code: def process_message_notification(request, messages_path):
      
      if not messages_path:
          return
  
      global _MESSAGES_CACHE
      global _MESSAGES_MTIME
  
      # NOTE (lhcheng): Cache the processed messages to avoid parsing
      # the files every time. Check directory modification time if
      # reload is necessary.
      if (_MESSAGES_CACHE is None or
              _MESSAGES_MTIME != os.path.getmtime(messages_path)):
          _MESSAGES_CACHE = _get_processed_messages(messages_path)
          _MESSAGES_MTIME = os.path.getmtime(messages_path)
  
      for msg in _MESSAGES_CACHE:
          msg.send_message(request)
docs: Process all the msg file found in the message directory