1 files changed, 88 insertions, 0 deletions
diff --git a/src/python/grpcio_status/grpc_status/rpc_status.py b/src/python/grpcio_status/grpc_status/rpc_status.py
new file mode 100644
index 0000000000..36c8eba37d
--- /dev/null
+++ b/src/python/grpcio_status/grpc_status/rpc_status.py
@@ -0,0 +1,88 @@
+# Copyright 2018 The gRPC Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+"""Reference implementation for status mapping in gRPC Python."""
+
+import collections
+
+import grpc
+
+# TODO(https://github.com/bazelbuild/bazel/issues/6844)
+# Due to Bazel issue, the namespace packages won't resolve correctly.
+# Adding this unused-import as a workaround to avoid module-not-found error
+# under Bazel builds.
+import google.protobuf  # pylint: disable=unused-import
+from google.rpc import status_pb2
+
+_CODE_TO_GRPC_CODE_MAPPING = dict([(x.value[0], x) for x in grpc.StatusCode])
+
+_GRPC_DETAILS_METADATA_KEY = 'grpc-status-details-bin'
+
+
+class _Status(
+        collections.namedtuple(
+            '_Status', ('code', 'details', 'trailing_metadata')), grpc.Status):
+    pass
+
+
+def _code_to_grpc_status_code(code):
+    try:
+        return _CODE_TO_GRPC_CODE_MAPPING[code]
+    except KeyError:
+        raise ValueError('Invalid status code %s' % code)
+
+
+def from_call(call):
+    """Returns a google.rpc.status.Status message corresponding to a given grpc.Call.
+
+    Args:
+      call: A grpc.Call instance.
+
+    Returns:
+      A google.rpc.status.Status message representing the status of the RPC.
+
+    Raises:
+      ValueError: If the status code, status message is inconsistent with the rich status
+        inside of the google.rpc.status.Status.
+    """
+    for key, value in call.trailing_metadata():
+        if key == _GRPC_DETAILS_METADATA_KEY:
+            rich_status = status_pb2.Status.FromString(value)
+            if call.code().value[0] != rich_status.code:
+                raise ValueError(
+                    'Code in Status proto (%s) doesn\'t match status code (%s)'
+                    % (_code_to_grpc_status_code(rich_status.code),
+                       call.code()))
+            if call.details() != rich_status.message:
+                raise ValueError(
+                    'Message in Status proto (%s) doesn\'t match status details (%s)'
+                    % (rich_status.message, call.details()))
+            return rich_status
+    return None
+
+
+def to_status(status):
+    """Convert a google.rpc.status.Status message to grpc.Status.
+
+    Args:
+      status: a google.rpc.status.Status message representing the non-OK status
+        to terminate the RPC with and communicate it to the client.
+
+    Returns:
+      A grpc.Status instance.
+    """
+    return _Status(
+        code=_code_to_grpc_status_code(status.code),
+        details=status.message,
+        trailing_metadata=((_GRPC_DETAILS_METADATA_KEY,
+                            status.SerializeToString()),))