beedb/include/buffer/lru_k_strategy.h

55 lines
2.4 KiB
C++

/*------------------------------------------------------------------------------*
* Architecture & Implementation of DBMS *
*------------------------------------------------------------------------------*
* Copyright 2022 Databases and Information Systems Group TU Dortmund *
* Visit us at *
* http://dbis.cs.tu-dortmund.de/cms/en/home/ *
* *
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS *
* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, *
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL *
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR *
* OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, *
* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR *
* OTHER DEALINGS IN THE SOFTWARE. *
* *
* Authors: *
* Maximilian Berens <maximilian.berens@tu-dortmund.de> *
* Roland Kühn <roland.kuehn@cs.tu-dortmund.de> *
* Jan Mühlig <jan.muehlig@tu-dortmund.de> *
*------------------------------------------------------------------------------*
*/
#pragma once
#include "replacement_strategy.h"
#include <list>
namespace beedb::buffer
{
class LRUKStrategy final : public ReplacementStrategy
{
public:
LRUKStrategy(std::size_t count_frames, std::size_t k);
~LRUKStrategy() override = default;
std::size_t find_victim(std::vector<storage::Page> &pages) override;
void on_pin(std::size_t frame_index, std::size_t timestamp) override;
private:
// Configured K-parameter.
const std::size_t _k = 0;
// List of timestamps for every page.
std::vector<std::vector<std::size_t>> _history;
[[nodiscard]] std::size_t last_timestamp(std::size_t frame_index) const
{
if (_history[frame_index].empty())
{
return std::numeric_limits<std::size_t>::max();
}
return _history[frame_index].back();
}
};
} // namespace beedb::buffer