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//
// Created by 马也驰 on 2024/12/29.
//
#ifndef LEVELDB_VLOG_GC_H
#define LEVELDB_VLOG_GC_H
#include <string>
#include <mutex>
#include "../db/slotpage.h"
#include "../db/vlog.h"
#include "../db/gc_executor.h"
// 前向声明 VlogSet
class VlogSet;
class VlogGC {
#define THREAD_NUM 8
friend class gc_executor;
public:
VlogGC(SlotPage *s, VlogSet *vs) : slot_page_(s), vlog_set(vs),max_thread_nums_(THREAD_NUM),
curr_thread_nums_(0), gc_num(0) {}
~VlogGC() {}
void do_gc(size_t old_vlog_num, size_t new_vlog_num);
private:
void exec_gc(size_t gc_num_);
void gc_counter_increment();
void gc_counter_decrement();
inline bool value_deleted(uint16_t value_len) {
return !(value_len >> 15);
}
inline uint16_t get_value_len(char *value) {
uint16_t value_len;
memcpy(&value_len, value, sizeof(uint16_t));
return value_len;
}
inline size_t get_value_slotnum(char *value) {
size_t slot_num;
memcpy(&slot_num, &value[sizeof(uint16_t)], sizeof(size_t));
return slot_num;
}
inline size_t get_gc_num() {
gc_num_latch_.lock();
size_t _gc_num_ = gc_num ++;
gc_num_latch_.unlock();
return _gc_num_;
}
inline bool vlog_in_gc(size_t vlog_num) {
ovn_map_latch_.lock();
bool flag = false;
if (ovn_map_.find(vlog_num) != ovn_map_.end()) {
flag = true;
}
ovn_map_latch_.unlock();
return flag;
}
inline void add_vlog_in_gc(size_t vlog_num) {
ovn_map_latch_.lock();
ovn_map_[vlog_num] = true;
ovn_map_latch_.unlock();
}
inline void del_vlog_in_gc(size_t vlog_num) {
ovn_map_latch_.lock();
ovn_map_.erase(vlog_num);
ovn_map_latch_.unlock();
}
SlotPage *slot_page_;
VlogSet *vlog_set; // 仅声明为指针,具体定义放在 vlog_gc.cpp
// NOTE: threadpool
std::mutex full_latch_; // indicate thread pool is full when set as locked
size_t max_thread_nums_;
std::mutex curr_thread_nums_latch_;
size_t curr_thread_nums_;
std::mutex gc_num_latch_;
size_t gc_num;
std::mutex ovn_map_latch_;
std::unordered_map<size_t, bool> ovn_map_;
};
#endif // LEVELDB_VLOG_GC_H