On Wed, May 28, 2025 at 07:20:07PM -0400, Taylor Blau wrote:
> Range-diff against v3:
Hmm. My tool for submitting patches botched the range-diff here. The
correct range-diff is:
1: 986bef29b5 ! 1: 2753e29648 pack-objects: limit scope in 'add_object_entry_from_pack()'
@@ builtin/pack-objects.c: static int add_object_entry_from_pack(const struct objec
if (p) {
- struct rev_info *revs = _data;
struct object_info oi = OBJECT_INFO_INIT;
--
+
oi.typep = &type;
-+
- if (packed_object_info(the_repository, p, ofs, &oi) < 0) {
+@@ builtin/pack-objects.c: static int add_object_entry_from_pack(const struct object_id *oid,
die(_("could not get type of object %s in pack %s"),
oid_to_hex(oid), p->pack_name);
} else if (type == OBJ_COMMIT) {
2: 6f8fe8a4e1 = 2: 32b49d9073 pack-objects: factor out handling '--stdin-packs'
3: 2a235461a6 = 3: a797ff3a83 pack-objects: declare 'rev_info' for '--stdin-packs' earlier
4: 240e90b68d = 4: 29bf05633a pack-objects: perform name-hash traversal for unpacked objects
5: 9a18fa2e52 = 5: 0696fa1736 pack-objects: fix typo in 'show_object_pack_hint()'
6: 6c997853f1 = 6: 1cc45b4472 pack-objects: swap 'show_{object,commit}_pack_hint'
7: 0ff699f056 = 7: 3e3d929bd0 pack-objects: introduce '--stdin-packs=follow'
8: 58891101f3 ! 8: 52a069ef48 repack: exclude cruft pack(s) from the MIDX where possible
@@ Commit message
MIDX with '--write-midx' to ensure that the resulting MIDX was always
closed under reachability in order to generate reachability bitmaps.
- Suppose (prior to this patch) you have a once-unreachable object packed
- in a cruft pack, which later on becomes reachable from one or more
- objects in a geometrically repacked pack. That once-unreachable object
- *won't* appear in the new pack, since the cruft pack was specified as
- neither included nor excluded to 'pack-objects --stdin-packs'. If the
+ While the previous patch added the '--stdin-packs=follow' option to
+ pack-objects, it is not yet on by default. Given that, suppose you have
+ a once-unreachable object packed in a cruft pack, which later becomes
+ reachable from one or more objects in a geometrically repacked pack.
+ That once-unreachable object *won't* appear in the new pack, since the
+ cruft pack was not specified as included or excluded when the
+ geometrically repacked pack was created with 'pack-objects
+ --stdin-packs' (*not* '--stdin-packs=follow', which is not on). If that
new pack is included in a MIDX without the cruft pack, then trying to
generate bitmaps for that MIDX may fail. This happens when the bitmap
selection process picks one or more commits which reach the
- once-unreachable objects, commit ddee3703b3 ensures that the MIDX will
- be closed under reachability. Without it, we would fail to generate a
- MIDX bitmap.
+ once-unreachable objects.
+ To mitigate this failure mode, commit ddee3703b3 ensures that the MIDX
+ will be closed under reachability by including cruft pack(s). If cruft
+ pack(s) were not included, we would fail to generate a MIDX bitmap. But
ddee3703b3 alludes to the fact that this is sub-optimal by saying
[...] it's desirable to avoid including cruft packs in the MIDX
Thanks,
Taylor
