From: Johannes Schindelin <Johannes.Schindelin@gmx.de>
To: Taylor Blau <me@ttaylorr.com>
Cc: "Johannes Schindelin via GitGitGadget" <gitgitgadget@gmail.com>,
git@vger.kernel.org, "René Scharfe" <l.s.r@web.de>,
"Ævar Arnfjörð Bjarmason" <avarab@gmail.com>
Subject: Re: [PATCH v4 2/2] tests(mingw): avoid very slow `mingw_test_cmp`
Date: Fri, 18 Nov 2022 14:32:28 +0100 (CET) [thread overview]
Message-ID: <qp0556o2-6q18-8556-0n8s-p28831qr6qs6@tzk.qr> (raw)
In-Reply-To: <Y3LD1CtKBoDhPdSZ@nand.local>
Hi Taylor,
On Mon, 14 Nov 2022, Taylor Blau wrote:
> On Mon, Nov 14, 2022 at 02:06:52PM +0000, Johannes Schindelin via GitGitGadget wrote:
> > From: Johannes Schindelin <johannes.schindelin@gmx.de>
> >
> > It is more performant to run `git diff --no-index` than running the
> > `mingw_test_cmp` code with MSYS2's Bash, i.e. the Bash that Git for
> > Windows uses. And a lot more readable.
> >
> > The original reason why Git's test suite needs the `mingw_test_cmp`
> > function at all (and why `cmp` is not good enough) is that Git's test
> > suite is not actually trying to compare binary files when it calls
> > `test_cmp`, but it compares text files. And those text files can contain
> > CR/LF line endings depending on the circumstances.
> >
> > Note: The original fix in the Git for Windows project implemented a test
> > helper that avoids the overhead of the diff machinery, in favor of
> > implementing a behavior that is more in line with what `mingw_test_cmp`
> > does now. This was done to minimize the risk in using something as
> > complex as the diff machinery to perform something as simple as
> > determining whether text output is identical to the expected output or
> > not. This approach has served Git for Windows well for years, but the
> > attempt to upstream this saw a lot of backlash and distractions during
> > the review, was disliked by the Git maintainer and was therefore
> > abandoned. For full details, see the thread at
> > https://lore.kernel.org/git/pull.1309.git.1659106382128.gitgitgadget@gmail.com/t
>
> In the previous round, you wrote that this paragraph:
>
> It explains why we replace a relatively simple logic with a relatively
> complex one.
Yes. And I obviously got myself misunderstood.
The simple logic I refer to is the `t/helper/test-cmp.c` that I abandoned.
The complex logic is the diff machinery we now call, which is a lot more
involved and goes through a lot more code paths.
> But I'm not sure the rewritten version does what you claim, at least in
> my own personal opinion.
>
> It is not helpful to say the original approach "saw a lot of backlash".
It is the nicest thing I can say about it.
And I want people who are curious what happened to Git for Windows' custom
code to have an explanation in the commit messages.
> It is helpful, on the other hand, to say what about the original
> approach gave reviewers pause, and why that alternative approach isn't
> pursued here.
>
> Maybe I'm splitting hairs here, but I really do stand by my original
> suggestion from back in [1].
We can also keep hitting a dead horse, but I don't think that will make
anything any better.
