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# Copyright 2017 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.
"""Implementation of gRPC Python interceptors."""
import collections
import sys
import grpc
class _ServicePipeline(object):
def __init__(self, interceptors):
self.interceptors = tuple(interceptors)
def _continuation(self, thunk, index):
return lambda context: self._intercept_at(thunk, index, context)
def _intercept_at(self, thunk, index, context):
if index < len(self.interceptors):
interceptor = self.interceptors[index]
thunk = self._continuation(thunk, index + 1)
return interceptor.intercept_service(thunk, context)
else:
return thunk(context)
def execute(self, thunk, context):
return self._intercept_at(thunk, 0, context)
def service_pipeline(interceptors):
return _ServicePipeline(interceptors) if interceptors else None
class _ClientCallDetails(
collections.namedtuple('_ClientCallDetails',
('method', 'timeout', 'metadata', 'credentials',
'wait_for_ready', 'compression')),
grpc.ClientCallDetails):
pass
def _unwrap_client_call_details(call_details, default_details):
try:
method = call_details.method
except AttributeError:
method = default_details.method
try:
timeout = call_details.timeout
except AttributeError:
timeout = default_details.timeout
try:
metadata = call_details.metadata
except AttributeError:
metadata = default_details.metadata
try:
credentials = call_details.credentials
except AttributeError:
credentials = default_details.credentials
try:
wait_for_ready = call_details.wait_for_ready
except AttributeError:
wait_for_ready = default_details.wait_for_ready
try:
compression = call_details.compression
except AttributeError:
compression = default_details.compression
return method, timeout, metadata, credentials, wait_for_ready, compression
class _FailureOutcome(grpc.RpcError, grpc.Future, grpc.Call): # pylint: disable=too-many-ancestors
def __init__(self, exception, traceback):
super(_FailureOutcome, self).__init__()
self._exception = exception
self._traceback = traceback
def initial_metadata(self):
return None
def trailing_metadata(self):
return None
def code(self):
return grpc.StatusCode.INTERNAL
def details(self):
return 'Exception raised while intercepting the RPC'
def cancel(self):
return False
def cancelled(self):
return False
def is_active(self):
return False
def time_remaining(self):
return None
def running(self):
return False
def done(self):
return True
def result(self, ignored_timeout=None):
raise self._exception
def exception(self, ignored_timeout=None):
return self._exception
def traceback(self, ignored_timeout=None):
return self._traceback
def add_callback(self, unused_callback):
return False
def add_done_callback(self, fn):
fn(self)
def __iter__(self):
return self
def __next__(self):
raise self._exception
def next(self):
return self.__next__()
class _UnaryOutcome(grpc.Call, grpc.Future):
def __init__(self, response, call):
self._response = response
self._call = call
def initial_metadata(self):
return self._call.initial_metadata()
def trailing_metadata(self):
return self._call.trailing_metadata()
def code(self):
return self._call.code()
def details(self):
return self._call.details()
def is_active(self):
return self._call.is_active()
def time_remaining(self):
return self._call.time_remaining()
def cancel(self):
return self._call.cancel()
def add_callback(self, callback):
return self._call.add_callback(callback)
def cancelled(self):
return False
def running(self):
return False
def done(self):
return True
def result(self, ignored_timeout=None):
return self._response
def exception(self, ignored_timeout=None):
return None
def traceback(self, ignored_timeout=None):
return None
def add_done_callback(self, fn):
fn(self)
class _UnaryUnaryMultiCallable(grpc.UnaryUnaryMultiCallable):
def __init__(self, thunk, method, interceptor):
self._thunk = thunk
self._method = method
self._interceptor = interceptor
def __call__(self,
request,
timeout=None,
metadata=None,
credentials=None,
wait_for_ready=None,
compression=None):
response, ignored_call = self._with_call(request,
timeout=timeout,
metadata=metadata,
credentials=credentials,
wait_for_ready=wait_for_ready,
compression=compression)
return response
def _with_call(self,
request,
timeout=None,
metadata=None,
credentials=None,
wait_for_ready=None,
compression=None):
client_call_details = _ClientCallDetails(self._method, timeout,
metadata, credentials,
wait_for_ready, compression)
def continuation(new_details, request):
