From da777207528513c858395758bf4c023da2c2c1a3 Mon Sep 17 00:00:00 2001 From: Patrick Cloke Date: Thu, 8 Dec 2022 11:35:49 -0500 Subject: Check the stream position before checking if the cache is empty. (#14639) An empty cache does not mean the entity has no changed, if it is earlier than the earliest known stream position return that the entity *has* changed since the cache cannot accurately answer that query. --- synapse/util/caches/stream_change_cache.py | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) (limited to 'synapse') diff --git a/synapse/util/caches/stream_change_cache.py b/synapse/util/caches/stream_change_cache.py index c8b17acb59..1657459549 100644 --- a/synapse/util/caches/stream_change_cache.py +++ b/synapse/util/caches/stream_change_cache.py @@ -213,16 +213,17 @@ class StreamChangeCache: """ assert isinstance(stream_pos, int) - if not self._cache: - # If the cache is empty, nothing can have changed. - return False - # _cache is not valid at or before the earliest known stream position, so # return that an entity has changed. if stream_pos <= self._earliest_known_stream_pos: self.metrics.inc_misses() return True + # If the cache is empty, nothing can have changed. + if not self._cache: + self.metrics.inc_misses() + return False + self.metrics.inc_hits() return stream_pos < self._cache.peekitem()[0] -- cgit 1.4.1