Factor out ExpiringCache from StateHandler

pull/79/head
Erik Johnston 2015-02-16 16:16:47 +00:00
parent a5ad6f862c
commit 2674aeb96a
2 changed files with 124 additions and 37 deletions

View File

@ -18,6 +18,7 @@ from twisted.internet import defer
from synapse.util.logutils import log_function
from synapse.util.async import run_on_reactor
from synapse.util.expiringcache import ExpiringCache
from synapse.api.constants import EventTypes
from synapse.api.errors import AuthError
from synapse.events.snapshot import EventContext
@ -51,7 +52,6 @@ class _StateCacheEntry(object):
def __init__(self, state, state_group, ts):
self.state = state
self.state_group = state_group
self.ts = ts
class StateHandler(object):
@ -69,12 +69,15 @@ class StateHandler(object):
def start_caching(self):
logger.debug("start_caching")
self._state_cache = {}
self._state_cache = ExpiringCache(
cache_name="state_cache",
clock=self.clock,
max_len=SIZE_OF_CACHE,
expiry_ms=EVICTION_TIMEOUT_SECONDS*1000,
reset_expiry_on_get=True,
)
def f():
self._prune_cache()
self.clock.looping_call(f, 5*1000)
self._state_cache.start()
@defer.inlineCallbacks
def get_current_state(self, room_id, event_type=None, state_key=""):
@ -409,34 +412,3 @@ class StateHandler(object):
return -int(e.depth), hashlib.sha1(e.event_id).hexdigest()
return sorted(events, key=key_func)
def _prune_cache(self):
logger.debug(
"_prune_cache. before len: %d",
len(self._state_cache.keys())
)
now = self.clock.time_msec()
if len(self._state_cache.keys()) > SIZE_OF_CACHE:
sorted_entries = sorted(
self._state_cache.items(),
key=lambda k, v: v.ts,
)
for k, _ in sorted_entries[SIZE_OF_CACHE:]:
self._state_cache.pop(k)
keys_to_delete = set()
for key, cache_entry in self._state_cache.items():
if now - cache_entry.ts > EVICTION_TIMEOUT_SECONDS*1000:
keys_to_delete.add(key)
for k in keys_to_delete:
self._state_cache.pop(k)
logger.debug(
"_prune_cache. after len: %d",
len(self._state_cache.keys())
)

View File

@ -0,0 +1,115 @@
# -*- 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)
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 _purge_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