dequeue-bitnext.hpp

T* dequeue(void) {
  while (true) {
    Node* lhead = hp.protectPtr(kHpHead, head.load());
    if (lhead != head.load()) continue;
    Node* lnext = lhead->next.load();
    if (isMark(lnext)) {
      if (getUnmark(lnext) == nullptr) return nullptr;
      if (casHead(lhead, getUnmark(lnext))) hp.retire(lhead);
      continue;
    }
    if (lhead->casNext(lnext, getMark(lnext))) {
      return lhead->item;
    }
  }
}