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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 logging
import threading
from typing import Callable, Optional, Type
import grpc
from grpc import _common
from grpc._cython import cygrpc
from grpc._typing import MetadataType
_LOGGER = logging.getLogger(__name__)
class _AuthMetadataContext(
collections.namedtuple('AuthMetadataContext', (
'service_url',
'method_name',
)), grpc.AuthMetadataContext):
pass
class _CallbackState(object):
def __init__(self):
self.lock = threading.Lock()
self.called = False
self.exception = None
class _AuthMetadataPluginCallback(grpc.AuthMetadataPluginCallback):
_state: _CallbackState
_callback: Callable
def __init__(self, state: _CallbackState, callback: Callable):
self._state = state
self._callback = callback
def __call__(self, metadata: MetadataType,
error: Optional[Type[BaseException]]):
with self._state.lock:
if self._state.exception is None:
if self._state.called:
raise RuntimeError(
'AuthMetadataPluginCallback invoked more than once!')
else:
self._state.called = True
else:
raise RuntimeError(
'AuthMetadataPluginCallback raised exception "{}"!'.format(
self._state.exception))
if error is None:
self._callback(metadata, cygrpc.StatusCode.ok, None)
else:
self._callback(None, cygrpc.StatusCode.internal,
_common.encode(str(error)))
class _Plugin(object):
_metadata_plugin: grpc.AuthMetadataPlugin
def __init__(self, metadata_plugin: grpc.AuthMetadataPlugin):
self._metadata_plugin = metadata_plugin
self._stored_ctx = None
try:
import contextvars # pylint: disable=wrong-import-position
# The plugin may be invoked on a thread created by Core, which will not
# have the context propagated. This context is stored and installed in
# the thread invoking the plugin.
self._stored_ctx = contextvars.copy_context()
except ImportError:
# Support versions predating contextvars.
pass
def __call__(self, service_url: str, method_name: str, callback: Callable):
context = _AuthMetadataContext(_common.decode(service_url),
_common.decode(method_name))
callback_state = _CallbackState()
try:
self._metadata_plugin(
context, _AuthMetadataPluginCallback(callback_state, callback))
except Exception as exception: # pylint: disable=broad-except
_LOGGER.exception(
'AuthMetadataPluginCallback "%s" raised exception!',
self._metadata_plugin)
with callback_state.lock:
callback_state.exception = exception
if callback_state.called:
return
callback(None, cygrpc.StatusCode.internal,
_common.encode(str(exception)))
def metadata_plugin_call_credentials(
metadata_plugin: grpc.AuthMetadataPlugin,
name: Optional[str]) -> grpc.CallCredentials:
if name is None:
try:
effective_name = metadata_plugin.__name__
except AttributeError:
effective_name = metadata_plugin.__class__.__name__
else:
effective_name = name
return grpc.CallCredentials(
cygrpc.MetadataPluginCallCredentials(_Plugin(metadata_plugin),
_common.encode(effective_name)))
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