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synapse/tests/util/test_lrucache.py
Sean Quah 7ff22d6da4
Fix LruCache corruption bug with a size_callback that can return 0 (#11454)
When all entries in an `LruCache` have a size of 0 according to the
provided `size_callback`, and `drop_from_cache` is called on a cache
node, the node would be unlinked from the LRU linked list but remain in
the cache dictionary. An assertion would be later be tripped due to the
inconsistency.

Avoid unintentionally calling `__len__` and use a strict `is None`
check instead when unwrapping the weak reference.
2021-11-30 16:28:02 +00:00

318 lines
9.4 KiB
Python

# 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.
from typing import List
from unittest.mock import Mock
from synapse.util.caches.lrucache import LruCache, setup_expire_lru_cache_entries
from synapse.util.caches.treecache import TreeCache
from tests import unittest
from tests.unittest import override_config
class LruCacheTestCase(unittest.HomeserverTestCase):
def test_get_set(self):
cache = LruCache(1)
cache["key"] = "value"
self.assertEquals(cache.get("key"), "value")
self.assertEquals(cache["key"], "value")
def test_eviction(self):
cache = LruCache(2)
cache[1] = 1
cache[2] = 2
self.assertEquals(cache.get(1), 1)
self.assertEquals(cache.get(2), 2)
cache[3] = 3
self.assertEquals(cache.get(1), None)
self.assertEquals(cache.get(2), 2)
self.assertEquals(cache.get(3), 3)
def test_setdefault(self):
cache = LruCache(1)
self.assertEquals(cache.setdefault("key", 1), 1)
self.assertEquals(cache.get("key"), 1)
self.assertEquals(cache.setdefault("key", 2), 1)
self.assertEquals(cache.get("key"), 1)
cache["key"] = 2 # Make sure overriding works.
self.assertEquals(cache.get("key"), 2)
def test_pop(self):
cache = LruCache(1)
cache["key"] = 1
self.assertEquals(cache.pop("key"), 1)
self.assertEquals(cache.pop("key"), None)
def test_del_multi(self):
cache = LruCache(4, cache_type=TreeCache)
cache[("animal", "cat")] = "mew"
cache[("animal", "dog")] = "woof"
cache[("vehicles", "car")] = "vroom"
cache[("vehicles", "train")] = "chuff"
self.assertEquals(len(cache), 4)
self.assertEquals(cache.get(("animal", "cat")), "mew")
self.assertEquals(cache.get(("vehicles", "car")), "vroom")
cache.del_multi(("animal",))
self.assertEquals(len(cache), 2)
self.assertEquals(cache.get(("animal", "cat")), None)
self.assertEquals(cache.get(("animal", "dog")), None)
self.assertEquals(cache.get(("vehicles", "car")), "vroom")
self.assertEquals(cache.get(("vehicles", "train")), "chuff")
# Man from del_multi say "Yes".
def test_clear(self):
cache = LruCache(1)
cache["key"] = 1
cache.clear()
self.assertEquals(len(cache), 0)
@override_config({"caches": {"per_cache_factors": {"mycache": 10}}})
def test_special_size(self):
cache = LruCache(10, "mycache")
self.assertEqual(cache.max_size, 100)
class LruCacheCallbacksTestCase(unittest.HomeserverTestCase):
def test_get(self):
m = Mock()
cache = LruCache(1)
cache.set("key", "value")
self.assertFalse(m.called)
cache.get("key", callbacks=[m])
self.assertFalse(m.called)
cache.get("key", "value")
self.assertFalse(m.called)
cache.set("key", "value2")
self.assertEquals(m.call_count, 1)
cache.set("key", "value")
self.assertEquals(m.call_count, 1)
def test_multi_get(self):
m = Mock()
cache = LruCache(1)
cache.set("key", "value")
self.assertFalse(m.called)
cache.get("key", callbacks=[m])
self.assertFalse(m.called)
cache.get("key", callbacks=[m])
self.assertFalse(m.called)
cache.set("key", "value2")
self.assertEquals(m.call_count, 1)
cache.set("key", "value")
self.assertEquals(m.call_count, 1)
def test_set(self):
m = Mock()
cache = LruCache(1)
cache.set("key", "value", callbacks=[m])
self.assertFalse(m.called)
cache.set("key", "value")
self.assertFalse(m.called)
cache.set("key", "value2")
self.assertEquals(m.call_count, 1)
cache.set("key", "value")
self.assertEquals(m.call_count, 1)
def test_pop(self):
m = Mock()
cache = LruCache(1)
cache.set("key", "value", callbacks=[m])
self.assertFalse(m.called)
cache.pop("key")
