package main
import (
"fmt"
"time"
"github.com/go-kit/kit/metrics"
)
func instrumentingMiddleware(
requestCount metrics.Counter,
requestLatency metrics.TimeHistogram,
countResult metrics.Histogram,
) ServiceMiddleware {
return func(next StringService) StringService {
return instrmw{requestCount, requestLatency, countResult, next}
}
}
type instrmw struct {
requestCount metrics.Counter
requestLatency metrics.TimeHistogram
countResult metrics.Histogram
StringService
}
func (mw instrmw) Uppercase(s string) (output string, err error) {
defer func(begin time.Time) {
methodField := metrics.Field{Key: "method", Value: "uppercase"}
errorField := metrics.Field{Key: "error", Value: fmt.Sprintf("%v", err)}
mw.requestCount.With(methodField).With(errorField).Add(1)
mw.requestLatency.With(methodField).With(errorField).Observe(time.Since(begin))
}(time.Now())
output, err = mw.StringService.Uppercase(s)
return
}
func (mw instrmw) Count(s string) (n int) {
defer func(begin time.Time) {
methodField := metrics.Field{Key: "method", Value: "count"}
errorField := metrics.Field{Key: "error", Value: fmt.Sprintf("%v", error(nil))}
mw.requestCount.With(methodField).With(errorField).Add(1)
mw.requestLatency.With(methodField).With(errorField).Observe(time.Since(begin))
mw.countResult.Observe(int64(n))
}(time.Now())
n = mw.StringService.Count(s)
return
}