synapse-product/synapse/rest/client/v1/base.py
Kegan Dougal 2771447c29 Store Promise<Response> instead of Response for HTTP API transactions
This fixes a race whereby:
 - User hits an endpoint.
 - No cached transaction so executes main code.
 - User hits same endpoint.
 - No cache transaction so executes main code.
 - Main code finishes executing and caches response and returns.
 - Main code finishes executing and caches response and returns.

 This race is common in the wild when Synapse is struggling under load.
 This commit fixes the race by:
  - User hits an endpoint.
  - Caches the promise to execute the main code and executes main code.
  - User hits same endpoint.
  - Yields on the same promise as the first request.
  - Main code finishes executing and returns, unblocking both requests.
2016-11-10 14:49:26 +00:00

63 lines
2.0 KiB
Python

# -*- coding: utf-8 -*-
# Copyright 2014-2016 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 base REST classes for constructing client v1 servlets.
"""
from synapse.http.servlet import RestServlet
from synapse.api.urls import CLIENT_PREFIX
from .transactions import HttpTransactionCache
import re
import logging
logger = logging.getLogger(__name__)
def client_path_patterns(path_regex, releases=(0,), include_in_unstable=True):
"""Creates a regex compiled client path with the correct client path
prefix.
Args:
path_regex (str): The regex string to match. This should NOT have a ^
as this will be prefixed.
Returns:
SRE_Pattern
"""
patterns = [re.compile("^" + CLIENT_PREFIX + path_regex)]
if include_in_unstable:
unstable_prefix = CLIENT_PREFIX.replace("/api/v1", "/unstable")
patterns.append(re.compile("^" + unstable_prefix + path_regex))
for release in releases:
new_prefix = CLIENT_PREFIX.replace("/api/v1", "/r%d" % release)
patterns.append(re.compile("^" + new_prefix + path_regex))
return patterns
class ClientV1RestServlet(RestServlet):
"""A base Synapse REST Servlet for the client version 1 API.
"""
def __init__(self, hs):
"""
Args:
hs (synapse.server.HomeServer):
"""
self.hs = hs
self.builder_factory = hs.get_event_builder_factory()
self.auth = hs.get_v1auth()
self.txns = HttpTransactionCache()