On 1/11/2019 3:25 PM, Junio C Hamano wrote:
Junio C Hamano <gitster@xxxxxxxxx> writes:
So, I assumed that the implementation was wrong, but it is the other
way around. You do mean to pick only already uninteresting trees
out of "set" and mark its reachables.
One thing that would make me worried is what help the callers of
this function will get (or they may have to devise the way
themselves) to avoid having to traverse the same tree number of
times. A tree can be made uninteresting after a traversal of
another tree that contains it, but the logic in this function
+ if (tree->object.flags & UNINTERESTING) {
+ /*
+ * Remove the flag so the next call
+ * is not a no-op. The flag is added
+ * in mark_tree_unintersting().
+ */
+ tree->object.flags ^= UNINTERESTING;
+ mark_tree_uninteresting(r, tree);
+ }
ignores the fact that it is already UNINTERESTING (in fact, in a
sense it is even worse---it cannot be used to make a not-yet
UNINTERESTING one into UNINTERESTING), drops the UNINTERESING bit
and forces the traversal of that tree. The only thing I see that
would work as a saving grace is that mark_tree_uninteresting()
itself would honor existing UNINTERESING bit and refuses to recurse
into its subtrees, but that means blobs at the top-level of such a
tree would be marked UNINTERESING while those in its subtrees can be
left not-UNINTERESING, which sounds like inviting a mess.
It does *not* immediately mean this function is misdesigned. It
just means that the caller needs to carefully follow whatever
calling convention this series will establish in the later patches
(which we haven't seen yet at this point).
I'm sorry that this implementation is particularly confusing. It is
created only as a placeholder so we can wire up the --sparse option to
use this method without being "wrong" but is then removed entirely in
PATCH 4/6:
...
void mark_trees_uninteresting_sparse(struct repository *r,
struct oidset *set)
{
+ unsigned has_interesting = 0, has_uninteresting = 0;
+ struct hashmap map;
+ struct hashmap_iter map_iter;
+ struct path_and_oids_entry *entry;
struct object_id *oid;
struct oidset_iter iter;
oidset_iter_init(set, &iter);
- while ((oid = oidset_iter_next(&iter))) {
+ while ((!has_interesting || !has_uninteresting) &&
+ (oid = oidset_iter_next(&iter))) {
struct tree *tree = lookup_tree(r, oid);
if (!tree)
continue;
- if (tree->object.flags & UNINTERESTING) {
- /*
- * Remove the flag so the next call
- * is not a no-op. The flag is added
- * in mark_tree_unintersting().
- */
- tree->object.flags ^= UNINTERESTING;
- mark_tree_uninteresting(r, tree);
- }
+ if (tree->object.flags & UNINTERESTING)
+ has_uninteresting = 1;
+ else
+ has_interesting = 1;
+ }
...
You are definitely correct that "set" is not a valuable variable name. It could instead be "tree_oids" to be slightly more informative.
Thanks,
-Stolee
