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Re: [PATCH v5] revision.c: implement --max-count-oldest

From
Junio C Hamano <gitster@pobox.com>
Date
May 4, 2026, 05:19 UTC
Message-ID
<xmqqik93px8s.fsf@gitster.g>
In-Reply-To
<2f71a00b035e25b971641b77a6fa7626f1e2459c.1777578676.git.mroik@delayed.space>
Mirko Faina <mroik@delayed.space> writes:
> --max-count is a commit limiting option sets a maximum amount of commits
> to be shown. If a user wants to see only the first N commits of the
> history (the oldest commits) they'd have to combine --max-count with
> --skip. This is not very user-friendly.

To use "--skip=<n>" for this purose, you'd need to know how many records are going to be omitted to begin with, but that means you'd run the command without count limitation once only to find out how many records there are. "not very user-friendly" sounds like an understatement of the year.

They can do with something silly like
    git rev-list ... |
    tail -n N |
    xargs -n1 git show ...
and that does count as "not very user-friendly", I would think.
Show 9 quoted lines
> Teach get_revision() the --max-count-oldest option.
>
> Signed-off-by: Mirko Faina <mroik@delayed.space>
> ---
>  Documentation/rev-list-options.adoc |  3 ++
>  revision.c                          | 77 +++++++++++++++++++++++++++--
>  revision.h                          |  2 +
>  t/t4202-log.sh                      | 14 ++++++
>  4 files changed, 93 insertions(+), 3 deletions(-)

It looks like this needs measurably smaller damage to the codebase than the other --reverse=before approach ;-).

