// Use Close to ensure resources are released on incomplete streams.
//
// input 'on' is always recommended such that this function works
// properly, because we do not wish to create an object even if
// client closed the stream prematurely.
func newS2CompressReader(r io.Reader, on int64, encrypted bool) (rc io.ReadCloser, idx func() []byte) {
	pr, pw := io.Pipe()
	// Copy input to compressor