Method WriteCache

src/data/sparse_page_source.h:349–367

  }

  void WriteCache() {
    CHECK(!cache_info_->written);
    common::Timer timer;
    timer.Start();
    auto fmt{this->CreatePageFormat(this->param_)};

    auto name = cache_info_->ShardName();
    std::unique_ptr<typename FormatStreamPolicy::WriterT> fo{
        this->CreateWriter(StringView{name}, this->Iter())};
    auto bytes = fmt->Write(*page_, fo.get());

    timer.Stop();
    if (bytes != InvalidPageSize()) {
      // Not entirely accurate, the kernel doesn't have to flush the data.
      LOG(INFO) << common::HumanMemUnit(bytes) << " written in " << timer.ElapsedSeconds()
                << " seconds.";
      cache_info_->Push(bytes);
    }
  }

  virtual void Fetch() = 0;