Re: [PATCH 1/3] commit-reach: implement get_reachable_subset

[Elijah Newren <newren@gmail.com>]

On Tue, Oct 30, 2018 at 7:16 AM Derrick Stolee via GitGitGadget
<gitgitgadget@gmail.com> wrote:
> --- a/commit-reach.c
> +++ b/commit-reach.c
> @@ -688,3 +688,73 @@ int can_all_from_reach(struct commit_list *from, struct commit_list *to,
>         object_array_clear(&from_objs);
>         return result;
>  }
> +
> +struct commit_list *get_reachable_subset(struct commit **from, int nr_from,
> +                                        struct commit **to, int nr_to,
> +                                        int reachable_flag)
> +{
> +       struct commit **item;
> +       struct commit *current;
> +       struct commit_list *found_commits = NULL;
> +       struct commit **to_last = to + nr_to;
> +       struct commit **from_last = from + nr_from;
> +       uint32_t min_generation = GENERATION_NUMBER_INFINITY;
> +       int num_to_find = 0;
> +
> +       struct prio_queue queue = { compare_commits_by_gen_then_commit_date };
> +
> +       for (item = to; item < to_last; item++) {
> +               struct commit *c = *item;
> +
> +               parse_commit(c);
> +               if (c->generation < min_generation)
> +                       min_generation = c->generation;

So, when we don't have a commit-graph, is c->generation just going to
be 0, making min_generation also be 0? (meaning we get no possible
speed benefit from the commit-graph, since we just don't have that
information available)?

> +
> +               if (!(c->object.flags & PARENT1)) {
> +                       c->object.flags |= PARENT1;
> +                       num_to_find++;
> +               }
> +       }
> +
> +       for (item = from; item < from_last; item++) {
> +               struct commit *c = *item;
> +               if (!(c->object.flags & PARENT2)) {
> +                       c->object.flags |= PARENT2;
> +                       parse_commit(c);
> +
> +                       prio_queue_put(&queue, *item);
> +               }
> +       }
> +
> +       while (num_to_find && (current = prio_queue_get(&queue)) != NULL) {
> +               struct commit_list *parents;
> +
> +               if (current->object.flags & PARENT1) {
> +                       current->object.flags &= ~PARENT1;
> +                       current->object.flags |= reachable_flag;
> +                       commit_list_insert(current, &found_commits);
> +                       num_to_find--;
> +               }
> +
> +               for (parents = current->parents; parents; parents = parents->next) {
> +                       struct commit *p = parents->item;
> +
> +                       parse_commit(p);
> +
> +                       if (p->generation < min_generation)
> +                               continue;
> +
> +                       if (p->object.flags & PARENT2)
> +                               continue;
> +
> +                       p->object.flags |= PARENT2;
> +                       prio_queue_put(&queue, p);
> +               }
> +       }
> +
> +       clear_commit_marks_many(nr_to, to, PARENT1);
> +       clear_commit_marks_many(nr_from, from, PARENT2);
> +
> +       return found_commits;
> +}
> +
> diff --git a/commit-reach.h b/commit-reach.h
> index 7d313e297..43bd50a70 100644
> --- a/commit-reach.h
> +++ b/commit-reach.h
> @@ -74,4 +74,14 @@ int can_all_from_reach_with_flag(struct object_array *from,
>  int can_all_from_reach(struct commit_list *from, struct commit_list *to,
>                        int commit_date_cutoff);
>
> +
> +/*
> + * Return a list of commits containing the commits in the 'to' array
> + * that are reachable from at least one commit in the 'from' array.
> + * Also add the given 'flag' to each of the commits in the returned list.
> + */
> +struct commit_list *get_reachable_subset(struct commit **from, int nr_from,
> +                                        struct commit **to, int nr_to,
> +                                        int reachable_flag);
> +
>  #endif
> --
> gitgitgadget
>