How to create timer events using C++ 11?

Question

How to create timer events using C++ 11?

I need something like: “Call me after 1 second from now”.

Is there any library?

Answer 1

If you are on Windows, you can use the CreateThreadpoolTimer function to schedule a callback without needing to worry about thread management and without blocking the current thread.

template
static void __stdcall timer_fired(PTP_CALLBACK_INSTANCE, PVOID context, PTP_TIMER timer)
{
    CloseThreadpoolTimer(timer);
    std::unique_ptr callable(reinterpret_cast(context));
    (*callable)();
}

template 
void call_after(T callable, long long delayInMs)
{
    auto state = std::make_unique(std::move(callable));
    auto timer = CreateThreadpoolTimer(timer_fired, state.get(), nullptr);
    if (!timer)
    {
        throw std::runtime_error("Timer");
    }

    ULARGE_INTEGER due;
    due.QuadPart = static_cast(-(delayInMs * 10000LL));

    FILETIME ft;
    ft.dwHighDateTime = due.HighPart;
    ft.dwLowDateTime = due.LowPart;

    SetThreadpoolTimer(timer, &ft, 0 /*msPeriod*/, 0 /*msWindowLength*/);
    state.release();
}

int main()
{
    auto callback = []
    {
        std::cout << "in callback\n";
    };

    call_after(callback, 1000);
    std::cin.get();
}