Re: [PATCH 10/16] worktree: make branch creation distinct from worktree population

> On Sat, Jul 11, 2015 at 10:48 PM, Duy Nguyen <pclouds@gmail.com> wrote:
>> The "shouldn't affect" is potentially a problem.If the current
>> 'worktree add' process caches something (in ref handling, for example)
>> that the 'git branch' process changes, then we may need to invalidate
>> cache in 'worktree add' process after run_command(). I guess it's ok
>> in this case since all we do is run_command(), we do not lookup refs
>> or anything else afterwards.
>
> With this patch series applied, the code effectively does this:
>
>     branch = ...
>     if (create_new_branch) {
>         exec "git branch newbranch branch"
>         branch = newbranch;
>     }
>     if (ref_exists(branch) && !detach)
>         exec "git symbolic-ref HEAD branch"
>     else
>         exec "git update-ref HEAD $(git rev-parse branch)"
>     exec "git reset --hard"
>
> So, if I understand your concern correctly, then you are worried that,
> following the git-branch invocation, ref_exists() could return the
> wrong answer with a pluggable ref-backend since it might be answering
> based upon stale information. Is that what you mean? If so, I can see
> how that it could be an issue. (As far as I can tell, the current
> file-based backend doesn't have a problem with this since it's hitting
> the filesystem directly to answer the ref_exists() question.)