two revnums of interest (was: Re: ancestor path / revision)

On Tue, Dec 19, 2000 at 11:06:30AM -0600, Ben Collins-Sussman wrote:
> Greg Stein <gstein@lyra.org> writes:
> > When doing a checkout/update, when would ancestor path ever get set? It
> > would seem that the client doesn't care about the ancestory -- that is only
> > important for the client to track when a "svn move" or "svn copy" is
> > performed (and then forgotten during the commit).
>
> Greg, I haven't yet read/processed your long technical responses yet
> (getting ready to!), but a simple answer occurs to me at first:
>
> As Karl said before, the concept of revision and ancestor-path are
> inseparable.

When you're talking about what to copy from, yes... they are inseparable.

However, Karl specifically said that we also want to know the revision that
we are attempting to update. In short he said:

1) crawl is performed, we find foo.c is at rev 6
2) [begin time-consuming task]
   a) send info (foo.c / 6) to server
   b) server says: you'll need to update foo.c to v7
   c) client asks for diff between 6 and 7 for foo.c
   d) client applies the diff
   [end]
3) while (2) is occuring, something goes and updates foo.c from 6 to 7.

Result: double application of the 6/7 diff to foo.c

My posts were about the fact that we need the old revision number when we go
to make some kind of change to the WC. Every change must be applied with the
assumption that it is operating against revision OLD-REV.

The current editor interface doesn't deal with the double revnum issue.

Cheers,
-g

-- 
Greg Stein, http://www.lyra.org/