Deprecate non-direct-call API (#7336)

python/ray/remote_function.py

@@ -2,7 +2,6 @@ import logging
 from functools import wraps
 
 from ray import cloudpickle as pickle
-from ray import ray_constants
 from ray._raylet import PythonFunctionDescriptor
 from ray import cross_language, Language
 import ray.signature
@@ -96,7 +95,6 @@ class RemoteFunction:
             return self._remote(args=args, kwargs=kwargs)
 
         self.remote = _remote_proxy
-        self.direct_call_enabled = ray_constants.direct_call_enabled()
 
     def __call__(self, *args, **kwargs):
         raise Exception("Remote functions cannot be called directly. Instead "
@@ -182,8 +180,8 @@ class RemoteFunction:
 
         if num_return_vals is None:
             num_return_vals = self._num_return_vals
-        if is_direct_call is None:
-            is_direct_call = self.direct_call_enabled
+        if is_direct_call is not None and not is_direct_call:
+            raise ValueError("Non-direct call tasks are no longer supported.")
         if max_retries is None:
             max_retries = self._max_retries
 
@@ -211,7 +209,7 @@ class RemoteFunction:
             else:
                 object_ids = worker.core_worker.submit_task(
                     self._language, self._function_descriptor, list_args,
-                    num_return_vals, is_direct_call, resources, max_retries)
+                    num_return_vals, resources, max_retries)
 
             if len(object_ids) == 1:
                 return object_ids[0]