Re: [PATCH 2/4] reachable.c: mark reachable objects in index from all worktrees

[Eric Sunshine <sunshine@sunshineco.com>]

On Wed, Jun 1, 2016 at 6:45 AM, Nguyễn Thái Ngọc Duy <pclouds@gmail.com> wrote:
> Current mark_reachable_objects() only marks objects from index from
> _current_ worktree as reachable instead of all worktrees. Because this
> function is used for pruning, there is a chance that objects referenced
> by other worktrees may be deleted. Fix that.
>
> Small behavior change in "one worktree" case, the index is read again
> from file. In the current implementation, if the_index is already
> loaded, the index file will not be read from file again. This adds some
> more cost to this operation, hopefully insignificant because
> reachability test is usually very expensive already.

Could this extra index read be avoided by taking advantage of 'struct
worktree::is_current'[1] and passing the already-loaded index to
add_index_objects_to_pending() if true?

Or, am I misunderstanding the issue?

[1]: http://article.gmane.org/gmane.comp.version-control.git/292194

> Reported-by: Johannes Sixt <j6t@kdbg.org>
> Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
> ---
> diff --git a/reachable.c b/reachable.c
> @@ -155,6 +156,32 @@ int add_unseen_recent_objects_to_traversal(struct > +static void add_objects_from_worktree(struct rev_info *revs)
> +{
> +       struct worktree **worktrees, **p;
> +
> +       worktrees = get_worktrees();
> +       for (p = worktrees; *p; p++) {
> +               struct worktree *wt = *p;
> +               struct index_state istate;
> +
> +               memset(&istate, 0, sizeof(istate));
> +               if (read_index_from(&istate,
> +                                   worktree_git_path(wt, "index")) > 0)
> +                       add_index_objects_to_pending(revs, 0, &istate);
> +               discard_index(&istate);
> +       }
> +       free_worktrees(worktrees);
> +
> +       /*
> +        * this is in case the index is already updated but not
> +        * written down in file yet, then add_index_... in the above
> +        * loop will miss new objects that are just created or
> +        * referenced.
> +        */
> +       add_index_objects_to_pending(revs, 0, &the_index);
> +}