docs: public boolean backup() {
  		Date lastBackupTime = this.getLastBackupTime();
  		boolean isLastTime = this.isLastTime(lastBackupTime);
  		if (!isLastTime) {
  			// 别的redis连接已经备份过.
  			return false;
  		}
  		this.bgsave();
  		// this.bgrewriteaof();
  		return true;
  	}