Re: [PATCH 0/2] finding the fork point from reflog entries

On Thu, Oct 24, 2013 at 02:20:29PM -0700, Junio C Hamano wrote:

John Keeping [off-list ref] writes:

quoted

On Thu, Oct 24, 2013 at 12:11:22PM -0700, Junio C Hamano wrote:

quoted

The first one is a clean-up of the code to parse command line
options to "git merge-base".  Options such as "--independent",
"--is-ancestor" and "--octopus" are mutually exclusive and it is
better expressed in terms of the recently introduced OPT_CMDMODE.

The second one implements the entire logic of the for loop we see in
"git pull --rebase" directly using get_merge_bases_many() and
postprocessing the result.

Nice!  I tried this in the case where the target commit happens to be
the 63rd reflog entry:

$ time sh -c 'for rev in $(git rev-list -g origin/master 2>/dev/null)
do
    git merge-base --is-ancestor $rev b2edae0 && break
done
'

real    0m3.772s
user    0m3.338s
sys     0m0.440s

$ time git merge-base --reflog origin/master b2edae0

real    0m0.156s
user    0m0.138s
sys     0m0.018s

The real question is if the C code computes the same as the shell
loop.

And in fact it doesn't - if you replace the "break" with "echo $rev" the
shell version prints b2edae0... but the C version prints nothing (and
exists with status 1).