Re: [Monotone-devel] What are rosters?

[William Uther]

On 20/08/2007, at 3:46 PM, Brian May wrote:

> > > > > > "William" == William Uther  
> > > > > > <address@hidden> writes:
>
>     William> - I think this procedure is equivalent to mark-merge:
>     William> - If a node is in the same state on both sides of a  
> merge then  it
>     William> is in that state in the result.  Otherwise,
>     William> - If a node is in different states on either side of a  
> merge  then
>     William> we check the uncommon ancestors (UA) on each side of  
> the merge  for
>     William> marks.  If one side has a mark and the other side  
> doesn't, then  that
>     William> side wins cleanly.  If both sides have a mark then  
> there is a
>     William> conflict.
>     William> - If the nodes are in a different state on each side  
> of the
>     William> merge, but neither set of uncommon ancestors has a  
> mark, then we've
>     William> got an invariant failure.
>
> Sounds good to me, so far.

Heh,  Unfortunately, it no longer sounds as good to me.  I managed to  
find some examples that concern me.  I haven't given up on it yet,  
but it may need some tweaks.

I'm going to label the merge above 'uncommon ancestor' merge.  It is  
a quick approximation of mark merge, and I may be able to make it  
equivalent enough for boolean merge.

> How would you deal with conflicts?

Complain to the user.  Tell them to either delete the file from one  
side, or add it to the other, then merge again.

> Just to confirm I have understood this correctly: would this mean it
> is possible to undelete a file that was deleted?

Yeah - but don't get too excited.  I'm pretty busy at the moment and  
this is pretty core stuff.  I want to be somewhat cautious.  Mistakes  
in this code are easy, and lead to annoying, subtle, bugs.

Cheers,

Will        :-}