Re: Re: Updating a submodule with a compatible version from another submodule version using the parent meta-repository

Hi,

After a couple of hours, I have finally succeeded to go through the
entire history of a repository and I can detect the submodules in a
tree of a commit. For those interested here is the source code:

http://gitorious.org/julian_ibarz_git/julian_ibarz_git/blobs/submodule_checkout/builtin/submodulecheckout.c

Next time I will build the list of commits of a submodule in the
entire history. Then I will need to find the distance of each commit
in the list compared to the current  commit of a submodule and keep
the closest one (which has to be a parent so an algebric distance
would be good to have).

So now my two questions that could save me some time are:
- is there a function that gives the distance between two commits? I'm
sure there is something like this coded somewhere but I didn't find it
yet
- is the struct decorate a hash map and if yes could someone explain
me how to use it or point me to a location where it is used?

Except from that I think I have all the information I need.

Best regards,
Julian Ibarz

On Sun, Jan 30, 2011 at 4:44 AM, Julian Ibarz [off-list ref] wrote:

Today I have started to implement a proof of concept in C (I know a
script would be better but I am really not good in sh so...). I
struggle with the manipulation of the git API. I have pushed my work
here:

http://gitorious.org/julian_ibarz_git/julian_ibarz_git

in branch submodule_checkout

My work is in:

builtin/submodulecheckout.c

And my questions are prepended by the keyword QUESTION (two questions
for now only).

Any help is welcome.

Thanks,

Julian Ibarz

On Sat, Jan 29, 2011 at 6:08 AM, Heiko Voigt [off-list ref] wrote:

quoted

Hi,

On Wed, Jan 26, 2011 at 02:05:43PM -0800, Junio C Hamano wrote:

quoted

If that version of submodule B is explicitly bound to a commit in the
superproject A, you know which version of A and C were recorded, and the
problem is solved.

[...]

quoted

If you are confident that you didn't introduce different kind of
dependency to other submodules while developing your "old_feature" branch
in submodule B, one strategy may be to find an ancestor, preferrably the
fork point, of your "old_feature" branch that is bound to the superproject
A.  Then at that point at least you know whoever made that commit in A
tested the combination of what was recorded in that commit, together with
the version of B and C, and you can go forward from there, replaying the
changes you made to the "old_feature" branch in submodule B.

Lets extend your explanation a little further and maybe demonstrate the problem
Julian is having a little more. I think what Julian searches for is a tool in
git that does the lookup for you which is AFAIK not that easy currently. It
seems to be a quite useful feature. Here what I understand Julian wants:

1. Find the most recent superproject commit X'' in A that records a submodule
  commit X' in B which contains the commit X in B you are searching for.

  For this we would need use something similar to git describe --contains
  but instead of using the list of existing tags in B it should use the list
  of commits in B which are recorded in A.

  Here a drawing to explain (linear history for simplicity):

  superproject A:

     O---O---X''---O
              \
  submodule B: \
                \
     O---X---O---X'---O---O

2. Look up the commit of C which is recorded in X'' of A and check it
  out.

Step 2 is easy but for Step 1 the lookup of X' is missing for the commandline.
Is there already anything that implements git describe --contains for a defined
list of commits instead of refs?

Cheers Heiko