From 7c9ac01eb5fd18e564d6650c2c0f853822aec212 Mon Sep 17 00:00:00 2001
From: Erik Johnston <erikj@element.io>
Date: Fri, 3 May 2024 18:00:08 +0100
Subject: [PATCH] Fix bug where `StreamChangeCache` would not respect cache
 factors (#17152)

Annoyingly mypy didn't pick up this typo.
---
 changelog.d/17152.bugfix                   | 1 +
 synapse/util/caches/stream_change_cache.py | 2 +-
 2 files changed, 2 insertions(+), 1 deletion(-)
 create mode 100644 changelog.d/17152.bugfix

diff --git a/changelog.d/17152.bugfix b/changelog.d/17152.bugfix
new file mode 100644
index 000000000..67aee9167
--- /dev/null
+++ b/changelog.d/17152.bugfix
@@ -0,0 +1 @@
+Fix bug where `StreamChangeCache` would not respect configured cache factors.
diff --git a/synapse/util/caches/stream_change_cache.py b/synapse/util/caches/stream_change_cache.py
index d8253bd94..2079ca789 100644
--- a/synapse/util/caches/stream_change_cache.py
+++ b/synapse/util/caches/stream_change_cache.py
@@ -115,7 +115,7 @@ class StreamChangeCache:
         """
         new_size = math.floor(self._original_max_size * factor)
         if new_size != self._max_size:
-            self.max_size = new_size
+            self._max_size = new_size
             self._evict()
             return True
         return False