Re: [PATCH] protocol upload-pack-v2

[Martin Fick <mfick@codeaurora.org>]

> The current protocol has the following problems that limit
> us:
> 
>  - It is not easy to make it resumable, because we
> recompute every time.  This is especially problematic for
> the initial fetch aka "clone" as we will be talking about
> a large transfer. Redirection to a bundle hosted on CDN
> might be something we could do transparently.
> 
>  - The protocol extension has a fairly low length limit.
> 
>  - Because the protocol exchange starts by the server side
> advertising all its refs, even when the fetcher is
> interested in a single ref, the initial overhead is
> nontrivial, especially when you are doing a small
> incremental update.  The worst case is an auto-builder
> that polls every five minutes, even when there is no new
> commits to be fetched.

A lot of focus about the problems with ref advertisement is 
about the obvious problem mentioned above (a bad problem 
indeed).  I would like to add that there is another related 
problem that all potential solutions to the above problem do 
not neccessarily improve.   When polling regularly there is 
also no current efficient way to check on the current state of 
all refs.  It would be nice to also be able to get an 
incremental update on large refs spaces.

Thanks,

-Martin

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