Completed D400 for airflow/listener/* directory (#27731)

airflow/listeners/events.py

@@ -30,6 +30,8 @@
 
 def on_task_instance_state_session_flush(session, flush_context):
     """
+    Flush task instance's state.
+
     Listens for session.flush() events that modify TaskInstance's state, and notify listeners that listen
     for that event. Doing it this way enable us to be stateless in the SQLAlchemy event listener.
     """
@@ -69,13 +71,15 @@ def on_task_instance_state_session_flush(session, flush_context):
 
 
 def register_task_instance_state_events():
+    """Register a task instance state event"""
     global _is_listening
     if not _is_listening:
         event.listen(Session, "after_flush", on_task_instance_state_session_flush)
         _is_listening = True
 
 
 def unregister_task_instance_state_events():
+    """Unregister a task instance state event"""
     global _is_listening
     event.remove(Session, "after_flush", on_task_instance_state_session_flush)
     _is_listening = False

airflow/listeners/listener.py

@@ -35,7 +35,7 @@
 
 
 class ListenerManager:
-    """Class that manages registration of listeners and provides hook property for calling them"""
+    """Manage listener registration and provides hook property for calling them."""
 
     def __init__(self):
         from airflow.listeners import spec
@@ -49,7 +49,7 @@ def has_listeners(self) -> bool:
 
     @property
     def hook(self) -> _HookRelay:
-        """Returns hook, on which plugin methods specified in spec can be called."""
+        """Return hook, on which plugin methods specified in spec can be called."""
         return self.pm.hook
 
     def add_listener(self, listener):
@@ -60,12 +60,13 @@ def add_listener(self, listener):
         self.pm.register(listener)
 
     def clear(self):
-        """Remove registered plugins"""
+        """Remove registered plugins."""
         for plugin in self.pm.get_plugins():
             self.pm.unregister(plugin)
 
 
 def get_listener_manager() -> ListenerManager:
+    """Get singleton listener manager"""
     global _listener_manager
     if not _listener_manager:
         _listener_manager = ListenerManager()