  static void clearReservation(Buffer::RawSlice* iovecs, uint64_t num_iovecs, OwnedImpl& buffer) {
    for (uint64_t i = 0; i < num_iovecs; i++) {
      iovecs[i].len_ = 0;
    }
    buffer.commit(iovecs, num_iovecs);
  }
  static void clearReservation(Buffer::RawSlice* iovecs, uint64_t num_iovecs, OwnedImpl& buffer) {
    for (uint64_t i = 0; i < num_iovecs; i++) {
      iovecs[i].len_ = 0;
    }
    buffer.commit(iovecs, num_iovecs);
  }