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128 lines
3.0 KiB
128 lines
3.0 KiB
//
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// Created by 马也驰 on 2025/1/4.
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//
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#ifndef LEVELDB_VLOG_CACHE_H
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#define LEVELDB_VLOG_CACHE_H
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#include <cassert>
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#include <mutex>
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#include <string>
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#define BLOCK_SIZE 4096
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struct frame_info {
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std::mutex info_latch_;
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bool used;
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std::string vlog_name;
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size_t vlog_block_num;
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bool is_dirty;
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inline void set_used() {
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info_latch_.lock();
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assert(used == false);
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used = true;
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info_latch_.unlock();
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}
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inline void set_unused() {
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info_latch_.lock();
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assert(used == true);
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used = false;
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info_latch_.unlock();
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}
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inline void set_dirty() {
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info_latch_.lock();
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assert(is_dirty == false);
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is_dirty = true;
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info_latch_.unlock();
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}
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inline void set_nondirty() {
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info_latch_.lock();
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assert(is_dirty == true);
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is_dirty = false;
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info_latch_.unlock();
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}
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inline void set_vlog_block_num(size_t vb) {
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info_latch_.lock();
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vlog_block_num = vb;
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info_latch_.unlock();
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}
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inline void set_vlog_name(std::string &vn) {
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info_latch_.lock();
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vlog_name = vn;
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info_latch_.unlock();
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}
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inline bool cache_hit(std::string &vn, size_t vbn) {
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return used && (vlog_name == vn) && (vlog_block_num == vbn);
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}
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};
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struct block_frame {
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// 读,写,块置换 必须对这个mutex上锁，保证线性化
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// 读写必须对这个mutex上锁，保证线性化
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std::mutex mtx;
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frame_info frame_info_;
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char *block_buff;
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block_frame() {
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frame_info_.used = false;
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frame_info_.is_dirty = false;
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block_buff = static_cast<char*>(malloc(BLOCK_SIZE));
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}
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void free_block_buff() {
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free(block_buff);
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}
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};
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class VlogCache {
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#define BLOCK_NUMS 1024
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#define VALUE_ACROSS_BLOCK(offset, len) (((offset)/BLOCK_SIZE) != (((offset)+(len)-1)/BLOCK_SIZE))
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#define DATA_SIZE_MASK 0x7fff
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#define DATA_DELE_MASK 0x8000
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public:
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VlogCache() {
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for (auto i = 0; i < BLOCK_NUMS; i++) {
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block_frames[i] = new block_frame();
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}
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}
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~VlogCache() {
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flush_all_blocks();
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for (auto i = 0; i < BLOCK_NUMS; i++) {
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block_frames[i]->free_block_buff();
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}
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}
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public:
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void read_data(std::string &vlog_name, std::string& value, size_t offset, size_t len);
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void write_data(std::string &vlog_name, std::string& value, size_t offset, size_t len);
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uint16_t delete_data(std::string &vlog_name, size_t offset);
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private:
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void read_data_inblock(std::string &vlog_name, std::string& value, size_t offset, size_t len);
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void write_data_inblock(std::string &vlog_name, std::string& value, size_t offset, size_t len);
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void write_back_block(size_t block_num);
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void read_in_block(size_t block_num, std::string &vlog_name, size_t vlog_block_num);
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private:
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void flush_all_blocks();
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inline size_t offset_2_blocknum(size_t offset) {
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return (offset / BLOCK_SIZE) % BLOCK_NUMS;
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}
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inline size_t offset_2_inblock_offset(size_t offset) {
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return offset % BLOCK_SIZE;
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}
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private:
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block_frame *block_frames[BLOCK_NUMS];
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};
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#endif // LEVELDB_VLOG_CACHE_H
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