func ExampleTimer_gauge() error {
// The Set method of the Gauge is used to observe the duration.
timer := prometheus.NewTimer(prometheus.ObserverFunc(funcDuration.Set))
defer timer.ObserveDuration()
// Do something. Return errors as encountered. The use of 'defer' above
// makes sure the function is still timed properly.
return nil
}
func handler(w http.ResponseWriter, r *http.Request) {
status := http.StatusOK
// The ObserverFunc gets called by the deferred ObserveDuration and
// decides wich Histogram's Observe method is called.
timer := prometheus.NewTimer(prometheus.ObserverFunc(func(v float64) {
switch {
case status >= 500: // Server error.
apiRequestDuration.WithLabelValues("5xx").Observe(v)
case status >= 400: // Client error.
apiRequestDuration.WithLabelValues("4xx").Observe(v)
case status >= 300: // Redirection.
apiRequestDuration.WithLabelValues("3xx").Observe(v)
case status >= 200: // Success.
apiRequestDuration.WithLabelValues("2xx").Observe(v)
default: // Informational.
apiRequestDuration.WithLabelValues("1xx").Observe(v)
}
}))
defer timer.ObserveDuration()
// Handle the request. Set status accordingly.
// ...
}