[Enhancement] MessageHub.get_info() supports returning a default value

mmengine/logging/message_hub.py

@@ -296,22 +296,29 @@ def get_scalar(self, key: str) -> HistoryBuffer:
                            f'instance name is: {MessageHub.instance_name}')
         return self.log_scalars[key]
 
-    def get_info(self, key: str) -> Any:
-        """Get runtime information by key.
+    def get_info(self, key: str, default: Optional[Any] = None) -> Any:
+        """Get runtime information by key. if the key does not exist, this
+        method will return default information.
 
         Args:
             key (str): Key of runtime information.
+            default (Any, optional): The default returned value for the
+                given key.
 
         Returns:
             Any: A copy of corresponding runtime information if the key exists.
         """
         if key not in self.runtime_info:
-            raise KeyError(f'{key} is not found in Messagehub.log_buffers: '
-                           f'instance name is: {MessageHub.instance_name}')
-
-        # TODO： There are restrictions on objects that can be saved
-        # return copy.deepcopy(self._runtime_info[key])
-        return self._runtime_info[key]
+            if default is not None:
+                return default
+            else:
+                raise KeyError(
+                    f'Can not find {key} in runtime information of message_hub'
+                )
+        else:
+            # TODO： There are restrictions on objects that can be saved
+            # return copy.deepcopy(self._runtime_info[key])
+            return self._runtime_info[key]
 
     def _get_valid_value(
         self,

tests/test_logging/test_message_hub.py

@@ -83,7 +83,7 @@ def test_get_scalar(self):
     def test_get_runtime(self):
         message_hub = MessageHub.get_instance('mmengine')
         with pytest.raises(KeyError):
-            message_hub.get_info('unknown')
+            message_hub.get_info('unknown', ['test_value'])
         recorded_dict = dict(a=1, b=2)
         message_hub.update_info('test_value', recorded_dict)
         assert message_hub.get_info('test_value') == recorded_dict