Re: [PATCH 4/3] git-fetch: test avoiding unnecessary copying from alternates

["Shawn O. Pearce" <spearce@spearce.org>]

"Shawn O. Pearce" <spearce@spearce.org> wrote:
> This test verifies my prior "avoid local fetching from alternate"
> patch is functional and doesn't regress in the future during any
> additional improvements made to git.
...
> +test_expect_success 'quickfetch should not copy from alternate' '
> +
> +	(
> +		mkdir quickclone &&
> +		cd quickclone &&
> +		git init-db &&
> +		(cd ../.git/objects && pwd) >.git/objects/info/alternates &&
> +		git remote add origin .. &&
> +		git fetch -k -k

Hmmph.  On second thought I think this is a little sketchy for
a test.  Versions without my quickfetch patch fail this test and
versions with it pass.  But it depends on the implementation of
`-k -k` to always call index-pack over unpack-objects.

I'm using -k -k here to ensure we keep the pack fetched as we're only
fetching 6 objects and they are already reachable in the quickclone
repository thanks to the alternate ODB.  If we use unpack-objects
during this fetch we will still pass this test because the objects
won't be unpacked if they are already reachable locally.

Of course this test is for a performance optimization.  For 6
tiny objects it really doesn't matter if we copy them or not, or
if we copy them over a pipe only to discard them because they are
already reachable.  It does however matter when you are talking
about nearly 300MB worth of objects.  :-\

-- 
Shawn.