From: Patrick Steinhardt <ps@pks.im>
To: Glen Choo <chooglen@google.com>
Cc: git@vger.kernel.org, Jonathan Tan <jonathantanmy@google.com>
Subject: Re: [PATCH 8/8] fetch: introduce machine-parseable "porcelain" output format
Date: Thu, 27 Apr 2023 12:58:18 +0200 [thread overview]
Message-ID: <ZEpVSrz-uUcfN_3_@ncase> (raw)
In-Reply-To: <kl6lzg6umne9.fsf@chooglen-macbookpro.roam.corp.google.com>
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On Wed, Apr 26, 2023 at 12:52:46PM -0700, Glen Choo wrote:
> Patrick Steinhardt <ps@pks.im> writes:
>
> > The output format is quite simple:
> >
> > ```
> > <flag> <old-object-id> <new-object-id> <local-reference>\n
> > ```
>
> This format doesn't show the remote name or url that was fetched. That
> seems okay when fetching with a single remote, but it seems necessary
> with "--all". Perhaps you were planning to add that in a later series?
> If so, I think it's okay to call the "porcelain" format experimental,
> and forbid porcelain + --all until then.
The reason is mostly that I didn't find an output format that I really
liked here. We'd basically have to repeat the remote URL for every
single reference: just repeating it once per remote doesn't fly because
with `--parallel` the output could be intermingled. But doing that feels
wasteful to me, so I bailed. I guess I'm also biased here because it
just wouldn't be useful to myself.
So with that in mind, I'd like to continue ignoring this issue for now
and just not report the remote that the ref came from. But I'd also
argue that we don't have to restrict porcelain mode to single-remote
fetches: it can still be useful to do multi-remote fetches even without
the information where a certain reference update comes from. So any kind
of restriction would feel artificial to me here.
Furthermore, I'd argue that it is not necessary to label the format as
experimental only because of this limitation. With the refactorings done
in this and the preceding patch series it is easy to add a new format in
case there indeed is somebody that would have a usecase for this. The
"porcelain" format should stay stable, and if we decide that we want to
also report the remote for each reference in a follow-up we can easily
add a "porcelain-v2" or "porcelain-with-remote" format.
As I said though: I'm clearly biased, so if you feel like my train of
though is simply me being lazy then I'd carve in and adapt.
> > We assume two conditions which are generally true:
> >
> > - The old and new object IDs have fixed known widths and cannot
> > contain spaces.
> >
> > - References cannot contain newlines.
>
> This seems like a non-issue if we add a -z CLI option to indicate that
> entries should be NUL terminated instead of newline terminated, but that
> can be done as a followup.
Yeah, either via `-z` or a new porcelain output format. But both of
these conditions should generally be true anyway, so I don't see that
those should become a problem.
> > With these assumptions, the output format becomes unambiguously
> > parseable. Furthermore, given that this output is designed to be
> > consumed by scripts, the machine-readable data is printed to stdout
> > instead of stderr like the human-readable output is. This is mostly done
> > so that other data printed to stderr, like error messages or progress
> > meters, don't interfere with the parseable data.
>
> Sending the 'main output' to stdout makes sense to me, but this (and
> possibly respecting -z) sounds like a different mode of operation, not
> just a matter of formats. It seems different enough that I'd prefer not
> to piggyback on "fetch.output" for this (even though this adds more
> surface to the interface...).
>
> We could add --porcelain and say that "fetch.output" is ignored if
> --porcelain is also given. That also eliminates the need for
> --output-format, I think.
I was thinking about this initially, as well. But ultimately I decided
against this especially because of your second paragraph: we'd now need
to think about precedence of options and mutual exclusion, and that to
me feels like an interface that is less obvious than a single knob that
works as you'd expect.
> The .c changes look good to me.
>
> > +test_expect_success 'fetch porcelain output with HEAD and --dry-run' '
> > + test_when_finished "rm -rf head" &&
> > + git clone . head &&
> > + COMMIT_ID=$(git rev-parse HEAD) &&
> > +
> > + git -C head fetch --output-format=porcelain --dry-run origin HEAD >actual &&
> > + cat >expect <<-EOF &&
> > + * $ZERO_OID $COMMIT_ID FETCH_HEAD
> > + EOF
> > + test_cmp expect actual &&
> > +
> > + git -C head fetch --output-format=porcelain --dry-run origin HEAD:foo >actual &&
> > + cat >expect <<-EOF &&
> > + * $ZERO_OID $COMMIT_ID refs/heads/foo
> > + EOF
> > + test_cmp expect actual
> > +'
>
> As mentioned upthread, I think this test isn't needed because
> "porcelain" wouldn't run into the bug we are checking for anyway.
The only reason that the other bug was able to survive for so long was
that we didn't have test coverage there. So I think it makes sense to
explicitly test this, too, also because it causes us to walk a different
code path.
