mirror of
https://git.anonymousland.org/anonymousland/synapse-product.git
synced 2024-10-01 08:25:44 -04:00
111 lines
3.4 KiB
Python
111 lines
3.4 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.
|
||
|
|
|
||
|
|
|
||
|
|
class LruCache(object):
|
||
|
|
"""Least-recently-used cache."""
|
||
|
|
# TODO(mjark) Add hit/miss counters
|
||
|
|
# TODO(mjark) Add mutex for linked list for thread safety.
|
||
|
|
def __init__(self, max_size):
|
||
|
|
cache = {}
|
||
|
|
list_root = []
|
||
|
|
list_root[:] = [list_root, list_root, None, None]
|
||
|
|
|
||
|
|
PREV, NEXT, KEY, VALUE = 0, 1, 2, 3
|
||
|
|
|
||
|
|
def add_node(key, value):
|
||
|
|
prev_node = list_root
|
||
|
|
next_node = prev_node[NEXT]
|
||
|
|
node = [prev_node, next_node, key, value]
|
||
|
|
prev_node[NEXT] = node
|
||
|
|
next_node[PREV] = node
|
||
|
|
cache[key] = node
|
||
|
|
|
||
|
|
def move_node_to_front(node):
|
||
|
|
prev_node = node[PREV]
|
||
|
|
next_node = node[NEXT]
|
||
|
|
prev_node[NEXT] = next_node
|
||
|
|
next_node[PREV] = prev_node
|
||
|
|
prev_node = list_root
|
||
|
|
next_node = prev_node[NEXT]
|
||
|
|
node[PREV] = prev_node
|
||
|
|
node[NEXT] = next_node
|
||
|
|
prev_node[NEXT] = node
|
||
|
|
next_node[PREV] = node
|
||
|
|
|
||
|
|
def delete_node(node):
|
||
|
|
prev_node = node[PREV]
|
||
|
|
next_node = node[NEXT]
|
||
|
|
prev_node[NEXT] = next_node
|
||
|
|
next_node[PREV] = prev_node
|
||
|
|
cache.pop(node[KEY], None)
|
||
|
|
|
||
|
|
def cache_get(key, default=None):
|
||
|
|
node = cache.get(key, None)
|
||
|
|
if node is not None:
|
||
|
|
move_node_to_front(node)
|
||
|
|
return node[VALUE]
|
||
|
|
else:
|
||
|
|
return default
|
||
|
|
|
||
|
|
def cache_set(key, value):
|
||
|
|
node = cache.get(key, None)
|
||
|
|
if node is not None:
|
||
|
|
move_node_to_front(node)
|
||
|
|
node[VALUE] = value
|
||
|
|
else:
|
||
|
|
add_node(key, value)
|
||
|
|
if len(cache) > max_size:
|
||
|
|
delete_node(list_root[PREV])
|
||
|
|
|
||
|
|
def cache_set_default(key, value):
|
||
|
|
node = cache.get(key, None)
|
||
|
|
if node is not None:
|
||
|
|
return node[VALUE]
|
||
|
|
else:
|
||
|
|
add_node(key, value)
|
||
|
|
if len(cache) > max_size:
|
||
|
|
delete_node(list_root[PREV])
|
||
|
|
return value
|
||
|
|
|
||
|
|
def cache_pop(key, default=None):
|
||
|
|
node = cache.get(key, None)
|
||
|
|
if node:
|
||
|
|
delete_node(node)
|
||
|
|
return node[VALUE]
|
||
|
|
else:
|
||
|
|
return default
|
||
|
|
|
||
|
|
self.sentinel = object()
|
||
|
|
self.get = cache_get
|
||
|
|
self.set = cache_set
|
||
|
|
self.setdefault = cache_set_default
|
||
|
|
self.pop = cache_pop
|
||
|
|
|
||
|
|
def __getitem__(self, key):
|
||
|
|
result = self.get(key, self.sentinel)
|
||
|
|
if result is self.sentinel:
|
||
|
|
raise KeyError()
|
||
|
|
else:
|
||
|
|
return result
|
||
|
|
|
||
|
|
def __setitem__(self, key, value):
|
||
|
|
self.set(key, value)
|
||
|
|
|
||
|
|
def __delitem__(self, key, value):
|
||
|
|
result = self.pop(key, self.sentinel)
|
||
|
|
if result is self.sentinel:
|
||
|
|
raise KeyError()
|