On Wed, Apr 03, 2019 at 10:27:21AM -0700, Josh Steadmon wrote:
> For partial clones, doing a full connectivity check is wasteful; we skip
> promisor objects (which, for a partial clone, is all known objects), and
> excluding them all from the connectivity check can take a significant
> amount of time on large repos.
>
> At most, we want to make sure that we get the objects referred to by any
> wanted refs. For partial clones, just check that these objects were
> transferred.
This isn't strictly true, since we could get objects from elsewhere via
--shared or --reference. Those might not be promisor objects.
Shouldn't we be able to stop a traversal as soon as we see that an
object is in a promisor pack?
I.e., here:
> + if (opt->check_refs_only) {
> + /*
> + * For partial clones, we don't want to walk the full commit
> + * graph because we're skipping promisor objects anyway. We
> + * should just check that objects referenced by wanted refs were
> + * transferred.
> + */
> + do {
> + if (!repo_has_object_file(the_repository, &oid))
> + return 1;
> + } while (!fn(cb_data, &oid));
> + return 0;
> + }
for each object where you ask "do we have this?" we could, for the same
cost, ask "do we have this in a promisor pack?". And the answer would be
yes for each in a partial clone.
But that would also cleanly handle --shared, etc, that I mentioned. And
more importantly, it would _also_ work on fetches. If I fetch from you
and get a promisor pack, then there is no point in me enumerating every
tree you sent. As long as you gave me a tip tree, then you have promised
that you'd give me all the others if I ask.
So it seems like this should be a feature of the child rev-list, to stop
walking the graph at any object that is in a promisor pack.
-Peff
