C++ shared_future

#include <iostream>
#include <future>

int mythread()
{
   std::cout << "mythread " << std::this_thread::get_id() << std::endl;
   std::chrono::milliseconds second(3000);
   std::this_thread::sleep_for(second);
   return 5;
}

int main()
{
   std::cout << "main " << std::this_thread::get_id() << std::endl;

   std::packaged_task<int(void)> pt(mythread);
   std::thread t(std::ref(pt));
   t.join();
   std::future<int> future = pt.get_future();
   std::shared_future<int> sfuture(future.share());

   /* 可用于多线程 */
   std::cout << "shared_future " << sfuture.get() << std::endl;
   std::cout << "shared_future " << sfuture.get() << std::endl;

   return 0;
}

$ ./a.out 
main 140470666590016
mythread 140470649251584
shared_future 5
shared_future 5