Re: [PATCH v5 0/6] Introduce git-last-modified(1) command

[Taylor Blau <me@ttaylorr.com>]

On Wed, Jul 16, 2025 at 03:32:00PM +0200, Toon Claes wrote:
> This series adds the git-last-modified(1) to feed this view. In the past
> the subcommand was proposed[1] to be named git-blame-tree(1). This
> version is based on the patches shared by the kind people at GitHub[2].

Sorry for completely dropping this from my review queue. Let me try and
give it a read...

> What is different from the series shared by GitHub:
>
> * Renamed the subcommand from `blame-tree` to `last-modified`. There was
>   some consensus[5] this name works better, so let's give it a try and
>   see how this name feels.

Hmmph. I prefer the "blame-tree" name personally, but I am (a) biased,
and (b) used to it over "last-modified", so I don't think my preference
or bias should count for much here.

> * Patches for --max-depth are excluded. I think it's a separate topic to
>   discuss and I'm not sure it needs to be part of series anyway. The
>   main patch was submitted in the previous attempt[3] and if people
>   consider it valuable, I'm happy to discuss that in a separate patch
>   series.

Yeah, makes sense.

> * The last-modified command isn't recursive by default. If you want
>   recurse into subtrees, you need to pass `-r`.

OK.

> * The patches in 'tb/blame-tree' at Taylor's fork[4] implements a
>   caching layer. This feature reads/writes cached results in
>   `.git/blame-tree/<hash>.btc`. To keep this series to a reviewable
>   size, that feature is excluded from this series. I think it's better
>   to submit this as a separate series.

Makes sense; the caching feature was primarily implemented by Stolee and
I think for our purposes here can be considered additive and not
essential to the basic functionality of this new command. For what it's
worth, I *would* like[^1] to see those features sent to the list at some
point, but I agree that they are a significant source of additional
complexity. So punting on them for now seems like the right direction to
me.

[^1]: My ulterior motive here would be to eventually ditch GitHub's
  "blame-tree" command entirely and remove it from GitHub's diff to
  upstream. I'm happy to help however I can with that effort once this
  series lands.

> * Squashed various commits together. Like they introduced a flag
>   `--go-faster`, which later became the default and only implementation.
>   That story was wrapped up in a single commit.

Perfect, thank you. I figured that we would not want to keep temporary
measures around like the "--go-faster" flag, but I also figured that
they may be helpful in unpacking the history of this command, hence why
I sent them in the first place.

> * Dropped the patches that attempt to increase performance for tree
>   entries that have not been updated in a long time. In my testing I've
>   seen both performance improvements *and* degradation with these
>   changes:
>
>   Test                                        HEAD~             HEAD
>   ------------------------------------------------------------------------------------
>   8020.1: top-level last-modified             4.52(4.38+0.11)   2.03(1.93+0.08) -55.1%
>   8020.2: top-level recursive last-modified   5.79(5.64+0.11)   8.34(8.17+0.11) +44.0%
>   8020.3: subdir last-modified                0.15(0.09+0.06)   0.19(0.14+0.06) +26.7%
>
>   Before we include these patches, I want to make sure these changes
>   have positive impact in all/most scenarios. This can happen in a
>   separate series.

Hmm. It's been long enough that I honestly don't remember the details
here, but I agree that this is worth looking into at some point in the
future.

> I've set myself as the author and added Based-on-patch-by trailers to
> credit the original authors. Let me know if you disagree.

I can't speak for the other authors of this command, but I have no issue
being ~~blamed~~ credited with a "Based-on-patch-by" trailer ;-).

> Again thanks to Taylor and the people at GitHub for sharing these
> patches. I hope we can work together to get this upstreamed.

Ditto.

Thanks,
Taylor