Remove stream ordering from Metadata dict (#8452)

There's no need for it to be in the dict as well as the events table. Instead,
we store it in a separate attribute in the EventInternalMetadata object, and
populate that on load.

This means that we can rely on it being correctly populated for any event which
has been persited to the database.

changelog.d/8452.misc

@@ -0,0 +1 @@
+Remove redundant databae loads of stream_ordering for events we already have.

synapse/events/__init__.py

@@ -97,13 +97,16 @@ def __get__(self, instance, owner=None):
 
 
 class _EventInternalMetadata:
-    __slots__ = ["_dict"]
+    __slots__ = ["_dict", "stream_ordering"]
 
     def __init__(self, internal_metadata_dict: JsonDict):
         # we have to copy the dict, because it turns out that the same dict is
         # reused. TODO: fix that
         self._dict = dict(internal_metadata_dict)
 
+        # the stream ordering of this event. None, until it has been persisted.
+        self.stream_ordering = None  # type: Optional[int]
+
     outlier = DictProperty("outlier")  # type: bool
     out_of_band_membership = DictProperty("out_of_band_membership")  # type: bool
     send_on_behalf_of = DictProperty("send_on_behalf_of")  # type: str
@@ -113,7 +116,6 @@ def __init__(self, internal_metadata_dict: JsonDict):
     redacted = DictProperty("redacted")  # type: bool
     txn_id = DictProperty("txn_id")  # type: str
     token_id = DictProperty("token_id")  # type: str
-    stream_ordering = DictProperty("stream_ordering")  # type: int
 
     # XXX: These are set by StreamWorkerStore._set_before_and_after.
     # I'm pretty sure that these are never persisted to the database, so shouldn't

synapse/events/utils.py

@@ -49,6 +49,11 @@ def prune_event(event: EventBase) -> EventBase:
         pruned_event_dict, event.room_version, event.internal_metadata.get_dict()
     )
 
+    # copy the internal fields
+    pruned_event.internal_metadata.stream_ordering = (
+        event.internal_metadata.stream_ordering
+    )
+
     # Mark the event as redacted
     pruned_event.internal_metadata.redacted = True
 

synapse/federation/sender/__init__.py

@@ -297,6 +297,8 @@ async def _send_pdu(self, pdu: EventBase, destinations: Iterable[str]) -> None:
         sent_pdus_destination_dist_total.inc(len(destinations))
         sent_pdus_destination_dist_count.inc()
 
+        assert pdu.internal_metadata.stream_ordering
+
         # track the fact that we have a PDU for these destinations,
         # to allow us to perform catch-up later on if the remote is unreachable
         # for a while.

synapse/federation/sender/per_destination_queue.py

@@ -158,6 +158,7 @@ def send_pdu(self, pdu: EventBase) -> None:
             # yet know if we have anything to catch up (None)
             self._pending_pdus.append(pdu)
         else:
+            assert pdu.internal_metadata.stream_ordering
             self._catchup_last_skipped = pdu.internal_metadata.stream_ordering
 
         self.attempt_new_transaction()
@@ -361,6 +362,7 @@ async def _transaction_transmission_loop(self) -> None:
                         last_successful_stream_ordering = (
                             final_pdu.internal_metadata.stream_ordering
                         )
+                        assert last_successful_stream_ordering
                         await self._store.set_destination_last_successful_stream_ordering(
                             self._destination, last_successful_stream_ordering
                         )

synapse/handlers/federation.py

@@ -3008,6 +3008,9 @@ async def _notify_persisted_event(
         elif event.internal_metadata.is_outlier():
             return
 
+        # the event has been persisted so it should have a stream ordering.
+        assert event.internal_metadata.stream_ordering
+
         event_pos = PersistedEventPosition(
             self._instance_name, event.internal_metadata.stream_ordering
         )

synapse/handlers/message.py

@@ -682,7 +682,9 @@ async def send_nonmember_event(
                     event.event_id,
                     prev_event.event_id,
                 )
-                return await self.store.get_stream_id_for_event(prev_event.event_id)
+                # we know it was persisted, so must have a stream ordering
+                assert prev_event.internal_metadata.stream_ordering
+                return prev_event.internal_metadata.stream_ordering
 
         return await self.handle_new_client_event(
             requester=requester, event=event, context=context, ratelimit=ratelimit

synapse/handlers/room_member.py

@@ -194,8 +194,9 @@ async def _local_membership_update(
         )
         if duplicate is not None:
             # Discard the new event since this membership change is a no-op.
-            _, stream_id = await self.store.get_event_ordering(duplicate.event_id)
-            return duplicate.event_id, stream_id
+            # we know it was persisted, so must have a stream ordering.
+            assert duplicate.internal_metadata.stream_ordering
+            return duplicate.event_id, duplicate.internal_metadata.stream_ordering
 
         prev_state_ids = await context.get_prev_state_ids()
 
