问题 在Qt中使用多线程时的事件循环和信号槽处理

我在使用时遇到了一些问题 QThreads 这让我在找到合适的组合之前探索了不同的组合。但是，在事件循环和信号槽处理方面，我仍然不完全理解下面所示的四种情况。

我在OUTPUT部分添加了一些注释，但正如您所看到的，我不确定我对观察到的行为的原因是否正确。我也不确定是否 case 3 是可以在实际代码中使用的东西。这是我的测试代码（仅限于 main.cpp 每个案例都有所不同）：

worker.h：

#include <QObject>
#include <QDebug>
#include <QThread>

class Worker : public QObject
{
    Q_OBJECT
public:
    explicit Worker(QObject *parent = 0) { this->isRunning_ = false;}
    bool isRunning() const { return isRunning_; }

signals:
    void processingFinished();
    void inProgress();

public slots:
    void process()
    {
        this->isRunning_ = true;
        qDebug() << this << "processing started";
        for (int i = 0; i < 5; i++)
        {
            QThread::usleep(1000);
            emit this->inProgress();
        }
        qDebug() << this << "processing finished";
        this->isRunning_ = false;
        emit this->processingFinished();
    }

private:
    bool isRunning_;
};

workermanager.h：

#include "worker.h"

class WorkerManager : public QObject
{
    Q_OBJECT
public:
    explicit WorkerManager(QObject *parent = 0) :
        QObject(parent) {}

public slots:
    void process()
    {
        QThread *thread = new QThread();
        Worker  *worker = new Worker();

        connect(thread,SIGNAL(started()),worker,SLOT(process()));
        connect(worker,SIGNAL(processingFinished()),this,SLOT(slot1()));
        connect(worker,SIGNAL(inProgress()),this,SLOT(slot2()));
        worker->moveToThread(thread);

        qDebug() << "starting";
        thread->start();
        QThread::usleep(500);
        while(worker->isRunning()) { }
        qDebug() << "finished";
    }

    void slot1() { qDebug() << "slot1"; }
    void slot2() { qDebug() << "slot2"; }
};

main.cpp（案例1 - 没有单独的线程 workerManager）：

#include <QCoreApplication>
#include "workermanager.h"

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);

    WorkerManager* workerManager = new WorkerManager;    
    workerManager->process();
    qDebug() << "end";
    return a.exec();
}

输出 - 两者 slot1 和 slot2 叫来 a.exec() （??? - 使用主事件循环？）：

starting 
Worker(0x112db20) processing started 
Worker(0x112db20) processing finished 
finished 
end
slot2 
slot2 
slot2 
slot2 
slot2 
slot1 

main.cpp（案例2 - workerManager 移动到单独的线程，但线程未启动）：

#include <QCoreApplication>
#include "workermanager.h"

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);

    WorkerManager* workerManager = new WorkerManager;
    QThread *thread = new QThread();   
    workerManager->moveToThread(thread);       
    workerManager->process();
    qDebug() << "end";
    return a.exec();
}

输出 - 两者都没有 slot1 也不 slot2 被称为 - （???与线程相关的事件循环接收信号，但由于线程未启动，因此未调用插槽？）：

starting 
Worker(0x112db20) processing started 
Worker(0x112db20) processing finished 
finished 
end

main.cpp（案例3 - workerManager 移动到单独的线程，线程启动但是 workerManager::process() 通过呼叫 workerManager->process()）：

#include <QCoreApplication>
#include "workermanager.h"

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);

    WorkerManager* workerManager = new WorkerManager;
    QThread *thread = new QThread();   
    workerManager->moveToThread(thread); 
    thread->start();     
    workerManager->process();
    qDebug() << "end";
    return a.exec();
}

输出 - slot2 叫来 Worker 仍在执行它 process() （???）：

starting 
Worker(0x197bb20) processing started 
slot2 
slot2 
slot2 
slot2 
Worker(0x197bb20) processing finished 
finished 
end 
slot2 
slot1 

main.cpp（案例4 - workerManager 移动到单独的线程，线程启动但是 workerManager::process() 叫做使用 started() 信号来自 thread）：

#include <QCoreApplication>
#include "workermanager.h"

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);

    WorkerManager* workerManager = new WorkerManager;
    QThread *thread = new QThread();    
    workerManager->moveToThread(thread);
    QObject::connect(thread,SIGNAL(started()),workerManager,SLOT(process()));
    thread->start();
    qDebug() << "end";
    return a.exec();
}

输出 - 到达后处理的所有事件 a.exec() （???）：

end 
starting 
Worker(0x7f1d700013d0) processing started 
Worker(0x7f1d700013d0) processing finished 
finished 
slot2 
slot2 
slot2 
slot2 
slot2 
slot1 

谢谢你的任何澄清。