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1# Copyright 2020 Google LLC
2#
3# Licensed under the Apache License, Version 2.0 (the "License");
4# you may not use this file except in compliance with the License.
5# You may obtain a copy of the License at
6#
7# http://www.apache.org/licenses/LICENSE-2.0
8#
9# Unless required by applicable law or agreed to in writing, software
10# distributed under the License is distributed on an "AS IS" BASIS,
11# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12# See the License for the specific language governing permissions and
13# limitations under the License.
15"""AsyncIO helpers for :mod:`grpc` supporting 3.7+.
17Please combine more detailed docstring in grpc_helpers.py to use following
18functions. This module is implementing the same surface with AsyncIO semantics.
19"""
21import asyncio
22import functools
24from typing import AsyncGenerator, Generic, Iterator, Optional, TypeVar
26import grpc
27from grpc import aio
29from google.api_core import exceptions, grpc_helpers
31# denotes the proto response type for grpc calls
32P = TypeVar("P")
34# NOTE(lidiz) Alternatively, we can hack "__getattribute__" to perform
35# automatic patching for us. But that means the overhead of creating an
36# extra Python function spreads to every single send and receive.
39class _WrappedCall(aio.Call):
40 def __init__(self):
41 self._call = None
43 def with_call(self, call):
44 """Supplies the call object separately to keep __init__ clean."""
45 self._call = call
46 return self
48 async def initial_metadata(self):
49 return await self._call.initial_metadata()
51 async def trailing_metadata(self):
52 return await self._call.trailing_metadata()
54 async def code(self):
55 return await self._call.code()
57 async def details(self):
58 return await self._call.details()
60 def cancelled(self):
61 return self._call.cancelled()
63 def done(self):
64 return self._call.done()
66 def time_remaining(self):
67 return self._call.time_remaining()
69 def cancel(self):
70 return self._call.cancel()
72 def add_done_callback(self, callback):
73 self._call.add_done_callback(callback)
75 async def wait_for_connection(self):
76 try:
77 await self._call.wait_for_connection()
78 except grpc.RpcError as rpc_error:
79 raise exceptions.from_grpc_error(rpc_error) from rpc_error
82class _WrappedUnaryResponseMixin(Generic[P], _WrappedCall):
83 def __await__(self) -> Iterator[P]:
84 try:
85 response = yield from self._call.__await__()
86 return response
87 except grpc.RpcError as rpc_error:
88 raise exceptions.from_grpc_error(rpc_error) from rpc_error
91class _WrappedStreamResponseMixin(Generic[P], _WrappedCall):
92 def __init__(self):
93 self._wrapped_async_generator = None
95 async def read(self) -> P:
96 try:
97 return await self._call.read()
98 except grpc.RpcError as rpc_error:
99 raise exceptions.from_grpc_error(rpc_error) from rpc_error
101 async def _wrapped_aiter(self) -> AsyncGenerator[P, None]:
102 try:
103 # NOTE(lidiz) coverage doesn't understand the exception raised from
104 # __anext__ method. It is covered by test case:
105 # test_wrap_stream_errors_aiter_non_rpc_error
106 async for response in self._call: # pragma: no branch
107 yield response
108 except grpc.RpcError as rpc_error:
109 raise exceptions.from_grpc_error(rpc_error) from rpc_error
111 def __aiter__(self) -> AsyncGenerator[P, None]:
112 if not self._wrapped_async_generator:
113 self._wrapped_async_generator = self._wrapped_aiter()
114 return self._wrapped_async_generator
117class _WrappedStreamRequestMixin(_WrappedCall):
118 async def write(self, request):
119 try:
120 await self._call.write(request)
121 except grpc.RpcError as rpc_error:
122 raise exceptions.from_grpc_error(rpc_error) from rpc_error
124 async def done_writing(self):
125 try:
126 await self._call.done_writing()
127 except grpc.RpcError as rpc_error:
128 raise exceptions.from_grpc_error(rpc_error) from rpc_error
131# NOTE(lidiz) Implementing each individual class separately, so we don't
132# expose any API that should not be seen. E.g., __aiter__ in unary-unary
133# RPC, or __await__ in stream-stream RPC.