Show 165 quoted lines
> diff --git a/Documentation/rev-list-options.adoc b/Documentation/rev-list-options.adoc
> index 2d195a1474..736f34efab 100644
> --- a/Documentation/rev-list-options.adoc
> +++ b/Documentation/rev-list-options.adoc
> @@ -18,6 +18,9 @@ ordering and formatting options, such as `--reverse`.
>  `--max-count=<number>`::
>  	Limit the output to _<number>_ commits.
>  
> +`--max-count-oldest=<number>`::
> +	Limit the output to the _<number>_ oldest commits.
> +
>  `--skip=<number>`::
>  	Skip _<number>_ commits before starting to show the commit output.
>  
> diff --git a/revision.c b/revision.c
> index 599b3a66c3..3aaa77ced5 100644
> --- a/revision.c
> +++ b/revision.c
> @@ -2339,10 +2339,24 @@ static int handle_revision_opt(struct rev_info *revs, int argc, const char **arg
>  	}
>  
>  	if ((argcount = parse_long_opt("max-count", argv, &optarg))) {
> +		if (revs->max_count_type == 1)
> +			die(_("can't use --max-count with --max-count-oldest"));
>  		revs->max_count = parse_count(optarg);
>  		revs->no_walk = 0;
> +		revs->max_count_type = 0;
>  		return argcount;
> +	} else if ((argcount = parse_long_opt("max-count-oldest", argv, &optarg))) {
> +		if (revs->max_count_type == 0 && revs->max_count != -1)
> +			die(_("can't use --max-count with --max-count-oldest"));
> +		if (revs->skip_count > 0)
> +			die(_("con't use --max-count-oldest with --skip"));
> +		revs->max_count = parse_count(optarg);
> +		revs->no_walk = 0;
> +		revs->max_count_type = 1;
> +		revs->max_count_stage = 0;
>  	} else if ((argcount = parse_long_opt("skip", argv, &optarg))) {
> +		if (revs->max_count_type == 1)
> +			die(_("con't use --max-count-oldest with --skip"));
>  		revs->skip_count = parse_count(optarg);
>  		return argcount;
>  	} else if ((*arg == '-') && isdigit(arg[1])) {
> @@ -4521,15 +4535,68 @@ static struct commit *get_revision_internal(struct rev_info *revs)
>  	return c;
>  }
>  
> +static void retrieve_oldest_commits(struct rev_info *revs,
> +				    struct commit_list **queue)
> +{
> +	struct commit *c;
> +	int max_count = revs->max_count;
> +	int queuei_count = 0;
> +	int queueo_count = 0;
> +	struct commit_list *queueo = NULL;
> +	struct commit_list *queuei = NULL;
> +	struct commit_list *reversed_queue = NULL;
> +
> +	revs->max_count = -1;
> +	while ((c = get_revision_internal(revs))) {
> +		c->object.flags &= ~SHOWN;
> +		commit_list_insert(c, &queuei);
> +		queuei_count++;
> +		while (queuei_count + queueo_count > max_count) {
> +			if (!queueo_count) {
> +				while (queuei_count > 0) {
> +					c = pop_commit(&queuei);
> +					queuei_count--;
> +					commit_list_insert(c, &queueo);
> +					queueo_count++;
> +				}
> +			}
> +			pop_commit(&queueo);
> +			queueo_count--;
> +		}
> +	}
> +
> +	while ((c = pop_commit(&queueo)))
> +		commit_list_insert(c, &reversed_queue);
> +	while ((c = pop_commit(&queuei)))
> +		commit_list_insert(c, &queueo);
> +	while ((c = pop_commit(&queueo)))
> +		commit_list_insert(c, &reversed_queue);
> +
> +	while ((c = pop_commit(&reversed_queue)))
> +		commit_list_insert(c, queue);
> +}
> +
>  struct commit *get_revision(struct rev_info *revs)
>  {
>  	struct commit *c;
>  	struct commit_list *reversed;
> +	struct commit_list *queue = NULL;
> +
> +	if (revs->max_count_type == 1 && !revs->max_count_stage) {
> +		retrieve_oldest_commits(revs, &queue);
> +		commit_list_free(revs->commits);
> +		revs->commits = queue;
> +		revs->max_count_stage = 1;
> +	}
>  
>  	if (revs->reverse) {
>  		reversed = NULL;
> -		while ((c = get_revision_internal(revs)))
> -			commit_list_insert(c, &reversed);
> +		if (revs->max_count_type == 1)
> +			while ((c = pop_commit(&revs->commits)))
> +				commit_list_insert(c, &reversed);
> +		else
> +			while ((c = get_revision_internal(revs)))
> +				commit_list_insert(c, &reversed);
>  		commit_list_free(revs->commits);
>  		revs->commits = reversed;
>  		revs->reverse = 0;
> @@ -4543,7 +4610,11 @@ struct commit *get_revision(struct rev_info *revs)
>  		return c;
>  	}
>  
> -	c = get_revision_internal(revs);
> +	if (revs->max_count_stage)
> +		c = pop_commit(&revs->commits);
> +	else
