//rdb API

 int rdbSaveType(rio *rdb, unsigned char type);

 int rdbLoadType(rio *rdb);

 int rdbSaveTime(rio *rdb, time_t t);

 time_t rdbLoadTime(rio *rdb);

 int rdbSaveLen(rio *rdb, uint32_t len);

 uint32_t rdbLoadLen(rio *rdb, int *isencoded);

 int rdbSaveObjectType(rio *rdb, robj *o);

 int rdbLoadObjectType(rio *rdb);

 int rdbLoad(char *filename);

 int rdbSaveBackground(char *filename);

 void rdbRemoveTempFile(pid_t childpid);

 int rdbSave(char *filename);

 int rdbSaveObject(rio *rdb, robj *o);

 off_t rdbSavedObjectLen(robj *o);

 off_t rdbSavedObjectPages(robj *o);

 robj *rdbLoadObject(int type, rio *rdb);

 void backgroundSaveDoneHandler(int exitcode, int bysignal);

 int rdbSaveKeyValuePair(rio *rdb, robj *key, robj *val, long long expiretime, long long now);

 robj *rdbLoadStringObject(rio *rdb);