message: Use timer helper
diff: @@ -12,7 +12,6 @@ import (
  "io"
  "io/ioutil"
  "net/http"
  - "time"
  )
  var (
  @@ -175,9 +174,8 @@ func writeRPCError(w http.ResponseWriter, id *int, code int, msg string) {
  func instrumentedHdlr(h http.Handler) http.HandlerFunc {
  return func(w http.ResponseWriter, r *http.Request) {
  httpRequestsCtr.Inc()
  - start := time.Now()
  + timer := prometheus.NewTimer(httpRequestDurationSummary)
  + defer timer.ObserveDuration()
  h.ServeHTTP(w, r)
  - dur := time.Since(start)
  - httpRequestDurationSummary.Observe(float64(dur) / float64(time.Second))
  }
  }
  