Re: [PATCH] rebase: be cleverer with rebased upstream branches

On Wed, 16 Feb 2011, Santi B?jar wrote:

On Wed, Feb 16, 2011 at 3:03 AM, Martin von Zweigbergk
[off-list ref] wrote:

quoted

On Tue, 15 Feb 2011, Junio C Hamano wrote:

quoted

Martin von Zweigbergk [off-list ref] writes:

quoted

diff --git a/git-rebase.sh b/git-rebase.sh
index 5abfeac..1bc0c29 100755
--- a/git-rebase.sh
+++ b/git-rebase.sh

      test -n "$upstream_name" &&
        for reflog in $(git rev-list ...)
        do
              ...
      done

Don't you need to make sure $upstream_name is a branch (or a ref in
general that can have a reflog), or does it not matter because the
"rev-list -g" will die without producing anything and you are discarding
the error message?

Exactly as you suspect. Is it too ugly?

I also prefer Junio's version.

I fixed the test + for loop, if that's what you mean by "Junio's
version". Or did you mean "make sure $upstream_name is a branch"? I
could do that as well if you like. I have no preference.

quoted

       .-u@{0}
      /
     .---u@{1}
    /
x---y-----u@{2}
    \
     .---u@{3}---b
      \
       .-u@{4}


I have an idea inspired by bisection, Thomas's exponential stride, and
what someone (you?) mentioned the other day about virtual merge
commits. I haven't tried it out, but let me know what you think. I'll
try to explain it using an example only:

Exponential stride phase:
1. candidates={ u@{0} }
  merge-base b $candidates -> y, _not_ in $candidates
2. candidates={ u@{1} u@{2} }
  merge-base b $candidates -> y, _not_ in $candidates
3. candidates={ u@{3} u@{4} u@{5} u@{6} }
  merge-base b $candidates -> u@{3}, in $candidates

Doesn't it indicate that u@{3} is the commit we are looking for? I
haven't found a counterexample...

Yes, of course. Stupid me ;-). Forget about the other half. (I think
that's what I did manually to match the sha1 back to the ref name, but
that is of course complete non-sense to do in the script.)

If this is true the following patch can implement it for git-pull.sh and
git-rebase.sh (sorry if it is space damaged):

Thanks! Will have a closer look at it later today. If I understand
correctly, you simply call merge-base with the _entire_ reflog. I
would have thought that would be slow, but it's great if that is fast
enough. The resulting code looks very nice and short. Thanks again.


/Martin