119 lines
4.0 KiB
Python
119 lines
4.0 KiB
Python
# -*- coding: utf-8 -*- #
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# Copyright 2021 Google LLC. All Rights Reserved.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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"""Utilities for Pub/Sub Lite subscriptions."""
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from __future__ import absolute_import
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from __future__ import division
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from __future__ import unicode_literals
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from concurrent import futures
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import time
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from typing import Optional
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from google.cloud.pubsublite import cloudpubsub
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from google.cloud.pubsublite import types
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from google.pubsub_v1 import PubsubMessage
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from googlecloudsdk.command_lib.pubsub import lite_util
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from googlecloudsdk.core import exceptions
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from googlecloudsdk.core import gapic_util
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from googlecloudsdk.core import log
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from six.moves import queue
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_MAX_INT64 = 0x7FFFFFFFFFFFFFFF
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class SubscribeOperationException(exceptions.Error):
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"""Error when something went wrong while subscribing."""
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def GetDefaultSubscriberClient():
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return cloudpubsub.SubscriberClient(
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credentials=gapic_util.GetGapicCredentials())
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class SubscriberClient(object):
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"""GCloud wrapper client for a Pub/Sub Lite subscriber."""
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def __init__(self,
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subscription_resource,
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partitions,
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max_messages,
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auto_ack,
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client=None):
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self._client = client or GetDefaultSubscriberClient()
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self._messages = queue.Queue()
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self._subscription = self._SubscriptionResourceToPath(subscription_resource)
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self._partitions = {types.Partition(partition) for partition in partitions}
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self._flow_control_settings = types.FlowControlSettings(
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messages_outstanding=max_messages,
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bytes_outstanding=_MAX_INT64,
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)
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self._auto_ack = auto_ack
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self._pull_future = None
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def __enter__(self):
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self._client.__enter__()
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self._pull_future = self._client.subscribe(
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self._subscription,
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callback=self._messages.put,
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per_partition_flow_control_settings=self._flow_control_settings,
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fixed_partitions=self._partitions)
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return self
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def __exit__(self, exc_type, exc_value, traceback):
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time.sleep(1) # Wait 1 second to ensure all acks have been processed
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if not self._pull_future.done():
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try:
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# Cancel the streaming pull future and get the result to prevent
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# logging an abandoned future.
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self._pull_future.cancel()
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self._pull_future.result()
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except futures.CancelledError:
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pass
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self._client.__exit__(exc_type, exc_value, traceback)
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def _SubscriptionResourceToPath(self, resource):
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return types.SubscriptionPath(
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project=lite_util.ProjectIdToProjectNumber(resource.projectsId),
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location=lite_util.LocationToZoneOrRegion(resource.locationsId),
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name=resource.subscriptionsId)
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def _RaiseIfFailed(self):
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if self._pull_future.done():
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e = self._pull_future.exception()
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if e:
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raise SubscribeOperationException(
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'Subscribe operation failed with error: {error}'.format(error=e))
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log.debug('The streaming pull future completed unexpectedly without '
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'raising an exception.')
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raise exceptions.InternalError(
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'The subscribe stream terminated unexpectedly.')
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def Pull(self) -> Optional[PubsubMessage]:
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"""Pulls and optionally acks a message from the provided subscription.
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Returns:
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A PubsubMessage pulled from the subscription.
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"""
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self._RaiseIfFailed()
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try:
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message = self._messages.get(timeout=1)
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if self._auto_ack:
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message.ack()
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return message
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except queue.Empty:
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return None
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