自由意志

黑人夏川

优雅的退出一个正在sleep的线程

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主要是依靠条件变量的直接唤醒和时间到期唤醒

QT代码如下

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class Thread : public QThread
{
public:
    Thread(QObject *parent = nullptr)
        : QThread(parent)
    {}

    ~Thread() { stopThread(); }

    void startThread()
    {
        m_runing = true;
        if (isRunning()) {
            return;
        }
        start();
    }

    void stopThread()
    {
        m_runing = false;
        if (isRunning()) {
            m_waitCondition.wakeOne();
            quit();
            wait();
        }
    }

protected:
    void run()
    {
        while (m_runing) {
            qDebug() << QDateTime::currentDateTime().toString("yyyy-MM-dd hh:mm:ss") << "start";
            //QThread::sleep(30); 弃用
            QMutexLocker locker(&m_mutex);
            m_waitCondition.wait(&m_mutex, QDeadlineTimer(30 * 1000)); // 30s
            qDebug() << QDateTime::currentDateTime().toString("yyyy-MM-dd hh:mm:ss") << "stop";
        }
    }

private:
    volatile bool m_runing = false;
    QMutex m_mutex;
    QWaitCondition m_waitCondition;
};

标准库代码如下

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class Thread : public QThread
{
public:
    Thread(QObject *parent = nullptr)
        : QThread(parent)
    {}

    ~Thread() { stopThread(); }

    void startThread()
    {
        m_runing = true;
        if (isRunning()) {
            return;
        }
        start();
    }

    void stopThread()
    {
        m_runing = false;
        if (isRunning()) {
            m_cv.notify_one();
            quit();
            wait();
        }
    }

protected:
    void run()
    {
        while (m_runing) {
            qDebug() << QDateTime::currentDateTime().toString("yyyy-MM-dd hh:mm:ss") << "start";
            // std::this_thread::sleep_for(std::chrono::seconds(30)); 弃用
            std::unique_lock locker(m_mutex);
            m_cv.wait_for(locker, std::chrono::seconds(30)); // 30s
            qDebug() << QDateTime::currentDateTime().toString("yyyy-MM-dd hh:mm:ss") << "stop";
        }
    }

private:
    volatile bool m_runing = false;
    std::condition_variable m_cv;
    std::mutex m_mutex;
};

可以在任意时间点调用 stopThread();，直接退出当前线程