Function BM_DecodingSpaced

cpp/src/parquet/encoding_benchmark.cc:336–368

template <typename ParquetType>
static void BM_DecodingSpaced(benchmark::State& state, Encoding::type encoding) {
  using ArrowType = typename BM_SpacedEncodingTraits<ParquetType>::ArrowType;
  using ArrayType = typename BM_SpacedEncodingTraits<ParquetType>::ArrayType;
  using CType = typename BM_SpacedEncodingTraits<ParquetType>::CType;

  const int num_values = static_cast<int>(state.range(0));
  const auto null_percent = static_cast<double>(state.range(1)) / 10000.0;

  auto rand = ::arrow::random::RandomArrayGenerator(1923);
  std::shared_ptr<::arrow::Array> array;
  if constexpr (std::is_same_v<ParquetType, BooleanType>) {
    array = rand.Boolean(num_values, /*true_probability*/ 0.5, null_percent);
  } else {
    array = rand.Numeric<ArrowType>(num_values, -100, 100, null_percent);
  }
  const auto valid_bits = array->null_bitmap_data();
  const int null_count = static_cast<int>(array->null_count());
  const auto array_actual = ::arrow::internal::checked_pointer_cast<ArrayType>(array);

  auto encoder = MakeTypedEncoder<ParquetType>(encoding);
  encoder->Put(*array);
  std::shared_ptr<Buffer> buf = encoder->FlushValues();

  auto decoder = MakeTypedDecoder<ParquetType>(encoding);
  std::vector<uint8_t> decode_values(num_values * sizeof(CType));
  auto decode_buf = reinterpret_cast<CType*>(decode_values.data());
  for (auto _ : state) {
    decoder->SetData(num_values - null_count, buf->data(), static_cast<int>(buf->size()));
    decoder->DecodeSpaced(decode_buf, num_values, null_count, valid_bits, 0);
  }
  state.counters["null_percent"] = null_percent * 100;
  state.SetBytesProcessed(state.iterations() * num_values * sizeof(CType));
}

template <typename ParquetType>
static void BM_PlainDecodingSpaced(benchmark::State& state) {