Switching _grpc_catch_rendezvous to a context manager.

Author: dhermes

datastore/google/cloud/datastore/connection.py

@@ -14,6 +14,7 @@
 
 """Connections to Google Cloud Datastore API servers."""
 
+import contextlib
 import os
 
 from google.rpc import status_pb2
@@ -237,35 +238,19 @@ def allocate_ids(self, project, request_pb):
                          _datastore_pb2.AllocateIdsResponse)
 
 
-def _grpc_catch_rendezvous(to_call, *args, **kwargs):
-    """Call a method/function and re-map gRPC exceptions.
+@contextlib.contextmanager
+def _grpc_catch_rendezvous():
+    """Re-map gRPC exceptions that happen in context.
 
     .. _code.proto: https://github.com/googleapis/googleapis/blob/\
                     master/google/rpc/code.proto
 
     Remaps gRPC exceptions to the classes defined in
     :mod:`~google.cloud.exceptions` (according to the description
     in `code.proto`_).
-
-    :type to_call: callable
-    :param to_call: Callable that makes a request which may raise a
-                    :class:`~google.cloud.exceptions.GrpcRendezvous`.
-
-    :type args: tuple
-    :param args: Positional arugments to the callable.
-
-    :type kwargs: dict
-    :param kwargs: Keyword arguments to the callable.
-
-    :rtype: object
-    :returns: The value returned from ``to_call``.
-    :raises: :class:`~google.cloud.exceptions.GrpcRendezvous` if one
-             is encountered that can't be re-mapped, otherwise maps
-             to a :class:`~google.cloud.exceptions.GoogleCloudError`
-             subclass.
     """
     try:
-        return to_call(*args, **kwargs)
+        yield
     except exceptions.GrpcRendezvous as exc:
         error_code = exc.code()
         error_class = _GRPC_ERROR_MAPPING.get(error_code)
@@ -331,8 +316,8 @@ def run_query(self, project, request_pb):
         :returns: The returned protobuf response object.
         """
         request_pb.project_id = project
-        return _grpc_catch_rendezvous(
-            self._stub.RunQuery, request_pb)
+        with _grpc_catch_rendezvous():
+            return self._stub.RunQuery(request_pb)
 
     def begin_transaction(self, project, request_pb):
         """Perform a ``beginTransaction`` request.
@@ -349,8 +334,8 @@ def begin_transaction(self, project, request_pb):
         :returns: The returned protobuf response object.
         """
         request_pb.project_id = project
-        return _grpc_catch_rendezvous(
-            self._stub.BeginTransaction, request_pb)
+        with _grpc_catch_rendezvous():
+            return self._stub.BeginTransaction(request_pb)
 
     def commit(self, project, request_pb):
         """Perform a ``commit`` request.
@@ -366,8 +351,8 @@ def commit(self, project, request_pb):
         :returns: The returned protobuf response object.
         """
         request_pb.project_id = project
-        return _grpc_catch_rendezvous(
-            self._stub.Commit, request_pb)
+        with _grpc_catch_rendezvous():
+            return self._stub.Commit(request_pb)
 
     def rollback(self, project, request_pb):
         """Perform a ``rollback`` request.
@@ -383,8 +368,8 @@ def rollback(self, project, request_pb):
         :returns: The returned protobuf response object.
         """
         request_pb.project_id = project
-        return _grpc_catch_rendezvous(
-            self._stub.Rollback, request_pb)
+        with _grpc_catch_rendezvous():
+            return self._stub.Rollback(request_pb)
 
     def allocate_ids(self, project, request_pb):
         """Perform an ``allocateIds`` request.
@@ -400,8 +385,8 @@ def allocate_ids(self, project, request_pb):
         :returns: The returned protobuf response object.
         """
         request_pb.project_id = project
-        return _grpc_catch_rendezvous(
-            self._stub.AllocateIds, request_pb)
+        with _grpc_catch_rendezvous():
+            return self._stub.AllocateIds(request_pb)
 
 
 class Connection(connection_module.Connection):

datastore/unit_tests/test_connection.py

@@ -109,9 +109,9 @@ def test__request_not_200(self):
 @unittest.skipUnless(_HAVE_GRPC, 'No gRPC')
 class Test__grpc_catch_rendezvous(unittest.TestCase):
 
-    def _callFUT(self, to_call, *args, **kwargs):
+    def _callFUT(self):
         from google.cloud.datastore.connection import _grpc_catch_rendezvous
-        return _grpc_catch_rendezvous(to_call, *args, **kwargs)
+        return _grpc_catch_rendezvous()
 
     @staticmethod
     def _fake_method(exc, result=None):
@@ -122,7 +122,8 @@ def _fake_method(exc, result=None):
 
     def test_success(self):
         expected = object()
-        result = self._callFUT(self._fake_method, None, expected)
+        with self._callFUT():
+            result = self._fake_method(None, expected)
         self.assertIs(result, expected)
 
     def test_failure_aborted(self):
@@ -135,7 +136,8 @@ def test_failure_aborted(self):
         exc_state = _RPCState((), None, None, StatusCode.ABORTED, details)
         exc = GrpcRendezvous(exc_state, None, None, None)
         with self.assertRaises(Conflict):
-            self._callFUT(self._fake_method, exc)
+            with self._callFUT():
+                self._fake_method(exc)
 
     def test_failure_invalid_argument(self):
         from grpc import StatusCode
@@ -149,7 +151,8 @@ def test_failure_invalid_argument(self):
                               StatusCode.INVALID_ARGUMENT, details)
         exc = GrpcRendezvous(exc_state, None, None, None)
         with self.assertRaises(BadRequest):
-            self._callFUT(self._fake_method, exc)
+            with self._callFUT():
+                self._fake_method(exc)
 
     def test_failure_cancelled(self):
         from grpc import StatusCode
@@ -159,12 +162,14 @@ def test_failure_cancelled(self):
         exc_state = _RPCState((), None, None, StatusCode.CANCELLED, None)
         exc = GrpcRendezvous(exc_state, None, None, None)
         with self.assertRaises(GrpcRendezvous):
-            self._callFUT(self._fake_method, exc)
+            with self._callFUT():
+                self._fake_method(exc)
 
     def test_commit_failure_non_grpc_err(self):
         exc = RuntimeError('Not a gRPC error')
         with self.assertRaises(RuntimeError):
-            self._callFUT(self._fake_method, exc)
+            with self._callFUT():
+                self._fake_method(exc)
 
 
 class Test_DatastoreAPIOverGRPC(unittest.TestCase):