State events filtering database api (#438)

This PR adds a gomatrixserverlib.Filter parameter to functions handling the syncapi_current_room_state table. It does not implement any filtering logic inside the syncapi IncrementalSync/CompleteSync functions, just the APIs for future use.

Default filters are provided as placeholders in IncrementalSync/CompleteSync, so behaviour should be unchanged (except the default 20 event limit)

SQL table will be changed. You can upgrade an existing database using:

```
ALTER TABLE syncapi_current_room_state  ADD COLUMN IF NOT EXISTS sender text;
UPDATE syncapi_current_room_state SET sender=(event_json::json->>'sender');
ALTER TABLE syncapi_current_room_state ALTER COLUMN sender SET NOT NULL;
ALTER TABLE syncapi_current_room_state  ADD COLUMN IF NOT EXISTS contains_url bool;
UPDATE syncapi_current_room_state SET contains_url=(event_json::json->>'content')::json->>'url' IS NOT NULL;
ALTER TABLE syncapi_current_room_state ALTER COLUMN contains_url SET NOT NULL;
```

Note: This depends on #436 (and includes all its commits). I'm not sure if Github will remove the duplicated commits once #436 is merged.

1 files changed, 4 insertions, 1 deletions

diff --git a/syncapi/routing/state.go b/syncapi/routing/state.go
index 5571a052..87a93d19 100644
--- a/syncapi/routing/state.go
+++ b/syncapi/routing/state.go
@@ -44,7 +44,10 @@ func OnIncomingStateRequest(req *http.Request, db *storage.SyncServerDatasource,
 	// TODO(#287): Auth request and handle the case where the user has left (where
 	// we should return the state at the poin they left)
 
-	stateEvents, err := db.GetStateEventsForRoom(req.Context(), roomID)
+	stateFilterPart := gomatrixserverlib.DefaultFilterPart()
+	// TODO: stateFilterPart should not limit the number of state events (or only limits abusive number of events)
+
+	stateEvents, err := db.GetStateEventsForRoom(req.Context(), roomID, &stateFilterPart)
 	if err != nil {
 		return httputil.LogThenError(req, err)
 	}