native_filesystem.h

// Copyright 2017 Rice University, COMP 413 2017

#include <easylogging++.h>
#include <stdio.h>
#include <stdlib.h>

#include <fstream>
#include <mutex>
#include <iostream>
#include <map>
#include <string>
#include <vector>

#pragma once

namespace nativefs {

typedef struct {
  uint64_t blockid;
  uint64_t offset;  // Address in the FS
  uint32_t len;  // length of the data
  // in the block
  uint32_t allocated_size;  // total
  // allocated size for this block
  bool free;
} block_info;

const size_t MIN_BLOCK_POWER = 13;
const size_t MAX_BLOCK_POWER = 27;
constexpr size_t MIN_BLOCK_SIZE = 1 << MIN_BLOCK_POWER;
constexpr size_t MAX_BLOCK_SIZE = 1 << MAX_BLOCK_POWER;
constexpr size_t FREE_LIST_SIZE = MAX_BLOCK_POWER - MIN_BLOCK_POWER + 1;
constexpr size_t DISK_SIZE = MAX_BLOCK_SIZE * 6;
constexpr size_t BLOCK_LIST_LEN = DISK_SIZE / MIN_BLOCK_SIZE;
constexpr size_t BLOCK_LIST_SIZE = BLOCK_LIST_LEN * sizeof(block_info);
// If MAGIC changes, make sure to change the 8 in RESERVED_SIZE too.
const char MAGIC[] = "LIVEBEEF";
// Reserved space for magic bytes + block_info array.
constexpr size_t RESERVED_SIZE = BLOCK_LIST_SIZE + 8;

class NativeFS {
 public:
  explicit NativeFS(std::string);
  ~NativeFS();
  bool writeBlock(uint64_t, const std::string &);
  bool getBlock(uint64_t, std::string &);
  bool hasBlock(uint64_t);
  bool rmBlock(uint64_t);
  uint64_t getTotalSpace();
  uint64_t getFreeSpace();

  std::vector<std::uint64_t> getKnownBlocks();

  bool fetchBlock(uint64_t, block_info &info);

  bool extendBlock(uint64_t block_id, std::string block_data);

 private:
  int addBlock(const block_info &info);
  void freeRange(uint64_t start, uint64_t end);
  bool allocateBlock(size_t size, uint64_t &offset);
  void constructFreeLists();
  void flushAllBlocks();
  void flushBlock(int block_index);

  size_t findBlock(uint64_t block_id);

  void printFreeBlocks();

  block_info *blocks;
  mutable std::mutex listMtx;
  std::vector<std::vector<uint64_t>> freeLists;
  std::fstream disk;
  static const std::string CLASS_NAME;
};

}  // namespace nativefs