switch ver {
	case dataUsageCacheVerV1:
		return errors.New("cache version deprecated (will autoupdate)")
	case dataUsageCacheVerV2:
		// Zstd compressed.
		dec, err := zstd.NewReader(r, zstd.WithDecoderConcurrency(2))
		if err != nil {
			return err
		}
		defer dec.Close()

		dold := &dataUsageCacheV2{}
		if err = dold.DecodeMsg(msgp.NewReader(dec)); err != nil {
			return err
		}

			pbzip2.BZConcurrencyPool(bz2Limiter),
		))
		pr.closer = &nopReadCloser{fn: cancel}
	case zstdType:
		// Set a max window of 64MB. More than reasonable.
		zr, err := zstd.NewReader(scannedReader, zstd.WithDecoderConcurrency(2), zstd.WithDecoderMaxWindow(64<<20))
		if err != nil {
			return nil, errInvalidCompression(err, compType)
		}
		r = zr
		pr.closer = zr.IOReadCloser()
	case lz4Type: