Re: [PATCH 3/5] commit-graph: validate layers for generation data

[Taylor Blau <me@ttaylorr.com>]

On Mon, Feb 01, 2021 at 05:15:05PM +0000, Derrick Stolee via GitGitGadget wrote:
> diff --git a/commit-graph.c b/commit-graph.c
> index edbb3a0f2cc..13992137dd0 100644
> --- a/commit-graph.c
> +++ b/commit-graph.c
> @@ -614,19 +614,26 @@ static struct commit_graph *load_commit_graph_chain(struct repository *r,
>  	return graph_chain;
>  }
>
> -static void validate_mixed_generation_chain(struct commit_graph *g)
> +/*
> + * returns 1 if and only if all graphs in the chain have
> + * corrected commit dates stored in the generation_data chunk.
> + */
> +static int validate_mixed_generation_chain(struct commit_graph *g)

Thanks for the comment. It does make me wonder if the function name
needs updating, though. I'm having some trouble coming up with a better
alternative, though, so maybe it's fine...

>  {
> -	int read_generation_data;
> +	int read_generation_data = 1;

OK, we might not ever enter the while loops below, so this needs
initializing.

> +	struct commit_graph *p = g;
>
> -	if (!g)
> -		return;
> -
> -	read_generation_data = !!g->chunk_generation_data;
> +	while (read_generation_data && p) {
> +		read_generation_data = p->read_generation_data;
> +		p = p->base_graph;
> +	}

This could probably be guarded with an 'if !read_generation_data', since
if the previous while loop always read '1' from
'p->read_generation_data', then nothing needs updating, no?

(If you do make this change, please don't add '!read_generation_data' to
the while expression, since it isn't a property of the loop.)

>  	while (g) {
>  		g->read_generation_data = read_generation_data;
>  		g = g->base_graph;
>  	}
> +
> +	return read_generation_data;
>  }
>
>  struct commit_graph *read_commit_graph_one(struct repository *r,
> --
> gitgitgadget
>

Thanks,
Taylor