diff --git a/synapse/handlers/message.py b/synapse/handlers/message.py
index 9dfeab09cd..e2a7d567fa 100644
--- a/synapse/handlers/message.py
+++ b/synapse/handlers/message.py
@@ -432,6 +432,8 @@ class EventCreationHandler:
self._ephemeral_events_enabled = hs.config.enable_ephemeral_messages
+ self._external_cache = hs.get_external_cache()
+
async def create_event(
self,
requester: Requester,
@@ -939,6 +941,8 @@ class EventCreationHandler:
await self.action_generator.handle_push_actions_for_event(event, context)
+ await self.cache_joined_hosts_for_event(event)
+
try:
# If we're a worker we need to hit out to the master.
writer_instance = self._events_shard_config.get_instance(event.room_id)
@@ -978,6 +982,44 @@ class EventCreationHandler:
await self.store.remove_push_actions_from_staging(event.event_id)
raise
+ async def cache_joined_hosts_for_event(self, event: EventBase) -> None:
+ """Precalculate the joined hosts at the event, when using Redis, so that
+ external federation senders don't have to recalculate it themselves.
+ """
+
+ if not self._external_cache.is_enabled():
+ return
+
+ # We actually store two mappings, event ID -> prev state group,
+ # state group -> joined hosts, which is much more space efficient
+ # than event ID -> joined hosts.
+ #
+ # Note: We have to cache event ID -> prev state group, as we don't
+ # store that in the DB.
+ #
+ # Note: We always set the state group -> joined hosts cache, even if
+ # we already set it, so that the expiry time is reset.
+
+ state_entry = await self.state.resolve_state_groups_for_events(
+ event.room_id, event_ids=event.prev_event_ids()
+ )
+
+ if state_entry.state_group:
+ joined_hosts = await self.store.get_joined_hosts(event.room_id, state_entry)
+
+ await self._external_cache.set(
+ "event_to_prev_state_group",
+ event.event_id,
+ state_entry.state_group,
+ expiry_ms=60 * 60 * 1000,
+ )
+ await self._external_cache.set(
+ "get_joined_hosts",
+ str(state_entry.state_group),
+ list(joined_hosts),
+ expiry_ms=60 * 60 * 1000,
+ )
+
async def _validate_canonical_alias(
self, directory_handler, room_alias_str: str, expected_room_id: str
) -> None:
|