(new_method, new_timeout, new_metadata, new_credentials,
new_wait_for_ready,
new_compression) = (_unwrap_client_call_details(
new_details, client_call_details))
try:
response, call = self._thunk(new_method).with_call(
request,
timeout=new_timeout,
metadata=new_metadata,
credentials=new_credentials,
wait_for_ready=new_wait_for_ready,
compression=new_compression)
return _UnaryOutcome(response, call)
except grpc.RpcError as rpc_error:
return rpc_error
except Exception as exception: # pylint:disable=broad-except
return _FailureOutcome(exception, sys.exc_info()[2])
call = self._interceptor.intercept_unary_unary(continuation,
client_call_details,
request)
return call.result(), call
def with_call(self,
request,
timeout=None,
metadata=None,
credentials=None,
wait_for_ready=None,
compression=None):
return self._with_call(request,
timeout=timeout,
metadata=metadata,
credentials=credentials,
wait_for_ready=wait_for_ready,
compression=compression)
def future(self,
request,
timeout=None,
metadata=None,
credentials=None,
wait_for_ready=None,
compression=None):
client_call_details = _ClientCallDetails(self._method, timeout,
metadata, credentials,
wait_for_ready, compression)
def continuation(new_details, request):
(new_method, new_timeout, new_metadata, new_credentials,
new_wait_for_ready,
new_compression) = (_unwrap_client_call_details(
new_details, client_call_details))
return self._thunk(new_method).future(
request,
timeout=new_timeout,
metadata=new_metadata,
credentials=new_credentials,
wait_for_ready=new_wait_for_ready,
compression=new_compression)
try:
return self._interceptor.intercept_unary_unary(
continuation, client_call_details, request)
except Exception as exception: # pylint:disable=broad-except
return _FailureOutcome(exception, sys.exc_info()[2])
class _UnaryStreamMultiCallable(grpc.UnaryStreamMultiCallable):
def __init__(self, thunk, method, interceptor):
self._thunk = thunk
self._method = method
self._interceptor = interceptor
def __call__(self,
request,
timeout=None,
metadata=None,
credentials=None,
wait_for_ready=None,
compression=None):
client_call_details = _ClientCallDetails(self._method, timeout,
metadata, credentials,
wait_for_ready, compression)
def continuation(new_details, request):
(new_method, new_timeout, new_metadata, new_credentials,
new_wait_for_ready,
new_compression) = (_unwrap_client_call_details(
new_details, client_call_details))
return self._thunk(new_method)(request,
timeout=new_timeout,
metadata=new_metadata,
credentials=new_credentials,
wait_for_ready=new_wait_for_ready,
compression=new_compression)
try:
return self._interceptor.intercept_unary_stream(
continuation, client_call_details, request)
except Exception as exception: # pylint:disable=broad-except
return _FailureOutcome(exception, sys.exc_info()[2])
class _StreamUnaryMultiCallable(grpc.StreamUnaryMultiCallable):
def __init__(self, thunk, method, interceptor):
self._thunk = thunk
self._method = method
self._interceptor = interceptor
def __call__(self,
request_iterator,
timeout=None,
metadata=None,
credentials=None,
wait_for_ready=None,
compression=None):
response, ignored_call = self._with_call(request_iterator,
timeout=timeout,
metadata=metadata,
credentials=credentials,
wait_for_ready=wait_for_ready,
compression=compression)
return response
def _with_call(self,
request_iterator,
timeout=None,
metadata=None,
credentials=None,
wait_for_ready=None,
compression=None):
client_call_details = _ClientCallDetails(self._method, timeout,
metadata, credentials,
wait_for_ready, compression)
def continuation(new_details, request_iterator):
(new_method, new_timeout, new_metadata, new_credentials,
new_wait_for_ready,
new_compression) = (_unwrap_client_call_details(
new_details, client_call_details))
try:
response, call = self._thunk(new_method).with_call(
request_iterator,
timeout=new_timeout,
metadata=new_metadata,
credentials=new_credentials,
wait_for_ready=new_wait_for_ready,
compression=new_compression)
return _UnaryOutcome(response, call)
except grpc.RpcError as rpc_error:
return rpc_error
except Exception as exception: # pylint:disable=broad-except
return _FailureOutcome(exception, sys.exc_info()[2])
call = self._interceptor.intercept_stream_unary(continuation,
client_call_details,
request_iterator)
return call.result(), call
def with_call(self,
request_iterator,
timeout=None,
metadata=None,
credentials=None,
wait_for_ready=None,
compression=None):
return self._with_call(request_iterator,
timeout=timeout,
metadata=metadata,
credentials=credentials,
