mirror of
https://git.anonymousland.org/anonymousland/synapse-product.git
synced 2024-12-29 19:56:14 -05:00
116 lines
3.5 KiB
Python
116 lines
3.5 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.
|
|
|
|
import logging
|
|
|
|
|
|
logger = logging.getLogger(__name__)
|
|
|
|
|
|
class ExpiringCache(object):
|
|
def __init__(self, cache_name, clock, max_len=0, expiry_ms=0,
|
|
reset_expiry_on_get=False):
|
|
"""
|
|
Args:
|
|
cache_name (str): Name of this cache, used for logging.
|
|
clock (Clock)
|
|
max_len (int): Max size of dict. If the dict grows larger than this
|
|
then the oldest items get automatically evicted. Default is 0,
|
|
which indicates there is no max limit.
|
|
expiry_ms (int): How long before an item is evicted from the cache
|
|
in milliseconds. Default is 0, indicating items never get
|
|
evicted based on time.
|
|
reset_expiry_on_get (bool): If true, will reset the expiry time for
|
|
an item on access. Defaults to False.
|
|
|
|
"""
|
|
self._cache_name = cache_name
|
|
|
|
self._clock = clock
|
|
|
|
self._max_len = max_len
|
|
self._expiry_ms = expiry_ms
|
|
|
|
self._reset_expiry_on_get = reset_expiry_on_get
|
|
|
|
self._cache = {}
|
|
|
|
def start(self):
|
|
if not self._expiry_ms:
|
|
# Don't bother starting the loop if things never expire
|
|
return
|
|
|
|
def f():
|
|
self._prune_cache()
|
|
|
|
self._clock.looping_call(f, self._expiry_ms/2)
|
|
|
|
def __setitem__(self, key, value):
|
|
now = self._clock.time_msec()
|
|
self._cache[key] = _CacheEntry(now, value)
|
|
|
|
# Evict if there are now too many items
|
|
if self._max_len and len(self._cache.keys()) > self._max_len:
|
|
sorted_entries = sorted(
|
|
self._cache.items(),
|
|
key=lambda (k, v): v.time,
|
|
)
|
|
|
|
for k, _ in sorted_entries[self._max_len:]:
|
|
self._cache.pop(k)
|
|
|
|
def __getitem__(self, key):
|
|
entry = self._cache[key]
|
|
|
|
if self._reset_expiry_on_get:
|
|
entry.time = self._clock.time_msec()
|
|
|
|
return entry.value
|
|
|
|
def get(self, key, default=None):
|
|
try:
|
|
return self[key]
|
|
except KeyError:
|
|
return default
|
|
|
|
def _prune_cache(self):
|
|
if not self._expiry_ms:
|
|
# zero expiry time means don't expire. This should never get called
|
|
# since we have this check in start too.
|
|
return
|
|
begin_length = len(self._cache)
|
|
|
|
now = self._clock.time_msec()
|
|
|
|
keys_to_delete = set()
|
|
|
|
for key, cache_entry in self._cache.items():
|
|
if now - cache_entry.time > self._expiry_ms:
|
|
keys_to_delete.add(key)
|
|
|
|
for k in keys_to_delete:
|
|
self._cache.pop(k)
|
|
|
|
logger.debug(
|
|
"[%s] _prune_cache before: %d, after len: %d",
|
|
self._cache_name, begin_length, len(self._cache.keys())
|
|
)
|
|
|
|
|
|
class _CacheEntry(object):
|
|
def __init__(self, time, value):
|
|
self.time = time
|
|
self.value = value
|