void XBridgeTransactionsModel::onTimer()
{
    // check pending transactions
    for (unsigned int i = 0; i < m_transactions.size(); ++i)
    {
        boost::posix_time::time_duration td =
                boost::posix_time::second_clock::universal_time() -
                m_transactions[i].txtime;

        auto id = m_transactions[i].id;
        if (m_transactions[i].state == XBridgeTransactionDescr::trNew &&
                td.total_seconds() > XBridgeTransaction::TTL/60)
        {
            m_transactions[i].state = XBridgeTransactionDescr::trOffline;
            emit dataChanged(index(i, FirstColumn), index(i, LastColumn));
        }
        else if (m_transactions[i].state == XBridgeTransactionDescr::trPending &&
                td.total_seconds() > XBridgeTransaction::TTL/6)
        {
            m_transactions[i].state = XBridgeTransactionDescr::trExpired;
            emit dataChanged(index(i, FirstColumn), index(i, LastColumn));
        }
        else if ((m_transactions[i].state == XBridgeTransactionDescr::trExpired ||
                  m_transactions[i].state == XBridgeTransactionDescr::trOffline) &&
                         td.total_seconds() < XBridgeTransaction::TTL/6)
        {
            m_transactions[i].state = XBridgeTransactionDescr::trPending;
            emit dataChanged(index(i, FirstColumn), index(i, LastColumn));
        }
        else if (m_transactions[i].state == XBridgeTransactionDescr::trExpired &&
                td.total_seconds() > XBridgeTransaction::TTL)
        {
            emit beginRemoveRows(QModelIndex(), i, i);
            m_transactions.erase(m_transactions.begin()+i);
            emit endRemoveRows();
            --i;
            }
        }
        }

    }
}