NAME¶

std::jthread::get_stop_token - std::jthread::get_stop_token

Synopsis¶

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

Returns a std::stop_token associated with the same shared stop-state held internally
by the jthread object.

Parameters¶

(none)

Return value¶

A value of type std::stop_token associated with stop-state held internally by
jthread object.

Example¶

// Run this code

#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;

// A worker thread that will listen to stop requests
std::jthread stop_worker(finite_sleepy);

// A worker thread that will only stop when completed
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 << "\nRequest and join stop_worker:\n";
stop_worker.request_stop();
stop_worker.join();

std::cout << "\nRequest and join 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);
}

Possible output:¶

def_token : stop_possible = false, stop_requested = false
stop_token: stop_possible = true, stop_requested = false
inf_token : stop_possible = true, stop_requested = false

Request and join stop_worker:
Run as long as we want
Sleepy worker is requested to stop

Request and join 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