From: Derrick Stolee <stolee@gmail.com>
Date: Fri, 26 Jun 2026 14:35:17 GMT
Subject: Re: [PATCH v3 7/8] commit-reach: terminate merge-base walk when one paint side is exhausted
Message-ID: <5edd5912-80b2-4372-b921-52c20e496276@gmail.com>
In-Reply-To: <f3572a8a89c74fad54a9e53be6f0e34daa2d50c2.1782479286.git.gitgitgadget@gmail.com>

On 6/26/2026 9:08 AM, Kristofer Karlsson via GitGitGadget wrote:
> From: Kristofer Karlsson <krka@spotify.com>

> @@ -140,9 +144,16 @@ static struct commit *paint_queue_get(struct paint_state *state)
>  
>  	commit->object.flags &= ~ENQUEUED;
>  
> -	if (!state->p1_count && !state->p2_count &&
> -	    !state->pending_merge_bases)
> -		return NULL;
> +	if (!state->pending_merge_bases) {
> +		/* only stale entries remain */
> +		if (!state->p1_count && !state->p2_count)
> +			return NULL;
> +
> +		/* one side is exhausted */
> +		if ((!state->p1_count || !state->p2_count) &&
> +		    commit_graph_generation(commit) < GENERATION_NUMBER_INFINITY)
> +			return NULL;
> +	}

This continues to look correct.  
>  	paint_count_update(state, commit->object.flags, -1);
>  	return commit;
> @@ -188,7 +199,7 @@ static int paint_down_to_common(struct repository *r,
>  		timestamp_t generation = commit_graph_generation(commit);
>  		steps++;
>  
> -		if (min_generation && generation > last_gen)
> +		if (generation > last_gen)
>  			BUG("bad generation skip %"PRItime" > %"PRItime" at %s",
>  			    generation, last_gen,
>  			    oid_to_hex(&commit->object.oid));

You mention in your own reply that this is broken. This also looks
like a stray change for this patch, so perhaps your end state is
correct despite this patch causing failures. Will inspect soon.

> -	test_paint_down_steps 45 2 25 3
> +	test_paint_down_steps 45 1 25 1
...> -	test_paint_down_steps 81 80 81 81
> +	test_paint_down_steps 81 9 57 10
These diffs are satisfying.

Thanks,
-Stolee