequestHandler\GuzzleRequestHandler; |
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use VDB\Spider\RequestHandler\RequestHandlerInterface; |
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use VDB\Spider\Filter\PostFetchFilterInterface; |
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use VDB\Spider\Resource; |
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use VDB\Spider\Uri\DiscoveredUri; |
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class Downloader implements DownloaderInterface |
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{ |
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/** @var EventDispatcherInterface */ |
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private $dispatcher; |
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/** @var PersistenceHandlerInterface */ |
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private $persistenceHandler; |
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/** @var RequestHandlerInterface */ |
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private $requestHandler; |
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/** @var int the maximum number of downloaded resources. 0 means no limit */ |
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private $downloadLimit = 0; |
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/** @var PostFetchFilterInterface[] */ |
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private $postFetchFilters = array(); |
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/** |
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* @param int Maximum number of resources to download |
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* @return $this |
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*/ |
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public function setDownloadLimit($downloadLimit) |
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{ |
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$this->downloadLimit = $downloadLimit; |
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return $this; |
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} |
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/** |
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* @return int Maximum number of resources to download |
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*/ |
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public function getDownloadLimit() |
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{ |
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return $this->downloadLimit; |
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} |
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/** |
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* @param PostFetchFilterInterface $filter |
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*/ |
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public function addPostFetchFilter(PostFetchFilterInterface $filter) |
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{ |
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$this->postFetchFilters[] = $filter; |
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} |
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/** |
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* @param DiscoveredUri $uri |
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* @return false|Resource |
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*/ |
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public function download(DiscoveredUri $uri) |
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{ |
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// Fetch the document |
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if (!$resource = $this->fetchResource($uri)) { |
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return false; |
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} |
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if ($this->matchesPostfetchFilter($resource)) { |
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return false; |
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} |
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$this->getPersistenceHandler()->persist($resource); |
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return $resource; |
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} |
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public function isDownLoadLimitExceeded() |
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{ |
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return $this->getDownloadLimit() !== 0 && $this->getPersistenceHandler()->count() >= $this->getDownloadLimit(); |
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} |
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/** |
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* A shortcut for EventDispatcher::dispatch() |
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* |
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* @param string $eventName |
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* @param null|Event $event |
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*/ |
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private function dispatch($eventName, Event $event = null) |
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{ |
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$this->getDispatcher()->dispatch($eventName, $event); |
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} |
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/** |
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* @param EventDispatcherInterface $eventDispatcher |
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* @return $this |
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*/ |
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public function setDispatcher(EventDispatcherInterface $eventDispatcher) |
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{ |
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$this->dispatcher = $eventDispatcher; |
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return $this; |
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} |
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/** |
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* @return EventDispatcherInterface |
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*/ |
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public function getDispatcher() |
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{ |
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if (!$this->dispatcher) { |
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$this->dispatcher = new EventDispatcher(); |
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} |
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return $this->dispatcher; |
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} |
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/** |
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* @param DiscoveredUri $uri |
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* @return Resource|false |
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*/ |
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protected function fetchResource(DiscoveredUri $uri) |
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{ |
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$resource = false; |
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$this->dispatch(SpiderEvents::SPIDER_CRAWL_PRE_REQUEST, new GenericEvent($this, array('uri' => $uri))); |
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try { |
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$resource = $this->getRequestHandler()->request($uri); |
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} catch (\Exception $e) { |
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$this->dispatch( |
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SpiderEvents::SPIDER_CRAWL_ERROR_REQUEST, |
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new GenericEvent($this, array('uri' => $uri, 'message' => $e->getMessage())) |
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); |
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} finally { |
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$this->dispatch(SpiderEvents::SPIDER_CRAWL_POST_REQUEST, new GenericEvent($this, array('uri' => $uri))); |
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} |
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return $resource; |
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} |
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/** |
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* @param Resource $resource |
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* @return bool |
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*/ |
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private function matchesPostfetchFilter(Resource $resource) |
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{ |
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foreach ($this->postFetchFilters as $filter) { |
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if ($filter->match($resource)) { |
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$this->dispatch( |
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SpiderEvents::SPIDER_CRAWL_FILTER_POSTFETCH, |
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new GenericEvent($this, array('uri' => $resource->getUri())) |
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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 PersistenceHandlerInterface $persistenceHandler |
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*/ |
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public function setPersistenceHandler(PersistenceHandlerInterface $persistenceHandler) |
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{ |
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$this->persistenceHandler = $persistenceHandler; |
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} |
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/** |
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* @return PersistenceHandlerInterface |
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*/ |
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public function getPersistenceHandler() |
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{ |
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if (!$this->persistenceHandler) { |
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$this->persistenceHandler = new MemoryPersistenceHandler(); |
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} |
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return $this->persistenceHandler; |
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} |
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/** |
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* @param RequestHandlerInterface $requestHandler |
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*/ |
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public function setRequestHandler(RequestHandlerInterface $requestHandler) |
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{ |
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$this->requestHandler = $requestHandler; |
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} |
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/** |
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* @return RequestHandlerInterface |
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*/ |
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public function getRequestHandler() |
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{ |
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if (!$this->requestHandler) { |
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$this->requestHandler = new GuzzleRequestHandler(); |
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} |
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return $this->requestHandler; |
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} |
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} |
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mvdbos /
php-spider
