From: Junio C Hamano <gitster@pobox.com>
To: "Torsten Bögershausen" <tboegi@web.de>
Cc: git@vger.kernel.org, Mike Crowe <mac@mcrowe.com>
Subject: Re: git diff --quiet exits with 1 on clean tree with CRLF conversions
Date: Mon, 27 Feb 2017 12:17:22 -0800 [thread overview]
Message-ID: <xmqqefyjwfql.fsf@gitster.mtv.corp.google.com> (raw)
In-Reply-To: <20170225153230.GA30565@mcrowe.com> (Mike Crowe's message of "Sat, 25 Feb 2017 15:32:30 +0000")
Torsten, you've been quite active in fixing various glitches around
the EOL conversion in the latter half of last year. Have any
thoughts to share on this topic?
Thanks.
Mike Crowe <mac@mcrowe.com> writes:
> On Monday 20 February 2017 at 13:25:01 -0800, Junio C Hamano wrote:
>> This almost makes me suspect that the place that checks lengths of
>> one and two in order to refrain from running more expensive content
>> comparison you found earlier need to ask would_convert_to_git()
>> before taking the short-cut, something along the lines of this (for
>> illustration purposes only, not even compile-tested). The "almost"
>> comes to me because I do not offhand know the performance implications
>> of making calls to would_convert_to_git() here.
>>
>> diff.c | 18 ++++++++++++++----
>> 1 file changed, 14 insertions(+), 4 deletions(-)
>>
>> diff --git a/diff.c b/diff.c
>> index 051761be40..094d5913da 100644
>> --- a/diff.c
>> +++ b/diff.c
>> @@ -4921,9 +4921,10 @@ static int diff_filespec_check_stat_unmatch(struct diff_filepair *p)
>> * differences.
>> *
>> * 2. At this point, the file is known to be modified,
>> - * with the same mode and size, and the object
>> - * name of one side is unknown. Need to inspect
>> - * the identical contents.
>> + * with the same mode and size, the object
>> + * name of one side is unknown, or size comparison
>> + * cannot be depended upon. Need to inspect the
>> + * contents.
>> */
>> if (!DIFF_FILE_VALID(p->one) || /* (1) */
>> !DIFF_FILE_VALID(p->two) ||
>> @@ -4931,7 +4932,16 @@ static int diff_filespec_check_stat_unmatch(struct diff_filepair *p)
>> (p->one->mode != p->two->mode) ||
>> diff_populate_filespec(p->one, CHECK_SIZE_ONLY) ||
>> diff_populate_filespec(p->two, CHECK_SIZE_ONLY) ||
>> - (p->one->size != p->two->size) ||
>> +
>> + /*
>> + * only if eol and other conversions are not involved,
>> + * we can say that two contents of different sizes
>> + * cannot be the same without checking their contents.
>> + */
>> + (!would_convert_to_git(p->one->path) &&
>> + !would_convert_to_git(p->two->path) &&
>> + (p->one->size != p->two->size)) ||
>> +
>> !diff_filespec_is_identical(p->one, p->two)) /* (2) */
>> p->skip_stat_unmatch_result = 1;
>> return p->skip_stat_unmatch_result;
>>
>>
>
> Thanks for investigating this. I think you are correct that I was misguided
> in my previous "fix". However, your change above does fix the problem for
> me.
>
> It looks like the main cost of convert_to_git is in convert_attrs which
> ends up doing various path operations in attr.c. After that, both
> apply_filter and crlf_to_git return straight away if there's nothing to do.
>
> I experimented several times with running "git diff -quiet" after touching
> every file in Git's own worktree and any difference in total time was lost
> in the noise.
