C++多线程-stop_stop_token-condition_variable_any

类是 std::condition_variable 的泛化。 虽然std::condition_variable 仅适用于 std::unique_lock<std::mutex>，但 condition_variable_any 可以对满足 要求的任何锁进行操作。

示例

#include <iostream>
#include <thread>
#include <chrono>
#include <mutex>
#include <condition_variable>



using namespace std::chrono_literals;


void Xworker(std::stop_token stoken, int argX)
{
    std::cout << "thread-" << std::this_thread::get_id() << " argX = " << argX << "
";

    while (true) {
        std::this_thread::sleep_for(1s);
        if (stoken.stop_requested()) {
            std::cout << "thread-" << std::this_thread::get_id() << " Xworker is requested to stop
";
            return;
        }
        std::cout << "thread-" << std::this_thread::get_id() << " Xworker goes back to sleep
";
    }
}

int main()
{
    unsigned int n = std::thread::hardware_concurrency(); // 当前硬件支持线程并发数
    std::cout << n << " concurrent threads are supported.
";

    // A sleepy worker thread
    std::jthread sleepy_worker([](std::stop_token stoken) {
       // for (int i = 10; i; --i) {
        while (true) {
            std::this_thread::sleep_for(100ms);
            if (stoken.stop_requested()) {
                std::cout << "thread-" << std::this_thread::get_id() << " Sleepy worker is requested to stop
";
                return;
            }
            std::cout << "thread-" << std::this_thread::get_id() << " Sleepy worker goes back to sleep
";
        }
        });

    // A waiting worker thread
    // The condition variable will be awoken by the stop request.
    std::jthread waiting_worker([](std::stop_token stoken) {
        std::mutex mutex;
        std::unique_lock lock(mutex);
        std::condition_variable_any().wait(lock, stoken,  [&stoken] {
                if (stoken.stop_requested()) {
                    std::cout << "thread-" << std::this_thread::get_id() << " Waiting worker wakeup
";
                    return true;
                }
                else {
                    std::cout << "thread-" << std::this_thread::get_id() << " Waiting worker sleep...
";
                    return false;
                }
            });

            //if (stoken.stop_requested()) {
            //    std::cout << "thread-" << std::this_thread::get_id() << " Waiting worker is requested to stop
";
            //    return;
            //}
        });

    std::jthread xworker(Xworker, 2);

    // std::jthread::request_stop() can be called explicitly:
    std::this_thread::sleep_for(1s);
    std::cout << "Requesting stop of sleepy worker
";
    sleepy_worker.request_stop();
    sleepy_worker.join();
    std::cout << "Sleepy worker joined
";

    std::this_thread::sleep_for(5s);
    // Or automatically using RAII:
    // waiting_workers destructor will call request_stop()
    // and join the thread automatically.
}

运行结果

16 concurrent threads are supported. thread-1616 argX = 2 thread-2248 Waiting worker sleep... thread-24232 Sleepy worker goes back to sleep thread-24232 Sleepy worker goes back to sleep thread-24232 Sleepy worker goes back to sleep thread-24232 Sleepy worker goes back to sleep thread-24232 Sleepy worker goes back to sleep thread-24232 Sleepy worker goes back to sleep thread-24232 Sleepy worker goes back to sleep thread-24232 Sleepy worker goes back to sleep thread-24232 Sleepy worker goes back to sleep Requesting stop of sleepy worker thread-1616 Xworker goes back to sleep thread-24232 Sleepy worker is requested to stop Sleepy worker joined thread-1616 Xworker goes back to sleep thread-1616 Xworker goes back to sleep thread-1616 Xworker goes back to sleep thread-1616 Xworker goes back to sleep thread-1616 Xworker goes back to sleep thread-1616 Xworker is requested to stop thread-2248 Waiting worker wakeup