Function MakeJittery

cpp/src/arrow/util/async_generator_test.cc:42–52

template <typename T>
AsyncGenerator<T> MakeJittery(AsyncGenerator<T> source) {
  auto latency_generator = arrow::io::LatencyGenerator::Make(0.01);
  return MakeMappedGenerator(std::move(source), [latency_generator](const T& res) {
    auto out = Future<T>::Make();
    std::thread([out, res, latency_generator]() mutable {
      latency_generator->Sleep();
      out.MarkFinished(res);
    }).detach();
    return out;
  });
}

// Yields items with a small pause between each one from a background thread
std::function<Future<TestInt>()> BackgroundAsyncVectorIt(