+ bool IsOldObject(const std::string &checksum, int64_t size, double *age,
+ int *group);
+ bool IsAvailable(const ObjectReference &ref);
+ void UseObject(const ObjectReference& ref);
+
+ void SetSegmentChecksum(const std::string &segment, const std::string &path,
+ const std::string &checksum);
+ bool GetSegmentChecksum(const std::string &segment,
+ std::string *seg_path, std::string *seg_checksum);