packed_refs_unlock(), packed_refs_is_locked(): new functions

Add two new public functions, `packed_refs_unlock()` and
`packed_refs_is_locked()`, with which callers can manage and query the
`packed-refs` lock externally.

Call `packed_refs_unlock()` from `commit_packed_refs()` and
`rollback_packed_refs()`.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

refs/packed-backend.c

@@ -563,6 +563,29 @@ int packed_refs_lock(struct ref_store *ref_store, int flags, struct strbuf *err)
 	return 0;
 }
 
+void packed_refs_unlock(struct ref_store *ref_store)
+{
+	struct packed_ref_store *refs = packed_downcast(
+			ref_store,
+			REF_STORE_READ | REF_STORE_WRITE,
+			"packed_refs_unlock");
+
+	if (!is_lock_file_locked(&refs->lock))
+		die("BUG: packed_refs_unlock() called when not locked");
+	rollback_lock_file(&refs->lock);
+	release_packed_ref_cache(refs->cache);
+}
+
+int packed_refs_is_locked(struct ref_store *ref_store)
+{
+	struct packed_ref_store *refs = packed_downcast(
+			ref_store,
+			REF_STORE_READ | REF_STORE_WRITE,
+			"packed_refs_is_locked");
+
+	return is_lock_file_locked(&refs->lock);
+}
+
 /*
  * The packed-refs header line that we write out.  Perhaps other
  * traits will be added later.  The trailing space is required.
@@ -649,8 +672,7 @@ error:
 	delete_tempfile(&refs->tempfile);
 
 out:
-	rollback_lock_file(&refs->lock);
-	release_packed_ref_cache(packed_ref_cache);
+	packed_refs_unlock(ref_store);
 	return ret;
 }
 
@@ -661,14 +683,11 @@ out:
  */
 static void rollback_packed_refs(struct packed_ref_store *refs)
 {
-	struct packed_ref_cache *packed_ref_cache = get_packed_ref_cache(refs);
-
 	packed_assert_main_repository(refs, "rollback_packed_refs");
 
 	if (!is_lock_file_locked(&refs->lock))
 		die("BUG: packed-refs not locked");
-	rollback_lock_file(&refs->lock);
-	release_packed_ref_cache(packed_ref_cache);
+	packed_refs_unlock(&refs->base);
 	clear_packed_ref_cache(refs);
 }
 

refs/packed-backend.h

@@ -11,6 +11,9 @@ struct ref_store *packed_ref_store_create(const char *path,
  */
 int packed_refs_lock(struct ref_store *ref_store, int flags, struct strbuf *err);
 
+void packed_refs_unlock(struct ref_store *ref_store);
+int packed_refs_is_locked(struct ref_store *ref_store);
+
 void add_packed_ref(struct ref_store *ref_store,
 		    const char *refname, const struct object_id *oid);