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From: Taylor Blau <me@ttaylorr.com>
To: Derrick Stolee <stolee@gmail.com>
Cc: Junio C Hamano <gitster@pobox.com>, Taylor Blau <me@ttaylorr.com>,
	Derrick Stolee via GitGitGadget <gitgitgadget@gmail.com>,
	git@vger.kernel.org, jnareb@gmail.com, garimasigit@gmail.com,
	Derrick Stolee <dstolee@microsoft.com>
Subject: Re: [PATCH v2 2/4] commit: write commit-graph with Bloom filters
Date: Tue, 14 Apr 2020 18:17:13 -0600	[thread overview]
Message-ID: <20200415001713.GB7457@syl.local> (raw)
In-Reply-To: <36f321b9-e2ff-60c3-637a-38682ee5d9f0@gmail.com>

On Tue, Apr 14, 2020 at 01:40:53PM -0400, Derrick Stolee wrote:
> On 4/14/2020 1:26 PM, Junio C Hamano wrote:
> > Derrick Stolee <stolee@gmail.com> writes:
> >
> >> On 4/13/2020 6:21 PM, Junio C Hamano wrote:
> >>> Taylor Blau <me@ttaylorr.com> writes:
> >>>
> >>>> Hmm. I'm not crazy about a library function looking at 'GIT_TEST_*'
> >>>> environment variables and potentially ignoring its arguments, but given
> >>>> the discussion we had in v1, I don't feel strongly enough to recommend
> >>>> that you change this.
> >>>>
> >>>> For what it's worth, I think that 'write_commit_graph' could behave more
> >>>> purely if callers checked 'GIT_TEST_COMMIT_GRAPH_CHANGED_PATHS' and set
> >>>> 'flags' appropriately from the outside,...
> >>>
> >>> Yeah, I agree that it would be a lot cleaner if that is easy to
> >>> arrange.  I have a suspicion that Derrick already tried and the
> >>> resulting code looked messier and was discarded?
> >>
> >> Perhaps I could fix both concerns by
> >>
> >> 1. Use a macro instead of a library call.
> >>
> >> 2. Check the _CHANGED_PATHS variable in the macro.
> >
> > I am not sure how use of a macro "fixes" purity, though.  And what
> > is the other concern?
>
> The concern was (1) checking the environment and (2) die()ing in the
> library.

I think that we might as well use a plain old function here instead of a
macro, especially since the macro is just expanding out to what that
function would be if we had written it that way.

For what it's worth, my concern was more that I don't mind dying, but
I'd rather do so in a calling function, and that by the time we're
calling 'write_commit_graph', that we should be using return values
instead of 'die()' or 'error()'.

> > How widely would this "if we are testing, write out the graph file"
> > call be sprinkled over the codebase?  I am hoping that it won't be
> > "everywhere", but only at strategic places (like "just once before
> > we leave a subcommand that creates one or bunch of commits").  And
> > how often would they be called?  I am also hoping that it won't be
> > "inside a tight loop".  In short, I am wondering if we can promise
> > our codebase that
> >
> >  - git_test_write_commit_graph_or_die() calls won't be an eyesore
> >    (and/or distraction) for developers too much.
> >
> >  - git_env_bool() call won't have performance impact.
>
> I could add a comment to the header file to say "this is only for
> improving coverage of optional features in the test suite. Do not
> call this method unless you know what you are doing."

Works for me.

> My intention right now is to only include this in 'git commit'
> and 'git merge'. Earlier discussion included thoughts about
> 'git rebase' and similar, but those are more rarely used when
> constructing an "example repo" in the test scripts.

Ditto. I think that there's benefit in having it in some places but not
all (as Stolee pointed out earlier in the thread), and that trying to
have it everywhere is a fool's errand.