wait_for_ready=wait_for_ready,
compression=compression)
def future(self,
request_iterator,
timeout=None,
metadata=None,
credentials=None,
wait_for_ready=None,
compression=None):
client_call_details = _ClientCallDetails(self._method, timeout,
metadata, credentials,
wait_for_ready, compression)
def continuation(new_details, request_iterator):
(new_method, new_timeout, new_metadata, new_credentials,
new_wait_for_ready,
new_compression) = (_unwrap_client_call_details(
new_details, client_call_details))
return self._thunk(new_method).future(
request_iterator,
timeout=new_timeout,
metadata=new_metadata,
credentials=new_credentials,
wait_for_ready=new_wait_for_ready,
compression=new_compression)
try:
return self._interceptor.intercept_stream_unary(
continuation, client_call_details, request_iterator)
except Exception as exception: # pylint:disable=broad-except
return _FailureOutcome(exception, sys.exc_info()[2])
class _StreamStreamMultiCallable(grpc.StreamStreamMultiCallable):
def __init__(self, thunk, method, interceptor):
self._thunk = thunk
self._method = method
self._interceptor = interceptor
def __call__(self,
request_iterator,
timeout=None,
metadata=None,
credentials=None,
wait_for_ready=None,
compression=None):
client_call_details = _ClientCallDetails(self._method, timeout,
metadata, credentials,
wait_for_ready, compression)
def continuation(new_details, request_iterator):
(new_method, new_timeout, new_metadata, new_credentials,
new_wait_for_ready,
new_compression) = (_unwrap_client_call_details(
new_details, client_call_details))
return self._thunk(new_method)(request_iterator,
timeout=new_timeout,
metadata=new_metadata,
credentials=new_credentials,
wait_for_ready=new_wait_for_ready,
compression=new_compression)
try:
return self._interceptor.intercept_stream_stream(
continuation, client_call_details, request_iterator)
except Exception as exception: # pylint:disable=broad-except
return _FailureOutcome(exception, sys.exc_info()[2])
class _Channel(grpc.Channel):
def __init__(self, channel, interceptor):
self._channel = channel
self._interceptor = interceptor
def subscribe(self, callback, try_to_connect=False):
self._channel.subscribe(callback, try_to_connect=try_to_connect)
def unsubscribe(self, callback):
self._channel.unsubscribe(callback)
def unary_unary(self,
method,
request_serializer=None,
response_deserializer=None):
thunk = lambda m: self._channel.unary_unary(m, request_serializer,
response_deserializer)
if isinstance(self._interceptor, grpc.UnaryUnaryClientInterceptor):
return _UnaryUnaryMultiCallable(thunk, method, self._interceptor)
else:
return thunk(method)
def unary_stream(self,
method,
request_serializer=None,
response_deserializer=None):
thunk = lambda m: self._channel.unary_stream(m, request_serializer,
response_deserializer)
if isinstance(self._interceptor, grpc.UnaryStreamClientInterceptor):
return _UnaryStreamMultiCallable(thunk, method, self._interceptor)
else:
return thunk(method)
def stream_unary(self,
method,
request_serializer=None,
response_deserializer=None):
thunk = lambda m: self._channel.stream_unary(m, request_serializer,
response_deserializer)
if isinstance(self._interceptor, grpc.StreamUnaryClientInterceptor):
return _StreamUnaryMultiCallable(thunk, method, self._interceptor)
else:
return thunk(method)
def stream_stream(self,
method,
request_serializer=None,
response_deserializer=None):
thunk = lambda m: self._channel.stream_stream(m, request_serializer,
response_deserializer)
if isinstance(self._interceptor, grpc.StreamStreamClientInterceptor):
return _StreamStreamMultiCallable(thunk, method, self._interceptor)
else:
return thunk(method)
def _close(self):
self._channel.close()
def __enter__(self):
return self
def __exit__(self, exc_type, exc_val, exc_tb):
self._close()
return False
def close(self):
self._channel.close()
def intercept_channel(channel, *interceptors):
for interceptor in reversed(list(interceptors)):
if not isinstance(interceptor, grpc.UnaryUnaryClientInterceptor) and \
not isinstance(interceptor, grpc.UnaryStreamClientInterceptor) and \
not isinstance(interceptor, grpc.StreamUnaryClientInterceptor) and \
not isinstance(interceptor, grpc.StreamStreamClientInterceptor):
raise TypeError('interceptor must be '
'grpc.UnaryUnaryClientInterceptor or '
'grpc.UnaryStreamClientInterceptor or '
'grpc.StreamUnaryClientInterceptor or '
'grpc.StreamStreamClientInterceptor or ')
channel = _Channel(channel, interceptor)
return channel
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