Core: allow async def functions as commands (#5859)

MultiServer.py

@@ -1302,6 +1302,13 @@ class CommandMeta(type):
             commands.update(base.commands)
         commands.update({command_name[5:]: method for command_name, method in attrs.items() if
                          command_name.startswith("_cmd_")})
+        for command_name, method in commands.items():
+            # wrap async def functions so they run on default asyncio loop
+            if inspect.iscoroutinefunction(method):
+                def _wrapper(self, *args, _method=method, **kwargs):
+                    return async_start(_method(self, *args, **kwargs))
+                functools.update_wrapper(_wrapper, method)
+                commands[command_name] = _wrapper
         return super(CommandMeta, cls).__new__(cls, name, bases, attrs)