From a4f062eb79490f70cf0b598719ba86157c85fdd9 Mon Sep 17 00:00:00 2001 From: "Kai A. Hiller" Date: Thu, 17 Oct 2019 19:34:07 +0200 Subject: [PATCH] Fix LruCache callback deduplication Signed-off-by: Kai A. Hiller --- changelog.d/6213.bugfix | 1 + synapse/util/caches/descriptors.py | 25 ++++++++++++++++--------- 2 files changed, 17 insertions(+), 9 deletions(-) create mode 100644 changelog.d/6213.bugfix diff --git a/changelog.d/6213.bugfix b/changelog.d/6213.bugfix new file mode 100644 index 000000000000..072264fba395 --- /dev/null +++ b/changelog.d/6213.bugfix @@ -0,0 +1 @@ +Fix LruCache callback deduplication. diff --git a/synapse/util/caches/descriptors.py b/synapse/util/caches/descriptors.py index 5ac2530a6a72..fcea2f68df93 100644 --- a/synapse/util/caches/descriptors.py +++ b/synapse/util/caches/descriptors.py @@ -17,7 +17,6 @@ import inspect import logging import threading -from collections import namedtuple from typing import Any, cast from six import itervalues @@ -625,14 +624,22 @@ def errback(f): return wrapped -class _CacheContext(namedtuple("_CacheContext", ("cache", "key"))): - # We rely on _CacheContext implementing __eq__ and __hash__ sensibly, - # which namedtuple does for us (i.e. two _CacheContext are the same if - # their caches and keys match). This is important in particular to - # dedupe when we add callbacks to lru cache nodes, otherwise the number - # of callbacks would grow. - def invalidate(self): - self.cache.invalidate(self.key) +class _CacheContext: + # We make sure identical _CacheContext objects share the same invalidate + # function. This is important in particular to dedupe when we add callbacks + # to lru cache nodes, otherwise the number of callbacks would grow. + _invalidate_funcs = {} + + def __init__(self, cache, cache_key): + key = (cache, cache_key) + + def invalidate(): + cache.invalidate(cache_key) + + if key not in self._invalidate_funcs: + self._invalidate_funcs[key] = invalidate + + self.invalidate = self._invalidate_funcs[key] def cached(