code: public function calculateRequestFilename(Request $request) {
          $string = $request->getUri();
          $filename = parse_url($string, PHP_URL_HOST);
          $filename .= '_'.parse_url($string, PHP_URL_PATH);
          $headers = $request->getAllHeaders();
          ksort($headers);
          foreach ($headers as $header => $values) {
              $string .= $header;
              foreach ($values as $value) {
                  $string .= $value;
              }
          }
  
          $filename .= '_'.sha1($string);
  
          if (strpos($filename, '_') === 0) {
              //Makes sorting not be crap
              $filename = substr($filename, 1);
          }
  
          return $this->cacheDirectory.'/'.$filename.'.cache';
      }
docs: Calculate the filename that the request should be cached as