Re: [boost] Using Boost.Atomic for shared_ptr

On Mon, 21 Dec 2009, Peter Dimov wrote:

Relaxed is fine for add_ref. The decrements need to be acqrel. use_count() needs acquire.

I think that decrement can be: if (use_count_.fetch_sub(1, memory_order_release)==1) { atomic_thread_fence(memory_order_acquire); ... } i.e. save the acquire unless the object is going to be deleted. Helge