diskmgr.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
 */
 
 
#ifndef _SWATDB_DISKMGR_H_
#define  _SWATDB_DISKMGR_H_
 
#include<iostream>
#include<string>
#include <fstream>
#include <vector>
#include <unordered_set>
#include <unordered_map>
#include <mutex>
 
#include "swatdb_types.h"
 
class Catalog;
class Page;
 
class DiskManager {
 
  public:
 
    DiskManager(Catalog *catalog);
 
    ~DiskManager();
 
    void createFile(FileId file_id);
 
    void removeFile(FileId file_id);
 
    PageId allocatePage(FileId file_id);
 
    void deallocatePage(PageId page_id);
 
    void readPage(PageId page_id, Page* page);
 
    void writePage(PageId page_id, Page* page);
 
    bool isValidPage(PageId page_id);
 
    void printFile(FileId file_id);
 
    std::uint32_t getCapacity(FileId file_id);
 
    std::uint32_t getSize(FileId file_id);
 
  private:
 
    // this needs a comment describing this expression!
    static const std::uint32_t DISK_HEADER_SIZE =
      ((((MAX_PAGE_NUM/8)+1+(sizeof(std::uint32_t)*2))/PAGE_SIZE)+1)*PAGE_SIZE;
 
    static const std::uint32_t DISK_HEADER_BITMAP_SIZE =
        DISK_HEADER_SIZE - (sizeof(std::uint32_t)*2);
 
    struct SerializedFileHeader{
      std::uint32_t size;
      std::uint32_t capacity;
      char bitmap[DISK_HEADER_BITMAP_SIZE];
    };
 
    struct DiskFileInfo{
 
      std::fstream file;
 
      std::uint32_t capacity;
 
      std::unordered_set<PageNum> unused_pages;
 
      std::mutex file_mtx;
    };
 
    std::unordered_map <FileId, DiskFileInfo*> file_map;
 
    Catalog* catalog;
 
    std::mutex file_map_mtx;
 
    char temp_page[PAGE_SIZE];
 
    void _getDiskFileInfo(FileId file_id, DiskFileInfo**
      disk_file_info);
 
    void _flushDiskFileInfo(FileId file_id);
 
    void _serializeFileHeader(SerializedFileHeader* file_header,
      DiskFileInfo* disk_file_info);
 
    void _deserializeFileHeader(SerializedFileHeader* file_header,
      DiskFileInfo* disk_file_info);
 
};
 
#endif