std::stop_token::stop_possible(3)

NAME
std::stop_token::stop_possible - std::stop_token::stop_possible

Synopsis
   [[nodiscard]] bool stop_possible() const noexcept; (since C++20)
   Checks if the stop_token object has associated stop-state, and that state either has
   already had a stop requested or it has associated std::stop_source object(s).
   A default constructed stop_token has no associated stop-state, and thus cannot be
   stopped; the associated stop-state for which no std::stop_source object(s) exist can
   also not be stopped if such a request has not already been made.

Parameters
   (none)

Return value
   false if the stop_token object has no associated stop-state, or it did not yet
   receive a stop request and there are no associated std::stop_source object(s); true
   otherwise.

Notes
   If the stop_token object has associated stop-state and a stop request has already
   been made, this function still returns true.
   If the stop_token object has associated stop-state from a std::jthread—for example,
   the stop_token was retrieved by invoking get_stop_token() on a std::jthread
   object—then this function always returns true. A std::jthread always has an internal
   std::stop_source object, even if the thread's invoking function does not check it.

Example
// Run this code
 #include <chrono>
 #include <condition_variable>
 #include <format>
 #include <iostream>
 #include <mutex>
 #include <string_view>
 #include <thread>
 using namespace std::chrono_literals;
 int main()
 {
     std::cout << std::boolalpha;
     auto print = [](std::string_view name, const std::stop_token& token)
     {
         std::cout << std::format("{}: stop_possible = {:s}, stop_requested = {:s}\n",
             name, token.stop_possible(), token.stop_requested()
         );
     };
     // A worker thread that will listen to stop requests
     auto stop_worker = std::jthread([](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";
         }
     });
     // A worker thread that will only stop when completed
     auto inf_worker = std::jthread([]()
     {
         for (int i = 5; i; --i)
         {
             std::this_thread::sleep_for(300ms);
             std::cout << " Run as long as we want\n";
         }
     });
     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