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# Copyright 2024 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.
"""Helpers for asynchronous server-side streaming in REST."""
from typing import Union
import proto
try:
import google.auth.aio.transport
except ImportError as e: # pragma: NO COVER
raise ImportError(
"`google-api-core[async_rest]` is required to use asynchronous rest streaming. "
"Install the `async_rest` extra of `google-api-core` using "
"`pip install google-api-core[async_rest]`."
) from e
import google.protobuf.message
from google.api_core._rest_streaming_base import BaseResponseIterator
class AsyncResponseIterator(BaseResponseIterator):
"""Asynchronous Iterator over REST API responses.
Args:
response (google.auth.aio.transport.Response): An API response object.
response_message_cls (Union[proto.Message, google.protobuf.message.Message]): A response
class expected to be returned from an API.
Raises:
ValueError:
- If `response_message_cls` is not a subclass of `proto.Message` or `google.protobuf.message.Message`.
"""
def __init__(
self,
response: google.auth.aio.transport.Response,
response_message_cls: Union[proto.Message, google.protobuf.message.Message],
):
self._response = response
self._chunk_size = 1024
# TODO(https://github.com/googleapis/python-api-core/issues/703): mypy does not recognize the abstract content
# method as an async generator as it looks for the `yield` keyword in the implementation.
# Given that the abstract method is not implemented, mypy fails to recognize it as an async generator.
# mypy warnings are silenced until the linked issue is resolved.
self._response_itr = self._response.content(self._chunk_size).__aiter__() # type: ignore
super(AsyncResponseIterator, self).__init__(
response_message_cls=response_message_cls
)
async def __aenter__(self):
return self
async def cancel(self):
"""Cancel existing streaming operation."""
await self._response.close()
async def __anext__(self):
while not self._ready_objs:
try:
chunk = await self._response_itr.__anext__()
chunk = chunk.decode("utf-8")
self._process_chunk(chunk)
except StopAsyncIteration as e:
if self._level > 0:
raise ValueError("i Unfinished stream: %s" % self._obj)
raise e
except ValueError as e:
raise e
return self._grab()
def __aiter__(self):
return self
async def __aexit__(self, exc_type, exc, tb):
"""Cancel existing async streaming operation."""
await self._response.close()
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