Deprecate cloudpickle.is_tornado_coroutine

cloudpickle/cloudpickle.py

@@ -71,6 +71,7 @@
 import types
 import typing
 import uuid
+import warnings
 import weakref
 
 # The following import is required to be imported in the cloudpickle
@@ -429,6 +430,26 @@ def _extract_class_dict(cls):
     return clsdict
 
 
+def is_tornado_coroutine(func):
+    """Return whether `func` is a Tornado coroutine function.
+
+    Running coroutines are not supported.
+    """
+    warnings.warn(
+        "is_tornado_coroutine is deprecated in cloudpickle 3.0 and will be "
+        "removed in cloudpickle 4.0. Use tornado.gen.is_coroutine_function "
+        "directly instead.",
+        category=DeprecationWarning,
+    )
+    if 'tornado.gen' not in sys.modules:
+        return False
+    gen = sys.modules['tornado.gen']
+    if not hasattr(gen, "is_coroutine_function"):
+        # Tornado version is too old
+        return False
+    return gen.is_coroutine_function(func)
+
+
 def subimport(name):
     # We cannot do simply: `return __import__(name)`: Indeed, if ``name`` is
     # the name of a submodule, __import__ will return the top-level root module

tests/cloudpickle_test.py

@@ -991,6 +991,9 @@ def g(y):
             res = yield f(0.01, y)  # noqa: F821
             raise gen.Return(res + 1)
 
+        with pytest.warns(DeprecationWarning):
+            assert cloudpickle.is_tornado_coroutine(g)
+
         data = cloudpickle.dumps([g, g], protocol=self.protocol)
         del f, g
         g2, g3 = pickle.loads(data)