Files
BH-Bookstore-2023/backend/include/drivearray.hpp
2023-12-05 15:34:22 +00:00

203 lines
6.9 KiB
C++

#ifndef BPT_DriveArray_HPP
#define BPT_DriveArray_HPP
#include <algorithm>
#include <cstring>
#include <fstream>
#include <queue>
#include <stack>
#include <string>
#include <unordered_map>
template <class T, const int info_len = 2, const int kBufSize = 100>
class DriveArray {
private:
static const int kPageSize = 4096;
static const int kDataBiginOffset =
((info_len + 2) * sizeof(int) + kPageSize - 1) / kPageSize * kPageSize;
static const int sizeofT = sizeof(T);
struct DataType {
int next_vacant_data_index;
T val;
};
static const int kBlockSize =
(sizeof(DataType) + kPageSize - 1) / kPageSize * kPageSize;
static const int kDataPerBlock = kBlockSize / sizeof(DataType);
struct BlockType {
DataType data[kDataPerBlock];
};
char rest[kBlockSize - sizeof(BlockType)];
static_assert(kBlockSize % kPageSize == 0, "kBlockSize % kPageSize != 0");
std::string file_name;
int total_block_number = 0, first_vacant_data_index = 0;
/**
* DataIndex=(BlockIndex-1)*kDataPerBlock+InnnerIndex
*/
std::unordered_map<int, BlockType *> cache;
std::queue<int> vis_que;
void LoadCache(int block_index) {
BlockType *tmp = new BlockType;
fs.seekg(kDataBiginOffset + (block_index - 1) * kBlockSize, std::ios::beg);
fs.read(reinterpret_cast<char *>(tmp), sizeof(BlockType));
cache[block_index] = tmp;
vis_que.push(block_index);
}
void ReleaseOldestCache() {
int block_index = vis_que.front();
vis_que.pop();
fs.seekp(kDataBiginOffset + (block_index - 1) * kBlockSize, std::ios::beg);
fs.write(reinterpret_cast<char *>(cache[block_index]), sizeof(BlockType));
delete cache[block_index];
cache.erase(block_index);
}
BlockType *OrderBlock(int block_index) {
if (cache.find(block_index) != cache.end()) return cache[block_index];
if (cache.size() == kBufSize) ReleaseOldestCache();
LoadCache(block_index);
return cache[block_index];
}
int AppEndBlock() {
fs.seekp(0, std::ios::end);
BlockType tmp;
fs.write(reinterpret_cast<char *>(&tmp), sizeof(BlockType));
fs.write(rest, kBlockSize - sizeof(BlockType));
++total_block_number;
return total_block_number;
}
public:
std::fstream fs;
DriveArray() = default;
DriveArray(const DriveArray &) = delete;
DriveArray &operator=(const DriveArray &) = delete;
DriveArray(const std::string &file_name) : file_name(file_name) {
OpenFile(file_name);
}
inline bool IsOpen() const noexcept { return fs.is_open(); }
~DriveArray() { CloseFile(); }
void CloseFile() {
if (!fs.is_open()) return;
while (cache.size() > 0) ReleaseOldestCache();
fs.seekp(sizeof(int) * info_len, std::ios::beg);
fs.write(reinterpret_cast<char *>(&first_vacant_data_index), sizeof(int));
fs.write(reinterpret_cast<char *>(&total_block_number), sizeof(int));
fs.close();
file_name = "";
first_vacant_data_index = 0;
total_block_number = 0;
}
void OpenFile(const std::string &__file_name) {
if (fs.is_open()) CloseFile();
file_name = __file_name;
fs.open(file_name, std::ios::in | std::ios::out | std::ios::binary);
if (!fs.is_open()) {
fs.open(file_name, std::ios::out | std::ios::binary);
fs.seekp(0, std::ios::beg);
int tmp = 0;
total_block_number = 0;
first_vacant_data_index = 0;
for (int i = 0; i < kDataBiginOffset / sizeof(int); ++i) {
