Tracked_ptr – when shared_ptr is not enough

Herb Sutter pointed out the need to add a tracked pointer to C++. He proposed the concept of deferred_ptr a few years ago. I implemented the tracked_ptr concept with one tracked heap. Advantages: - Thread safe - Does not use reference counters - Easy to use like shared_ptr - Less memory overhead than shared_ptr - Faster than shared_ptr in many scenarios - Automatic roots registration - Never stop the world - Cyclic data structures friendly - CoW friendly - Executing destructors in a separate thread - Atomic pointers always lock-free - Only one header file