func metricsMiddleware(requestCount metrics.Counter) endpoint.Middleware {
return func(next endpoint.Endpoint) endpoint.Endpoint {
return func(ctx context.Context, request interface{}) (interface{}, error) {
requestCount.Add(1)
return next(ctx, request)
}
}
}
func httpInstrument(requests metrics.Counter, duration metrics.Histogram) func(http.Handler) http.Handler {
return func(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
requests.Add(1)
defer func(begin time.Time) { duration.Observe(time.Since(begin).Nanoseconds()) }(time.Now())
next.ServeHTTP(w, r)
})
}
}
func instrument(requests metrics.Counter, duration metrics.TimeHistogram) func(Add) Add {
return func(next Add) Add {
return func(ctx context.Context, a, b int64) int64 {
defer func(begin time.Time) {
requests.Add(1)
duration.Observe(time.Since(begin))
}(time.Now())
return next(ctx, a, b)
}
}
}
// TestCounter puts some deltas through the counter, and then calls the value
// func to check that the counter has the correct final value.
func TestCounter(counter metrics.Counter, value func() float64) error {
a := rand.Perm(100)
n := rand.Intn(len(a))
var want float64
for i := 0; i < n; i++ {
f := float64(a[i])
counter.Add(f)
want += f
}
if have := value(); want != have {
return fmt.Errorf("want %f, have %f", want, have)
}
return nil
}