59 lines
2.8 KiB
C++
59 lines
2.8 KiB
C++
/*------------------------------------------------------------------------------*
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* Architecture & Implementation of DBMS *
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*------------------------------------------------------------------------------*
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* Copyright 2022 Databases and Information Systems Group TU Dortmund *
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* Visit us at *
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* http://dbis.cs.tu-dortmund.de/cms/en/home/ *
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* *
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS *
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* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, *
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL *
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* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR *
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* OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, *
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* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR *
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* OTHER DEALINGS IN THE SOFTWARE. *
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* *
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* Authors: *
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* Maximilian Berens <maximilian.berens@tu-dortmund.de> *
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* Roland Kühn <roland.kuehn@cs.tu-dortmund.de> *
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* Jan Mühlig <jan.muehlig@tu-dortmund.de> *
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*------------------------------------------------------------------------------*
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*/
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#pragma once
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#include <storage/page.h>
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#include <vector>
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namespace beedb::buffer
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{
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/**
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* The BufferReplacementStrategy decides which frame should
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* be re-used for a new page, when no free frame is available.
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*/
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class ReplacementStrategy
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{
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public:
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ReplacementStrategy() = default;
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virtual ~ReplacementStrategy() = default;
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/**
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* Picks a frame that holds a unused page and should be
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* replaced by a new page, requested by a query.
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*
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* @param frame_information Information of all frames.
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* @return Index of the frame, that should be used for a new page.
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*/
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virtual std::size_t find_victim(std::vector<storage::Page> &pages) = 0;
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/**
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* This callback is called every time the buffer manager pins a page
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* to given index in the frame buffer. This gives the strategy the
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* possibility to notice some additional information like the pin
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* history that is used for finding a victim.
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* @param frame_index Index in the frame buffer that is used for pinning.
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* @param timestamp Timestamp the page was pinned in the frame buffer.
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*/
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virtual void on_pin(std::size_t frame_index, std::size_t timestamp) = 0;
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};
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} // namespace beedb::buffer
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