Method connectWithRetry

app/src/IO/Drivers/Modbus.cpp:462–498

* @brief Connects the Modbus client. For TCP it retries a few times with a short backoff so a * server a control-script onConnect() just launched has time to start listening; the * per-attempt errors are swallowed via m_connecting. RTU connects once (no server race). */

 *        per-attempt errors are swallowed via m_connecting. RTU connects once (no server race).
 */
bool IO::Drivers::Modbus::connectWithRetry()
{
  const int attempts = (m_protocolIndex == 1) ? kTcpConnectAttempts : 1;

  m_connecting   = true;
  bool connected = false;
  for (int attempt = 0; attempt < attempts; ++attempt) {
    if (m_device->connectDevice()) {
      QEventLoop loop;
      QTimer timeout;
      timeout.setSingleShot(true);
      connect(&timeout, &QTimer::timeout, &loop, &QEventLoop::quit);
      connect(
        m_device, &QModbusClient::stateChanged, &loop, &QEventLoop::quit, Qt::UniqueConnection);
      connect(
        m_device, &QModbusClient::errorOccurred, &loop, &QEventLoop::quit, Qt::UniqueConnection);

      timeout.start(kTcpConnectTimeoutMs);
      // code-verify off
      while (m_device->state() == QModbusDevice::ConnectingState && timeout.isActive())
        loop.exec();
      // code-verify on

      if (m_device->state() == QModbusDevice::ConnectedState) {
        connected = true;
        break;
      }
    }

    m_device->disconnectDevice();
    if (attempt + 1 < attempts)
      QThread::msleep(kTcpConnectBackoffMs);
  }

  m_connecting = false;
  return connected;
}

//--------------------------------------------------------------------------------------------------
// Property getters