91 lines
2.9 KiB
Python
91 lines
2.9 KiB
Python
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# Copyright 2015 Google Inc. 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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"""Define API Topics."""
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import base64
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from gcloud._helpers import _rfc3339_to_datetime
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class Message(object):
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"""Messages can be published to a topic and received by subscribers.
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See:
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https://cloud.google.com/pubsub/reference/rest/v1/PubsubMessage
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:type data: bytes
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:param data: the payload of the message
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:type message_id: string
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:param message_id: An ID assigned to the message by the API.
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:type attributes: dict or None
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:param attributes: Extra metadata associated by the publisher with the
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message.
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"""
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_service_timestamp = None
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def __init__(self, data, message_id, attributes=None):
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self.data = data
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self.message_id = message_id
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self._attributes = attributes
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@property
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def attributes(self):
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"""Lazily-constructed attribute dictionary"""
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if self._attributes is None:
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self._attributes = {}
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return self._attributes
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@property
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def timestamp(self):
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"""Return sortable timestamp from attributes, if passed.
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Allows sorting messages in publication order (assuming consistent
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clocks across all publishers).
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:rtype: :class:`datetime.datetime`
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:returns: timestamp (in UTC timezone) parsed from RFC 3339 timestamp
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:raises: ValueError if timestamp not in ``attributes``, or if it does
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not match the RFC 3339 format.
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"""
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stamp = self.attributes.get('timestamp')
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if stamp is None:
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raise ValueError('No timestamp')
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return _rfc3339_to_datetime(stamp)
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@property
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def service_timestamp(self):
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"""Return server-set timestamp.
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:rtype: string
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:returns: timestamp (in UTC timezone) in RFC 3339 format
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"""
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return self._service_timestamp
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@classmethod
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def from_api_repr(cls, api_repr):
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"""Factory: construct message from API representation.
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:type api_repr: dict or None
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:param api_repr: The API representation of the message
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"""
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data = base64.b64decode(api_repr.get('data', b''))
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instance = cls(
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data=data, message_id=api_repr['messageId'],
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attributes=api_repr.get('attributes'))
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instance._service_timestamp = api_repr.get('publishTimestamp')
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return instance
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