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std::jthread:: get_stop_token

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std:: stop_token get_stop_token ( ) const noexcept ;
(seit C++20)

Gibt einen std::stop_token zurück, der mit demselben gemeinsamen Stopp-Zustand verknüpft ist, der intern vom jthread -Objekt gehalten wird.

Parameter

(keine)

Rückgabewert

Ein Wert vom Typ std::stop_token assoziiert mit dem Stop-Zustand, der intern vom jthread -Objekt gehalten wird.

Beispiel

#include <chrono>
#include <condition_variable>
#include <iostream>
#include <mutex>
#include <string_view>
#include <thread>
using namespace std::chrono_literals;
void print(std::string_view name, const std::stop_token& token)
{
    std::cout << name << ": stop_possible = " << token.stop_possible();
    std::cout << ", stop_requested = " << token.stop_requested() << '\n';
}
void finite_sleepy(std::stop_token stoken)
{
    for (int i = 10; i; --i)
    {
        std::this_thread::sleep_for(300ms);
        if (stoken.stop_requested())
        {
            std::cout << "  Sleepy worker is requested to stop\n";
            return;
        }
        std::cout << "  Sleepy worker goes back to sleep\n";
    }
}
void infinite_sleepy()
{
    for (int i = 5; i; --i)
    {
        std::this_thread::sleep_for(300ms);
        std::cout << "  Run as long as we want\n";
    }
}
int main()
{
    std::cout << std::boolalpha;
    // Ein Worker-Thread, der auf Stop-Anforderungen hört
    std::jthread stop_worker(finite_sleepy);
    // Ein Worker-Thread, der nur stoppt, wenn er fertig ist
    std::jthread inf_worker(infinite_sleepy);
    std::stop_token def_token;
    std::stop_token stop_token = stop_worker.get_stop_token();
    std::stop_token inf_token = inf_worker.get_stop_token();
    print("def_token ", def_token);
    print("stop_token", stop_token);
    print("inf_token ", inf_token);
    std::cout << "\nAnfordern und joinen von stop_worker:\n";
    stop_worker.request_stop();
    stop_worker.join();
    std::cout << "\nAnfordern und joinen von inf_worker:\n";
    inf_worker.request_stop();
    inf_worker.join();
    std::cout << '\n';
    print("def_token ", def_token);
    print("stop_token", stop_token);
    print("inf_token ", inf_token);
}

Mögliche Ausgabe:

def_token : stop_possible = false, stop_requested = false
stop_token: stop_possible = true, stop_requested = false
inf_token : stop_possible = true, stop_requested = false
Anfordern und joinen von stop_worker:
  Run as long as we want
  Sleepy worker is requested to stop
Anfordern und joinen von inf_worker:
  Run as long as we want
  Run as long as we want
  Run as long as we want
  Run as long as we want
def_token : stop_possible = false, stop_requested = false
stop_token: stop_possible = true, stop_requested = true
inf_token : stop_possible = true, stop_requested = true