Handle RRs which arrive before their events

synapse/storage/receipts.py

@@ -13,7 +13,7 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
-from synapse.api.errors import NotFoundError
+
 from ._base import SQLBaseStore
 from .util.id_generators import StreamIdGenerator
 from synapse.util.caches.descriptors import cachedInlineCallbacks, cachedList, cached
@@ -340,17 +340,11 @@ class ReceiptsStore(ReceiptsWorkerStore):
             allow_none=True
         )
 
-        if not res:
-            raise NotFoundError(
-                "Cannot set read receipt on unknown event %s" % (
-                    event_id,
-                ),
-            )
-
-        stream_ordering = int(res["stream_ordering"])
+        stream_ordering = int(res["stream_ordering"]) if res else None
 
         # We don't want to clobber receipts for more recent events, so we
         # have to compare orderings of existing receipts
+        if stream_ordering is not None:
             sql = (
                 "SELECT stream_ordering, event_id FROM events"
                 " INNER JOIN receipts_linearized as r USING (event_id, room_id)"
@@ -413,7 +407,7 @@ class ReceiptsStore(ReceiptsWorkerStore):
             }
         )
 
-        if receipt_type == "m.read":
+        if receipt_type == "m.read" and stream_ordering is not None:
             self._remove_old_push_actions_before_txn(
                 txn,
                 room_id=room_id,