From 408c13801a244a89d23f9c8e8ccce1b3d049abb6 Mon Sep 17 00:00:00 2001 From: Erik Johnston Date: Mon, 30 Oct 2023 14:47:57 +0000 Subject: [PATCH] Add fast path for replication events stream fetch (#16580) We can bail early if the from token is greater than or equal to the current token. --- changelog.d/16580.bugfix | 1 + synapse/replication/tcp/streams/events.py | 6 ++++++ 2 files changed, 7 insertions(+) create mode 100644 changelog.d/16580.bugfix diff --git a/changelog.d/16580.bugfix b/changelog.d/16580.bugfix new file mode 100644 index 000000000..4f4a0380c --- /dev/null +++ b/changelog.d/16580.bugfix @@ -0,0 +1 @@ +Fix a long-standing, exceedingly rare edge case where the first event persisted by a new event persister worker might not be sent down `/sync`. diff --git a/synapse/replication/tcp/streams/events.py b/synapse/replication/tcp/streams/events.py index 38823113d..57138fea8 100644 --- a/synapse/replication/tcp/streams/events.py +++ b/synapse/replication/tcp/streams/events.py @@ -157,6 +157,12 @@ class EventsStream(_StreamFromIdGen): current_token: Token, target_row_count: int, ) -> StreamUpdateResult: + # The events stream cannot be "reset", so its safe to return early if + # the from token is larger than the current token (the DB query will + # trivially return 0 rows anyway). + if from_token >= current_token: + return [], current_token, False + # the events stream merges together three separate sources: # * new events # * current_state changes