Take named arguments to @cached() decorator, add a 'max_entries' limit

This commit is contained in:
Paul "LeoNerd" Evans 2015-02-19 18:36:02 +00:00
parent 077d200342
commit ebc3db295b
3 changed files with 114 additions and 16 deletions

View File

@ -39,8 +39,8 @@ transaction_logger = logging.getLogger("synapse.storage.txn")
# * Move this somewhere higher-level, shared;
# * more generic key management
# * export monitoring stats
# * maximum size; just evict things at random, or consider LRU?
def cached(orig):
# * consider other eviction strategies - LRU?
def cached(max_entries=1000):
""" A method decorator that applies a memoizing cache around the function.
The function is presumed to take one additional argument, which is used as
@ -50,6 +50,7 @@ def cached(orig):
The wrapped function has an additional member, a callable called
"invalidate". This can be used to remove individual entries from the cache.
"""
def wrap(orig):
cache = {}
@defer.inlineCallbacks
@ -59,6 +60,12 @@ def cached(orig):
ret = yield orig(self, key)
while len(cache) > max_entries:
# TODO(paul): This feels too biased. However, a random index
# would be a bit inefficient, walking the list of keys just
# to ignore most of them?
del cache[cache.keys()[0]]
cache[key] = ret;
defer.returnValue(ret)
@ -69,6 +76,8 @@ def cached(orig):
wrapped.invalidate = invalidate
return wrapped
return wrap
class LoggingTransaction(object):
"""An object that almost-transparently proxies for the 'txn' object

View File

@ -247,7 +247,7 @@ class RoomMemberStore(SQLBaseStore):
results = self._parse_events_txn(txn, rows)
return results
@cached
@cached()
def get_rooms_for_user(self, user_id):
return self.get_rooms_for_user_where_membership_is(
user_id, membership_list=[Membership.JOIN],

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@ -0,0 +1,89 @@
# -*- 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.
from tests import unittest
from twisted.internet import defer
from synapse.storage._base import cached
class CacheDecoratorTestCase(unittest.TestCase):
@defer.inlineCallbacks
def test_passthrough(self):
@cached()
def func(self, key):
return key
self.assertEquals((yield func(self, "foo")), "foo")
self.assertEquals((yield func(self, "bar")), "bar")
@defer.inlineCallbacks
def test_hit(self):
callcount = [0]
@cached()
def func(self, key):
callcount[0] += 1
return key
yield func(self, "foo")
self.assertEquals(callcount[0], 1)
self.assertEquals((yield func(self, "foo")), "foo")
self.assertEquals(callcount[0], 1)
@defer.inlineCallbacks
def test_invalidate(self):
callcount = [0]
@cached()
def func(self, key):
callcount[0] += 1
return key
yield func(self, "foo")
self.assertEquals(callcount[0], 1)
func.invalidate("foo")
yield func(self, "foo")
self.assertEquals(callcount[0], 2)
@defer.inlineCallbacks
def test_max_entries(self):
callcount = [0]
@cached(max_entries=10)
def func(self, key):
callcount[0] += 1
return key
for k in range(0,12):
yield func(self, k)
self.assertEquals(callcount[0], 12)
# There must have been at least 2 evictions, meaning if we calculate
# all 12 values again, we must get called at least 2 more times
for k in range(0,12):
yield func(self, k)
self.assertTrue(callcount[0] >= 14,
msg="Expected callcount >= 14, got %d" % (callcount[0]))