bufmgr.h

Go to the documentation of this file.

/*
 * SwatDB
 *
 * @authors: See Contributors.doc for code contributors
 *
 * Copyright (c) 2020 Swarthmore College Computer Science Department
 * Swarthmore PA, Professors Tia Newhall, Ameet Soni
 */

#pragma once

#include <utility>
#include <unordered_map>
#include <mutex>

#include "swatdb_types.h"
#include "page.h"     // need for alignment of Page object

class BufferManager;
class DiskManager;

class Frame {

  friend class BufferManager;

  public:

    Frame();

    ~Frame();

    void resetFrame();

    void loadFrame(PageId page_id);

  private:

    PageId page_id;

    int pin_count;

    bool valid;

    bool dirty;

    bool ref_bit;

    std::mutex frame_mtx;
};

struct BufHash{
  std::size_t operator()(const PageId& page_id) const{
    return (std::hash<unsigned int>() (page_id.file_id)) ^
        (std::hash<unsigned int>() (page_id.page_num));
  }
};

class BufferMap {

  public:

    BufferMap(){ }

    ~BufferMap(){ }

    FrameId get(PageId page_id);

    bool contains(PageId page_id);

    void insert(PageId page_id, FrameId frame_id);

    void remove(PageId page_id);

  private:

    std::unordered_map<PageId,FrameId,BufHash> buf_map;
};

struct BufferState{

  std::uint32_t total;

  std::uint32_t valid;

  std::uint32_t pinned;

  std::uint32_t unpinned;

  std::uint32_t dirty;

  std::uint32_t ref_bit;

  std::uint32_t clock_hand;
};

class BufferManager {

  public:

    BufferManager(DiskManager* disk_mgr);

    ~BufferManager();

    std::pair<Page*,PageId> allocatePage(FileId file_id);

    void deallocatePage(PageId page_id);

    Page* getPage(PageId page_id);

    void releasePage(PageId page_id, bool dirty);

    void setDirty(PageId page_id);

    void flushPage(PageId page_id);

    void createFile(FileId file_id);

    void removeFile(FileId file_id);

    void clearBuffer();

    BufferState getBufferState();

    void printAllFrames();

    void printValidFrames();

    void printFrame(FrameId frame_id);

    void printPage(PageId page_id);

    void printBufferState();

  private:

    BufferMap buf_map;

    Frame frame_table[BUF_SIZE];

    Page buf_pool[BUF_SIZE];

    DiskManager* disk_mgr;

    std::uint32_t clock_hand;

    std::mutex buf_map_mtx;

    FrameId _allocateFrame();

    void _advanceClock();
};