Re: Git Smart HTTP with HTTP/2.0

From: Ilari Liusvaara <ilari.liusvaara@elisanet.fi>
Date: Jul 11, 2015, 18:26 UTC
Message-ID: <20150711182657.GA8589@LK-Perkele-VII>
In-Reply-To: <CAJo=hJs21m1C6+rdvCid311-TapK=QKLkqrH8aUZmzHH7CpVug@mail.gmail.com>

On Sat, Jul 11, 2015 at 10:23:09AM -0700, Shawn Pearce wrote:

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> On Sat, Jul 11, 2015 at 12:00 AM, Ilari Liusvaara
> <ilari.liusvaara@elisanet.fi> wrote:
> > On Sat, Jul 11, 2015 at 11:10:48AM +0800, ForceCharlie wrote:
> >
> >> Frequently used Git developers often feel Git HTTP protocol is not
> >> satisfactory, slow and unstable.This is because the HTTP protocol itself
> >> decides
> >
> > Note that there are already two versions of HTTP transport, the old "dumb"
> > one and the newer "smart" one.
> >
> > The smart one is difficult to speed up (due to nature of the negotiations),
> > but usually is pretty reliable (the efficiency isn't horrible).
> 
> The negotiation in smart-HTTP actually has some bad corner cases. Each
> round of negotiation requires a new POST resupplying all previously
> agreed upon SHA-1s, and a batch of new SHA-1s. We have observed many
> rounds where this POST is MiBs in size because the peers can't quite
> agree and have to keep digging through history.

Oh yeah that... Well, that is artifact of HTTP semantics.

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> > Now, the old "dumb" protocol is pretty unreliable and slow. HTTP/2 probably
> > can't do anything with the reliability problems, but probably could improve
> > the speed a bit.
> >
> > Websockets over HTTP/2 (a.k.a. "websockets2") has not been defined yet.
> > With Websockets(1), it would probably already be possible to tunnel the
> > native git smart transport protocol over it. Probably not worth it.
> 
> Another option is to tunnel using gRPC (grpc.io). libcurl probably
> can't do this. And linking grpc.io library into git-core is crazy. So
> its probably a non-starter. But food for thought.

Wouldn't it link into git-remote-http (and on the server side, one could use pipes to talk to git)?

But supporting websockets in git-remote-http could get annoying, especially for wss:// (https://). Dunno how bad gRPC would be.

-Ilari