Last but not least: this test uncovered a segfault I had in a previous
version. So I'd rather keep it :)
Patrick
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next prev parent reply other threads:[~2023-04-27 10:58 UTC|newest]
Thread overview: 120+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-04-19 12:31 [PATCH 0/8] fetch: introduce machine-parseable output Patrick Steinhardt
2023-04-19 12:31 ` [PATCH 1/8] fetch: split out tests for output format Patrick Steinhardt
2023-04-19 12:31 ` [PATCH 2/8] fetch: add a test to exercise invalid output formats Patrick Steinhardt
2023-04-19 12:31 ` [PATCH 3/8] fetch: fix missing from-reference when fetching HEAD:foo Patrick Steinhardt
2023-04-26 19:20 ` Jacob Keller
2023-04-27 10:58 ` Patrick Steinhardt
2023-04-26 19:21 ` Jacob Keller
2023-04-27 10:58 ` Patrick Steinhardt
2023-04-26 19:25 ` Glen Choo
2023-04-27 10:58 ` Patrick Steinhardt
2023-04-19 12:31 ` [PATCH 4/8] fetch: introduce `display_format` enum Patrick Steinhardt
2023-04-19 12:31 ` [PATCH 5/8] fetch: move display format parsing into main function Patrick Steinhardt
2023-04-19 12:31 ` [PATCH 6/8] fetch: move option related variables " Patrick Steinhardt
2023-04-19 12:31 ` [PATCH 7/8] fetch: introduce new `--output-format` option Patrick Steinhardt
2023-04-26 19:40 ` Glen Choo
2023-04-27 10:58 ` Patrick Steinhardt
2023-04-19 12:31 ` [PATCH 8/8] fetch: introduce machine-parseable "porcelain" output format Patrick Steinhardt
2023-04-26 19:52 ` Glen Choo
2023-04-27 10:58 ` Patrick Steinhardt [this message]
2023-04-27 23:20 ` Glen Choo
2023-04-28 8:51 ` Patrick Steinhardt
2023-04-28 17:20 ` Glen Choo
2023-05-02 20:55 ` Felipe Contreras
2023-04-24 20:17 ` [PATCH 0/8] fetch: introduce machine-parseable output Felipe Contreras
2023-04-25 9:58 ` Patrick Steinhardt
2023-04-26 19:14 ` Jacob Keller
2023-04-26 20:23 ` Junio C Hamano
2023-04-26 20:30 ` Jacob Keller
2023-04-27 10:58 ` Patrick Steinhardt
2023-04-27 19:46 ` Jacob Keller
2023-04-27 22:49 ` Glen Choo
2023-04-26 20:24 ` Junio C Hamano
2023-04-26 18:54 ` Glen Choo
2023-04-26 21:14 ` Glen Choo
2023-04-26 19:17 ` Jacob Keller
2023-04-27 11:13 ` [PATCH v2 " Patrick Steinhardt
2023-04-27 11:13 ` [PATCH v2 1/8] fetch: split out tests for output format Patrick Steinhardt
2023-04-29 17:34 ` SZEDER Gábor
2023-05-03 11:21 ` Patrick Steinhardt
2023-04-27 11:13 ` [PATCH v2 2/8] fetch: add a test to exercise invalid output formats Patrick Steinhardt
2023-04-27 11:13 ` [PATCH v2 3/8] fetch: fix missing from-reference when fetching HEAD:foo Patrick Steinhardt
2023-04-27 17:26 ` Glen Choo
2023-04-27 19:49 ` Jacob Keller
2023-04-27 11:13 ` [PATCH v2 4/8] fetch: introduce `display_format` enum Patrick Steinhardt
2023-04-27 11:13 ` [PATCH v2 5/8] fetch: move display format parsing into main function Patrick Steinhardt
2023-04-27 11:13 ` [PATCH v2 6/8] fetch: move option related variables " Patrick Steinhardt
2023-04-27 21:52 ` Junio C Hamano
2023-04-27 11:13 ` [PATCH v2 7/8] fetch: introduce new `--output-format` option Patrick Steinhardt
2023-04-27 22:01 ` Junio C Hamano
2023-04-28 22:03 ` Glen Choo
2023-05-03 9:12 ` Patrick Steinhardt
2023-04-28 22:31 ` Glen Choo
2023-05-03 9:43 ` Patrick Steinhardt
2023-05-03 11:36 ` Patrick Steinhardt
2023-04-27 11:13 ` [PATCH v2 8/8] fetch: introduce machine-parseable "porcelain" output format Patrick Steinhardt
2023-04-27 19:52 ` Jacob Keller
2023-04-28 22:42 ` Glen Choo
2023-05-03 11:34 ` [PATCH v3 0/8] fetch: introduce machine-parseable output Patrick Steinhardt
2023-05-03 11:34 ` [PATCH v3 1/8] fetch: fix `--no-recurse-submodules` with multi-remote fetches Patrick Steinhardt
2023-05-08 22:51 ` Glen Choo
2023-05-09 12:41 ` Patrick Steinhardt
2023-05-03 11:34 ` [PATCH v3 2/8] fetch: split out tests for output format Patrick Steinhardt
