Method DecodeArrowDense

cpp/src/parquet/decoder.cc:2145–2185

  }

  Status DecodeArrowDense(int num_values, int null_count, const uint8_t* valid_bits,
                          int64_t valid_bits_offset,
                          typename EncodingTraits<DType>::Accumulator* out,
                          int* out_num_values) {
    ARROW_ASSIGN_OR_RAISE(
        auto values_buffer,
        ::arrow::AllocateBuffer(sizeof(ByteArray) * (num_values - null_count), pool_));
    auto values_data = values_buffer->template mutable_data_as<ByteArray>();

    const int num_valid_values = GetInternal(values_data, num_values - null_count);
    if (ARROW_PREDICT_FALSE(num_values - null_count != num_valid_values)) {
      throw ParquetException("Expected to decode ", num_values - null_count,
                             " values, but decoded ", num_valid_values, " values.");
    }

    auto visit_binary_helper = [&](auto* helper) {
      auto values_ptr = reinterpret_cast<const ByteArray*>(values_data);
      int value_idx = 0;

      PARQUET_THROW_NOT_OK(
          VisitBitRuns(valid_bits, valid_bits_offset, num_values,
                       [&](int64_t position, int64_t run_length, bool is_valid) {
                         if (is_valid) {
                           for (int64_t i = 0; i < run_length; ++i) {
                             const auto& val = values_ptr[value_idx];
                             RETURN_NOT_OK(helper->AppendValue(
                                 val.ptr, static_cast<int32_t>(val.len)));
                             ++value_idx;
                           }
                           return Status::OK();
                         } else {
                           return helper->AppendNulls(run_length);
                         }
                       }));

      *out_num_values = num_valid_values;
      return Status::OK();
    };
    return DispatchArrowBinaryHelper<DType>(out, num_values, /*estimated_data_length=*/{},
                                            visit_binary_helper);
  }

  MemoryPool* pool_;