public void waitForInitNotification() throws InterruptedException {
      // wait slightly more than 5 mins to ensure routerUpdater refreshes the snapshot.
      if (!routingTableInitLatch.await(320, TimeUnit.SECONDS)) {
        throw new IllegalStateException(
            "Initial routing table change from helix cluster " + helixClusterName + "in dc " + dcName
                + " didn't come within 5 mins");
      }
    }
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