public static void loop()

in src/main/java/org/mariadb/jdbc/internal/protocol/MastersSlavesProtocol.java [88:197]
90 lines of code
35 McCabe index (conditional complexity)

  public static void loop(
      MastersSlavesListener listener,
      final GlobalStateInfo globalInfo,
      final List<HostAddress> addresses,
      SearchFilter searchFilter)
      throws SQLException {

    MastersSlavesProtocol protocol;
    ArrayDeque<HostAddress> loopAddresses = new ArrayDeque<>(addresses);
    if (loopAddresses.isEmpty()) {
      resetHostList(listener, loopAddresses);
    }

    int maxConnectionTry = listener.getRetriesAllDown();
    SQLException lastQueryException = null;
    boolean firstLoop = true;
    while (!loopAddresses.isEmpty() || (!searchFilter.isFailoverLoop() && maxConnectionTry > 0)) {
      protocol = getNewProtocol(listener.getProxy(), globalInfo, listener.getUrlParser());

      if (listener.isExplicitClosed()
          || (!listener.isSecondaryHostFailReconnect() && !listener.isMasterHostFailReconnect())) {
        return;
      }
      maxConnectionTry--;
      try {
        HostAddress host = loopAddresses.pollFirst();
        if (host == null) {
          loopAddresses.addAll(listener.getUrlParser().getHostAddresses());
          host = loopAddresses.pollFirst();
        }

        protocol.setHostAddress(host);

        protocol.connect();
        if (listener.isExplicitClosed()) {
          protocol.close();
          return;
        }

        listener.removeFromBlacklist(protocol.getHostAddress());

        if (listener.isMasterHostFailReconnect() && protocol.isMasterConnection()) {
          if (foundMaster(listener, protocol, searchFilter)) {
            return;
          }
        } else if (listener.isSecondaryHostFailReconnect() && !protocol.isMasterConnection()) {
          if (foundSecondary(listener, protocol, searchFilter)) {
            return;
          }
        } else {
          protocol.close();
        }

      } catch (SQLException e) {
        lastQueryException = e;
        listener.addToBlacklist(protocol.getHostAddress());
      }

      if (!listener.isMasterHostFailReconnect() && !listener.isSecondaryHostFailReconnect()) {
        return;
      }

      // in case master not found but slave is , and allowing master down
      if (loopAddresses.isEmpty()
          && (listener.isMasterHostFailReconnect()
              && listener.urlParser.getOptions().allowMasterDownConnection
              && !listener.isSecondaryHostFailReconnect())) {
        return;
      }

      // on connection and all slaves have been tested, use master if on
      if (loopAddresses.isEmpty()
          && searchFilter.isInitialConnection()
          && !listener.isMasterHostFailReconnect()) {
        return;
      }

      // if server has try to connect to all host, and there is remaining master or slave that fail
      // add all servers back to continue looping until maxConnectionTry is reached
      if (loopAddresses.isEmpty() && !searchFilter.isFailoverLoop() && maxConnectionTry > 0) {
        resetHostList(listener, loopAddresses);

        if (firstLoop) {
          firstLoop = false;
        } else {
          try {
            // wait 250ms before looping through all connection another time
            Thread.sleep(250);
          } catch (InterruptedException interrupted) {
            // interrupted, continue
          }
        }
      }
    }

    if (listener.isMasterHostFailReconnect() || listener.isSecondaryHostFailReconnect()) {
      String error = "No active connection found for replica";
      if (listener.isMasterHostFailReconnect()) {
        error = "No active connection found for master";
      }
      if (lastQueryException != null) {
        throw new SQLException(
            error + " : " + lastQueryException.getMessage(),
            lastQueryException.getSQLState(),
            lastQueryException.getErrorCode(),
            lastQueryException);
      }
      throw new SQLException(error);
    }
  }