2023-05-03 11:34 ` [PATCH v3 3/8] fetch: add a test to exercise invalid output formats Patrick Steinhardt
2023-05-03 11:34 ` [PATCH v3 4/8] fetch: fix missing from-reference when fetching HEAD:foo Patrick Steinhardt
2023-05-03 11:34 ` [PATCH v3 5/8] fetch: introduce `display_format` enum Patrick Steinhardt
2023-05-03 11:34 ` [PATCH v3 6/8] fetch: move display format parsing into main function Patrick Steinhardt
2023-05-03 11:34 ` [PATCH v3 7/8] fetch: move option related variables " Patrick Steinhardt
2023-05-03 11:34 ` [PATCH v3 8/8] fetch: introduce machine-parseable "porcelain" output format Patrick Steinhardt
2023-05-08 23:42 ` Glen Choo
2023-05-09 12:41 ` Patrick Steinhardt
2023-05-09 0:03 ` Glen Choo
2023-05-03 16:48 ` [PATCH v3 0/8] fetch: introduce machine-parseable output Junio C Hamano
2023-05-03 16:53 ` Junio C Hamano
2023-05-04 7:57 ` Patrick Steinhardt
2023-05-09 0:06 ` Glen Choo
2023-05-09 12:42 ` Patrick Steinhardt
2023-05-09 13:01 ` [PATCH v4 " Patrick Steinhardt
2023-05-09 13:02 ` [PATCH v4 1/8] fetch: fix `--no-recurse-submodules` with multi-remote fetches Patrick Steinhardt
2023-05-09 17:49 ` Junio C Hamano
2023-05-09 18:27 ` Glen Choo
2023-05-10 12:34 ` Patrick Steinhardt
2023-05-09 13:02 ` [PATCH v4 2/8] fetch: split out tests for output format Patrick Steinhardt
2023-05-09 13:02 ` [PATCH v4 3/8] fetch: add a test to exercise invalid output formats Patrick Steinhardt
2023-05-09 17:58 ` Junio C Hamano
2023-05-10 12:34 ` Patrick Steinhardt
2023-05-09 13:02 ` [PATCH v4 4/8] fetch: fix missing from-reference when fetching HEAD:foo Patrick Steinhardt
2023-05-09 19:28 ` Junio C Hamano
2023-05-10 12:34 ` Patrick Steinhardt
2023-05-09 13:02 ` [PATCH v4 5/8] fetch: introduce `display_format` enum Patrick Steinhardt
2023-05-09 20:19 ` Junio C Hamano
2023-05-10 12:35 ` Patrick Steinhardt
2023-05-09 13:02 ` [PATCH v4 6/8] fetch: move display format parsing into main function Patrick Steinhardt
2023-05-09 20:35 ` Junio C Hamano
2023-05-09 22:30 ` Glen Choo
2023-05-10 12:35 ` Patrick Steinhardt
2023-05-09 13:02 ` [PATCH v4 7/8] fetch: move option related variables " Patrick Steinhardt
2023-05-09 13:02 ` [PATCH v4 8/8] fetch: introduce machine-parseable "porcelain" output format Patrick Steinhardt
2023-05-09 20:43 ` Junio C Hamano
2023-05-10 12:35 ` Patrick Steinhardt
2023-05-10 12:33 ` [PATCH v5 0/9] fetch: introduce machine-parseable output Patrick Steinhardt
2023-05-10 12:34 ` [PATCH v5 1/9] fetch: fix `--no-recurse-submodules` with multi-remote fetches Patrick Steinhardt
2023-05-10 12:34 ` [PATCH v5 2/9] fetch: split out tests for output format Patrick Steinhardt
2023-05-10 12:34 ` [PATCH v5 3/9] fetch: add a test to exercise invalid output formats Patrick Steinhardt
2023-05-10 12:34 ` [PATCH v5 4/9] fetch: print left-hand side when fetching HEAD:foo Patrick Steinhardt
2023-05-12 0:16 ` Glen Choo
2023-05-13 16:59 ` Jeff King
2023-05-15 5:15 ` Patrick Steinhardt
2023-05-10 12:34 ` [PATCH v5 5/9] fetch: refactor calculation of the display table width Patrick Steinhardt
2023-05-12 0:49 ` Glen Choo
2023-05-10 12:34 ` [PATCH v5 6/9] fetch: introduce `display_format` enum Patrick Steinhardt
2023-05-10 12:34 ` [PATCH v5 7/9] fetch: lift up parsing of "fetch.output" config variable Patrick Steinhardt
2023-05-10 12:34 ` [PATCH v5 8/9] fetch: move option related variables into main function Patrick Steinhardt
2023-05-10 12:34 ` [PATCH v5 9/9] fetch: introduce machine-parseable "porcelain" output format Patrick Steinhardt
2023-05-12 1:02 ` Glen Choo
2023-05-10 18:05 ` [PATCH v5 0/9] fetch: introduce machine-parseable output Junio C Hamano
2023-05-11 11:05 ` Patrick Steinhardt
2023-05-11 16:53 ` Junio C Hamano
2023-05-11 17:24 ` Felipe Contreras
2023-05-12 1:09 ` Glen Choo
2023-05-12 7:16 ` Patrick Steinhardt
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