From: Taylor Blau <me@ttaylorr.com>
To: Jeff King <peff@peff.net>
Cc: git@vger.kernel.org
Subject: Re: [PATCH 3/3] transport.c: introduce core.alternateRefsPrefixes
Date: Thu, 20 Sep 2018 16:12:35 -0400 [thread overview]
Message-ID: <20180920201235.GB83799@syl> (raw)
In-Reply-To: <20180920194734.GD29603@sigill.intra.peff.net>
On Thu, Sep 20, 2018 at 03:47:34PM -0400, Jeff King wrote:
> On Thu, Sep 20, 2018 at 02:04:13PM -0400, Taylor Blau wrote:
>
> > The recently-introduced "core.alternateRefsCommand" allows callers to
> > specify with high flexibility the tips that they wish to advertise from
> > alternates. This flexibility comes at the cost of some inconvenience
> > when the caller only wishes to limit the advertisement to one or more
> > prefixes.
>
> To be clear: this isn't something we plan to use at GitHub at all. It
> just seemed like a nice "in between" the current inflexible state and
> the "incredibly flexible but not trivial to use" command from patch 2.
>
> Note that unlike core.alternateRefsCommand, there are no security issues
> here with reading this from the alternate, although:
>
> - it's a little awkward to read the config from the alternate
>
> - since these are clearly related config, it probably makes sense for
> them to be consistent
Another note is that the thing we are planning on using
("core.alternateRefsCommand") could also be implemented as a hook,
e.g., .git/hooks/gather-alternate-refs.
That said, I think that this makes more sense when the alternate is
doing the configuring, not the ohter way around.
> > For example, to advertise only tags, a caller using
> > 'core.alternateRefsCommand' would have to do:
> >
> > $ git config core.alternateRefsCommand ' \
> > git -C "$1" for-each-ref refs/tags \
> > --format="%(objectname) %(refname)" \
> > '
>
> I think it's more likely that advertising only heads would make sense.
> The pathological repos I see are usually a sane number of branches and
> then an absurd number of tags.
I agree with you. I used "refs/tags" as the prefix here since I'd like
different output than when "core.alternateRefsPrefixes" isn't configured
at all. Since we have a tag for each commit (we use test_commit to do
so), and refs/heads/{a,b,c,master}, we'd get the same output whether we
configured the prefix to be refs/heads, or didn't configure it at all.
Since using 'git for-each-ref' sorts in order of refname, a prefix of
"refs/tags" sorts in order of tagname, so we'll get different output
because of it.
That said, I think that this test is a little fragile as-is, since it'll
break if we change the ordering of 'git for-each-ref'. Maybe we should
`| sort >actual.haves`?
> Not that it's super important, but I wonder if we should give a
> motivating example like this in the documentation. In which case we'd
> probably want to give the most plausible one.
Maybe. I don't feel strongly about it, though.
> > Since the value of "core.alternateRefsPrefixes" is appended to 'git
> > for-each-ref' and then executed, include a "--" before taking the
> > configured value to avoid misinterpreting arguments as flags to 'git
> > for-each-ref'.
>
> Good idea.
>
> > diff --git a/Documentation/config.txt b/Documentation/config.txt
> > index b908bc5825..d768c57310 100644
> > --- a/Documentation/config.txt
> > +++ b/Documentation/config.txt
> > @@ -622,6 +622,12 @@ core.alternateRefsCommand::
> > linkgit:git-for-each-ref[1]. The first argument is the path of the alternate.
> > Output must be of the form: `%(objectname) SPC %(refname)`.
> >
> > +core.alternateRefsPrefixes::
> > + When listing references from an alternate, list only references that begin
> > + with the given prefix. To list multiple prefixes, separate them with a
> > + whitespace character. If `core.alternateRefsCommand` is set, setting
> > + `core.alternateRefsPrefixes` has no effect.
>
> I can't remember all of the rules for how for-each-ref matches prefixes,
> but I remember that it's subtly different than git-branch (and that's
> why ref-filter.c has two matching modes). Do we need to spell out the
> rules here (or at least say "it matches like for-each-ref")?
Good idea. I'll do that.