self.assertEquals(m.call_count, 1)
cache.set("key", "value")
self.assertEquals(m.call_count, 1)
cache.pop("key")
self.assertEquals(m.call_count, 1)
def test_del_multi(self):
m1 = Mock()
m2 = Mock()
m3 = Mock()
m4 = Mock()
cache = LruCache(4, cache_type=TreeCache)
cache.set(("a", "1"), "value", callbacks=[m1])
cache.set(("a", "2"), "value", callbacks=[m2])
cache.set(("b", "1"), "value", callbacks=[m3])
cache.set(("b", "2"), "value", callbacks=[m4])
self.assertEquals(m1.call_count, 0)
self.assertEquals(m2.call_count, 0)
self.assertEquals(m3.call_count, 0)
self.assertEquals(m4.call_count, 0)
cache.del_multi(("a",))
self.assertEquals(m1.call_count, 1)
self.assertEquals(m2.call_count, 1)
self.assertEquals(m3.call_count, 0)
self.assertEquals(m4.call_count, 0)
def test_clear(self):
m1 = Mock()
m2 = Mock()
cache = LruCache(5)
cache.set("key1", "value", callbacks=[m1])
cache.set("key2", "value", callbacks=[m2])
self.assertEquals(m1.call_count, 0)
self.assertEquals(m2.call_count, 0)
cache.clear()
self.assertEquals(m1.call_count, 1)
self.assertEquals(m2.call_count, 1)
def test_eviction(self):
m1 = Mock(name="m1")
m2 = Mock(name="m2")
m3 = Mock(name="m3")
cache = LruCache(2)
cache.set("key1", "value", callbacks=[m1])
cache.set("key2", "value", callbacks=[m2])
self.assertEquals(m1.call_count, 0)
self.assertEquals(m2.call_count, 0)
self.assertEquals(m3.call_count, 0)
cache.set("key3", "value", callbacks=[m3])
self.assertEquals(m1.call_count, 1)
self.assertEquals(m2.call_count, 0)
self.assertEquals(m3.call_count, 0)
cache.set("key3", "value")
self.assertEquals(m1.call_count, 1)
self.assertEquals(m2.call_count, 0)
self.assertEquals(m3.call_count, 0)
cache.get("key2")
self.assertEquals(m1.call_count, 1)
self.assertEquals(m2.call_count, 0)
self.assertEquals(m3.call_count, 0)
cache.set("key1", "value", callbacks=[m1])
self.assertEquals(m1.call_count, 1)
self.assertEquals(m2.call_count, 0)
self.assertEquals(m3.call_count, 1)
class LruCacheSizedTestCase(unittest.HomeserverTestCase):
def test_evict(self):
cache = LruCache(5, size_callback=len)
cache["key1"] = [0]
cache["key2"] = [1, 2]
cache["key3"] = [3]
cache["key4"] = [4]
self.assertEquals(cache["key1"], [0])
self.assertEquals(cache["key2"], [1, 2])
self.assertEquals(cache["key3"], [3])
self.assertEquals(cache["key4"], [4])
self.assertEquals(len(cache), 5)
cache["key5"] = [5, 6]
self.assertEquals(len(cache), 4)
self.assertEquals(cache.get("key1"), None)
self.assertEquals(cache.get("key2"), None)
self.assertEquals(cache["key3"], [3])
self.assertEquals(cache["key4"], [4])
self.assertEquals(cache["key5"], [5, 6])
def test_zero_size_drop_from_cache(self) -> None:
"""Test that `drop_from_cache` works correctly with 0-sized entries."""
cache: LruCache[str, List[int]] = LruCache(5, size_callback=lambda x: 0)
cache["key1"] = []
self.assertEqual(len(cache), 0)
cache.cache["key1"].drop_from_cache()
self.assertIsNone(
cache.pop("key1"), "Cache entry should have been evicted but wasn't"
)
class TimeEvictionTestCase(unittest.HomeserverTestCase):
"""Test that time based eviction works correctly."""
def default_config(self):
config = super().default_config()
config.setdefault("caches", {})["expiry_time"] = "30m"
return config
def test_evict(self):
setup_expire_lru_cache_entries(self.hs)
cache = LruCache(5, clock=self.hs.get_clock())
# Check that we evict entries we haven't accessed for 30 minutes.
cache["key1"] = 1
cache["key2"] = 2
self.reactor.advance(20 * 60)
self.assertEqual(cache.get("key1"), 1)
self.reactor.advance(20 * 60)
# We have only touched `key1` in the last 30m, so we expect that to
# still be in the cache while `key2` should have been evicted.
self.assertEqual(cache.get("key1"), 1)
self.assertEqual(cache.get("key2"), None)
# Check that re-adding an expired key works correctly.
cache["key2"] = 3
self.assertEqual(cache.get("key2"), 3)
self.reactor.advance(20 * 60)
self.assertEqual(cache.get("key2"), 3)
self.reactor.advance(20 * 60)
self.assertEqual(cache.get("key1"), None)
self.assertEqual(cache.get("key2"), 3)