std::jthread::get_stop_token

 

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std::jthread

Member functions

jthread::jthread

jthread::~jthread

jthread::operator=

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jthread::joinable

jthread::get_id

jthread::native_handle

jthread::hardware_concurrency

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jthread::join

jthread::detach

jthread::swap

Stop token handling

jthread::get_stop_source

jthread::get_stop_token

jthread::request_stop

Non-member functions

swap(std::jthread)

 

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