> Also, a minor nit, but I think the argv_array_split() helper you're
> using soaks up arbitrary amounts of whitespace. So maybe "separate them
> with whitespace" instead of "a whitespace character". Or maybe we should
> be strict in what we suggest and liberal in what we parse. ;)
Yeah, I think that chaning "a whitespace character" -> "with
whitespace" is the easier thing to do ;-).
> > +test_expect_success 'with core.alternateRefsPrefixes' '
> > + test_config -C fork core.alternateRefsPrefixes "refs/tags" &&
> > + cat >expect <<-EOF &&
> > + $(git rev-parse one) .have
> > + $(git rev-parse three) .have
> > + $(git rev-parse two) .have
> > + EOF
> > + printf "0000" | git receive-pack fork | extract_haves >actual &&
> > + test_cmp expect actual
>
> Looks sane, though the same pipe comment applies as before.
Thanks. I applied that suggestion in both locations when reading your
last mail.
> > test_done
> > diff --git a/transport.c b/transport.c
> > index e7d2cdf00b..9323e5c3cd 100644
> > --- a/transport.c
> > +++ b/transport.c
> > @@ -1341,6 +1341,11 @@ static void fill_alternate_refs_command(struct child_process *cmd,
> > argv_array_pushf(&cmd->args, "--git-dir=%s", repo_path);
> > argv_array_push(&cmd->args, "for-each-ref");
> > argv_array_push(&cmd->args, "--format=%(objectname) %(refname)");
> > +
> > + if (!git_config_get_value("core.alternateRefsPrefixes", &value)) {
> > + argv_array_push(&cmd->args, "--");
> > + argv_array_split(&cmd->args, value);
> > + }
> > }
>
> The implementation ended up delightfully simple.
Thanks :-). It made me quite happy, too.
Thanks,
Taylor
next prev parent reply other threads:[~2018-09-20 20:12 UTC|newest]
Thread overview: 94+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-20 18:04 [PATCH 0/3] Filter alternate references Taylor Blau
2018-09-20 18:04 ` [PATCH 1/3] transport.c: extract 'fill_alternate_refs_command' Taylor Blau
2018-09-20 18:04 ` [PATCH 2/3] transport.c: introduce core.alternateRefsCommand Taylor Blau
2018-09-20 19:37 ` Jeff King
2018-09-20 20:00 ` Taylor Blau
2018-09-20 20:06 ` Jeff King
2018-09-21 16:39 ` Junio C Hamano
2018-09-21 17:48 ` Taylor Blau
2018-09-21 17:57 ` Taylor Blau
2018-09-21 19:59 ` Junio C Hamano
2018-09-26 0:56 ` Taylor Blau
2018-09-20 18:04 ` [PATCH 3/3] transport.c: introduce core.alternateRefsPrefixes Taylor Blau
2018-09-20 19:47 ` Jeff King
2018-09-20 20:12 ` Taylor Blau [this message]
2018-09-21 7:19 ` Eric Sunshine
2018-09-21 14:07 ` Taylor Blau
2018-09-21 16:45 ` Junio C Hamano
2018-09-21 17:49 ` Taylor Blau
2018-09-21 16:40 ` Junio C Hamano
2018-09-20 18:35 ` [PATCH 0/3] Filter alternate references Stefan Beller
2018-09-20 18:56 ` Taylor Blau
2018-09-20 19:27 ` Jeff King
2018-09-20 19:21 ` Jeff King
2018-09-21 18:47 ` [PATCH v2 " Taylor Blau
2018-09-21 18:47 ` [PATCH v2 1/3] transport.c: extract 'fill_alternate_refs_command' Taylor Blau
2018-09-21 18:47 ` [PATCH v2 2/3] transport.c: introduce core.alternateRefsCommand Taylor Blau
2018-09-21 20:18 ` Eric Sunshine
2018-09-26 0:59 ` Taylor Blau
2018-09-21 21:09 ` Junio C Hamano
