Re: [PATCH v4 0/4] Add --no-ahead-behind to status

[Jeff King <peff@peff.net>]

On Mon, Jan 08, 2018 at 03:04:20PM -0500, Jeff Hostetler wrote:

> > I was thinking about something similar to the logic we use today
> > about whether to start reporting progress on other long commands.
> > That would mean you could still get the ahead/behind values if you
> > aren't that far behind but would only get "different" if that
> > calculation gets too expensive (which implies the actual value isn't
> > going to be all that helpful anyway).
> 
> After a off-line conversation with the others I'm going to look into
> a version that is limited to n commits rather than be completely on or
> off.  I think if you are for example less than 100 a/b then those numbers
> have value; if you are past n, then they have much less value.
> 
> I'd rather do it by a fixed limit than by time to ensure that output
> is predictable on graph shape and not on system load.

I like this direction a lot. I had hoped we could say "100+ commits
ahead", but I don't think we can do so accurately without generation
numbers. E.g., the case I mentioned at the bottom of this mail:

  https://public-inbox.org/git/20171224143318.GC23648@sigill.intra.peff.net/

I haven't thought too hard on it, but I suspect with generation numbers
you could bound it and at least say "100+ ahead" or "100+ behind". But I
don't think you can approximate both ahead and behind together without
finding the actual merge base.

But even still, finding small answers quickly and accurately and punting
to "really far, I didn't bother to compute it" on the big ones would be
an improvement over always punting.

-Peff