c++标准库std::thread测试一(流程控制)

1.需求, 现在10个线程分别打印AAA... BBB... CCC...要求按顺序打印, 如图所示

Plan1:

#define THREAD_CNT 5

std::condition_variable g_cvs[THREAD_CNT];
std::condition_variable g_cv;
std::mutex g_mtx;

int g_curIndex = -1;

void PrintChar(char ch)
{
    int index = ch - 'A';
    int sleepMsTime = rand() % 2000;
    printf("%c ready
", ch);
    std::this_thread::sleep_for(std::chrono::milliseconds(sleepMsTime));
    printf("%c lock
", ch);
    std::unique_lock<std::mutex> lg(g_mtx);
    while (1)
    {
        g_cv.wait(lg);
        if (g_curIndex == index)
        {
            break;
        }
    }
    printf("%c unlock
", ch);
    printf("
");
    for (int i = 0; i < 10; ++i)
    {
        printf("%c", ch);
    }
    printf("
");
    ++g_curIndex;
    g_cv.notify_all();
}


int main()
{
    srand(time(nullptr));
    std::vector<std::thread> vecThreads;
    for (int i = 0; i < THREAD_CNT; ++i)
    {
        vecThreads.push_back(std::thread(PrintChar, i + 'A'));
    }
    std::this_thread::sleep_for(std::chrono::milliseconds(3000));
    g_curIndex = 0;
    g_cv.notify_all();
    for (auto &t : vecThreads)
    {
        t.join();
    }
    return 0;
}

Plan2:

#define THREAD_CNT 5

std::condition_variable g_cvs[THREAD_CNT];
std::condition_variable g_cv;
std::mutex g_mtx;

void PrintChar(char ch)
{
    int index = ch - 'A';
    int sleepMsTime = rand() % 2000;
    printf("%c ready
", ch);
    std::this_thread::sleep_for(std::chrono::milliseconds(sleepMsTime));
    printf("%c lock
", ch);
    std::unique_lock<std::mutex> lg(g_mtx);

    g_cvs[index].wait(lg);

    printf("%c unlock
", ch);
    printf("
");
    for (int i = 0; i < 10; ++i)
    {
        printf("%c", ch);
    }
    printf("
");
    if (index != THREAD_CNT - 1)
    {
        g_cvs[index + 1].notify_one();
    }
}


int main()
{
    srand(time(nullptr));
    std::vector<std::thread> vecThreads;
    for (int i = 0; i < THREAD_CNT; ++i)
    {
        vecThreads.push_back(std::thread(PrintChar, i + 'A'));
    }
    std::this_thread::sleep_for(std::chrono::milliseconds(3000));
    g_cvs[0].notify_one();
    for (auto &t : vecThreads)
    {
        t.join();
    }
    return 0;
}