mirror of
https://mau.dev/maunium/synapse.git
synced 2024-08-28 13:11:56 +00:00
![Erik Johnston](/assets/img/avatar_default.png)
This gives a bit of a grace period where we can attempt to refetch a remote `well-known`, while still using the cached result if that fails. Hopefully this will make the well-known resolution a bit more torelant of failures, rather than it immediately treating failures as "no result" and caching that for an hour.
165 lines
4.6 KiB
Python
165 lines
4.6 KiB
Python
# -*- coding: utf-8 -*-
|
|
# Copyright 2015, 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.
|
|
|
|
import logging
|
|
import time
|
|
|
|
import attr
|
|
from sortedcontainers import SortedList
|
|
|
|
from synapse.util.caches import register_cache
|
|
|
|
logger = logging.getLogger(__name__)
|
|
|
|
SENTINEL = object()
|
|
|
|
|
|
class TTLCache(object):
|
|
"""A key/value cache implementation where each entry has its own TTL"""
|
|
|
|
def __init__(self, cache_name, timer=time.time):
|
|
# map from key to _CacheEntry
|
|
self._data = {}
|
|
|
|
# the _CacheEntries, sorted by expiry time
|
|
self._expiry_list = SortedList()
|
|
|
|
self._timer = timer
|
|
|
|
self._metrics = register_cache("ttl", cache_name, self)
|
|
|
|
def set(self, key, value, ttl):
|
|
"""Add/update an entry in the cache
|
|
|
|
Args:
|
|
key: key for this entry
|
|
value: value for this entry
|
|
ttl (float): TTL for this entry, in seconds
|
|
"""
|
|
expiry = self._timer() + ttl
|
|
|
|
self.expire()
|
|
e = self._data.pop(key, SENTINEL)
|
|
if e != SENTINEL:
|
|
self._expiry_list.remove(e)
|
|
|
|
entry = _CacheEntry(expiry_time=expiry, ttl=ttl, key=key, value=value)
|
|
self._data[key] = entry
|
|
self._expiry_list.add(entry)
|
|
|
|
def get(self, key, default=SENTINEL):
|
|
"""Get a value from the cache
|
|
|
|
Args:
|
|
key: key to look up
|
|
default: default value to return, if key is not found. If not set, and the
|
|
key is not found, a KeyError will be raised
|
|
|
|
Returns:
|
|
value from the cache, or the default
|
|
"""
|
|
self.expire()
|
|
e = self._data.get(key, SENTINEL)
|
|
if e == SENTINEL:
|
|
self._metrics.inc_misses()
|
|
if default == SENTINEL:
|
|
raise KeyError(key)
|
|
return default
|
|
self._metrics.inc_hits()
|
|
return e.value
|
|
|
|
def get_with_expiry(self, key):
|
|
"""Get a value, and its expiry time, from the cache
|
|
|
|
Args:
|
|
key: key to look up
|
|
|
|
Returns:
|
|
Tuple[Any, float, float]: the value from the cache, the expiry time
|
|
and the TTL
|
|
|
|
Raises:
|
|
KeyError if the entry is not found
|
|
"""
|
|
self.expire()
|
|
try:
|
|
e = self._data[key]
|
|
except KeyError:
|
|
self._metrics.inc_misses()
|
|
raise
|
|
self._metrics.inc_hits()
|
|
return e.value, e.expiry_time, e.ttl
|
|
|
|
def pop(self, key, default=SENTINEL):
|
|
"""Remove a value from the cache
|
|
|
|
If key is in the cache, remove it and return its value, else return default.
|
|
If default is not given and key is not in the cache, a KeyError is raised.
|
|
|
|
Args:
|
|
key: key to look up
|
|
default: default value to return, if key is not found. If not set, and the
|
|
key is not found, a KeyError will be raised
|
|
|
|
Returns:
|
|
value from the cache, or the default
|
|
"""
|
|
self.expire()
|
|
e = self._data.pop(key, SENTINEL)
|
|
if e == SENTINEL:
|
|
self._metrics.inc_misses()
|
|
if default == SENTINEL:
|
|
raise KeyError(key)
|
|
return default
|
|
self._expiry_list.remove(e)
|
|
self._metrics.inc_hits()
|
|
return e.value
|
|
|
|
def __getitem__(self, key):
|
|
return self.get(key)
|
|
|
|
def __delitem__(self, key):
|
|
self.pop(key)
|
|
|
|
def __contains__(self, key):
|
|
return key in self._data
|
|
|
|
def __len__(self):
|
|
self.expire()
|
|
return len(self._data)
|
|
|
|
def expire(self):
|
|
"""Run the expiry on the cache. Any entries whose expiry times are due will
|
|
be removed
|
|
"""
|
|
now = self._timer()
|
|
while self._expiry_list:
|
|
first_entry = self._expiry_list[0]
|
|
if first_entry.expiry_time - now > 0.0:
|
|
break
|
|
del self._data[first_entry.key]
|
|
del self._expiry_list[0]
|
|
|
|
|
|
@attr.s(frozen=True, slots=True)
|
|
class _CacheEntry(object):
|
|
"""TTLCache entry"""
|
|
|
|
# expiry_time is the first attribute, so that entries are sorted by expiry.
|
|
expiry_time = attr.ib()
|
|
ttl = attr.ib()
|
|
key = attr.ib()
|
|
value = attr.ib()
|