builtin/repack: enumerate promisor blobs for --drop-filtered

Add enumeration logic for --drop-filtered. In --dry-run mode, print
the OIDs of locally-held promisor blobs that exceed the filter
threshold, as candidates for removal.

Reading from write_filtered_pack() cannot work for partial clones.
git repack routes promisor objects through a separate path:
repack_promisor_objects() repacks them first, and the main
pack-objects run uses --exclude-promisor-objects. By the time
write_filtered_pack() runs, the promisor blobs are already consumed by
the main pack. The filtered pack is always empty on a partial clone.

Instead, walk promisor objects directly via odb_for_each_object() with
ODB_FOR_EACH_OBJECT_PROMISOR_ONLY, collecting all promisor blobs into
an oidset. The blobs exceeding the filter threshold are then selected
using list_objects_filter__filter_oidset().

Every object enumerated this way is a promisor object, so it is
recoverable from the promisor remote in the same sense as the rest of a
partial clone, as long as the remote still has it. This holds without a
separate is_promisor_object() check. A future implementation can verify
availability against the remote directly once a client-side
remote-object-info query exists.

OBJECT_INFO_SKIP_FETCH_OBJECT is passed to every object info query so
enumeration never triggers a lazy fetch.

The enumeration collects candidates into a caller-provided oidset and
--dry-run prints them. Actually removing the objects, together with the
required promisor-remote verification, is written in a later commit.

Mentored-by: Christian Couder <christian.couder@gmail.com>
Mentored-by: Siddharth Asthana <siddharthasthana31@gmail.com>
Signed-off-by: Siddharth Shrimali <r.siddharth.shrimali@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

0 files changed, 0 insertions, 0 deletions