fs.write(reinterpret_cast<char *>(&tmp), sizeof(int));
}
fs.close();
fs.open(file_name, std::ios::in | std::ios::out | std::ios::binary);
}
fs.seekg(sizeof(int) * info_len, std::ios::beg);
fs.read(reinterpret_cast<char *>(&first_vacant_data_index), sizeof(int));
fs.read(reinterpret_cast<char *>(&total_block_number), sizeof(int));
}
void initialise(std::string FN = "") {
if (fs.is_open()) {
std::string name_bak = file_name;
CloseFile();
file_name = name_bak;
}
if (FN != "") file_name = FN;
if (file_name == "") return;
fs.open(file_name, std::ios::out | std::ios::binary);
fs.seekp(0, std::ios::beg);
int tmp = 0;
total_block_number = 0;
first_vacant_data_index = 0;
for (int i = 0; i < kDataBiginOffset / sizeof(int); ++i) {
fs.write(reinterpret_cast<char *>(&tmp), sizeof(int));
}
fs.close();
fs.open(file_name, std::ios::in | std::ios::out | std::ios::binary);
}
void get_info(int &tmp, int n) noexcept {
if (n > info_len) return;
fs.seekg((n - 1) * sizeof(int), std::ios::beg);
fs.read(reinterpret_cast<char *>(&tmp), sizeof(int));
}
void write_info(int tmp, int n) noexcept {
if (n > info_len) return;
fs.seekp((n - 1) * sizeof(int), std::ios::beg);
fs.write(reinterpret_cast<char *>(&tmp), sizeof(int));
}
void LoadInfoTo(int *dest) {
fs.seekg(0, std::ios::beg);
fs.read(reinterpret_cast<char *>(dest), sizeof(int) * info_len);
}
void WriteInfoFrom(int *src) {
fs.seekp(0, std::ios::beg);
fs.write(reinterpret_cast<char *>(src), sizeof(int) * info_len);
}
int write(T &t) noexcept {
if (first_vacant_data_index == 0) {
int new_block_index = AppEndBlock();
int index = (new_block_index - 1) * kDataPerBlock + 1;
BlockType *blk_ptr = OrderBlock(new_block_index);
if (kDataPerBlock > 1)
first_vacant_data_index = index + 1;
else
first_vacant_data_index = 0;
for (int i = 1; i < kDataPerBlock - 1; i++)
blk_ptr->data[i].next_vacant_data_index = index + i + 1;
blk_ptr->data[kDataPerBlock - 1].next_vacant_data_index = 0;
blk_ptr->data[0].next_vacant_data_index = 0;
blk_ptr->data[0].val = t;
return index;
} else {
int block_index = (first_vacant_data_index - 1) / kDataPerBlock + 1;
int inner_index = (first_vacant_data_index - 1) % kDataPerBlock + 1;
BlockType *blk_ptr = OrderBlock(block_index);
int index = first_vacant_data_index;
first_vacant_data_index =
blk_ptr->data[inner_index - 1].next_vacant_data_index;
blk_ptr->data[inner_index - 1].next_vacant_data_index = 0;
blk_ptr->data[inner_index - 1].val = t;
return index;
}
}
void update(T &t, const int index) noexcept {
int block_index = (index - 1) / kDataPerBlock + 1;
int inner_index = (index - 1) % kDataPerBlock + 1;
BlockType *blk_ptr = OrderBlock(block_index);
blk_ptr->data[inner_index - 1].val = t;
}
void read(T &t, const int index) noexcept {
int block_index = (index - 1) / kDataPerBlock + 1;
int inner_index = (index - 1) % kDataPerBlock + 1;
BlockType *blk_ptr = OrderBlock(block_index);
t = blk_ptr->data[inner_index - 1].val;
}
void Delete(int index) noexcept {
int block_index = (index - 1) / kDataPerBlock + 1;
int inner_index = (index - 1) % kDataPerBlock + 1;
BlockType *blk_ptr = OrderBlock(block_index);
blk_ptr->data[inner_index - 1].next_vacant_data_index =
first_vacant_data_index;
first_vacant_data_index = index;
}
};
#endif // BPT_DriveArray_HPP