rethread library contains implementation of cancellation_token along with RAII-compliant wrapper around C++11 std::thread

C++11 threads has one inherent problem - they aren't truly RAII-compliant. C++11 standard excerpt:

30.3.1.3 thread destructor
~thread();
If joinable() then terminate(), otherwise no effects.

Let's fix it: meet the cancellation_token object.

It is stored inside rethread::thread object and passed to invoked function, thus allowing graceful function cancelation from thread destructor. After notifying invoked function about requested cancellation, rethread::thread waits for it's completion by joining the underlying thread.

class thread
{
  // ...
  
  ~thread() {
    if (joinable())
    {
      token.cancel();
      join();
    }
  }
  
  // ...
};

Cancellation token adds cancellability to several blocking calls:

• this_thread::sleep_for
• Condition variables
• POSIX poll

TODO