cpp/thread/shared future

The class template provides a mechanism to access the result of asynchronous operations, similar to std, except that multiple threads are allowed to wait for the same shared state. Unlike std, which is only moveable (so only one instance can refer to any particular asynchronous result), is copyable and multiple shared future objects may refer to the same shared state.

Access to the same shared state from multiple threads is safe if each thread does it through its own copy of a object.