Minor improvements in ORM framework.

src/common/orm/Factory.py

@@ -27,6 +27,6 @@ def get_database_backend(backend : Optional[Union[str, BackendEnum]] = None, **s
     if backend is None: raise Exception('Database Backend not specified')
     if isinstance(backend, BackendEnum): backend = backend.value
     backend_class = BACKENDS.get(backend)
-    if backend_class is None: raise Exception('Unsupported DatabaseBackend({})'.format(backend))
-    LOGGER.info('Selected Database Backend: {}'.format(backend))
+    if backend_class is None: raise Exception('Unsupported DatabaseBackend({:s})'.format(backend))
+    LOGGER.info('Selected Database Backend: {:s}'.format(backend))
     return backend_class(**settings)

src/common/orm/backend/inmemory/InMemoryBackend.py

@@ -28,9 +28,9 @@ class InMemoryBackend(_Backend):
             for str_key in str_keys:
                 if (str_key in self._keys) and (len(self._keys[str_key]) > 0) and (self._keys[str_key] != owner_key):
                     # lock already acquired, cannot acquire all locks atomically
-                    for str_key in acquired_lock_keys.keys():
-                        if str_key not in self._keys: continue
-                        del self._keys[str_key]
+                    for str_key_acquired in acquired_lock_keys:
+                        if str_key_acquired not in self._keys: continue
+                        del self._keys[str_key_acquired]
                     return False, None
 
                 # lock available, temporarily acquire it; locks will be released if some of them for a requested