In order to write a bitmap, we need to have full coverage of all objects
that are about to be packed. In the traditional non-multi-pack-index
world this meant we need to do a full repack of all objects into a
single packfile. But in the new multi-pack-index world we can get away
with writing bitmaps when we have multiple packfiles as long as the
multi-pack-index covers all objects.
This is not always the case though. When writing multi-pack-indices in a
repository that is connected to an alternate object directory we may end
up writing a multi-pack-index that only has partial coverage of objects.
The end result is that writing the bitmap will fail:
$ git multi-pack-index write --stdin-packs --bitmap <packfiles
warning: Failed to write bitmap index. Packfile doesn't have full closure (object 1529341d78cf45377407369acb0f4ff2b5cdae42 is missing)
error: could not write multi-pack bitmap
Now there are two different ways to fix this. The first one would be to
amend git-multi-pack-index(1) to disable writing bitmaps when we notice
that we don't have full object coverage. But we ain't really got enough
information there, and seeing that it is a low-level plumbing command it
does not feel like the right place to fix this.
We can easily fix it at a higher level in git-repack(1) though. When all
of the following conditions are true:
- We are asked to write a multi-pack index with bitmaps.
- We are asked to only include local objects via `-l`.
- We are connected to an alternate repository that has packfiles.
Then we will override the user's ask and disable writing bitmaps with a
warning. This is similar to what we do in git-pack-objects(1), where we
also disable writing bitmaps in case we omit an object from the pack.
Signed-off-by: Patrick Steinhardt <ps@xxxxxx>
---
builtin/repack.c | 20 ++++++++++++++++++++
t/t7703-repack-geometric.sh | 27 +++++++++++++++++++++++++++
2 files changed, 47 insertions(+)
diff --git a/builtin/repack.c b/builtin/repack.c
index f57869f14a..07d92fdf87 100644
--- a/builtin/repack.c
+++ b/builtin/repack.c
@@ -881,6 +881,26 @@ int cmd_repack(int argc, const char **argv, const char *prefix)
if (pack_kept_objects < 0)
pack_kept_objects = write_bitmaps > 0 && !write_midx;
+ if (write_midx && write_bitmaps && geometric_factor && po_args.local) {
+ struct packed_git *p;
+
+ for (p = get_all_packs(the_repository); p; p = p->next) {
+ if (p->pack_local)
+ continue;
+
+ /*
+ * When asked to do a local repack, but we have
+ * packfiles that are inherited from an alternate, then
+ * we cannot guarantee that the multi-pack-index would
+ * have full coverage of all objects. We thus disable
+ * writing bitmaps in that case.
+ */
+ warning(_("disabling bitmap writing, as some objects are not being packed"));
+ write_bitmaps = 0;
+ break;
+ }
+ }
+
if (write_bitmaps && !(pack_everything & ALL_INTO_ONE) && !write_midx)
die(_(incremental_bitmap_conflict_error));
diff --git a/t/t7703-repack-geometric.sh b/t/t7703-repack-geometric.sh
index 96c8d4cdfa..0aaec9f853 100755
--- a/t/t7703-repack-geometric.sh
+++ b/t/t7703-repack-geometric.sh
@@ -420,4 +420,31 @@ test_expect_success '--geometric -l with non-intact geometric sequence across OD
test_cmp expected-objects actual-objects.sorted
'
+test_expect_success '--geometric -l disables writing bitmaps with non-local packfiles' '
+ test_when_finished "rm -fr shared member" &&
+
+ git init shared &&
+ test_commit_bulk -C shared --start=1 1 &&
+
+ git clone --shared shared member &&
+ test_commit_bulk -C member --start=2 1 &&
+
+ # When performing a geometric repack with `-l` while connecting to an
+ # alternate object database that has a packfile we do not have full
+ # coverage of objects. As a result, we expect that writing the bitmap
+ # will be disabled.
+ git -C member repack -l --geometric=2 --write-midx --write-bitmap-index 2>err &&
+ cat >expect <<-EOF &&
+ warning: disabling bitmap writing, as some objects are not being packed
+ EOF
+ test_cmp expect err &&
+ test ! -f member/.git/objects/pack/multi-pack-index-*.bitmap &&
+
+ # On the other hand, when we repack without `-l`, we should see that
+ # the bitmap gets created.
+ git -C member repack --geometric=2 --write-midx --write-bitmap-index 2>err &&
+ test_must_be_empty err &&
+ test -f member/.git/objects/pack/multi-pack-index-*.bitmap
+'
+
test_done
--
2.40.0
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