diff options
| -rw-r--r-- | changelog.d/11454.bugfix | 1 | ||||
| -rw-r--r-- | synapse/util/caches/lrucache.py | 5 | ||||
| -rw-r--r-- | tests/util/test_lrucache.py | 12 |
3 files changed, 17 insertions, 1 deletions
diff --git a/changelog.d/11454.bugfix b/changelog.d/11454.bugfix new file mode 100644 index 0000000000..096265cbc9 --- /dev/null +++ b/changelog.d/11454.bugfix @@ -0,0 +1 @@ +Fix an `LruCache` corruption bug, introduced in 1.38.0, that would cause certain requests to fail until the next Synapse restart. diff --git a/synapse/util/caches/lrucache.py b/synapse/util/caches/lrucache.py index 05c4dcb062..eb96f7e665 100644 --- a/synapse/util/caches/lrucache.py +++ b/synapse/util/caches/lrucache.py @@ -271,7 +271,10 @@ class _Node(Generic[KT, VT]): removed from all lists. """ cache = self._cache() - if not cache or not cache.pop(self.key, None): + if ( + cache is None + or cache.pop(self.key, _Sentinel.sentinel) is _Sentinel.sentinel + ): # `cache.pop` should call `drop_from_lists()`, unless this Node had # already been removed from the cache. self.drop_from_lists() diff --git a/tests/util/test_lrucache.py b/tests/util/test_lrucache.py index 6578f3411e..291644eb7d 100644 --- a/tests/util/test_lrucache.py +++ b/tests/util/test_lrucache.py @@ -13,6 +13,7 @@ # 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 @@ -261,6 +262,17 @@ class LruCacheSizedTestCase(unittest.HomeserverTestCase): 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.""" |