Re: Reverting an uncommitted revert

From: Nicolas Pitre <nico@cam.org>
Date: May 20, 2009, 18:19 UTC
Message-ID: <alpine.LFD.2.00.0905201406280.3906@xanadu.home>
In-Reply-To: <7vab57zmd8.fsf@alter.siamese.dyndns.org>

On Wed, 20 May 2009, Junio C Hamano wrote:

Show 15 quoted lines

> "Shawn O. Pearce" <spearce@spearce.org> writes:
> 
> > You did say "uncommitted entry causes reflog append", so in Peff's
> > original example of "git add a; vi a; git add a", we should be
> > creating a reflog entry for that first added state, which is clearly
> > not a disagreement.
> >
> > FWIW, I think this is a great idea, but lack the time to code it
> > myself, otherwise I probably would start hacking on it right now.
> 
> The devil's in the details.  There are at least four things you would need
> to design before start hacking.
> 
>  (0) Do you want this to apply only to Porcelains, or do you want to use
>      this for plumbing operations as well?

Depends if current plumbing already takes care of reflogs for normal operations.

>  (1) When would you "auto" write-tree?  When you do "git add" or anything
>      that adds new contents to the index?  Or immediately before you do
>      something destructive like "git reset"?  Or perhaps both?

Delaying any IO until it is clear that something is to be discarded is the best approach performance wise. So perhaps not on the first 'git add' but certainly on the second one with an already cached path for which new (different) content is going to replace previous content.

>  (2) Enumerate the operations that falls into the category you decided in
>      the above question.  For example, "git apply --index" and "git apply
>      --cached" would fall into the same category as "git add".  If you
>      cover plumbing, you would also need to cover "git update-index".

Plumbing should probably have the mechanism to create those trash reflogs if desired, but not active by default. Plumbing is normally for scripts, and once a script is debugged it shouldn't discard data by mistake. Let's not forget that this is a feature for mistake inducing humans.

Show 6 quoted lines

>  (3) What should happen when you cannot write the index out as a tree?  I
>      think it is easier to make mistakes during a conflicted merge
>      resolution than during a straight linear development of your own, and
>      one of the cases that would benefit most would be that you have
>      resolved a path to your satisfaction but then later you screw up
>      while resolving some other paths, losing an earlier resolution.

This one is tricky. Maybe storing two reflog entries corresponding to the unresolved stages?

Nicolas