private void sendPendingHaves() {
    if (destroyed) {

      return;
    }

    try {
      pending_haves_mon.enter();

      int num_haves = pending_haves.size();

      if (num_haves == 0) {

        return;
      }

      // single have -> use BT

      if (num_haves == 1 || az_have_version < BTMessageFactory.MESSAGE_VERSION_SUPPORTS_PADDING) {

        for (int i = 0; i < num_haves; i++) {

          Integer piece_num = (Integer) pending_haves.get(i);

          outgoing_message_q.addMessage(new BTHave(piece_num.intValue(), bt_have_version), true);
        }
      } else {

        int[] piece_numbers = new int[num_haves];

        for (int i = 0; i < num_haves; i++) {

          piece_numbers[i] = ((Integer) pending_haves.get(i)).intValue();
        }

        outgoing_message_q.addMessage(new AZHave(piece_numbers, az_have_version), true);
      }

      outgoing_message_q.doListenerNotifications();

      pending_haves.clear();

    } finally {

      pending_haves_mon.exit();
    }
  }