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connection.py
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connection.py
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# Copyright 2020 Google LLC
#
# 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.
from typing import Generic, TypeVar, AsyncContextManager
from abc import abstractmethod, ABCMeta
Request = TypeVar("Request")
Response = TypeVar("Response")
class Connection(
AsyncContextManager["Connection"], Generic[Request, Response], metaclass=ABCMeta
):
"""
A connection to an underlying stream. Only one call to 'read' may be outstanding at a time.
"""
@abstractmethod
async def write(self, request: Request) -> None:
"""
Write a message to the stream.
Raises:
GoogleAPICallError: When the connection terminates in failure.
"""
raise NotImplementedError()
@abstractmethod
async def read(self) -> Response:
"""
Read a message off of the stream.
Raises:
GoogleAPICallError: When the connection terminates in failure.
"""
raise NotImplementedError()
class ConnectionFactory(Generic[Request, Response], metaclass=ABCMeta):
"""A factory for producing Connections."""
@abstractmethod
async def new(self) -> Connection[Request, Response]:
raise NotImplementedError()