条件变量 condition_variable wait_until

wait_until(阻塞当前线程，直到条件变量被唤醒，或直到抵达指定时间点)

#include 
#include 
#include 
#include 
#include 
using namespace std::chrono_literals;
 
std::condition_variable cv;
std::mutex cv_m;
std::atomic i{0};
 
void waits(int idx)
{
    std::unique_lock lk(cv_m);
    auto now = std::chrono::system_clock::now();
    if(cv.wait_until(lk, now + idx*100ms, [](){return i == 1;}))
        std::cerr << "Thread " << idx << " finished waiting. i == " << i << '\n';
    else
        std::cerr << "Thread " << idx << " timed out. i == " << i << '\n';
}
 
void signals()
{
    std::this_thread::sleep_for(120ms);
    std::cerr << "Notifying...\n";
    cv.notify_all();
    std::this_thread::sleep_for(100ms);
    i = 1;
    std::cerr << "Notifying again...\n";
    cv.notify_all();
}
 
int main()
{
    std::thread t1(waits, 1), t2(waits, 2), t3(waits, 3), t4(signals);
    t1.join(); 
    t2.join();
    t3.join();
    t4.join();
}

转载于:https://www.cnblogs.com/smallredness/p/10904176.html