From: Derrick Stolee <stolee@gmail.com>
Date: Sun, 28 Jun 2026 15:16:29 GMT
Subject: Re: [PATCH v4 0/8] commit-reach: terminate merge-base walk when one side is exhausted
Message-ID: <48bfdb11-2624-4aa6-8fbd-d3f894c33bcc@gmail.com>
In-Reply-To: <pull.2149.v4.git.1782649547.gitgitgadget@gmail.com>

On 6/28/26 8:25 AM, Kristofer Karlsson via GitGitGadget wrote:
> commit-reach: terminate merge-base walk when one paint side is exhausted
> 
> Optimize paint_down_to_common() for merge-base queries that hit large
> one-sided histories.
> 
> When the walk from one side reaches a commit with a very low generation
> number that the other side never paints, the walk is forced to drain most of
> the graph. A common trigger is a repository import that grafts a separate
> history with its own root, but any merge that introduces a low-generation
> commit never painted by the other side has the same effect.

> Changes since v3:
> 
>   * Fixed BUG assertion that was accidentally made unconditional in v3:
>     restored the min_generation guard so it only fires when generation-based
>     ordering is active.
> 
>   * Moved generation cutoff and single-result termination conditions into the
>     documentation in patch 1/8, since they describe existing behavior.
> 
>   * Renamed paint_state counter fields for clarity: p1_count ->
>     parent1_count, p2_count -> parent2_count, pending_merge_bases ->
>     mb_candidate_count. Changed counter types from int to size_t. (Suggested
>     by Rene Scharfe.)

I reviewed the v3 discussion, the range-diff, and reread patch 8. I think
that this version is good to go.

Thanks for your hard work!
-Stolee