Fork-Join pattern in Qt

qt_fork_join_example.cpp

#include <QtCore>

class MyTask : public QRunnable
{
public:
    MyTask(int id, int value) : m_id(id), m_value(value) {}

    void run() override
    {
        qDebug() << "Task" << m_id << "started with value" << m_value;

        // Perform some computation
        int result = m_value * 2;

        qDebug() << "Task" << m_id << "completed with result" << result;

        // Store the result for later retrieval
        m_result = result;
    }

    int getResult() const
    {
        return m_result;
    }

private:
    int m_id;
    int m_value;
    int m_result;
};

int main()
{
    QThreadPool threadPool;
    threadPool.setMaxThreadCount(4);

    // Create tasks
    QList<MyTask*> tasks;
    for (int i = 0; i < 10; i++) {
        tasks.append(new MyTask(i, i + 1));
    }

    // Submit tasks to the thread pool
    for (MyTask* task : tasks) {
        threadPool.start(task);
    }

    // Wait for tasks to finish
    threadPool.waitForDone();

    // Collect results
    int sum = 0;
    for (MyTask* task : tasks) {
        sum += task->getResult();
    }

    qDebug() << "Sum of results:" << sum;

    // Clean up tasks
    qDeleteAll(tasks);

    return 0;
}


int main()
{
    // Create tasks
    QList<QFuture<void>> futures;
    for (int i = 0; i < 10; i++) {
        futures.append(QtConcurrent::run([i](){
            qDebug() << "Task" << i << "started";

            // Perform some computation
            QThread::msleep(1000);

            qDebug() << "Task" << i << "completed";
        }));
    }

    // Wait for a specific task to complete
    QFuture<void>& futureToWaitFor = futures[3];
    futureToWaitFor.waitForFinished();

    qDebug() << "Task" << 3 << "has completed";

    // Wait for all tasks to finish
    QFuture<void> allFutures = QtConcurrent::mapped(QList<QFuture<void>>(futures), [](const QFuture<void>& future) {
        return future;
    });
    allFutures.waitForFinished();

    return 0;
}