Re: [PATCH 6/8] commit-graph: introduce `ensure_generations_valid()`

> From: Taylor Blau <me@ttaylorr.com>
>
> Use the just-introduced compute_reachable_generation_numbers_1() to
> implement a function which dynamically computes topological levels (or
> corrected commit dates) for out-of-graph commits.
>
> This will be useful for the ahead-behind algorithm we are about to
> introduce, which needs accurate topological levels on _all_ commits
> reachable from the tips in order to avoid over-counting.

>
> Co-authored-by: Derrick Stolee <derrickstolee@github.com>
> Signed-off-by: Taylor Blau <me@ttaylorr.com>
> Signed-off-by: Derrick Stolee <derrickstolee@github.com>
> ---
>  commit-graph.c | 29 +++++++++++++++++++++++++++++
>  commit-graph.h |  7 +++++++
>  2 files changed, 36 insertions(+)
>
> diff --git a/commit-graph.c b/commit-graph.c
> index f04b02be1bb..a573d1b89ff 100644
> --- a/commit-graph.c
> +++ b/commit-graph.c
> @@ -1610,6 +1610,35 @@ static void compute_generation_numbers(struct write_commit_graph_context *ctx)
>  	stop_progress(&ctx->progress);
>  }
>  
> +static void set_generation_in_graph_data(struct commit *c, timestamp_t t,
> +					 void *data)
> +{
> +	commit_graph_data_at(c)->generation = t;
> +}
> +
> +/*
> + * After this method, all commits reachable from those in the given
> + * list will have non-zero, non-infinite generation numbers.
> + */
> +void ensure_generations_valid(struct commit **commits, size_t nr)
> +{
> +	struct repository *r = the_repository;
> +	int generation_version = get_configured_generation_version(r);
> +	struct packed_commit_list list = {
> +		.list = commits,
> +		.alloc = nr,
> +		.nr = nr,
> +	};
> +	struct compute_generation_info info = {
> +		.r = r,
> +		.commits = &list,
> +		.get_generation = get_generation_from_graph_data,
> +		.set_generation = set_generation_in_graph_data,
> +	};
> +
> +	compute_reachable_generation_numbers_1(&info, generation_version);
> +}
> +
>  static void trace2_bloom_filter_write_statistics(struct write_commit_graph_context *ctx)
>  {
>  	trace2_data_intmax("commit-graph", ctx->r, "filter-computed",
> diff --git a/commit-graph.h b/commit-graph.h
> index 37faee6b66d..a529c62b518 100644
> --- a/commit-graph.h
> +++ b/commit-graph.h
> @@ -190,4 +190,11 @@ struct commit_graph_data {
>   */
>  timestamp_t commit_graph_generation(const struct commit *);
>  uint32_t commit_graph_position(const struct commit *);
> +
> +/*
> + * After this method, all commits reachable from those in the given
> + * list will have non-zero, non-infinite generation numbers.
> + */
> +void ensure_generations_valid(struct commit **commits, size_t nr);
> +
>  #endif