I am creating a Qt-based application for monitoring and collecting data streams from a serial port. Data is displayed in real time, sent via TCP and stored in the SQLite database. Unfortunately, I found that SQLite inserts cause the GUI to stop responding because I am processing serial data, plotting, transmitting TCP and inserting the database in the context of the main loop. I explored splitting the database insert into another thread and came up with the following code.
#include <QObject>
#include <QDebug>
#include <QStringList>
#include <QSqlDatabase>
#include <QSqlQuery>
#include <QSqlError>
#include <QVariant>
#include <QObject>
#include <QList>
#include <QThread>
#include <QMutex>
#include <QWaitCondition>
#include <QSqlDatabase>
#include <QSqlRecord>
#include <QString>
#include "mMessage.h"
class Worker : public QObject
{
Q_OBJECT
public:
Worker( QObject* parent = 0);
~Worker();
bool insertADC(mMessage* insertMessage);
public slots:
void slotExecute( mMessage* insertMessage );
signals:
void queryResult(bool);
private:
QSqlDatabase m_database;
bool m_databaseOpen;
void prepareQueries();
QSqlQuery *m_accelerometerQuery;
QSqlQuery *m_adcQuery;
QSqlQuery *m_metricsQuery;
QSqlQuery *m_rssiQuery;
};
class mDatabaseThread : public QThread
{
Q_OBJECT
public:
mDatabaseThread(QObject *parent = 0);
~mDatabaseThread();
void executeInsertion( mMessage* insertMessage );
signals:
void progress( const QString& msg );
void ready(bool);
protected:
void run();
signals:
void executefwd( mMessage* insertMessage );
private:
Worker* m_worker;
};
CPP FILE
Worker::Worker( QObject* parent )
: QObject( parent )
{
m_database = QSqlDatabase::addDatabase( "QSQLITE",
"WorkerDatabase" );
m_database.setDatabaseName("trainingX.db3");
if ( !m_database.open() )
{
qWarning() << "Unable to connect to database, giving up:" << m_database.lastError().text();
m_databaseOpen = false;
return;
}
m_databaseOpen = true;
}
Worker::~Worker()
{
}
void Worker::prepareQueries()
{
if (m_databaseOpen)
{
m_accelerometerQuery->prepare("INSERT INTO accelerometer (key, timestamp, nickname, unitid,"
"sectorid, acc_x, acc_y, acc_z) "
"VALUES (NULL, :timestamp, :nickname, :unitid, :sectorid,"
":acc_x, :acc_y, :acc_z)");
m_adcQuery->prepare("INSERT INTO adc (key, timestamp, nickname, unitid, sectorid,"
"adc0, adc1, adc2, adc3, adc4, adc5, adc6, adc7) "
"VALUES (NULL, :timestamp, :nickname, :unitid, :sectorid,"
":adc0, :adc1, :adc2, :adc3, :adc4, :adc5, :adc6, :adc7)");
m_metricsQuery->prepare("INSERT INTO metrics (key, timestamp, nickname, unitid, sectorid, "
"acc_temp, unit_temp, unit_pressure, bpm_instant, bpm_average, base_pressure, base_temp) "
"VALUES (NULL, :timestamp, :nickname, :unitid, :sectorid,"
":acc_temp, :unit_temp, :unit_pressure, :bpm_instant, :bpm_average, :base_pressure, :base_temp)");
m_rssiQuery->prepare("INSERT INTO rssi (key, timestamp, nickname, unitid, sectorid, "
"rssi_1, rssi_2, rssi_3, rssi_4, rssi_avg) "
"VALUES (NULL, :timestamp, :nickname, :unitid, :sectorid,"
":rssi_1, :rssi_2, :rssi_3, :rssi_4, :rssi_avg)");
}
}
void Worker::slotExecute( mMessage* insertMessage )
{
m_accelerometerQuery = new QSqlQuery("WorkerDatabase");
m_adcQuery = new QSqlQuery("WorkerDatabase");
m_metricsQuery = new QSqlQuery("WorkerDatabase");
m_rssiQuery = new QSqlQuery("WorkerDatabase");
prepareQueries();
insertADC(insertMessage);
emit queryResult( true );
}
bool Worker::insertADC(mMessage *insertMessage)
{
if (m_databaseOpen)
{
m_adcQuery->bindValue(":timestamp",insertMessage->m_timestamp);
m_adcQuery->bindValue(":nickname",insertMessage->m_nickname);
m_adcQuery->bindValue(":unitid",insertMessage->m_unitId.toInt());
m_adcQuery->bindValue(":sectorid",insertMessage->m_sectorId.toInt());
m_adcQuery->bindValue(":adc0",insertMessage->m_adc0.toInt());
m_adcQuery->bindValue(":adc1",insertMessage->m_adc1.toInt());
m_adcQuery->bindValue(":adc2",insertMessage->m_adc2.toInt());
m_adcQuery->bindValue(":adc3",insertMessage->m_adc3.toInt());
m_adcQuery->bindValue(":adc4",insertMessage->m_adc4.toInt());
m_adcQuery->bindValue(":adc5",insertMessage->m_adc5.toInt());
m_adcQuery->bindValue(":adc6",insertMessage->m_adc6.toInt());
m_adcQuery->bindValue(":adc7",insertMessage->m_adc7.toInt());
if (m_adcQuery->exec())
{
return true;
}
else
{
qDebug() << "SQL ADC failed.";
qDebug() << m_adcQuery->lastError();
return false;
}
}
else
{
return false;
}
}
mDatabaseThread::mDatabaseThread(QObject *parent)
: QThread(parent)
{
}
mDatabaseThread::~mDatabaseThread()
{
delete m_worker;
}
void mDatabaseThread::executeInsertion( mMessage* insertMessage )
{
emit executefwd( insertMessage );
}
void mDatabaseThread::run()
{
emit ready(false);
m_worker = new Worker();
connect( this, SIGNAL( executefwd( mMessage* ) ),
m_worker, SLOT( slotExecute( mMessage* ) ) );
connect( m_worker, SIGNAL(queryResult(bool)), this, SIGNAL(ready(bool)));
emit ready(true);
exec();
}
mDatabaseThread , . . , QSqlQuery , , , , m_database /. http://www.linuxjournal.com/article/9602. mMessage - qObject, m_worker.
m_databaseThread- > start() , executeInsertion (mMessage *). m_database, QSqlQueries, , , , , , QSqlQuery .