add a cache to have_seen_event (#9953)

Empirically, this helped my server considerably when handling gaps in Matrix HQ. The problem was that we would repeatedly call have_seen_events for the same set of (50K or so) auth_events, each of which would take many minutes to complete, even though it's only an index scan.

1 files changed, 7 insertions, 5 deletions

diff --git a/synapse/handlers/federation.py b/synapse/handlers/federation.py

index bf11315251..49ed7cabcc 100644
--- a/synapse/handlers/federation.py
+++ b/synapse/handlers/federation.py
@@ -577,7 +577,9 @@ class FederationHandler(BaseHandler):
 
         # Fetch the state events from the DB, and check we have the auth events.
         event_map = await self.store.get_events(state_event_ids, allow_rejected=True)
-        auth_events_in_store = await self.store.have_seen_events(auth_event_ids)
+        auth_events_in_store = await self.store.have_seen_events(
+            room_id, auth_event_ids
+        )
 
         # Check for missing events. We handle state and auth event seperately,
         # as we want to pull the state from the DB, but we don't for the auth
@@ -610,7 +612,7 @@ class FederationHandler(BaseHandler):
 
             if missing_auth_events:
                 auth_events_in_store = await self.store.have_seen_events(
-                    missing_auth_events
+                    room_id, missing_auth_events
                 )
                 missing_auth_events.difference_update(auth_events_in_store)
 
@@ -710,7 +712,7 @@ class FederationHandler(BaseHandler):
 
         missing_auth_events = set(auth_event_ids) - fetched_events.keys()
         missing_auth_events.difference_update(
-            await self.store.have_seen_events(missing_auth_events)
+            await self.store.have_seen_events(room_id, missing_auth_events)
         )
         logger.debug("We are also missing %i auth events", len(missing_auth_events))
 
@@ -2475,7 +2477,7 @@ class FederationHandler(BaseHandler):
         #
         # we start by checking if they are in the store, and then try calling /event_auth/.
         if missing_auth:
-            have_events = await self.store.have_seen_events(missing_auth)
+            have_events = await self.store.have_seen_events(event.room_id, missing_auth)
             logger.debug("Events %s are in the store", have_events)
             missing_auth.difference_update(have_events)
 
@@ -2494,7 +2496,7 @@ class FederationHandler(BaseHandler):
                     return context
 
                 seen_remotes = await self.store.have_seen_events(
-                    [e.event_id for e in remote_auth_chain]
+                    event.room_id, [e.event_id for e in remote_auth_chain]
                 )
 
                 for e in remote_auth_chain: