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# -*- coding: utf-8 -*-
# Copyright 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.
from synapse.util.caches import cache_counter, caches_by_name
from blist import sorteddict
import logging
logger = logging.getLogger(__name__)
class RoomStreamChangeCache(object):
"""Keeps track of the stream_id of the latest change in rooms.
Given a list of rooms and stream key, it will give a subset of rooms that
may have changed since that key. If the key is too old then the cache
will simply return all rooms.
"""
def __init__(self, name, current_key, size_of_cache=10000):
self._size_of_cache = size_of_cache
self._room_to_key = {}
self._cache = sorteddict()
self._earliest_known_key = current_key
self.name = name
caches_by_name[self.name] = self._cache
def get_room_has_changed(self, room_id, key):
if key <= self._earliest_known_key:
return True
room_key = self._room_to_key.get(room_id, None)
if room_key is None:
return True
if key < room_key:
return True
return False
def get_rooms_changed(self, room_ids, key):
"""Returns subset of room ids that have had new things since the
given key. If the key is too old it will just return the given list.
"""
if key > self._earliest_known_key:
keys = self._cache.keys()
i = keys.bisect_right(key)
result = set(
self._cache[k] for k in keys[i:]
).intersection(room_ids)
cache_counter.inc_hits(self.name)
else:
result = room_ids
cache_counter.inc_misses(self.name)
return result
def room_has_changed(self, room_id, key):
"""Informs the cache that the room has been changed at the given key.
"""
if key > self._earliest_known_key:
old_key = self._room_to_key.get(room_id, None)
if old_key:
key = max(key, old_key)
self._cache.pop(old_key, None)
self._cache[key] = room_id
while len(self._cache) > self._size_of_cache:
k, r = self._cache.popitem()
self._earliest_key = max(k, self._earliest_key)
self._room_to_key.pop(r, None)
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