Qt Threading and Concurrency Invoking slots from other threads
Example
When a Qt event loop is used to perform operations and a non-Qt-saavy user needs to interact with that event loop, writing the slot to handle regular invocations from another thread can simplify things for other users.
main.cpp:
#include "OperationExecutioner.h"
#include <QCoreApplication>
#include <QThread>
int main(int argc, char** argv)
{
QCoreApplication app(argc, argv);
QThread thrd;
thrd.setObjectName("thrd");
thrd.start();
while(!thrd.isRunning())
QThread::msleep(10);
OperationExecutioner* oe = new OperationExecutioner;
oe->moveToThread(&thrd);
oe->doIt1(123,'A');
oe->deleteLater();
thrd.quit();
while(!thrd.isFinished())
QThread::msleep(10);
return 0;
}
OperationExecutioner.h:
#ifndef OPERATION_EXECUTIONER_H
#define OPERATION_EXECUTIONER_H
#include <QObject>
class OperationExecutioner : public QObject
{
Q_OBJECT
public slots:
void doIt1(int argi, char argc);
};
#endif // OPERATION_EXECUTIONER_H
OperationExecutioner.cpp:
#include "OperationExecutioner.h"
#include <QMetaObject>
#include <QThread>
#include <QDebug>
void OperationExecutioner::doIt1(int argi, char argc)
{
if (QThread::currentThread() != thread()) {
qInfo() << "Called from thread" << QThread::currentThread();
QMetaObject::invokeMethod(this, "doIt1", Qt::QueuedConnection,
Q_ARG(int,argi), Q_ARG(char,argc));
return;
}
qInfo() << "Called from thread" << QThread::currentThread()
<< "with args" << argi << argc;
}
OperationExecutioner.pro:
HEADERS += OperationExecutioner.h
SOURCES += main.cpp OperationExecutioner.cpp
QT -= gui
