code: func (mgr *blockfileMgr) loadCurrentInfo() (*checkpointInfo, error) {
  	var b []byte
  	var err error
  	if b, err = mgr.db.Get(blkMgrInfoKey); b == nil || err != nil {
  		return nil, err
  	}
  	i := &checkpointInfo{}
  	if err = i.unmarshal(b); err != nil {
  		return nil, err
  	}
  	logger.Debugf("loaded checkpointInfo:%s", i)
  	return i, nil
  }
docs: //Get the current checkpoint information that is stored in the database