code: public void refreshTopologies() {
          TimeTicker ticker = new TimeTicker(TimeUnit.MILLISECONDS, true);
          try {
              doRefreshTopologies();
              LOG.debug("Refresh topologies, cost:{}", ticker.stopAndRestart());
  
              if (!context.getNimbusData().isLeader()) { // won't hit...
                  syncTopologyMetaForFollower();
                  LOG.debug("Sync topology meta, cost:{}", ticker.stop());
              }
          } catch (Exception ex) {
              LOG.error("handleRefreshEvent error:", ex);
          }
      }
docs: refresh metric settings of topologies & metric meta