134class _WrappedUnaryUnaryCall(_WrappedUnaryResponseMixin[P], aio.UnaryUnaryCall):
135 """Wrapped UnaryUnaryCall to map exceptions."""
138class _WrappedUnaryStreamCall(_WrappedStreamResponseMixin[P], aio.UnaryStreamCall):
139 """Wrapped UnaryStreamCall to map exceptions."""
142class _WrappedStreamUnaryCall(
143 _WrappedUnaryResponseMixin[P], _WrappedStreamRequestMixin, aio.StreamUnaryCall
144):
145 """Wrapped StreamUnaryCall to map exceptions."""
148class _WrappedStreamStreamCall(
149 _WrappedStreamRequestMixin, _WrappedStreamResponseMixin[P], aio.StreamStreamCall
150):
151 """Wrapped StreamStreamCall to map exceptions."""
154# public type alias denoting the return type of async streaming gapic calls
155GrpcAsyncStream = _WrappedStreamResponseMixin[P]
156# public type alias denoting the return type of unary gapic calls
157AwaitableGrpcCall = _WrappedUnaryResponseMixin[P]
160def _wrap_unary_errors(callable_):
161 """Map errors for Unary-Unary async callables."""
163 @functools.wraps(callable_)
164 def error_remapped_callable(*args, **kwargs):
165 call = callable_(*args, **kwargs)
166 return _WrappedUnaryUnaryCall().with_call(call)
168 return error_remapped_callable
171def _wrap_stream_errors(callable_, wrapper_type):
172 """Map errors for streaming RPC async callables."""
174 @functools.wraps(callable_)
175 async def error_remapped_callable(*args, **kwargs):
176 call = callable_(*args, **kwargs)
177 call = wrapper_type().with_call(call)
178 await call.wait_for_connection()
179 return call
181 return error_remapped_callable
184def wrap_errors(callable_):
185 """Wrap a gRPC async callable and map :class:`grpc.RpcErrors` to
186 friendly error classes.
188 Errors raised by the gRPC callable are mapped to the appropriate
189 :class:`google.api_core.exceptions.GoogleAPICallError` subclasses. The
190 original `grpc.RpcError` (which is usually also a `grpc.Call`) is
191 available from the ``response`` property on the mapped exception. This
192 is useful for extracting metadata from the original error.
194 Args:
195 callable_ (Callable): A gRPC callable.
197 Returns: Callable: The wrapped gRPC callable.
198 """
199 grpc_helpers._patch_callable_name(callable_)
201 if isinstance(callable_, aio.UnaryStreamMultiCallable):
202 return _wrap_stream_errors(callable_, _WrappedUnaryStreamCall)
203 elif isinstance(callable_, aio.StreamUnaryMultiCallable):
204 return _wrap_stream_errors(callable_, _WrappedStreamUnaryCall)
205 elif isinstance(callable_, aio.StreamStreamMultiCallable):
206 return _wrap_stream_errors(callable_, _WrappedStreamStreamCall)
207 else:
208 return _wrap_unary_errors(callable_)
211def create_channel(
212 target,
213 credentials=None,
214 scopes=None,
215 ssl_credentials=None,
216 credentials_file=None,
217 quota_project_id=None,
218 default_scopes=None,
219 default_host=None,
220 compression=None,
221 attempt_direct_path: Optional[bool] = False,
222 **kwargs
223):
224 """Create an AsyncIO secure channel with credentials.
226 Args:
227 target (str): The target service address in the format 'hostname:port'.
228 credentials (google.auth.credentials.Credentials): The credentials. If
229 not specified, then this function will attempt to ascertain the
230 credentials from the environment using :func:`google.auth.default`.