>
> I've further improved my test case. Tests 3 and 4 fail without the above
> change but pass with it. Unfortunately I'm still unable to get those tests
> to fail without the above fix unless the sleeps are present. I've tried
> using the "touch -r .datetime" technique from racy-git.txt but it doesn't
> help. It seems that I'm unable to stop Git from using its cache without
> sleeping. :(
>
> diff --git a/t/t4063-diff-converted.sh b/t/t4063-diff-converted.sh
> new file mode 100755
> index 0000000..31a730d
> --- /dev/null
> +++ b/t/t4063-diff-converted.sh
> @@ -0,0 +1,44 @@
> +#!/bin/sh
> +#
> +# Copyright (c) 2017 Mike Crowe
> +#
> +# These tests ensure that files changing line endings in the presence
> +# of .gitattributes to indicate that line endings should be ignored
> +# don't cause 'git diff' or 'git diff --quiet' to think that they have
> +# been changed.
> +#
> +# The sleeps are necessary to reproduce the problem for reasons that I
> +# don't understand.
> +
> +test_description='git diff with files that require CRLF conversion'
> +
> +. ./test-lib.sh
> +
> +test_expect_success setup '
> + echo "* text=auto" > .gitattributes &&
> + printf "Hello\r\nWorld\r\n" > crlf.txt &&
> + printf "Hello\nWorld\n" > lf.txt &&
> + git add .gitattributes crlf.txt lf.txt &&
> + git commit -m "initial" && echo three
> +'
> +test_expect_success 'noisy diff works on file that requires CRLF conversion' '
> + git status >/dev/null &&
> + git diff >/dev/null &&
> + sleep 1 &&
> + touch crlf.txt lf.txt &&
> + git diff >/dev/null
> +'
> +test_expect_success 'quiet diff works on file that requires CRLF conversion with no changes' '
> + git status &&
> + git diff --quiet &&
> + sleep 1 &&
> + touch crlf.txt lf.txt &&
> + git diff --quiet
> +'
> +
> +test_expect_success 'quiet diff works on file with line-ending change that has no effect on repository' '
> + printf "Hello\nWorld\n" > crlf.txt &&
> + printf "Hello\r\nWorld\r\n" > lf.txt &&
> + git diff --quiet
> +'
> +test_done
>
>
> Mike.
next prev parent reply other threads:[~2017-02-28 0:40 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-02-17 21:26 git diff --quiet exits with 1 on clean tree with CRLF conversions Mike Crowe
2017-02-17 22:05 ` Junio C Hamano
2017-02-17 22:19 ` Mike Crowe
2017-02-20 15:33 ` Mike Crowe
2017-02-20 21:25 ` Junio C Hamano
2017-02-25 15:32 ` Mike Crowe
2017-02-27 20:17 ` Junio C Hamano [this message]
2017-02-28 18:06 ` Torsten Bögershausen
2017-02-28 21:50 ` Junio C Hamano
2017-03-01 17:04 ` [PATCH v1 1/1] " tboegi
2017-03-01 21:14 ` Junio C Hamano
2017-03-01 21:54 ` Junio C Hamano
2017-03-02 8:53 ` Jeff King
2017-03-02 17:52 ` Junio C Hamano
2017-03-02 19:12 ` Jeff King
2017-03-02 18:51 ` [PATCH v2] diff: do not short-cut CHECK_SIZE_ONLY check in diff_populate_filespec() Junio C Hamano
2017-03-02 14:20 ` [PATCH v1 1/1] git diff --quiet exits with 1 on clean tree with CRLF conversions Mike Crowe
2017-03-02 18:20 ` Torsten Bögershausen
2017-03-02 18:33 ` Junio C Hamano
2017-03-02 20:03 ` Mike Crowe
2017-03-03 17:02 ` Torsten Bögershausen
2017-03-03 17:47 ` Junio C Hamano
2017-03-04 6:25 ` Torsten Bögershausen
2017-03-04 19:59 ` Junio C Hamano
2017-03-01 21:25 ` Mike Crowe
2017-03-01 23:29 ` Junio C Hamano
2017-03-02 18:17 ` Torsten Bögershausen
2017-03-03 17:01 ` Mike Crowe
2017-03-02 15:38 ` git status reports file modified when only line-endings have changed (was git diff --quiet exits with 1 on clean tree with CRLF conversions) Mike Crowe
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