Add basic functionality for Cython functions and actors (#1193)

* Add basic functionality for Cython functions and actors

* Fix up per @pcmoritz comments

* Fixes per @richardliaw comments

* Fixes per @robertnishihara comments

* Forgot double quotes when updating masked_log

* Remove import typing for Python 2 compatibility

python/ray/utils.py

@@ -12,6 +12,21 @@ import sys
 import ray.local_scheduler
 
 
+def is_cython(obj):
+    """Check if an object is a Cython function or method"""
+
+    # TODO(suo): We could split these into two functions, one for Cython
+    # functions and another for Cython methods.
+    # TODO(suo): There doesn't appear to be a Cython function 'type' we can
+    # check against via isinstance. Please correct me if I'm wrong.
+    def check_cython(x):
+        return type(x).__name__ == "cython_function_or_method"
+
+    # Check if function or method, respectively
+    return check_cython(obj) or \
+        (hasattr(obj, "__func__") and check_cython(obj.__func__))
+
+
 def random_string():
     """Generate a random string to use as an ID.