[PATCH 4 of 4] revlog: support writing generaldelta revlogs

[Benoit Boissinot]

On May 6, 2011 1:55 PM, "Sune Foldager" <cryo at cyanite.org> wrote:
>
> On Fri, May 06, 2011 at 01:43:57 +0200, Benoit Boissinot wrote:
>
>> Sune, this makes me think about something we might not have emphasized
enough:
>> having an unconsistent deltabase in a revlog (e.g. mixed parent and
>> tip, or even random things when using generaldelta) makes it really
>> hard to generate a bundle suitable for older clients.
>
>
> Well not hard, just slow, right? You'll end up generating full revisions
> a lot, and calculating their deltas. But that's of course not so good.
>

It is really bad, reusing the delta helps a lot. Computing a bit more delta
means 10 min instead of 2min generation time on the server. We really don't
want that.
>
>> This has been one of the big problem for parentdelta (which I hoped
>> could solve by reordering the nodes when generating the bundle, but I
>> need to test that more).
>> I think there's more info on the parentdelta wiki page.
>
>
> Yeah, reordering might help a lot. Either revlog.group or the bundler
> could do some kinda deltaparent-aware toposort on the revs before the
> actual bundling process. I think that could work.
>
> --
> Sune
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