Rss-Bridge/lib/HttpCachingBridgeAbstract.php

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<?php
require_once(__DIR__ . '/BridgeInterface.php');
/**
* Extension of BridgeAbstract allowing caching of files downloaded over http.
* TODO allow file cache invalidation by touching files on access, and removing
* files/directories which have not been touched since ... a long time
*/
abstract class HttpCachingBridgeAbstract extends BridgeAbstract {
/**
* Maintain locally cached versions of pages to download, to avoid multiple downloads.
* @param url url to cache
* @param duration duration of the cache file in seconds (default: 24h/86400s)
* @return content of the file as string
*/
public function get_cached($url, $duration = 86400){
$filepath = $this->buildCacheFilePath($url);
if(file_exists($filepath) && filectime($filepath) < time() - $duration){
$this->debugMessage('Cache file ' . $filepath . ' exceeded duration of ' . $duration . ' seconds.');
unlink ($filepath);
$this->debugMessage('Cached file deleted: ' . $filepath);
}
if(file_exists($filepath)){
$this->debugMessage('loading cached file from ' . $filepath . ' for page at url ' . $url);
// TODO touch file and its parent, and try to do neighbour deletion
touch($filepath);
$content = file_get_contents($filepath);
} else {
$this->debugMessage('we have no local copy of ' . $url . ' Downloading to ' . $filepath);
$dir = substr($filepath, 0, strrpos($filepath, '/'));
if(!is_dir($dir)){
$this->debugMessage('creating directories for ' . $dir);
mkdir($dir, 0777, true);
}
$content = $this->getContents($url);
if($content !== false){
file_put_contents($filepath, $content);
}
}
return str_get_html($content);
}
private function buildCacheFilePath($url){
return __DIR__ . '/../cache/pages/' . sha1($url) . '.cache';
}
}