Method Fetch

src/data/sparse_page_source.h:604–616

class SortedCSCPageSource : public PageSourceIncMixIn<SortedCSCPage> {
 protected:
  void Fetch() final {
    if (!this->ReadCache()) {
      auto const& csr = this->source_->Page();
      this->page_.reset(new SortedCSCPage{});
      // we might be able to optimize this by merging transpose and pushcsc
      this->page_->PushCSC(csr->GetTranspose(n_features_, nthreads_));
      CHECK_EQ(this->page_->Size(), n_features_);
      CHECK_EQ(this->page_->data.Size(), csr->data.Size());
      this->page_->SortRows(this->nthreads_);
      page_->SetBaseRowId(csr->base_rowid);
      this->WriteCache();
    }
  }

 public:
  SortedCSCPageSource(float missing, int nthreads, bst_feature_t n_features, uint32_t n_batches,