@@ -441,12 +442,12 @@ async def _update_membership(
                 same_membership = old_membership == effective_membership_state
                 same_sender = requester.user.to_string() == old_state.sender
                 if same_sender and same_membership and same_content:
-                    _, stream_id = await self.store.get_event_ordering(
-                        old_state.event_id
-                    )
+                    # duplicate event.
+                    # we know it was persisted, so must have a stream ordering.
+                    assert old_state.internal_metadata.stream_ordering
                     return (
                         old_state.event_id,
-                        stream_id,
+                        old_state.internal_metadata.stream_ordering,
                     )
 
             if old_membership in ["ban", "leave"] and action == "kick":

synapse/rest/admin/__init__.py

@@ -57,6 +57,7 @@
     UsersRestServletV2,
     WhoisRestServlet,
 )
+from synapse.types import RoomStreamToken
 from synapse.util.versionstring import get_version_string
 
 logger = logging.getLogger(__name__)
@@ -109,7 +110,9 @@ async def on_POST(self, request, room_id, event_id):
             if event.room_id != room_id:
                 raise SynapseError(400, "Event is for wrong room.")
 
-            room_token = await self.store.get_topological_token_for_event(event_id)
+            room_token = RoomStreamToken(
+                event.depth, event.internal_metadata.stream_ordering
+            )
             token = await room_token.to_string(self.store)
 
             logger.info("[purge] purging up to token %s (event_id %s)", token, event_id)

synapse/storage/databases/main/events.py

@@ -331,6 +331,10 @@ def _persist_events_txn(
         min_stream_order = events_and_contexts[0][0].internal_metadata.stream_ordering
         max_stream_order = events_and_contexts[-1][0].internal_metadata.stream_ordering
 
+        # stream orderings should have been assigned by now
+        assert min_stream_order
+        assert max_stream_order
+
         self._update_forward_extremities_txn(
             txn,
             new_forward_extremities=new_forward_extremeties,

synapse/storage/databases/main/events_worker.py

@@ -723,6 +723,7 @@ async def _get_events_from_db(self, event_ids, allow_rejected=False):
                 internal_metadata_dict=internal_metadata,
                 rejected_reason=rejected_reason,
             )
+            original_ev.internal_metadata.stream_ordering = row["stream_ordering"]
 
             event_map[event_id] = original_ev
 
@@ -790,6 +791,8 @@ def _fetch_event_rows(self, txn, event_ids):
 
          * event_id (str)
 
+         * stream_ordering (int): stream ordering for this event
+
          * json (str): json-encoded event structure
 
          * internal_metadata (str): json-encoded internal metadata dict
@@ -822,13 +825,15 @@ def _fetch_event_rows(self, txn, event_ids):
             sql = """\
                 SELECT
                   e.event_id,
-                  e.internal_metadata,
-                  e.json,
-                  e.format_version,
+                  e.stream_ordering,
+                  ej.internal_metadata,
+                  ej.json,
+                  ej.format_version,
                   r.room_version,
                   rej.reason
-                FROM event_json as e
-                  LEFT JOIN rooms r USING (room_id)
+                FROM events AS e
+                  JOIN event_json AS ej USING (event_id)
+                  LEFT JOIN rooms r ON r.room_id = e.room_id
                   LEFT JOIN rejections as rej USING (event_id)
                 WHERE """
 
@@ -842,11 +847,12 @@ def _fetch_event_rows(self, txn, event_ids):
                 event_id = row[0]
                 event_dict[event_id] = {
                     "event_id": event_id,
-                    "internal_metadata": row[1],
-                    "json": row[2],
-                    "format_version": row[3],
-                    "room_version_id": row[4],
-                    "rejected_reason": row[5],
+                    "stream_ordering": row[1],
+                    "internal_metadata": row[2],
+                    "json": row[3],
+                    "format_version": row[4],
+                    "room_version_id": row[5],
+                    "rejected_reason": row[6],
                     "redactions": [],
                 }
 

synapse/storage/databases/main/stream.py

@@ -589,19 +589,6 @@ async def get_room_events_max_id(self, room_id: Optional[str] = None) -> str:
             )
             return "t%d-%d" % (topo, token)
 
-    async def get_stream_id_for_event(self, event_id: str) -> int:
-        """The stream ID for an event
-        Args:
-            event_id: The id of the event to look up a stream token for.
-        Raises:
-            StoreError if the event wasn't in the database.
-        Returns:
-            A stream ID.
-        """
-        return await self.db_pool.runInteraction(
-            "get_stream_id_for_event", self.get_stream_id_for_event_txn, event_id,
-        )
-
     def get_stream_id_for_event_txn(
         self, txn: LoggingTransaction, event_id: str, allow_none=False,
     ) -> int:

synapse/storage/persist_events.py

@@ -248,6 +248,8 @@ async def persist_event(
         await make_deferred_yieldable(deferred)
 
         event_stream_id = event.internal_metadata.stream_ordering
+        # stream ordering should have been assigned by now
+        assert event_stream_id
 
         pos = PersistedEventPosition(self._instance_name, event_stream_id)
         return pos, self.main_store.get_room_max_token()