Reintroduce #17291. (#17338)

This is #17291 (which got reverted), with some added fixups, and change so that tests actually pick up the error. The problem was that we were not calculating any new chain IDs due to a missing `not` in a condition.
element-hq · Jun 24, 2024 · 930a64b · 930a64b
1 parent 7a11c0a
commit 930a64b
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diff --git a/changelog.d/17338.misc b/changelog.d/17338.misc
@@ -0,0 +1 @@
+Do not block event sending/receiving while calculating large event auth chains.
diff --git a/synapse/storage/controllers/persist_events.py b/synapse/storage/controllers/persist_events.py
@@ -617,13 +617,25 @@ async def _persist_event_batch(
                         room_id, chunk
                     )
 
+            with Measure(self._clock, "calculate_chain_cover_index_for_events"):
+                # We now calculate chain ID/sequence numbers for any state events we're
+                # persisting. We ignore out of band memberships as we're not in the room
+                # and won't have their auth chain (we'll fix it up later if we join the
+                # room).
+                #
+                # See: docs/auth_chain_difference_algorithm.md
+                new_event_links = await self.persist_events_store.calculate_chain_cover_index_for_events(
+                    room_id, [e for e, _ in chunk]
+                )
+
             await self.persist_events_store._persist_events_and_state_updates(
                 room_id,
                 chunk,
                 state_delta_for_room=state_delta_for_room,
                 new_forward_extremities=new_forward_extremities,
                 use_negative_stream_ordering=backfilled,
                 inhibit_local_membership_updates=backfilled,
+                new_event_links=new_event_links,
             )
 
         return replaced_events

diff --git a/synapse/storage/databases/main/event_federation.py b/synapse/storage/databases/main/event_federation.py
@@ -148,6 +148,10 @@ def __init__(
             500000, "_event_auth_cache", size_callback=len
         )
 
+        # Flag used by unit tests to disable fallback when there is no chain cover
+        # index.
+        self.tests_allow_no_chain_cover_index = True
+
         self._clock.looping_call(self._get_stats_for_federation_staging, 30 * 1000)
 
         if isinstance(self.database_engine, PostgresEngine):
@@ -220,8 +224,10 @@ async def get_auth_chain_ids(
                 )
             except _NoChainCoverIndex:
                 # For whatever reason we don't actually have a chain cover index
-                # for the events in question, so we fall back to the old method.
-                pass
+                # for the events in question, so we fall back to the old method
+                # (except in tests)
+                if not self.tests_allow_no_chain_cover_index:
+                    raise
 
         return await self.db_pool.runInteraction(
             "get_auth_chain_ids",
@@ -271,7 +277,7 @@ def _get_auth_chain_ids_using_cover_index_txn(
         if events_missing_chain_info:
             # This can happen due to e.g. downgrade/upgrade of the server. We
             # raise an exception and fall back to the previous algorithm.
-            logger.info(
+            logger.error(
                 "Unexpectedly found that events don't have chain IDs in room %s: %s",
                 room_id,
                 events_missing_chain_info,
@@ -482,8 +488,10 @@ async def get_auth_chain_difference(
                 )
             except _NoChainCoverIndex:
                 # For whatever reason we don't actually have a chain cover index
-                # for the events in question, so we fall back to the old method.
-                pass
+                # for the events in question, so we fall back to the old method
+                # (except in tests)
+                if not self.tests_allow_no_chain_cover_index:
+                    raise
 
         return await self.db_pool.runInteraction(
             "get_auth_chain_difference",
@@ -710,7 +718,7 @@ def _fixup_auth_chain_difference_sets(
         if events_missing_chain_info - event_to_auth_ids.keys():
             # Uh oh, we somehow haven't correctly done the chain cover index,
             # bail and fall back to the old method.
-            logger.info(
+            logger.error(
                 "Unexpectedly found that events don't have chain IDs in room %s: %s",
                 room_id,
                 events_missing_chain_info - event_to_auth_ids.keys(),
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1 @@
		Do not block event sending/receiving while calculating large event auth chains.