code: func Init() {
  	driver := tikv.Driver{}
  	var err error
  	store, err = driver.Open(fmt.Sprintf("tikv://%s?cluster=1", *pdAddr))
  	terror.MustNil(err)
  
  	prometheus.MustRegister(txnCounter)
  	prometheus.MustRegister(txnRolledbackCounter)
  	prometheus.MustRegister(txnDurations)
  	http.Handle("/metrics", prometheus.Handler())
  
  	go func() {
  		err1 := http.ListenAndServe(":9191", nil)
  		terror.Log(errors.Trace(err1))
  	}()
  }
docs: // Init initializes information.