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# Copyright 2015 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.
import collections
import threading
import grpc
from grpc import _common
from grpc._cython import cygrpc
class AuthMetadataContext(
collections.namedtuple('AuthMetadataContext', (
'service_url', 'method_name',)), grpc.AuthMetadataContext):
pass
class AuthMetadataPluginCallback(grpc.AuthMetadataContext):
def __init__(self, callback):
self._callback = callback
def __call__(self, metadata, error):
self._callback(metadata, error)
class _WrappedCygrpcCallback(object):
def __init__(self, cygrpc_callback):
self.is_called = False
self.error = None
self.is_called_lock = threading.Lock()
self.cygrpc_callback = cygrpc_callback
def _invoke_failure(self, error):
# TODO(atash) translate different Exception superclasses into different
# status codes.
self.cygrpc_callback(_common.EMPTY_METADATA, cygrpc.StatusCode.internal,
_common.encode(str(error)))
def _invoke_success(self, metadata):
try:
cygrpc_metadata = _common.to_cygrpc_metadata(metadata)
except Exception as exception: # pylint: disable=broad-except
self._invoke_failure(exception)
return
self.cygrpc_callback(cygrpc_metadata, cygrpc.StatusCode.ok, b'')
def __call__(self, metadata, error):
with self.is_called_lock:
if self.is_called:
raise RuntimeError('callback should only ever be invoked once')
if self.error:
self._invoke_failure(self.error)
return
self.is_called = True
if error is None:
self._invoke_success(metadata)
else:
self._invoke_failure(error)
def notify_failure(self, error):
with self.is_called_lock:
if not self.is_called:
self.error = error
class _WrappedPlugin(object):
def __init__(self, plugin):
self.plugin = plugin
def __call__(self, context, cygrpc_callback):
wrapped_cygrpc_callback = _WrappedCygrpcCallback(cygrpc_callback)
wrapped_context = AuthMetadataContext(
_common.decode(context.service_url),
_common.decode(context.method_name))
try:
self.plugin(wrapped_context,
AuthMetadataPluginCallback(wrapped_cygrpc_callback))
except Exception as error:
wrapped_cygrpc_callback.notify_failure(error)
raise
def call_credentials_metadata_plugin(plugin, name):
"""
Args:
plugin: A callable accepting a grpc.AuthMetadataContext
object and a callback (itself accepting a list of metadata key/value
2-tuples and a None-able exception value). The callback must be eventually
called, but need not be called in plugin's invocation.
plugin's invocation must be non-blocking.
"""
return cygrpc.call_credentials_metadata_plugin(
cygrpc.CredentialsMetadataPlugin(
_WrappedPlugin(plugin), _common.encode(name)))
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