Stephan Beyer <s-be...@gmx.net> writes:
> Large repositories with a huge amount of merge commits in the
> bisection process could lead to stack overflows in git bisect.
> In order to prevent this, this commit uses an *iterative* version
> for counting the number of ancestors of a commit.
Yay!
> -/*
> - * This is a truly stupid algorithm, but it's only
> - * used for bisection, and we just don't care enough.
> - *
> - * We care just barely enough to avoid recursing for
> - * non-merge entries.
> - */
> static int count_distance(struct commit_list *entry)
> {
> int nr = 0;
> + struct commit_list *todo = NULL;
> + commit_list_append(entry->item, &todo);
>
> - while (entry) {
> - struct commit *commit = entry->item;
> - struct commit_list *p;
> + while (todo) {
> + struct commit *commit = pop_commit(&todo);
>
> - if (commit->object.flags & (UNINTERESTING | COUNTED))
> - break;
> - if (!(commit->object.flags & TREESAME))
> - nr++;
> - commit->object.flags |= COUNTED;
> - p = commit->parents;
> - entry = p;
> - if (p) {
> - p = p->next;
> - while (p) {
> - nr += count_distance(p);
> - p = p->next;
> + if (!(commit->object.flags & (UNINTERESTING | COUNTED))) {
> + struct commit_list *p;
> + if (!(commit->object.flags & TREESAME))
> + nr++;
> + commit->object.flags |= COUNTED;
> +
> + for (p = commit->parents; p; p = p->next) {
> + commit_list_insert(p->item, &todo);
> }
> }
> }
> @@ -287,7 +277,7 @@ static struct commit_list *do_find_bisection(struct
> commit_list *list,
> * can reach. So we do not have to run the expensive
> * count_distance() for single strand of pearls.
> *
> - * However, if you have more than one parents, you cannot
> + * However, if you have more than one parent, you cannot
Thanks. This grammo is mine, back in 1c4fea3a (git-rev-list
--bisect: optimization, 2007-03-21)
> @@ -296,17 +286,16 @@ static struct commit_list *do_find_bisection(struct
> commit_list *list,
> * way, and then fill the blanks using cheaper algorithm.
> */
> for (p = list; p; p = p->next) {
> - if (p->item->object.flags & UNINTERESTING)
> - continue;
> - if (weight(p) != -2)
> - continue;
> - weight_set(p, count_distance(p));
> - clear_distance(list);
> + if (!(p->item->object.flags & UNINTERESTING)
> + && (weight(p) == -2)) {
> + weight_set(p, count_distance(p));
> + clear_distance(list);
>
> - /* Does it happen to be at exactly half-way? */
> - if (!find_all && halfway(p, nr))
> - return p;
> - counted++;
> + /* Does it happen to be at exactly half-way? */
> + if (!find_all && halfway(p, nr))
> + return p;
> + counted++;
> + }
> }
I can buy collapsing two if() statements into one, but I'd prefer to
see us keep the structure:
loop () {
if (... || ...)
continue;
quite a
many
operations
here
}
>
> show_list("bisection 2 count_distance", counted, nr, list);
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