as many threads as process

Question

given a stringlist containing 4 names. I need to call qprocess for each name in loop. To avoid freezing I am using qthread as suggested in this forum.

given that (say):

QStringList queueList contains 4 elements all.q, a1.q, a2.q, a3.q

for(int z= 0; z < queueList.length(); z++) { // for each z call a thread that in turn will start a process to run an external // command (qconf -sq all.q) }

Brgds,

knish ( growing in qt )

Answer 1

Try something like this. QtConcurrent will optimize the thread count.

void executeInProcess(QString& text)
{
    QProcess::execute( "qconf", QStringList() << "-sq" <<  text);
}

void main()
{

    QApplication app;
    MainWindow mainWindow;
    //...
    QStringList queueList;
    QFutureWatcher watcher; 
    connect(&watcher, SIGNAL(finished()), &mainWindow, SLOT(whatEverYouWantToDo()));
    QFuture<void> result = QtConcurrent::map(queueList, executeInProcess);
    watcher.setFuture(result);
    //...
    app.exec();
}

Edit

If you want result from every process you need the mapped function QFuture<T> mapped ( const Sequence & sequence, MapFunction function ) and executeInProcess needs to return the result from the QProcess call.

QString executeInProcess(QString& text)
{
    QString result;
    QProcess::execute( "qconf", QStringList() << "-sq" <<  text);
    // ... 
    return 
}

in whatEverYouWantToDo() you can iterate over the results

QFuture<QString> result ;
QFutureIterator<QString> i(result);
while (i.hasNext()) {    
    qDebug() << i.next();
}