docs: protected void invokeCallbacks(ThreadLocalRandom r) {
          final Set<SelectionKey> selectedKeys = m_selector.selectedKeys();
          final int keyCount = selectedKeys.size();
          int startInx = r.nextInt(keyCount);
          int itInx = 0;
          Iterator<SelectionKey> it = selectedKeys.iterator();
          while(itInx < startInx) {
              it.next();
              itInx++;
          }
          while(itInx < keyCount) {
              final Object obj = it.next().attachment();
              if (obj == null) {
                  continue;
              }
              final VoltPort port = (VoltPort)obj;
              callPort(port);
              itInx++;
          }
          itInx = 0;
          it = selectedKeys.iterator();
          while(itInx < startInx) {
              final Object obj = it.next().attachment();
              if (obj == null) {
                  continue;
              }
              final VoltPort port = (VoltPort)obj;
              callPort(port);
              itInx++;
          }
          selectedKeys.clear();
      }