90 lines
3 KiB
PHP
90 lines
3 KiB
PHP
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<?php
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require_once(__DIR__ . '/BridgeInterface.php');
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/**
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* Extension of BridgeAbstract allowing caching of files downloaded over http.
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* TODO allow file cache invalidation by touching files on access, and removing
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* files/directories which have not been touched since ... a long time
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*/
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abstract class HttpCachingBridgeAbstract extends BridgeAbstract {
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/**
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* Maintain locally cached versions of pages to download, to avoid multiple downloads.
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* @param url url to cache
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* @return content of the file as string
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*/
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public function get_cached($url){
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// TODO build this from the variable given to Cache
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$cacheDir = __DIR__ . '/../cache/pages/';
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$filepath = $this->buildCacheFilePath($url, $cacheDir);
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if(file_exists($filepath)){
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$this->debugMessage('loading cached file from ' . $filepath . ' for page at url ' . $url);
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// TODO touch file and its parent, and try to do neighbour deletion
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$this->refresh_in_cache($cacheDir, $filepath);
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$content = file_get_contents($filepath);
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} else {
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$this->debugMessage('we have no local copy of ' . $url . ' Downloading to ' . $filepath);
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$dir = substr($filepath, 0, strrpos($filepath, '/'));
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if(!is_dir($dir)){
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$this->debugMessage('creating directories for ' . $dir);
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mkdir($dir, 0777, true);
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}
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$content = $this->getContents($url);
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if($content !== false){
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file_put_contents($filepath, $content);
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}
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}
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return str_get_html($content);
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}
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public function get_cached_time($url){
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// TODO build this from the variable given to Cache
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$cacheDir = __DIR__ . '/../cache/pages/';
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$filepath = $this->buildCacheFilePath($url, $cacheDir);
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if(!file_exists($filepath)){
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$this->get_cached($url);
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}
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return filectime($filepath);
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}
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private function refresh_in_cache($cacheDir, $filepath){
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$currentPath = $filepath;
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while(!$cacheDir == $currentPath){
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touch($currentPath);
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$currentPath = dirname($currentPath);
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}
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}
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private function buildCacheFilePath($url, $cacheDir){
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$simplified_url = str_replace(
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['http://', 'https://', '?', '&', '='],
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['', '', '/', '/', '/'],
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$url);
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if(substr($cacheDir, -1) !== '/'){
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$cacheDir .= '/';
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}
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$filepath = $cacheDir . $simplified_url;
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if(substr($filepath, -1) === '/'){
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$filepath .= 'index.html';
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}
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return $filepath;
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}
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public function remove_from_cache($url){
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// TODO build this from the variable given to Cache
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$cacheDir = __DIR__ . '/../cache/pages/';
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$filepath = $this->buildCacheFilePath($url, $cacheDir);
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$this->debugMessage('removing from cache \'' . $filepath . '\'');
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unlink($filepath);
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}
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}
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