Thanks,
Johannes
>
> Thanks,
> Taylor
>
> [1]: https://lore.kernel.org/git/Y3B36HjDJhIY5jNz@nand.local/
>
next prev parent reply other threads:[~2022-11-18 13:33 UTC|newest]
Thread overview: 58+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-07-29 14:53 [PATCH] tests: replace mingw_test_cmp with a helper in C Johannes Schindelin via GitGitGadget
2022-07-29 14:54 ` Johannes Schindelin
2022-07-29 16:44 ` Junio C Hamano
2022-09-06 13:10 ` Johannes Schindelin
2022-09-07 12:09 ` René Scharfe
2022-09-07 16:25 ` Junio C Hamano
2022-09-07 21:45 ` Re* " Junio C Hamano
2022-09-07 22:39 ` René Scharfe
2022-09-08 0:03 ` Junio C Hamano
2022-09-08 8:59 ` René Scharfe
2022-09-08 15:26 ` Ævar Arnfjörð Bjarmason
2022-09-08 20:54 ` Johannes Schindelin
2022-09-08 21:09 ` Junio C Hamano
2022-09-06 13:10 ` [PATCH v2 0/2] " Johannes Schindelin via GitGitGadget
2022-09-06 13:10 ` [PATCH v2 1/2] t0021: use Windows-friendly `pwd` Johannes Schindelin via GitGitGadget
2022-09-06 13:10 ` [PATCH v2 2/2] tests: replace mingw_test_cmp with a helper in C Johannes Schindelin via GitGitGadget
2022-09-07 11:57 ` Ævar Arnfjörð Bjarmason
2022-09-07 12:24 ` Ævar Arnfjörð Bjarmason
2022-09-07 19:45 ` Junio C Hamano
2022-09-07 9:04 ` [PATCH v2 0/2] " Johannes Schindelin
2022-11-12 22:07 ` [PATCH v3 " Johannes Schindelin via GitGitGadget
2022-11-12 22:07 ` [PATCH v3 1/2] t0021: use Windows-friendly `pwd` Johannes Schindelin via GitGitGadget
2022-11-12 22:07 ` [PATCH v3 2/2] tests(mingw): avoid very slow `mingw_test_cmp` Johannes Schindelin via GitGitGadget
2022-11-13 4:51 ` Taylor Blau
2022-11-14 13:34 ` Johannes Schindelin
2022-11-18 23:15 ` Junio C Hamano
2022-11-19 2:53 ` Taylor Blau
2022-11-19 12:03 ` Ævar Arnfjörð Bjarmason
2022-11-19 8:18 ` Johannes Sixt
2022-11-19 17:50 ` René Scharfe
2022-11-20 9:29 ` Torsten Bögershausen
2022-11-21 17:49 ` Johannes Sixt
2022-11-21 3:13 ` Junio C Hamano
2022-11-14 9:53 ` Phillip Wood
2022-11-14 13:47 ` Johannes Schindelin
2022-11-14 11:55 ` Ævar Arnfjörð Bjarmason
2022-11-14 14:02 ` Johannes Schindelin
2022-11-14 15:23 ` Ævar Arnfjörð Bjarmason
2022-11-18 23:19 ` Junio C Hamano
2022-11-19 2:56 ` Taylor Blau
2022-11-19 11:54 ` Ævar Arnfjörð Bjarmason
2022-11-21 3:17 ` Junio C Hamano
2022-11-14 14:06 ` [PATCH v4 0/2] tests(mingw): avoid super-slow mingw_test_cmp Johannes Schindelin via GitGitGadget
2022-11-14 14:06 ` [PATCH v4 1/2] t0021: use Windows-friendly `pwd` Johannes Schindelin via GitGitGadget
2022-11-14 14:06 ` [PATCH v4 2/2] tests(mingw): avoid very slow `mingw_test_cmp` Johannes Schindelin via GitGitGadget
2022-11-14 22:40 ` Taylor Blau
2022-11-18 13:32 ` Johannes Schindelin [this message]
2022-11-18 18:14 ` Taylor Blau
2022-11-20 23:36 ` Johannes Schindelin
2022-11-21 0:07 ` Taylor Blau
2022-12-06 15:07 ` [PATCH v5 0/2] tests(mingw): avoid super-slow mingw_test_cmp Johannes Schindelin via GitGitGadget
2022-12-06 15:07 ` [PATCH v5 1/2] t0021: use Windows-friendly `pwd` Johannes Schindelin via GitGitGadget
2022-12-06 15:07 ` [PATCH v5 2/2] tests(mingw): avoid very slow `mingw_test_cmp` Johannes Schindelin via GitGitGadget
2022-12-06 18:55 ` Ævar Arnfjörð Bjarmason
2022-12-06 21:52 ` Johannes Sixt
2022-12-06 21:54 ` René Scharfe
2022-12-07 4:33 ` Junio C Hamano
2022-12-07 1:31 ` Taylor Blau
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