class DownloadChain implements Runnable {

    public long processFetch() throws IOException {
        if (cache.isInterrupt()) throw InterruptException.SIGNAL;
        return fetchInterceptorList.get(fetchIndex++).interceptFetch(this);
    }

    private  DownloadChain(int blockIndex, @NonNull DownloadTask task, @NonNull BreakpointInfo info,
                          @NonNull DownloadCache cache, @NonNull DownloadStore store);

}