storage: move load/dumps into their own class methods (#4739)

wcs/qommon/storage.py

@@ -277,13 +277,17 @@ class StorableObject(object):
         return cls.get_ids(ids)
     get_with_indexed_value = classmethod(get_with_indexed_value)
 
-    def get_filename(cls, filename, ignore_errors=False, ignore_migration=False):
+    def storage_load(cls, fd):
         if get_publisher() and get_publisher().unpickler_class:
             unpickler = get_publisher().unpickler_class
         else:
             unpickler = pickle.Unpickler
+        return unpickler(fd).load()
+    storage_load = classmethod(storage_load)
+
+    def get_filename(cls, filename, ignore_errors=False, ignore_migration=False):
         try:
-            o = unpickler(file(filename)).load()
+            o = cls.storage_load(file(filename))
         except IOError:
             if ignore_errors:
                 return None
@@ -370,6 +374,10 @@ class StorableObject(object):
             objects_dir = self.get_objects_dir()
             return os.path.join(objects_dir, fix_key(self.id))
 
+    def storage_dumps(cls, object):
+        return pickle.dumps(object)
+    storage_dumps = classmethod(storage_dumps)
+
     def store(self, async=False):
         objects_dir = self.get_objects_dir()
         new_object = False
@@ -398,7 +406,7 @@ class StorableObject(object):
             previous_object_value = self.get_filename(object_filename,
                             ignore_errors=True, ignore_migration=True)
 
-        s = pickle.dumps(self)
+        s = self.storage_dumps(self)
         atomic_write(object_filename, s, async)
         # update last modified time
         if os.path.exists(objects_dir):