feat: very simple sliding sync implementation

src/service/rooms/state_accessor/mod.rs

@@ -11,6 +11,7 @@ use ruma::{
         room::{
             history_visibility::{HistoryVisibility, RoomHistoryVisibilityEventContent},
             member::{MembershipState, RoomMemberEventContent},
+            name::RoomNameEventContent,
         },
         StateEventType,
     },
@@ -269,4 +270,16 @@ impl Service {
     ) -> Result<Option<Arc<PduEvent>>> {
         self.db.room_state_get(room_id, event_type, state_key)
     }
+
+    pub fn get_name(&self, room_id: &RoomId) -> Result<Option<String>> {
+        services()
+            .rooms
+            .state_accessor
+            .room_state_get(&room_id, &StateEventType::RoomName, "")?
+            .map_or(Ok(None), |s| {
+                serde_json::from_str(s.content.get())
+                    .map(|c: RoomNameEventContent| c.name)
+                    .map_err(|_| Error::bad_database("Invalid room name event in database."))
+            })
+    }
 }