Qt Concurrent Example

CMakeLists.txt
main.cpp
Reference

Concurrent computing is a form of computing in which several computations are executed concurrently—during overlapping time periods—instead of sequentially—with one completing before the next starts¹. 어떠한 프로그래밍 로직이 요청한 결과를 순차적으로 처리하는 것이 아닌 여러 곳의 요청을 동시에 처리하는 것을 말한다.

Concurrency는 Parallelism의 난해함을 풀어낸 방법²인데 대표적인 것이 Coroutine(C#, Unity)이다. Rust 프로그래밍에서 Concurrency 예제³와 Go 프로그래밍에서 Concurrency 예제⁴는 과거 포스팅한 글에서 볼 수 있다. 이번 예제는 Qt(C++)에서 Concurrency를 구현하는 간단한 예제를 VoidRealms⁵강좌를 통해 소개하였다.

CMakeLists.txt

cmake_minimum_required(VERSION 3.14)
project(QtExam LANGUAGES CXX)
set(CMAKE_INCLUDE_CURRENT_DIR ON)
set(CMAKE_AUTOUIC ON)
set(CMAKE_AUTOMOC ON)
set(CMAKE_AUTORCC ON)
set(CMAKE_CXX_STANDARD 17)
set(CMAKE_CXX_STANDARD_REQUIRED ON)
find_package(QT NAMES Qt6 Qt5 COMPONENTS Core
    Concurrent REQUIRED)
find_package(Qt${QT_VERSION_MAJOR} COMPONENTS Core
    Concurrent REQUIRED)
add_executable(QtExam
  main.cpp
)
target_link_libraries(QtExam Qt${QT_VERSION_MAJOR}::Core
    Qt${QT_VERSION_MAJOR}::Concurrent)
#set_target_properties(QtExam PROPERTIES WIN32_EXECUTABLE TRUE)

main.cpp

#include <QCoreApplication>
#include <QFuture>
#include <QRandomGenerator>
#include <QThread>
#include <QtConcurrent>
#include <QtDebug>

void test()
{
    qInfo() << "Test :" << QThread::currentThread();
}

int testRandom(int min, int max)
{
    qInfo() << "Random :" << QThread::currentThread();
    QThread::currentThread()->msleep(3000);
    if (min >= max)
        min = 0;
    return QRandomGenerator::global()->bounded(min, max);
}

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);
    QThread::currentThread()->setObjectName("Main Thread");

    qInfo() << "Starting :" << QThread::currentThread();

    // Waiting
    QFuture<void> f1 = QtConcurrent::run(test);
    f1.waitForFinished();

    // Returning values
    QFuture<int> f2 = QtConcurrent::run(testRandom, 100, 200);
    qInfo() << "Random Result :" << f2.result();

    qInfo() << "Finished :" << QThread::currentThread();

    return a.exec();
}

Qt Concurrent Example

CMakeLists.txt

main.cpp

Reference