Method pop_front

src/common/PrioritizedQueue.h:109–124

      return cur->second.front();
    }
    T pop_front() {
      ceph_assert(!(q.empty()));
      ceph_assert(cur != q.end());
      T ret = std::move(cur->second.front().second);
      cur->second.pop_front();
      if (cur->second.empty()) {
	q.erase(cur++);
      } else {
	++cur;
      }
      if (cur == q.end()) {
	cur = q.begin();
      }
      size--;
      return ret;
    }
    unsigned length() const {
      ceph_assert(size >= 0);
      return (unsigned)size;