1# Copyright 2019 The gRPC Authors
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.
14"""Abstract base classes for client-side Call objects.
15
16Call objects represents the RPC itself, and offer methods to access / modify
17its information. They also offer methods to manipulate the life-cycle of the
18RPC, e.g. cancellation.
19"""
20
21from abc import ABCMeta
22from abc import abstractmethod
23from typing import Any, AsyncIterator, Generator, Generic, Optional, Union
24
25import grpc
26
27from ._metadata import Metadata
28from ._typing import DoneCallbackType
29from ._typing import EOFType
30from ._typing import RequestType
31from ._typing import ResponseType
32
33__all__ = "RpcContext", "Call", "UnaryUnaryCall", "UnaryStreamCall"
34
35
36class RpcContext(metaclass=ABCMeta):
37 """Provides RPC-related information and action."""
38
39 @abstractmethod
40 def cancelled(self) -> bool:
41 """Return True if the RPC is cancelled.
42
43 The RPC is cancelled when the cancellation was requested with cancel().
44
45 Returns:
46 A bool indicates whether the RPC is cancelled or not.
47 """
48
49 @abstractmethod
50 def done(self) -> bool:
51 """Return True if the RPC is done.
52
53 An RPC is done if the RPC is completed, cancelled or aborted.
54
55 Returns:
56 A bool indicates if the RPC is done.
57 """
58
59 @abstractmethod
60 def time_remaining(self) -> Optional[float]:
61 """Describes the length of allowed time remaining for the RPC.
62
63 Returns:
64 A nonnegative float indicating the length of allowed time in seconds
65 remaining for the RPC to complete before it is considered to have
66 timed out, or None if no deadline was specified for the RPC.
67 """
68
69 @abstractmethod
70 def cancel(self) -> bool:
71 """Cancels the RPC.
72
73 Idempotent and has no effect if the RPC has already terminated.
74
75 Returns:
76 A bool indicates if the cancellation is performed or not.
77 """
78
79 @abstractmethod
80 def add_done_callback(self, callback: DoneCallbackType) -> None:
81 """Registers a callback to be called on RPC termination.
82
83 Args:
84 callback: A callable object will be called with the call object as
85 its only argument.
86 """
87
88
89class Call(RpcContext, metaclass=ABCMeta):
90 """The abstract base class of an RPC on the client-side."""
91
92 @abstractmethod
93 async def initial_metadata(self) -> Metadata:
94 """Accesses the initial metadata sent by the server.
95
96 Returns:
97 The initial :term:`metadata`.
98 """
99
100 @abstractmethod
101 async def trailing_metadata(self) -> Metadata:
102 """Accesses the trailing metadata sent by the server.
103
104 Returns:
105 The trailing :term:`metadata`.
106 """
107
108 @abstractmethod
109 async def code(self) -> grpc.StatusCode:
110 """Accesses the status code sent by the server.
111
112 Returns:
113 The StatusCode value for the RPC.
114 """
115
116 @abstractmethod
117 async def details(self) -> str:
118 """Accesses the details sent by the server.
119
120 Returns:
121 The details string of the RPC.
122 """
123
124 @abstractmethod
125 async def wait_for_connection(self) -> None:
126 """Waits until connected to peer and raises aio.AioRpcError if failed.
127
128 This is an EXPERIMENTAL method.
129
130 This method ensures the RPC has been successfully connected. Otherwise,
131 an AioRpcError will be raised to explain the reason of the connection
132 failure.
133
134 This method is recommended for building retry mechanisms.
135 """
136
137
138class UnaryUnaryCall(
139 Generic[RequestType, ResponseType], Call, metaclass=ABCMeta
140):
141 """The abstract base class of a unary-unary RPC on the client-side."""
142
143 @abstractmethod
144 def __await__(self) -> Generator[Any, None, ResponseType]:
145 """Await the response message to be ready.
146
147 Returns:
148 The response message of the RPC.
149 """
150
151
152class UnaryStreamCall(
153 Generic[RequestType, ResponseType], Call, metaclass=ABCMeta
154):
155 @abstractmethod
156 def __aiter__(self) -> AsyncIterator[ResponseType]:
157 """Returns the async iterator representation that yields messages.
158
159 Under the hood, it is calling the "read" method.
160
161 Returns:
162 An async iterator object that yields messages.
163 """
164
165 @abstractmethod
166 async def read(self) -> Union[EOFType, ResponseType]:
167 """Reads one message from the stream.
168
169 Read operations must be serialized when called from multiple
170 coroutines.
171
172 Note that the iterator and read/write APIs may not be mixed on
173 a single RPC.
174
175 Returns:
176 A response message, or an `grpc.aio.EOF` to indicate the end of the
177 stream.
178 """
179
180
181class StreamUnaryCall(
182 Generic[RequestType, ResponseType], Call, metaclass=ABCMeta
183):
184 @abstractmethod
185 async def write(self, request: RequestType) -> None:
186 """Writes one message to the stream.
187
188 Note that the iterator and read/write APIs may not be mixed on
189 a single RPC.
190
191 Raises:
192 An RpcError exception if the write failed.
193 """
194
195 @abstractmethod
196 async def done_writing(self) -> None:
197 """Notifies server that the client is done sending messages.
198
199 After done_writing is called, any additional invocation to the write
200 function will fail. This function is idempotent.
201 """
202
203 @abstractmethod
204 def __await__(self) -> Generator[Any, None, ResponseType]:
205 """Await the response message to be ready.
206
207 Returns:
208 The response message of the stream.
209 """
210
211
212class StreamStreamCall(
213 Generic[RequestType, ResponseType], Call, metaclass=ABCMeta
214):
215 @abstractmethod
216 def __aiter__(self) -> AsyncIterator[ResponseType]:
217 """Returns the async iterator representation that yields messages.
218
219 Under the hood, it is calling the "read" method.
220
221 Returns:
222 An async iterator object that yields messages.
223 """
224
225 @abstractmethod
226 async def read(self) -> Union[EOFType, ResponseType]:
227 """Reads one message from the stream.
228
229 Read operations must be serialized when called from multiple
230 coroutines.
231
232 Note that the iterator and read/write APIs may not be mixed on
233 a single RPC.
234
235 Returns:
236 A response message, or an `grpc.aio.EOF` to indicate the end of the
237 stream.
238 """
239
240 @abstractmethod
241 async def write(self, request: RequestType) -> None:
242 """Writes one message to the stream.
243
244 Note that the iterator and read/write APIs may not be mixed on
245 a single RPC.
246
247 Raises:
248 An RpcError exception if the write failed.
249 """
250
251 @abstractmethod
252 async def done_writing(self) -> None:
253 """Notifies server that the client is done sending messages.
254
255 After done_writing is called, any additional invocation to the write
256 function will fail. This function is idempotent.
257 """