@Override
  public long getRPCQueueTime() {
    if (getState() != State.RUNNING) {
      return -1;
    }
    return rpcQueueTime;
  }
Accesses the queue time for the currently running RPC on the monitored Handler.
@return the queue timestamp or -1 if there is no RPC currently running.
hbase-server/src/main/java/org/apache/hadoop/hbase/monitoring/MonitoredRPCHandlerImpl.java