[C++][Parquet] Minor: avoid re-create a new Reader object in Decoder::SetData #39845
Description
Describe the enhancement requested
void SetData(int num_values, const uint8_t* data, int len) override {
// num_values is equal to page's num_values, including null values in this page
this->num_values_ = num_values;
decoder_ = std::make_shared<::arrow::bit_util::BitReader>(data, len);
}Should be
void SetData(int num_values, const uint8_t* data, int len) override {
// num_values is equal to page's num_values, including null values in this page
this->num_values_ = num_values;
if (decoder_ == nullptr) {
decoder_ = std::make_shared<::arrow::bit_util::BitReader>(data, len);
} else {
decoder_->Reset(data, len);
}
Component(s)
C++, Parquet