2018-09-21 22:13 ` Jeff King
2018-09-21 22:23 ` Junio C Hamano
2018-09-21 22:27 ` Jeff King
2018-09-26 1:06 ` Taylor Blau
2018-09-26 3:21 ` Jeff King
2018-09-21 21:10 ` Eric Sunshine
2018-09-22 18:02 ` brian m. carlson
2018-09-22 19:52 ` Jeff King
2018-09-23 14:53 ` brian m. carlson
2018-09-26 1:09 ` Taylor Blau
2018-09-26 3:33 ` Jeff King
2018-09-26 13:39 ` Taylor Blau
2018-09-26 18:38 ` Jeff King
2018-09-28 2:39 ` Taylor Blau
2018-09-21 18:47 ` [PATCH v2 3/3] transport.c: introduce core.alternateRefsPrefixes Taylor Blau
2018-09-21 21:14 ` Junio C Hamano
2018-09-21 21:37 ` Jeff King
2018-09-21 22:06 ` Junio C Hamano
2018-09-21 22:18 ` Jeff King
2018-09-21 22:23 ` Stefan Beller
2018-09-24 15:17 ` Junio C Hamano
2018-09-24 18:10 ` Jeff King
2018-09-24 20:32 ` Junio C Hamano
2018-09-24 20:50 ` Jeff King
2018-09-24 21:01 ` Jeff King
2018-09-24 21:55 ` Junio C Hamano
2018-09-24 23:14 ` Jeff King
2018-09-25 17:41 ` Junio C Hamano
2018-09-25 22:46 ` Taylor Blau
2018-09-25 23:56 ` Junio C Hamano
2018-09-26 1:18 ` Taylor Blau
2018-09-26 3:16 ` Jeff King
2018-09-28 4:25 ` [PATCH v3 0/4] Filter alternate references Taylor Blau
2018-09-28 4:25 ` [PATCH v3 1/4] transport: drop refnames from for_each_alternate_ref Jeff King
2018-09-28 4:58 ` Jeff King
2018-09-28 14:21 ` Taylor Blau
2018-09-28 4:25 ` [PATCH v3 2/4] transport.c: extract 'fill_alternate_refs_command' Taylor Blau
2018-09-28 4:59 ` Jeff King
2018-09-28 4:25 ` [PATCH v3 3/4] transport.c: introduce core.alternateRefsCommand Taylor Blau
2018-09-28 5:26 ` Jeff King
2018-09-28 22:04 ` Taylor Blau
2018-09-29 7:31 ` Jeff King
2018-10-02 1:56 ` Taylor Blau
2018-09-28 4:25 ` [PATCH v3 4/4] transport.c: introduce core.alternateRefsPrefixes Taylor Blau
2018-09-28 5:30 ` Jeff King
2018-09-28 22:05 ` Taylor Blau
2018-09-29 7:34 ` Jeff King
2018-10-02 1:57 ` Taylor Blau
2018-10-02 2:00 ` Taylor Blau
2018-10-02 2:23 ` [PATCH v4 0/4] Filter alternate references Taylor Blau
2018-10-02 2:23 ` [PATCH v4 1/4] transport: drop refnames from for_each_alternate_ref Taylor Blau
2018-10-02 2:23 ` [PATCH v4 2/4] transport.c: extract 'fill_alternate_refs_command' Taylor Blau
2018-10-02 2:23 ` [PATCH v4 3/4] transport.c: introduce core.alternateRefsCommand Taylor Blau
2018-10-02 23:40 ` Jeff King
2018-10-04 2:17 ` Taylor Blau
2018-10-02 2:24 ` [PATCH v4 4/4] transport.c: introduce core.alternateRefsPrefixes Taylor Blau
2018-10-02 15:13 ` Ramsay Jones
2018-10-02 23:28 ` Taylor Blau
2018-10-08 18:09 ` [PATCH v5 0/4] Filter alternate references Taylor Blau
2018-10-08 18:09 ` [PATCH v5 1/4] transport: drop refnames from for_each_alternate_ref Taylor Blau
2018-10-08 18:09 ` [PATCH v5 2/4] transport.c: extract 'fill_alternate_refs_command' Taylor Blau
2018-10-08 18:09 ` [PATCH v5 3/4] transport.c: introduce core.alternateRefsCommand Taylor Blau
2018-10-08 18:09 ` [PATCH v5 4/4] transport.c: introduce core.alternateRefsPrefixes Taylor Blau
2018-10-09 3:09 ` [PATCH v5 0/4] Filter alternate references Jeff King
2018-10-09 14:49 ` Taylor Blau
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