Method InitHeader

cpp/src/parquet/decoder.cc:1516–1554

  static constexpr int kMaxDeltaBitWidth = static_cast<int>(sizeof(T) * 8);

  void InitHeader() {
    if (!decoder_->GetVlqInt(&values_per_block_) ||
        !decoder_->GetVlqInt(&mini_blocks_per_block_) ||
        !decoder_->GetVlqInt(&total_value_count_) ||
        !decoder_->GetZigZagVlqInt(&last_value_)) {
      ParquetException::EofException("InitHeader EOF");
    }

    if (values_per_block_ == 0) {
      throw ParquetException("cannot have zero value per block");
    }
    if (values_per_block_ % 128 != 0) {
      throw ParquetException(
          "the number of values in a block must be multiple of 128, but it's " +
          std::to_string(values_per_block_));
    }
    if (mini_blocks_per_block_ == 0) {
      throw ParquetException("cannot have zero miniblock per block");
    }
    values_per_mini_block_ = values_per_block_ / mini_blocks_per_block_;
    if (values_per_mini_block_ == 0) {
      throw ParquetException("cannot have zero value per miniblock");
    }
    if (values_per_mini_block_ % 32 != 0) {
      throw ParquetException(
          "the number of values in a miniblock must be multiple of 32, but it's " +
          std::to_string(values_per_mini_block_));
    }

    total_values_remaining_ = total_value_count_;
    if (delta_bit_widths_ == nullptr) {
      delta_bit_widths_ = AllocateBuffer(pool_, mini_blocks_per_block_);
    } else {
      PARQUET_THROW_NOT_OK(
          delta_bit_widths_->Resize(mini_blocks_per_block_, /*shrink_to_fit*/ false));
    }
    first_block_initialized_ = false;
    values_remaining_current_mini_block_ = 0;
  }

  void InitBlock() {
    DCHECK_GT(total_values_remaining_, 0) << "InitBlock called at EOF";