C++ Details of Asymmetric Fences

Asymmetric Fences? While browsing through Folly’s synchronization primitives to study up on concurrency concepts, one familiar-looking name in the codebase caught my attention: Asymmetric Thread Fence. I already knew what std::atomic_thread_fence is meant to achieve, but what does this construct do? And what exactly is asymmetric about it? That question led me down an interesting rabbit hole: ...