231 scopes (Sequence[str]): A optional list of scopes needed for this
232 service. These are only used when credentials are not specified and
233 are passed to :func:`google.auth.default`.
234 ssl_credentials (grpc.ChannelCredentials): Optional SSL channel
235 credentials. This can be used to specify different certificates.
236 credentials_file (str): A file with credentials that can be loaded with
237 :func:`google.auth.load_credentials_from_file`. This argument is
238 mutually exclusive with credentials.
239 quota_project_id (str): An optional project to use for billing and quota.
240 default_scopes (Sequence[str]): Default scopes passed by a Google client
241 library. Use 'scopes' for user-defined scopes.
242 default_host (str): The default endpoint. e.g., "pubsub.googleapis.com".
243 compression (grpc.Compression): An optional value indicating the
244 compression method to be used over the lifetime of the channel.
245 attempt_direct_path (Optional[bool]): If set, Direct Path will be attempted
246 when the request is made. Direct Path is only available within a Google
247 Compute Engine (GCE) environment and provides a proxyless connection
248 which increases the available throughput, reduces latency, and increases
249 reliability. Note:
251 - This argument should only be set in a GCE environment and for Services
252 that are known to support Direct Path.
253 - If this argument is set outside of GCE, then this request will fail
254 unless the back-end service happens to have configured fall-back to DNS.
255 - If the request causes a `ServiceUnavailable` response, it is recommended
256 that the client repeat the request with `attempt_direct_path` set to
257 `False` as the Service may not support Direct Path.
258 - Using `ssl_credentials` with `attempt_direct_path` set to `True` will
259 result in `ValueError` as this combination is not yet supported.
261 kwargs: Additional key-word args passed to :func:`aio.secure_channel`.
263 Returns:
264 aio.Channel: The created channel.
266 Raises:
267 google.api_core.DuplicateCredentialArgs: If both a credentials object and credentials_file are passed.
268 ValueError: If `ssl_credentials` is set and `attempt_direct_path` is set to `True`.
269 """
271 # If `ssl_credentials` is set and `attempt_direct_path` is set to `True`,
272 # raise ValueError as this is not yet supported.
273 # See https://github.com/googleapis/python-api-core/issues/590
274 if ssl_credentials and attempt_direct_path:
275 raise ValueError("Using ssl_credentials with Direct Path is not supported")
277 composite_credentials = grpc_helpers._create_composite_credentials(
278 credentials=credentials,
279 credentials_file=credentials_file,
280 scopes=scopes,
281 default_scopes=default_scopes,
282 ssl_credentials=ssl_credentials,
283 quota_project_id=quota_project_id,
284 default_host=default_host,
285 )
287 if attempt_direct_path:
288 target = grpc_helpers._modify_target_for_direct_path(target)
290 return aio.secure_channel(
291 target, composite_credentials, compression=compression, **kwargs
292 )
295class FakeUnaryUnaryCall(_WrappedUnaryUnaryCall):
296 """Fake implementation for unary-unary RPCs.
298 It is a dummy object for response message. Supply the intended response
299 upon the initialization, and the coroutine will return the exact response
300 message.
301 """
303 def __init__(self, response=object()):
304 self.response = response
305 self._future = asyncio.get_event_loop().create_future()
306 self._future.set_result(self.response)
308 def __await__(self):
309 response = yield from self._future.__await__()
310 return response
313class FakeStreamUnaryCall(_WrappedStreamUnaryCall):
314 """Fake implementation for stream-unary RPCs.
316 It is a dummy object for response message. Supply the intended response
317 upon the initialization, and the coroutine will return the exact response
318 message.
319 """
321 def __init__(self, response=object()):
322 self.response = response
323 self._future = asyncio.get_event_loop().create_future()
324 self._future.set_result(self.response)
326 def __await__(self):
327 response = yield from self._future.__await__()
328 return response
330 async def wait_for_connection(self):
331 pass