From 6b61060b51970bd170fffd442df0e9f02ddcf678 Mon Sep 17 00:00:00 2001
From: Erik Johnston <erik@matrix.org>
Date: Thu, 2 Feb 2017 14:47:15 +0000
Subject: [PATCH] Comment
---
synapse/util/caches/descriptors.py | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/synapse/util/caches/descriptors.py b/synapse/util/caches/descriptors.py
index 3c6838df16..998de70d29 100644
--- a/synapse/util/caches/descriptors.py
+++ b/synapse/util/caches/descriptors.py
@@ -479,7 +479,10 @@ class CacheListDescriptor(object):
class _CacheContext(namedtuple("_CacheContext", ("cache", "key"))):
# We rely on _CacheContext implementing __eq__ and __hash__ sensibly,
- # which namedtuple does for us.
+ # 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)
--
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