mirror of
https://mau.dev/maunium/synapse.git
synced 2024-10-01 01:36:05 -04:00
72 lines
2.8 KiB
Python
72 lines
2.8 KiB
Python
# -*- coding: utf-8 -*-
|
|
# Copyright 2015 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.
|
|
|
|
from synapse.util.async import ObservableDeferred
|
|
|
|
|
|
class SnapshotCache(object):
|
|
|
|
DURATION_MS = 5 * 60 * 1000 # Cache results for 2 minutes.
|
|
|
|
def __init__(self):
|
|
self.pending_result_cache = {} # Request that haven't finished yet.
|
|
self.prev_result_cache = {} # The older requests that have finished.
|
|
self.next_result_cache = {} # The newer requests that have finished.
|
|
self.time_last_rotated_ms = 0
|
|
|
|
def rotate(self, time_now_ms):
|
|
# Rotate once if the cache duration has passed since the last rotation.
|
|
if time_now_ms - self.time_last_rotated_ms > self.DURATION_MS:
|
|
self.prev_result_cache = self.next_result_cache
|
|
self.next_result_cache = {}
|
|
self.time_last_rotated_ms += self.DURATION_MS
|
|
|
|
# Rotate again if the cache duration has passed twice since the last
|
|
# rotation.
|
|
if time_now_ms - self.time_last_rotated_ms > self.DURATION_MS:
|
|
self.prev_result_cache = self.next_result_cache
|
|
self.next_result_cache = {}
|
|
self.time_last_rotated_ms = time_now_ms
|
|
|
|
def get(self, time_now_ms, key):
|
|
self.rotate(time_now_ms)
|
|
# This cache is intended to deduplicate requests, so we expect it to be
|
|
# missed most of the time. So we just lookup the key in all of the
|
|
# dictionaries rather than trying to short circuit the lookup if the
|
|
# key is found.
|
|
result = self.prev_result_cache.get(key)
|
|
result = self.next_result_cache.get(key, result)
|
|
result = self.pending_result_cache.get(key, result)
|
|
if result is not None:
|
|
return result.observe()
|
|
|
|
def set(self, time_now_ms, key, deferred):
|
|
self.rotate(time_now_ms)
|
|
|
|
result = ObservableDeferred(deferred)
|
|
|
|
self.pending_result_cache[key] = result
|
|
|
|
def shuffle_along(r):
|
|
# When the deferred completes we shuffle it along to the first
|
|
# generation of the result cache. So that it will eventually
|
|
# expire from the rotation of that cache.
|
|
self.next_result_cache[key] = result
|
|
self.pending_result_cache.pop(key, None)
|
|
|
|
result.observe().addBoth(shuffle_along)
|
|
|
|
return result.observe()
|