[MERGE] documentation from the london sprint

[Robert Collins]

On Sun, 2007-06-03 at 22:28 -0400, Aaron Bentley wrote:

Thanks for the review. I've fixed the rest errors somewhat, it doesn't
complain, but it doesn't number them for me either; or should I not
expect that? Not a showstopper IMO. I attach a replacement bundle.

> > + * Perhaps multiparent deltas would allow us to not store the
> cached
> > +   annotations in each delta without losing performance or
> accuracy.
> 
> I think multiparent does give you that.  I think asking for
> non-multiparent deltas doesn't.
> 
> The algorithm I have for reconstructing texts in multiparent is always
> aware what revision it's pulling lines from.  But that means we
> continue
> to pun annotation storage with fulltext storage, which could be a
> loss.
> 
> One gain though, is that you can potentially use deltas in the
> sequence
> matching used by annotate-merge.  That would scale with the number of
> revisions and the size of the deltas, which is better than scaling
> with
> the square of the size of the text.

I'm not quite sure what to take from these comments - would you like
some prose added to the text there?


> > + 1. get 'new enough' hash data for the siblins of the scope: it can
> be out of date as long as its not older than the last move or rename
> out of that siblings scope.
> 
> I don't really understand this bit about "new enough" sibling data.

If you have a selected-path operation, say commit. Lets say that we're
committing just 'subtree2' and subtree1 has been altered - by a patch to
subtree1/foo.c.

If subtree2 has a new file, (subtree2/new.c) can we be sure the fileid
is unique without scanning the entire tree structure. 

The new enough bit is that the hash for the subtree1 (assuming the
hashes are directory aligned) can be stale (still be the one from the
time of checkout, for instance), as long as now
moves-into-or-out-of/adds/deletes have taken place within it. 

-Rob

-- 
GPG key available at: <http://www.robertcollins.net/keys.txt>.
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