Method gen

cpp/src/arrow/dataset/test_util_internal.h:79–107

  std::shared_ptr<Schema> schema;

  AsyncGenerator<std::optional<ExecBatch>> gen(bool parallel, bool slow) const {
    auto opt_batches = ::arrow::internal::MapVector(
        [](ExecBatch batch) { return std::make_optional(std::move(batch)); }, batches);

    AsyncGenerator<std::optional<ExecBatch>> gen;

    if (parallel) {
      // emulate batches completing initial decode-after-scan on a cpu thread
      gen = MakeBackgroundGenerator(MakeVectorIterator(std::move(opt_batches)),
                                    ::arrow::internal::GetCpuThreadPool())
                .ValueOrDie();

      // ensure that callbacks are not executed immediately on a background thread
      gen =
          MakeTransferredGenerator(std::move(gen), ::arrow::internal::GetCpuThreadPool());
    } else {
      gen = MakeVectorGenerator(std::move(opt_batches));
    }

    if (slow) {
      gen =
          MakeMappedGenerator(std::move(gen), [](const std::optional<ExecBatch>& batch) {
            SleepABit();
            return batch;
          });
    }

    return gen;
  }
};

Future<> StartAndFinish(ExecPlan* plan);