On Wed, Jan 04, 2023 at 03:11:35AM +1100, Mark Jamsek wrote:
> I often want to get a birdseye view of the changes in terms of total +/-
> for a given commit. The below diff adds the -d flag to 'got log' and the
> 'D' keymap to tog diff to display the number of lines added/removed for
> each file changed in the commit, and a summary line showing the total
> change across all files. But the implementation looks forward to making
> the diffstat available to 'got diff' too.
> 
> Although we have to compute the diff twice because the file changeset is
> output before the diff is computed and we need the diff to display the
> diffstat with the changeset, the performance impact is negligible for
> the average commit because we don't pay the high cost of formatting any
> output, we just want the diffreg_result so we can sum the changes. At
> the high end, the average increase in a 675k line diff is approximately
> 33% (i.e., 1.5 -> 2s), but for typical commits it's barely perceptible.
> 
> That said, if it's a concern, we could probably look at holding onto the
> diff result for the actual diff output, in which case there'd be no
> extra cost.
> 
> I opted to keep the diffstat output simple; for example:

Very nice. I like the short way of displaying this data. ok by me.

I would suggest to always turn this on in tog, replacing the -P style
path list display. And leave it off by default on the command line.
If this becomes a burdensome performance problem, we can look at ways
to speed it up or disable it by default. Keeping diff_result around is
a possible optimization that has been mentioned before.
Our current high-level diff APIs don't expose the diff_result, which
is suboptimal. We could add an extra set of API which expose it, or
change the existing APIs to follow the computation/output split that
is present in the diff.git API.