Class label_writer

src/common/perf_counters_key.cc:34–42

  using base_iterator = Iterator;

  struct label_writer {
    base_iterator pos; // write position

    label_writer& operator=(const label_pair& l) {
      pos = write(l.first, pos);
      pos = write(l.second, pos);
      return *this;
    }
  };
  label_writer label;

 public: