Re: GSOC proposal

[Fredrik Gustafsson <iveqy@iveqy.com>]

On Thu, Mar 24, 2011 at 04:47:41PM -0700, Junio C Hamano wrote:
> Jens Lehmann <Jens.Lehmann@web.de> writes:
> 
> >> == Preventing false "pointers" ==
> >> It's far too easy to push a gitrepo pointing to a submodule version that
> >> is not existing on the server. Prevent this by checking for available
> >> submodule versions before acceptingt the push.
> >
> > Yes, requiring to force such a push is an issue raised quite often (I
> > think addressing this issue would be a good starting point for people
> > who want to get involved in enhancing the submodule experience).
> 
> You need to be careful, though.
> 
> That check can only be sanely done at a hosting site that hosts _both_ the
> superproject and the submodule repositories.  It might make more sense to
> have this check on the side that pushes, which by definition should have
> both superprojet and the submodule.  Fail, or prompt to confirm, a push
> from the superproject when it is detected that the submodule commits bound
> to the commits in the superproject have not been pushed out.

I can see three different ways of doing this:
1. the reciever (server) checks for available submodules before
accepting a commit

2. the sender checks for available submodules on the server before
sending a commit.

3. each submodule contains a flag that tells if the last command was a
commit or a push. The core-repository wont allow a push if one (or more)
submodules has a commit as "last command".

Although alternative 1 is the only one that is certain of preventing the
problem with "false pointers", it has several other drawbacks. I believe
that alt. 3 is the proper way of handling this in git. Although we
doesn't guarantee a sane server-repo we does prevent the client from
doing stupid things by mistake.

-- 
Med vänliga hälsningar
Fredrik Gustafsson

tel: 0733-608274
e-post: iveqy@iveqy.com