it troubles me !!!! QserialPort

quelle.shen

a thread problme appear in my code
STATUS/1 @ init, L120: BaudRate: 230400QObject: Cannot create children for a parent that is in a different thread.
(Parent is QSerialPort(0x2952c7b8), parent's thread is QThread(0x259e38f0), current thread is QThread(0x14cc2e0)

my code :
HardDriver*
PlatformManager::addHardDriver(uint8_t driver_type, const char* device_port,
uint32_t baudrate)
{
#ifdef QT
if (driver_type == PlatformManager::SERIAL_DEVICE)
{

QThread*     serialEventThread = new QThread;
QHardDriver* driver            = new QHardDriver(0, device_port, baudrate);
driver->moveToThread(serialEventThread);
QObject::connect(serialEventThread, SIGNAL(started()), driver,
                 SLOT(init()));
QObject::connect(serialEventThread, SIGNAL(finished()), serialEventThread,
                 SLOT(deleteLater()));
serialEventThread->start();
QThread::msleep(100);
return driver;

}

void
QHardDriver::init()
{
initLock.lock();
if (this->getDeviceStatus())
{
initLock.unlock();
return;
}

port = new QSerialPort(QString(portName));
if (port != 0)
{
if (port->isOpen())
port->close();
port->setBaudRate(baudrate);
port->setParity(QSerialPort::NoParity);
port->setDataBits(QSerialPort::Data8);
port->setStopBits(QSerialPort::OneStop);
port->setFlowControl(QSerialPort::NoFlowControl);
if (port->open(QIODevice::ReadWrite))
{
DSTATUS("port %s open success", port->portName().toLocal8Bit().data());
setDeviceStatus(true);
DSTATUS("Read buf size: %d", port->readBufferSize());
}
else
{
DERROR("fail to open port %s", port->portName().toLocal8Bit().data());
setDeviceStatus(false);
}
DSTATUS("BaudRate: %d", port->baudRate());
}
initLock.unlock();
}

but run there it throws a problem
//! Serial Device call: last link in the send pipeline
DERROR("*****1");
ans = deviceDriver->send(buf, pHeader->length); // throws Cannot create children for a parent that is in a different thread.
//(Parent is QSerialPort(0x2952c7b8), parent's thread is
//QThread(0x259e38f0), current thread is QThread(0x14cc2e0)

quelle.shen

This post is deleted!

SGaist

Hi and welcome to devnet,

What does happen in deviceDriver->send ?
Where are you calling if from ?

What version of Qt are you using ?
What OS are you running ?

quelle.shen

hi ~ thank you first
it works on windows QT5.1

HardDriver* deviceDriver;
QHardDriver::send(const uint8_t* buf, size_t len)
{
sendLock.lock();
size_t sent = 0;
if (port != 0)
{
// if (port->isOpen())
while (sent != len)
{
sent += port->write(reinterpret_cast<const char*>(buf + sent), len);
port->waitForBytesWritten(2);
}
sendLock.unlock();
return sent;
}
else
{
sendLock.unlock();
return 0;
}
sendLock.unlock();
return sent;
}

aha_1980

@quelle.shen said in it troubles me !!!! QserialPort:

it works on windows QT5.1

QSerialPort was very new in Qt 5.1. I strongly recommend updating to a newer version.

That may not solve your problem, but avoid others.

quelle.shen

@aha_1980
maybe you are right ,but i have to run it on Qt5.1
the problem still troubles me !!

SGaist

You seem to move your serial port stuff in another thread and then calling its methods directly, is that the case ?

quelle.shen

@SGaist
yes ,but i dont know how to revision my code.

quelle.shen

@SGaist
why just call port->write() will trows the problem ?
i add some code but it doesnt work .
i add code :

QThread* serialEventThread = new QThread;
QHardDriver* driver = new QHardDriver(0, device_port, baudrate);
//driver->init();
driver->moveToThread(serialEventThread);
driver->port->moveToThread(serialEventThread);
//Qt:: DirectConnection
QObject::connect(serialEventThread, SIGNAL(started()), driver,
SLOT(init()));
QObject::connect(serialEventThread, SIGNAL(finished()), driver, SLOT(deleteLater()));
QObject::connect(serialEventThread, SIGNAL(finished()), serialEventThread,
SLOT(deleteLater()));
serialEventThread->start();
QThread::msleep(100);
return driver;

code_fodder

@quelle.shen said in it troubles me !!!! QserialPort:

QObject::connect(serialEventThread, SIGNAL(started()), driver,
SLOT(init()));

From our direct messages...

hmm.... When you call deviceDriver->send(), I assume that send() is a member of deviceDriver?. But deviceDriver is in a different thread! in addHardDriver() you return a device driver that was moved to a different thread. What you need to do now is create another slot/signal connection to send your write-data to your device driver via a call to a signal. Somthing like: QObject::connect(this, SIGNAL(send_to_driver(QVector data)), driver,SLOT(data_to_send(QVector data))); Then instead of doing driver->write() you do send_to_driver(data). I used QVector in my example - not but you can put what ever Q<data type> you want...

Note: You cannot ever safely call members directly in the device driver ever again once you have moved it into another thread :p ... this is exactly what slot/signals are for. Doing so breaks the thread boundaries and Qt rightfully complains. If you call a member function directly then everything that occurs in that function call occurs in the calling thread and not the thread that you moved that class into. Does that make sense?

quelle.shen

@code_fodder
thanks reply for my question ,you are right .
i think your advice is good way to solve my problem .