Re: RFC: Resumable clone based on hybrid "smart" and "dumb" HTTP

From: Junio C Hamano <gitster@pobox.com>
Date: Feb 10, 2016, 22:40 UTC
Message-ID: <xmqqwpqcxk87.fsf@gitster.mtv.corp.google.com>
In-Reply-To: <20160210214945.GA5853@sigill.intra.peff.net>

Jeff King <peff@peff.net> writes:

Show 5 quoted lines

> Clients do not have to _just_ fetch a packfile. They could get a bundle
> file that contains the roots along with the packfile. I know that one of
> your goals is not duplicating the storage of the packfile on the server,
> but it would not be hard for the server to store the packfile and the
> bundle header separately, and concatenate them on the fly.

Yeah, I was wondering about that. Just storing them as separate two-file pair on the server side and serving it as if it is a single file to the client does not sound like a rocket science, and a reasonable webserver should be able to serve even a byte-range request out of such a thing.

Of course, updating the clients to understand such a two-file pair as a valid bundle is a good thing to do, and I like that step 0. you outlined below.

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>   0. During gc, server generates pack-1234abcd.pack. It writes matching
>      tips into pack-1234abcd.info, which is essentially a bundle file
>      whose final line says "pack-1234abcd.pack".
>
>   1. Client contacts server via any git protocol. Server says
>      "resumable=<url>". Let's says that <url> is
>      https://example.com/repo/clones/1234abcd.bundle.
>
>   2. Client goes to <url>. They see that they are fetching a bundle,
>      and know not to do the usual smart-http or dumb-http protocols.
>      They can fetch the bundle header resumably (though it's tiny, so it
>      doesn't really matter).
> ...