vendredi 26 octobre 2018

is it possible to set a promise in a signal handler?

I was looking for a way to stop a thread that perform a task every 2 seconds. I decided to try to use a std::promise/future so that the thread can exit immediately when the promise is set.

#include <future>
#include <iostream>
#include <chrono>
#include <csignal>

std::promise<void> stop;

int main() {

    std::signal(SIGINT, [] (int)  { stop.set_value(); } );

    auto future = stop.get_future();

    while (future.wait_for(std::chrono::seconds(1)) != std::future_status::ready) {
            std::cout << "I'm still there" << std::endl;
    }
}

Actually this does not work and crashes that way:

$ ./a.out I'm still there ^Cterminate called after throwing an instance of 'std::system_error'
what(): Unknown error -1 Abandon (core dumped)

Ok, One should take care of what he does in handler context, but I must say I was not expecting this crash; and I don't really understand it... Do you have any idea?

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