wal.h

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#ifndef GRAPHSCOPE_DATABASE_WAL_H_
#define GRAPHSCOPE_DATABASE_WAL_H_
 
#include <fcntl.h>
#include <sys/mman.h>
#include <unistd.h>
 
#include <algorithm>
#include <filesystem>
#include <queue>
#include <string>
#include <thread>
 
#include "glog/logging.h"
 
namespace gs {
 
struct WalHeader {
  uint32_t timestamp;
  uint8_t type : 1;
  int32_t length : 31;
};
 
struct WalContentUnit {
  char* ptr{NULL};
  size_t size{0};
};
 
struct UpdateWalUnit {
  uint32_t timestamp{0};
  char* ptr{NULL};
  size_t size{0};
};
 
class WalWriter {
  static constexpr size_t TRUNC_SIZE = 1ul << 30;
 
 public:
  WalWriter() : fd_(-1), file_size_(0), file_used_(0) {}
  ~WalWriter() { close(); }
 
  void open(const std::string& prefix, int thread_id);
 
  void close();
 
  void append(const char* data, size_t length);
 
 private:
  int fd_;
  size_t file_size_;
  size_t file_used_;
};
 
class WalsParser {
 public:
  WalsParser(const std::vector<std::string>& paths);
  ~WalsParser();
 
  uint32_t last_ts() const;
  const WalContentUnit& get_insert_wal(uint32_t ts) const;
  const std::vector<UpdateWalUnit>& update_wals() const;
 
 private:
  std::vector<int> fds_;
  std::vector<void*> mmapped_ptrs_;
  std::vector<size_t> mmapped_size_;
  WalContentUnit* insert_wal_list_;
  size_t insert_wal_list_size_;
  uint32_t last_ts_{0};
 
  std::vector<UpdateWalUnit> update_wal_list_;
};
 
}  // namespace gs
 
#endif  // GRAPHSCOPE_DATABASE_WAL_H_