[RFE] Incremental download during initial installation

[smcv]

https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=850042 requests the ability to resume interrupted downloads.

My understanding is that OSTree already does incremental downloads on a per-blob basis (a blob is either fully downloaded, or only partially downloaded and hence discarded) so perhaps this is really a request to keep partially-downloaded blobs, and resume on a smaller-than-file granularity?

(Or perhaps the delta format in archive-z2 repositories breaks the incremental property by either keeping or discarding entire deltas, in this case about 120M?)

[smcv]

(I'm forwarding this because it was reported to Debian, but I personally think this is of considerably lower priority than making the current non-incremental downloads more reliable, e.g. #605.)

[cgwalters]

The libsoup code does do range requests. We do cache intermediate downloaded individual object blobs, as well as delta parts. Remember the delta generator by default chunks by 32MB, to avoid redownloading everything when faced with servers that don't do range requests.