Start application service stream token tracking from 1

changelog.d/12193.bugfix

@@ -0,0 +1 @@
+Fix a long-standing bug where excess presence events may be sent to an application service after it is initially configured.

synapse/handlers/presence.py

@@ -1627,7 +1627,7 @@ async def get_new_events(
             # We'll actually pull the presence updates for these users at the end.
             interested_and_updated_users: Union[Set[str], FrozenSet[str]] = set()
 
-            if from_key:
+            if from_key is not None:
                 # First get all users that have had a presence update
                 updated_users = stream_change_cache.get_all_entities_changed(from_key)
 

synapse/storage/databases/main/appservice.py

@@ -446,7 +446,8 @@ def get_type_stream_id_for_appservice_txn(txn):
             )
             last_stream_id = txn.fetchone()
             if last_stream_id is None or last_stream_id[0] is None:  # no row exists
-                return 0
+                # stream tokens always start from 1
+                return 1
             else:
                 return int(last_stream_id[0])
 

tests/storage/test_appservice.py

@@ -476,12 +476,12 @@ def test_get_type_stream_id_for_appservice_no_value(self) -> None:
         value = self.get_success(
             self.store.get_type_stream_id_for_appservice(self.service, "read_receipt")
         )
-        self.assertEqual(value, 0)
+        self.assertEqual(value, 1)
 
         value = self.get_success(
             self.store.get_type_stream_id_for_appservice(self.service, "presence")
         )
-        self.assertEqual(value, 0)
+        self.assertEqual(value, 1)
 
     def test_get_type_stream_id_for_appservice_invalid_type(self) -> None:
         self.get_failure(