Unbounded single-producer, multi-consumer queue.
Declared in <folly/concurrency/UnboundedQueue.h>
template<
typename T,
bool MayBlock,
size_t LgSegmentSize = 8,
size_t LgAlign = constexpr_log2(hardware_destructive_interference_size),
template<typename> typename Atom = atomic>
using USPMCQueue = UnboundedQueue<T, true, false, MayBlock, LgSegmentSize, LgAlign, Atom>;