/** * Look up the cache file and if it exists and hasn't expired return the * path to the cache file. * * @param string $header * The raw request header * @return string|bool */ protected function get_cache($header) { $key = $this->create_cache_key($header); $file = Net::tmpdir() . "/{$key}.cache"; if (file_exists($file)) { $mtime = filemtime($file); if (time() < $mtime + $this->cache) { $this->cache = 0; return $file; } else { unlink($file); } } return false; }