> +		c = get_revision_internal(revs);
> +
>  	if (c && revs->graph)
>  		graph_update(revs->graph, c);
>  	if (!c) {
> diff --git a/revision.h b/revision.h
> index 584f1338b5..e157463cb1 100644
> --- a/revision.h
> +++ b/revision.h
> @@ -309,6 +309,8 @@ struct rev_info {
>  	/* special limits */
>  	int skip_count;
>  	int max_count;
> +	unsigned int max_count_type:1;
> +	unsigned int max_count_stage:1;
>  	timestamp_t max_age;
>  	timestamp_t max_age_as_filter;
>  	timestamp_t min_age;
> diff --git a/t/t4202-log.sh b/t/t4202-log.sh
> index 05cee9e41b..668c231cf1 100755
> --- a/t/t4202-log.sh
> +++ b/t/t4202-log.sh
> @@ -1882,6 +1882,20 @@ test_expect_success 'log --graph with --name-status' '
>  	test_cmp_graph --name-status tangle..reach
>  '
>  
> +test_expect_success 'log --max-count-oldest=3 --oneline' '
> +	test_when_finished rm expect &&
> +	git log --oneline | tail -n3 >expect &&
> +	git log --oneline --max-count-oldest=3 >actual &&
> +	test_cmp expect actual
> +'
> +
> +test_expect_success 'log --max-count-oldest=3 --reverse --oneline' '
> +	test_when_finished rm expect &&
> +	git log --oneline | tail -n3 | tac >expect &&
> +	git log --oneline --max-count-oldest=3 --reverse >actual &&
> +	test_cmp expect actual
> +'
> +
>  cat >expect <<-\EOF
>  * reach
>  |
Previous: Mirko FainaNext: Mirko Faina
Message 38 of 63 in “revision.c: implement --reverse=before for walks”
  1. revision.c: implement --reverse=before for walksMirko Faina, Apr 18, 2026
  2. Tian YuchenApr 18, 2026
  3. Mirko FainaApr 18, 2026
  4. Mirko FainaApr 18, 2026
  5. Junio C HamanoApr 20, 2026
  6. Tian YuchenApr 20, 2026
  7. Mirko FainaApr 20, 2026
  8. Ben KnobleApr 19, 2026
  9. Mirko FainaApr 19, 2026
  10. D. Ben KnobleApr 19, 2026
  11. Mirko FainaApr 19, 2026
  12. Jeff KingApr 20, 2026
  13. Mirko FainaApr 20, 2026
  14. Mirko FainaApr 20, 2026
  15. Jeff KingApr 21, 2026
  16. D. Ben KnobleApr 22, 2026
  17. Mirko FainaApr 22, 2026
  18. Jeff KingApr 20, 2026
  19. Mirko FainaApr 20, 2026
  20. 0/2 revision.c: implement --reverse=before for walksMirko Faina, Apr 22, 2026
  21. Mirko FainaApr 22, 2026
  22. 0/2 revision.c: implement --reverse=before for walksMirko Faina, Apr 23, 2026
  23. 2/2 revision.c: reduce memory usage on reverse beforeMirko Faina, Apr 23, 2026
  24. 1/2 revision.c: implement --reverse=before for walksMirko Faina, Apr 23, 2026
  25. Junio C HamanoApr 28, 2026
  26. 0/2 revision.c: implement --reverse=before for walksMirko Faina, Apr 27, 2026
  27. 2/2 revision.c: reduce memory usage on reverse beforeMirko Faina, Apr 27, 2026
  28. Junio C HamanoApr 28, 2026
  29. 1/2 revision.c: implement --reverse=before for walksMirko Faina, Apr 27, 2026
  30. Junio C HamanoApr 27, 2026
  31. Johannes SixtApr 27, 2026
  32. Junio C HamanoApr 27, 2026
  33. Chris TorekApr 27, 2026
  34. Mirko FainaApr 27, 2026
  35. Junio C HamanoApr 28, 2026
  36. Junio C HamanoApr 28, 2026
  37. revision.c: implement --max-count-oldestMirko Faina, Apr 30, 2026
  38. Junio C HamanoMay 4, 2026
  39. Mirko FainaMay 4, 2026
  40. revision.c: implement --max-count-oldestMirko Faina, May 5, 2026
  41. Johannes SixtMay 6, 2026
  42. Mirko FainaMay 6, 2026
  43. Junio C HamanoMay 7, 2026
  44. Mirko FainaMay 8, 2026
  45. Jean-Noël AVILAMay 9, 2026
  46. Mirko FainaMay 10, 2026
  47. Junio C HamanoMay 9, 2026
  48. Mirko FainaMay 10, 2026
  49. revision.c: implement --max-count-oldestMirko Faina, May 15, 2026
  50. revision.c: implement --max-count-oldestMirko Faina, May 19, 2026
  51. Mirko FainaMay 19, 2026
  52. Junio C HamanoMay 20, 2026
  53. Mirko FainaMay 20, 2026
  54. revision.c: implement --max-count-oldestJunio C Hamano, Jun 1, 2026
  55. Mirko FainaJun 2, 2026
  56. Junio C HamanoMay 19, 2026
  57. Mirko FainaMay 19, 2026
  58. Junio C HamanoMay 9, 2026
  59. Mirko FainaMay 10, 2026
  60. 2/2 revision.c: reduce memory usage on reverse beforeMirko Faina, Apr 22, 2026
  61. 1/2 revision.c: implement --reverse=before for walksMirko Faina, Apr 22, 2026
  62. Jeff KingApr 22, 2026
  63. Mirko FainaApr 22, 2026

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