mirror of
https://git.anonymousland.org/anonymousland/synapse.git
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86 lines
3.0 KiB
Python
86 lines
3.0 KiB
Python
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# -*- coding: utf-8 -*-
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# Copyright 2014-2016 OpenMarket Ltd
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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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"""This module contains logic for storing HTTP PUT transactions. This is used
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to ensure idempotency when performing PUTs using the REST API."""
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import logging
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from synapse.api.auth import get_access_token_from_request
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from synapse.util.async import ObservableDeferred
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logger = logging.getLogger(__name__)
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def get_transaction_key(request):
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"""A helper function which returns a transaction key that can be used
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with TransactionCache for idempotent requests.
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Idempotency is based on the returned key being the same for separate
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requests to the same endpoint. The key is formed from the HTTP request
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path and the access_token for the requesting user.
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Args:
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request (twisted.web.http.Request): The incoming request. Must
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contain an access_token.
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Returns:
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str: A transaction key
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"""
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token = get_access_token_from_request(request)
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return request.path + "/" + token
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class HttpTransactionCache(object):
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def __init__(self):
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self.transactions = {
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# $txn_key: ObservableDeferred<(res_code, res_json_body)>
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}
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def fetch_or_execute_request(self, request, fn, *args, **kwargs):
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"""A helper function for fetch_or_execute which extracts
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a transaction key from the given request.
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See:
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fetch_or_execute
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"""
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return self.fetch_or_execute(
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get_transaction_key(request), fn, *args, **kwargs
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)
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def fetch_or_execute(self, txn_key, fn, *args, **kwargs):
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"""Fetches the response for this transaction, or executes the given function
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to produce a response for this transaction.
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Args:
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txn_key (str): A key to ensure idempotency should fetch_or_execute be
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called again at a later point in time.
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fn (function): A function which returns a tuple of
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(response_code, response_dict)d
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*args: Arguments to pass to fn.
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**kwargs: Keyword arguments to pass to fn.
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Returns:
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synapse.util.async.ObservableDeferred which resolves to a tuple
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of (response_code, response_dict).
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"""
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try:
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return self.transactions[txn_key]
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except KeyError:
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pass # execute the function instead.
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deferred = fn(*args, **kwargs)
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observable = ObservableDeferred(deferred)
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self.transactions[txn_key] = observable
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return observable
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