std::promise<R>::set_value_at_thread_exit (3) - Linux Man Pages
void set_value_at_thread_exit( const R& value ); (1) (member only of generic promise template)
void set_value_at_thread_exit( R&& value ); (2) (member only of generic promise template)
void set_value_at_thread_exit( R& value ); (3) (member only of promise<R&> template specialization)
void set_value_at_thread_exit() (4) (member only of promise<void> template specialization)
Stores the value into the shared state without making the state ready immediately. The state is made ready when the current thread exits, after all variables with thread-local storage duration have been destroyed.
The operation behaves as though set_value, set_exception, set_value_at_thread_exit, and set_exception_at_thread_exit acquire a single mutex associated with the promise object while updating the promise object.
An exception is thrown if there is no shared state or the shared state already stores a value or exception.
Calls to this function do not introduce data races with calls to get_future (but they need not synchronize with each other).
value - value to store in the shared state
std::future_error on the following conditions:
* *this has no shared state. The error category is set to no_state.
* The shared state already stores a value or exception. The error category is set to promise_already_satisfied.
1-2) Any exception thrown by the copy constructor of value
3) Any exception thrown by the move constructor of value
// Run this code