From 92c5817e34cb421dbe2c0df275238e84866932a8 Mon Sep 17 00:00:00 2001 From: Eric Eastwood Date: Tue, 30 Aug 2022 14:50:06 -0500 Subject: [PATCH] Give the correct next event when the message timestamps are the same - MSC3030 (#13658) Discovered while working on https://github.com/matrix-org/synapse/pull/13589 and I had all the messages at the same timestamp in the tests. Part of https://github.com/matrix-org/matrix-spec-proposals/pull/3030 Complement tests: https://github.com/matrix-org/complement/pull/457 --- changelog.d/13658.bugfix | 1 + synapse/storage/databases/main/events_worker.py | 12 ++++++++++-- 2 files changed, 11 insertions(+), 2 deletions(-) create mode 100644 changelog.d/13658.bugfix diff --git a/changelog.d/13658.bugfix b/changelog.d/13658.bugfix new file mode 100644 index 000000000..8740f066b --- /dev/null +++ b/changelog.d/13658.bugfix @@ -0,0 +1 @@ +Fix MSC3030 `/timestamp_to_event` endpoint to return the correct next event when the events have the same timestamp. diff --git a/synapse/storage/databases/main/events_worker.py b/synapse/storage/databases/main/events_worker.py index 8a7cdb024..9b997c304 100644 --- a/synapse/storage/databases/main/events_worker.py +++ b/synapse/storage/databases/main/events_worker.py @@ -2111,7 +2111,14 @@ class EventsWorkerStore(SQLBaseStore): AND room_id = ? /* Make sure event is not rejected */ AND rejections.event_id IS NULL - ORDER BY origin_server_ts %s + /** + * First sort by the message timestamp. If the message timestamps are the + * same, we want the message that logically comes "next" (before/after + * the given timestamp) based on the DAG and its topological order (`depth`). + * Finally, we can tie-break based on when it was received on the server + * (`stream_ordering`). + */ + ORDER BY origin_server_ts %s, depth %s, stream_ordering %s LIMIT 1; """ @@ -2130,7 +2137,8 @@ class EventsWorkerStore(SQLBaseStore): order = "ASC" txn.execute( - sql_template % (comparison_operator, order), (timestamp, room_id) + sql_template % (comparison_operator, order, order, order), + (timestamp, room_id), ) row = txn.fetchone() if row: