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# -*- coding: utf-8 -*-
# Copyright 2014 OpenMarket Ltd
#
# 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.
"""This module contains logic for storing HTTP PUT transactions. This is used
to ensure idempotency when performing PUTs using the REST API."""
import logging
logger = logging.getLogger(__name__)
class HttpTransactionStore(object):
def __init__(self):
# { key : (txn_id, response) }
self.transactions = {}
def get_response(self, key, txn_id):
"""Retrieve a response for this request.
Args:
key (str): A transaction-independent key for this request. Typically
this is a combination of the path (without the transaction id) and
the user's access token.
txn_id (str): The transaction ID for this request
Returns:
A tuple of (HTTP response code, response content) or None.
"""
try:
logger.debug("get_response Key: %s TxnId: %s", key, txn_id)
(last_txn_id, response) = self.transactions[key]
if txn_id == last_txn_id:
logger.info("get_response: Returning a response for %s", key)
return response
except KeyError:
pass
return None
def store_response(self, key, txn_id, response):
"""Stores an HTTP response tuple.
Args:
key (str): A transaction-independent key for this request. Typically
this is a combination of the path (without the transaction id) and
the user's access token.
txn_id (str): The transaction ID for this request.
response (tuple): A tuple of (HTTP response code, response content)
"""
logger.debug("store_response Key: %s TxnId: %s", key, txn_id)
self.transactions[key] = (txn_id, response)
def store_client_transaction(self, request, txn_id, response):
"""Stores the request/response pair of an HTTP transaction.
Args:
request (twisted.web.http.Request): The twisted HTTP request. This
request must have the transaction ID as the last path segment.
response (tuple): A tuple of (response code, response dict)
txn_id (str): The transaction ID for this request.
"""
self.store_response(self._get_key(request), txn_id, response)
def get_client_transaction(self, request, txn_id):
"""Retrieves a stored response if there was one.
Args:
request (twisted.web.http.Request): The twisted HTTP request. This
request must have the transaction ID as the last path segment.
txn_id (str): The transaction ID for this request.
Returns:
The response tuple.
Raises:
KeyError if the transaction was not found.
"""
response = self.get_response(self._get_key(request), txn_id)
if response is None:
raise KeyError("Transaction not found.")
return response
def _get_key(self, request):
token = request.args["access_token"][0]
path_without_txn_id = request.path.rsplit("/", 1)[0]
return path_without_txn_id + "/" + token
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