public RoutingTableSnapshot getRoutingTableSnapshot(String dcName) {
      RoutingTableSnapshot result;
      if (dcName == null || isAggregatedViewHandler) {
        result = globalRoutingTableSnapshotRef.get();
      } else {
        result = dcToRoutingTableSnapshotRef.get(dcName).get();
      }
      return result;
    }
Gets the helix {@link RoutingTableSnapshot} for a given data center.
@param dcName data center name.
@return the helix {@link RoutingTableSnapshot} for a given data center.
ambry-clustermap/src/main/java/com/github/ambry/clustermap/HelixClusterManager.java