C++ 使用boost:：upgrade_lock和shared_lock实现读/写线程安全 double x=10； boost:：shared_mutex xSharedMutex； void r（）{ boost：：共享锁（xSharedMutex）； 对于（int i=0；i

您需要唯一的所有权来写作：

double x = 10;
boost::shared_mutex xSharedMutex;


void r() {
    boost::shared_lock<boost::shared_mutex> lock(xSharedMutex);
    for (int i = 0; i < 100; i++) {
        cout << "**** READ **** " << x << endl;
        usleep(200);
    }
}

void w() {
    boost::upgrade_lock<boost::shared_mutex> lock(xSharedMutex);
    for (int i = 0; i < 100; i++) {
        x = i + 12;
        cout << "---- WRITE ---- " << x <<endl;
        usleep(200);
    }

}

int main() {
    boost::thread t1(&r);
    boost::thread t2(&w);

    sleep(3);
}

boost:：unique_lock锁（xSharedMutex）；
对于（int i=0；i<100；i++）{
x=i+12；
标准：：cout
boost::unique_lock<boost::shared_mutex> lock(xSharedMutex);
for (int i = 0; i < 100; i++) {
    x = i + 12;
    std::cout << "---- WRITE ---- " << x << std::endl;
    usleep(200);
}

upgrade_lock<shared_mutex> lock(xSharedMutex);
for (int i = 0; i < 100; i++) {
    {
        upgrade_to_unique_lock<shared_mutex> write_lock(lock);
        x = i + 12;
        std::cout << "---- WRITE ---- " << x << std::endl;
    }
    usleep(200);
}