> -Stolee

Thanks,
Taylor

  reply	other threads:[~2020-04-15  0:17 UTC|newest]

Thread overview: 48+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-11  1:02 [PATCH 0/3] Integrate changed-path Bloom filters with 'git blame' Derrick Stolee via GitGitGadget
2020-04-11  1:02 ` [PATCH 1/3] revision: complicated pathspecs disable filters Derrick Stolee via GitGitGadget
2020-04-11 21:40   ` Junio C Hamano
2020-04-13 11:49     ` Derrick Stolee
2020-04-14 18:25       ` Junio C Hamano
2020-04-15 13:27         ` Derrick Stolee
2020-04-15 18:37           ` Derrick Stolee
2020-04-15 19:32             ` Junio C Hamano
2020-04-15 19:39               ` Junio C Hamano
2020-04-15 21:25             ` Junio C Hamano
2020-04-16  0:56               ` Taylor Blau
2020-04-15 22:18             ` Jakub Narębski
2020-04-16  0:52               ` Taylor Blau
2020-04-16 13:26                 ` Derrick Stolee
2020-04-16 16:33                   ` Taylor Blau
2020-04-16 18:02                     ` Junio C Hamano
2020-04-12 22:22   ` Taylor Blau
2020-04-12 22:30     ` Junio C Hamano
2020-04-13  0:07       ` Taylor Blau
2020-04-13 11:54         ` Derrick Stolee
2020-04-11  1:03 ` [PATCH 2/3] commit: write commit-graph with bloom filters Derrick Stolee via GitGitGadget
2020-04-11 21:57   ` Junio C Hamano
2020-04-12 20:51     ` Taylor Blau
2020-04-13 12:08       ` Derrick Stolee
2020-04-13 22:11         ` Junio C Hamano
2020-04-11  1:03 ` [PATCH 3/3] blame: use changed-path Bloom filters Derrick Stolee via GitGitGadget
2020-04-11 22:03   ` Junio C Hamano
2020-04-12  7:39     ` Eric Sunshine
2020-04-11 21:30 ` [PATCH 0/3] Integrate changed-path Bloom filters with 'git blame' Junio C Hamano
2020-04-13 14:45 ` [PATCH v2 0/4] " Derrick Stolee via GitGitGadget
2020-04-13 14:45   ` [PATCH v2 1/4] revision: complicated pathspecs disable filters Derrick Stolee via GitGitGadget
2020-04-13 16:09     ` Taylor Blau
2020-04-13 22:18       ` Junio C Hamano
2020-04-13 14:45   ` [PATCH v2 2/4] commit: write commit-graph with Bloom filters Derrick Stolee via GitGitGadget
2020-04-13 16:12     ` Taylor Blau
2020-04-13 22:21       ` Junio C Hamano
2020-04-14 15:04         ` Derrick Stolee
2020-04-14 17:26           ` Junio C Hamano
2020-04-14 17:40             ` Derrick Stolee
2020-04-15  0:17               ` Taylor Blau [this message]
2020-04-13 14:45   ` [PATCH v2 3/4] commit-graph: write commit-graph in more tests Derrick Stolee via GitGitGadget
2020-04-13 14:45   ` [PATCH v2 4/4] blame: use changed-path Bloom filters Derrick Stolee via GitGitGadget
2020-04-13 16:21   ` [PATCH v2 0/4] Integrate changed-path Bloom filters with 'git blame' Taylor Blau
2020-04-16 20:14   ` [PATCH v3 0/3] " Derrick Stolee via GitGitGadget
2020-04-16 20:14     ` [PATCH v3 1/3] revision: complicated pathspecs disable filters Derrick Stolee via GitGitGadget
2020-06-07 20:33       ` SZEDER Gábor
2020-04-16 20:14     ` [PATCH v3 2/3] tests: write commit-graph with Bloom filters Derrick Stolee via GitGitGadget
2020-04-16 20:14     ` [PATCH v3 3/3] blame: use changed-path " Derrick Stolee via GitGitGadget

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