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docs: optimize drivearray

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This commit is contained in:
ZhuangYumin
2023-12-07 14:11:42 +00:00
parent a28a89ccce
commit 1b62026eca
1 changed files with 31 additions and 11 deletions
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42
backend/include/drivearray.hpp
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@ -27,6 +27,8 @@ class DriveArray {
};
char rest[kBlockSize];
static_assert(kBlockSize % kPageSize == 0, "kBlockSize % kPageSize != 0");
static_assert(kBlockSize >= sizeof(BlockType),
"kBlockSize < sizeof(BlockType)");
std::string file_name;
int total_block_number = 0, first_vacant_data_index = 0;
/**
@ -34,8 +36,9 @@ class DriveArray {
*/
std::unordered_map<int, BlockType *> cache;
std::queue<int> vis_que;
BlockType *cache_mem, **cache_mem_ptr, **cache_mem_ptr_beg;
void LoadCache(int block_index) {
BlockType *tmp = new BlockType;
BlockType *tmp = *(--cache_mem_ptr);
fs.seekg(kDataBiginOffset + (block_index - 1) * kBlockSize, std::ios::beg);
fs.read(reinterpret_cast<char *>(tmp), sizeof(BlockType));
cache[block_index] = tmp;
@ -46,7 +49,7 @@ class DriveArray {
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_mem_ptr++) = cache[block_index];
cache.erase(block_index);
}
BlockType *OrderBlock(int block_index) {
@ -57,9 +60,7 @@ class DriveArray {
}
int AppEndBlock() {
if (cache.size() == kBufSize) ReleaseOldestCache();
BlockType *tmp = new BlockType;
// fs.write(reinterpret_cast<char *>(tmp), sizeof(BlockType));
// fs.write(rest, kBlockSize - sizeof(BlockType));
BlockType *tmp = *(--cache_mem_ptr);
fs.seekp(0, std::ios::end);
fs.write(rest, kBlockSize);
++total_block_number;
@ -70,15 +71,32 @@ class DriveArray {
public:
std::fstream fs;
DriveArray() = default;
DriveArray() {
cache_mem = new BlockType[kBufSize + 5];
typedef BlockType *BlockTypePtr;
cache_mem_ptr = new BlockTypePtr[kBufSize + 5];
for (int i = 0; i < kBufSize + 5; i++) cache_mem_ptr[i] = &cache_mem[i];
cache_mem_ptr_beg = cache_mem_ptr;
cache_mem_ptr += kBufSize + 5;
}
DriveArray(const DriveArray &) = delete;
DriveArray &operator=(const DriveArray &) = delete;
DriveArray(const std::string &file_name) : file_name(file_name) {
cache_mem = new BlockType[kBufSize + 5];
typedef BlockType *BlockTypePtr;
cache_mem_ptr = new BlockTypePtr[kBufSize + 5];
for (int i = 0; i < kBufSize + 5; i++) cache_mem_ptr[i] = &cache_mem[i];
cache_mem_ptr_beg = cache_mem_ptr;
cache_mem_ptr += kBufSize + 5;
OpenFile(file_name);
}
inline bool IsOpen() const noexcept { return fs.is_open(); }
~DriveArray() { CloseFile(); }
~DriveArray() {
CloseFile();
delete[] cache_mem;
delete[] cache_mem_ptr_beg;
}
void CloseFile() {
if (!fs.is_open()) return;
while (cache.size() > 0) ReleaseOldestCache();
@ -100,8 +118,9 @@ class DriveArray {
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));
memset(rest, 0, kPageSize);
for (int i = 0; i < kDataBiginOffset / kPageSize; ++i) {
fs.write(reinterpret_cast<char *>(rest), kPageSize);
}
fs.close();
fs.open(file_name, std::ios::in | std::ios::out | std::ios::binary);
@ -123,8 +142,9 @@ class DriveArray {
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));
memset(rest, 0, kPageSize);
for (int i = 0; i < kDataBiginOffset / kPageSize; ++i) {
fs.write(reinterpret_cast<char *>(rest), kPageSize);
}
fs.close();
fs.open(file_name, std::ios::in | std::ios::out | std::ios::binary);