Method wait_and_pop

src/util/threadsafe_queue.h:25–30

  }

  void wait_and_pop(T& value) {
    std::unique_lock<std::mutex> lk(mut);
    data_cond.wait(lk, [this]{return !data_queue.empty();});
    value = std::move(data_queue.front());
    data_queue.pop();
  }

  std::shared_ptr<T> wait_and_pop() {
    std::unique_lock<std::mutex> lk(mut);