wal.h

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#ifndef ENGINES_GRAPH_DB_DATABASE_WAL_WAL_H_
#define ENGINES_GRAPH_DB_DATABASE_WAL_WAL_H_
 
#include <fcntl.h>
#include <sys/mman.h>
#include <unistd.h>
 
#include <algorithm>
#include <filesystem>
#include <queue>
#include <string>
#include <thread>
#include <unordered_map>
 
#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};
};
 
std::string get_wal_uri_scheme(const std::string& uri);
std::string get_wal_uri_path(const std::string& uri);
 
class IWalWriter {
 public:
  virtual ~IWalWriter() {}
 
  virtual std::string type() const = 0;
  virtual void open(const std::string& uri, int thread_id) = 0;
 
  virtual void close() = 0;
 
  virtual bool append(const char* data, size_t length) = 0;
};
 
class IWalParser {
 public:
  virtual ~IWalParser() {}
 
  virtual void open(const std::string& wal_uri) = 0;
 
  virtual void close() = 0;
 
  virtual uint32_t last_ts() const = 0;
 
  /*
   * Get the insert wal unit with the given timestamp.
   */
  virtual const WalContentUnit& get_insert_wal(uint32_t ts) const = 0;
 
  virtual const std::vector<UpdateWalUnit>& get_update_wals() const = 0;
};
 
class WalWriterFactory {
 public:
  using wal_writer_initializer_t = std::unique_ptr<IWalWriter> (*)();
 
  static void Init();
 
  static void Finalize();
 
  static std::unique_ptr<IWalWriter> CreateWalWriter(
      const std::string& wal_uri);
 
  static bool RegisterWalWriter(const std::string& wal_writer_type,
                                wal_writer_initializer_t initializer);
 
 private:
  static std::unordered_map<std::string, wal_writer_initializer_t>&
  getKnownWalWriters();
};
 
class WalParserFactory {
 public:
  using wal_writer_initializer_t = std::unique_ptr<IWalWriter> (*)();
  using wal_parser_initializer_t =
      std::unique_ptr<IWalParser> (*)(const std::string& wal_dir);
 
  static void Init();
 
  static void Finalize();
 
  static std::unique_ptr<IWalParser> CreateWalParser(
      const std::string& wal_uri);
 
  static bool RegisterWalParser(const std::string& wal_parser_type,
                                wal_parser_initializer_t initializer);
 
 private:
  static std::unordered_map<std::string, wal_parser_initializer_t>&
  getKnownWalParsers();
};
 
}  // namespace gs
 
#endif  // ENGINES_GRAPH_DB_DATABASE_WAL_WAL_H_