Re: [PATCH v2] Fix revision walk for commits with the same dates

[Junio C Hamano <gitster@pobox.com>]

Kacper Kornet <draenog@pld-linux.org> writes:

> Logic in still_interesting function allows to stop the commits
> traversing if the oldest processed commit is not older then the
> youngest commit on the list to process and the list contains only
> commits marked as not interesting ones. It can be premature when dealing
> with a set of coequal commits. For example git rev-list A^! --not B
> provides wrong answer if all commits in the range A..B had the same
> commit time and there are more then 7 of them.
>
> To fix this problem the relevant part of the logic in still_interesting
> is changed to: the walk can be stopped if the oldest processed commit is
> younger then the youngest commit on the list to processed.

Is the made-up test case to freeze the clock even interesting?  The
slop logic is merely a heuristic to compensate for effects caused by
skewed or non-monototic clocks, so in a different repository you may
even need to fuzz the timestamp comparison further

	if (date - 10 < src->item->date)

or something silly like that.



> Signed-off-by: Kacper Kornet <draenog@pld-linux.org>
> ---
>
> I don't know whether the first version was overlooked or deemed as not
> worthy. So just in case I resend it. Changes since the first version:
>
> 1. The test has been added
> 2. The commit log has been rewritten
>
>
>  revision.c                 |  2 +-
>  t/t6009-rev-list-parent.sh | 13 +++++++++++++
>  2 files changed, 14 insertions(+), 1 deletion(-)
>
> diff --git a/revision.c b/revision.c
> index ef60205..cf620c6 100644
> --- a/revision.c
> +++ b/revision.c
> @@ -709,7 +709,7 @@ static int still_interesting(struct commit_list *src, unsigned long date, int sl
>  	 * Does the destination list contain entries with a date
>  	 * before the source list? Definitely _not_ done.
>  	 */
> -	if (date < src->item->date)
> +	if (date <= src->item->date)
>  		return SLOP;
>  
>  	/*
> diff --git a/t/t6009-rev-list-parent.sh b/t/t6009-rev-list-parent.sh
> index 3050740..66cda17 100755
> --- a/t/t6009-rev-list-parent.sh
> +++ b/t/t6009-rev-list-parent.sh
> @@ -133,4 +133,17 @@ test_expect_success 'dodecapus' '
>  	check_revlist "--min-parents=13" &&
>  	check_revlist "--min-parents=4 --max-parents=11" tetrapus
>  '
> +
> +test_expect_success 'ancestors with the same commit time' '
> +
> +	test_tick_keep=$test_tick &&
> +	for i in 1 2 3 4 5 6 7 8; do
> +		test_tick=$test_tick_keep
> +		test_commit t$i
> +	done &&
> +	git rev-list t1^! --not t$i >result &&
> +	>expect &&
> +	test_cmp expect result
> +'
> +
>  test_done
> -- 
> 1.8.2