refs/files: remove empty parent dirs when ref creation fails

When creating a new reference in the "files" backend we first create the
directory hierarchy for that reference, then create the lockfile for
that reference, and finally rename the lockfile into place. When the
transaction gets aborted we prune the lockfile, but we don't clean up
the directory hierarchy that we may have created for the lockfile.

In some egde cases this can lead to lots of empty directories being
cluttered in the ".git/refs" directory that really serve no purpose at
all. We know to prune such empty directories when packing refs, but that
only patches over the issue.

Improve this by removing empty parents when cleaning up still-locked
references in `files_transaction_cleanup()`. This function is also
called when preparing or committing the transaction, so this change also
helps when not explicitly aborting the transaction.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/refs/files-backend.c b/refs/files-backend.c
index bf6f89b1d1938b6fae0c4125839c188b0d65fc86..00128f2183251e4b1170a8ce41b3d850202fb741 100644 (file)
--- a/refs/files-backend.c
+++ b/refs/files-backend.c
@@ -2760,6 +2760,8 @@ static void files_transaction_cleanup(struct files_ref_store *refs,
 
                if (lock) {
                        unlock_ref(lock);
+                       try_remove_empty_parents(refs, update->refname,
+                                                REMOVE_EMPTY_PARENTS_REF);
                        update->backend_data = NULL;
                }
        }

diff --git a/t/t1400-update-ref.sh b/t/t1400-update-ref.sh
index d29d23cb8905f865e68da0e782c3cbe1948c6c3f..42bbe22c850d26b069558abbdcd0383fa9baae4a 100755 (executable)
--- a/t/t1400-update-ref.sh
+++ b/t/t1400-update-ref.sh
@@ -2310,4 +2310,23 @@ test_expect_success 'update-ref should also create reflog for HEAD' '
        test_cmp expect actual
 '
 
+test_expect_success REFFILES 'empty directories are pruned when aborting a transaction' '
+       test_path_is_missing .git/refs/heads/nested &&
+       git update-ref --stdin <<-EOF &&
+       create refs/heads/nested/something HEAD
+       prepare
+       abort
+       EOF
+       test_path_is_missing .git/refs/heads/nested
+'
+
+test_expect_success REFFILES 'empty directories are pruned when not committing' '
+       test_path_is_missing .git/refs/heads/nested &&
+       git update-ref --stdin <<-EOF &&
+       create refs/heads/nested/something HEAD
+       prepare
+       EOF
+       test_path_is_missing .git/refs/heads/nested
+'
+
 test_done