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There is an issue in commit a43f270:
commit-reach: skip STALE drain in paint_down_to_common when only one merge-base needed

• First line of commit message is too long (> 76 columns)

There is an issue in commit 09c61b0:
commit-reach: skip STALE drain in paint_down_to_common when only one merge-base needed

• First line of commit message is too long (> 76 columns)

/allow

User spkrka is now allowed to use GitGitGadget.

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/preview

Preview email sent as pull.2109.git.1778252509243.gitgitgadget@gmail.com

/submit

Submitted as pull.2109.git.1778252837132.gitgitgadget@gmail.com

To fetch this version into FETCH_HEAD:

git fetch https://github.com/gitgitgadget/git/ pr-2109/spkrka/merge-base-early-exit-v1

To fetch this version to local tag pr-2109/spkrka/merge-base-early-exit-v1:

git fetch --no-tags https://github.com/gitgitgadget/git/ tag pr-2109/spkrka/merge-base-early-exit-v1

This patch series was integrated into seen via git@0b5178e.

This patch series was integrated into seen via git@b7cd8e6.

This branch is now known as kk/paint-down-to-common-optim.

This patch series was integrated into seen via git@f055420.

Junio C Hamano wrote on the Git mailing list (how to reply to this email):

"Kristofer Karlsson via GitGitGadget" <gitgitgadget@gmail.com>
writes:

> diff --git a/commit-reach.c b/commit-reach.c
> index d3a9b3ed6f..c9d2d594de 100644
> --- a/commit-reach.c
> +++ b/commit-reach.c
> @@ -55,14 +55,16 @@ static int paint_down_to_common(struct repository *r,
>  				struct commit **twos,
>  				timestamp_t min_generation,
>  				int ignore_missing_commits,
> +				int find_all,
>  				struct commit_list **result)
>  {
>  	struct prio_queue queue = { compare_commits_by_gen_then_commit_date };
>  	int i;
> +	int has_gens = min_generation || corrected_commit_dates_enabled(r);

Giving a name that identifies what the commonly-used logical
expression means is a very good idea, but don't some caller pass
min_generation==infinity (i.e., not zero) when there is no
generation available?  E.g., remove_redundant_no_gen() passes
the result of calling commit_graph_generation(), and without commit
graph, we would get infinity here, right?

Given that the second user of this variable is guarded by !find_all,
the variable being true even when we shouldn't be using generation
numbers may not matter for the purpose of the early break, but then
it means that the patch squanders the perfect opportunity to clarify
what the variable means, which is not very lovely.

>  	timestamp_t last_gen = GENERATION_NUMBER_INFINITY;
>  	struct commit_list **tail = result;
>  
> -	if (!min_generation && !corrected_commit_dates_enabled(r))
> +	if (!has_gens)
>  		queue.compare = compare_commits_by_commit_date;
>  
>  	one->object.flags |= PARENT1;
> @@ -97,6 +99,11 @@ static int paint_down_to_common(struct repository *r,
>  			if (!(commit->object.flags & RESULT)) {
>  				commit->object.flags |= RESULT;
>  				tail = commit_list_append(commit, tail);
> +				/* Generation-ordered queue: no later
> +				 * commit can dominate this one. */
> +				if (!find_all && has_gens &&
> +				    generation < GENERATION_NUMBER_INFINITY)
> +					break;

Three comments

 * See Documentation/CodingGuidelines for our preferred style for
   multi-line comments.

 * I do not think we often use "dominate" to describe relationship
   between commits, and I am not sure what you want the word to mean
   in this context.  Can you clarify?

 * The code is getting way too deeply indented.  Perhaps using a
   helper function and


                        if (!(commit->object.flags & RESULT)) {
                                if (mark_result(r, &tail, commit,
						find_all, min_generation))
                                        break;
                        }

   move the logic to mark the newly discovered commit as one of the
   possible result, and to tell the loop to terminate, to it, along
   with the comment on the meaning of its return value, may make the
   code easier to follow?

> +/* To be used only when object flags after this call no longer matter.
> + * When find_all is false and generation numbers are available, returns
> + * after finding the first merge-base, skipping the STALE drain. */

Ditto on the style.

There was a status update in the "New Topics" section about the branch kk/paint-down-to-common-optim on the Git mailing list:

"git merge-base" optimization.

Comments?
source: <pull.2109.git.1778252837132.gitgitgadget@gmail.com>

This patch series was integrated into seen via git@41a7672.

/submit

Submitted as pull.2109.v2.git.1778480348118.gitgitgadget@gmail.com

To fetch this version into FETCH_HEAD:

git fetch https://github.com/gitgitgadget/git/ pr-2109/spkrka/merge-base-early-exit-v2

To fetch this version to local tag pr-2109/spkrka/merge-base-early-exit-v2:

git fetch --no-tags https://github.com/gitgitgadget/git/ tag pr-2109/spkrka/merge-base-early-exit-v2

Patrick Steinhardt wrote on the Git mailing list (how to reply to this email):

On Mon, May 11, 2026 at 06:19:08AM +0000, Kristofer Karlsson via GitGitGadget wrote:
> diff --git a/commit-reach.c b/commit-reach.c
> index d3a9b3ed6f..b4ca00bb7e 100644
> --- a/commit-reach.c
> +++ b/commit-reach.c
> @@ -165,7 +175,7 @@ static int merge_bases_many(struct repository *r,
>  				     oid_to_hex(&twos[i]->object.oid));
>  	}
>  
> -	if (paint_down_to_common(r, one, n, twos, 0, 0, &list)) {
> +	if (paint_down_to_common(r, one, n, twos, 0, 0, find_all, &list)) {
>  		commit_list_free(list);
>  		return -1;
>  	}

Callsites like this are quite hard to read now with these boolean flags.
Would it be preferable to instead use flags?

    enum paint_down_to_common_flags {
        PAINT_DOWN_TO_COMMON_IGNORE_MISSING_COMMITS = (1 << 0),
        PAINT_DOWN_TO_COMMON_FIND_ALL = (1 << 1),
    };

It's more verbose of course, but that's kind of the point.

Only weirdness is that we don't only accept these flags in
`paint_down_to_common()`, but also in other functions that pass those
flags down.

Patrick

User Patrick Steinhardt <ps@pks.im> has been added to the cc: list.

This patch series was integrated into seen via git@dabfe27.