SSS: implement num_live

src/api/client_server/sync/msc4186.rs

@@ -571,7 +571,9 @@ pub(crate) async fn sync_events_v5_route(
 
     let mut rooms = BTreeMap::new();
     for (room_id, todo_room) in todo_rooms {
-        if let Some(room) = process_room(&sender_user, &room_id, &todo_room)? {
+        if let Some(room) =
+            process_room(&sender_user, &room_id, &todo_room, globalsince)?
+        {
             rooms.insert(room_id.clone(), room);
         }
     }
@@ -902,6 +904,7 @@ fn process_room(
     sender_user: &UserId,
     room_id: &RoomId,
     todo_room: &TodoRoom,
+    globalsince: u64,
 ) -> Result<Option<sync_events::v5::response::Room>> {
     let roomsincecount = PduCount::Normal(todo_room.roomsince);
 
@@ -940,6 +943,25 @@ fn process_room(
         }
     };
 
+    let num_live = Some(
+        timeline_pdus
+            .iter()
+            .filter(|(pdu_count, _)| match pdu_count {
+                // TODO check logic
+                PduCount::Backfilled(_) => false,
+                PduCount::Normal(pdu_count) => {
+                    if globalsince == 0 {
+                        false
+                    } else {
+                        *pdu_count > globalsince
+                    }
+                }
+            })
+            .count()
+            .try_into()
+            .unwrap_or(UInt::MAX),
+    );
+
     let room_events: Vec<_> =
         timeline_pdus.iter().map(|(_, pdu)| pdu.to_sync_room_event()).collect();
 
@@ -1115,8 +1137,7 @@ fn process_room(
                 .map(UInt::new_saturating)
                 .unwrap_or(uint!(0)),
         ),
-        // Count events in timeline greater than global sync counter
-        num_live: None,
+        num_live,
         bump_stamp,
         heroes,
     };