Re: [PATCH 0/3] Eliminate one user of extra_refs

On Fri, Jan 06, 2012 at 03:12:30PM +0100, mhagger@alum.mit.edu wrote:

Receive pack currently uses "extra refs" to keep track of ".have"
references, which in turn are used to tell the source the SHA1s of
references that are already known to the repository via alternates.

But the code already creates an array holding the alternate SHA1s.  So
just read the SHA1s out of this array rather then round-tripping them
through the extra_refs mechanism.

This is one step towards hopefully abolishing extra_refs altogether.
I still have to examine the other user.

Thanks, this is a nice simplification. The patches look good to me, and
they produce the same output for a simple test (I happened to be fiddling
with receive-pack and alternates yesterday, so I had a nice test case
right at hand :) ).

  receive-pack: move more work into write_head_info()

BTW, I have a patch to make sending ".have" refs configurable[1] (it
adds a receive.advertiseAlternates config variable), which this patch
conflicts with. I don't think that is your problem, but I thought I
would mention it since you are working in the area. Is that something we
want in git?

-Peff

[1] We are using it at GitHub because our alternates repos are so huge
    that the overhead of advertising the refs outweighs the minor
    benefits you get from avoiding object transfer.