Function IterateSynchronously

cpp/src/arrow/util/thread_pool.h:609–622

///   calls.
template <typename T>
Iterator<T> IterateSynchronously(
    FnOnce<Result<std::function<Future<T>()>>(Executor*)> get_gen, bool use_threads,
    Executor* executor) {
  if (use_threads) {
    auto used_executor = executor != NULLPTR ? executor : GetCpuThreadPool();
    auto maybe_gen = std::move(get_gen)(used_executor);
    if (!maybe_gen.ok()) {
      return MakeErrorIterator<T>(maybe_gen.status());
    }
    return MakeGeneratorIterator(*maybe_gen);
  } else {
    return SerialExecutor::IterateGenerator(std::move(get_gen));
  }
}

/// \brief Potentially iterate an async generator serially (if use_threads is false)
///   using the default CPU thread pool