package addservice
import (
"context"
"github.com/go-kit/kit/log"
"github.com/go-kit/kit/metrics"
)
// Middleware describes a service (as opposed to endpoint) middleware.
type Middleware func(Service) Service
// LoggingMiddleware takes a logger as a dependency
// and returns a ServiceMiddleware.
func LoggingMiddleware(logger log.Logger) Middleware {
return func(next Service) Service {
return loggingMiddleware{logger, next}
}
}
type loggingMiddleware struct {
logger log.Logger
next Service
}
func (mw loggingMiddleware) Sum(ctx context.Context, a, b int) (v int, err error) {
defer func() {
mw.logger.Log("method", "Sum", "a", a, "b", b, "v", v, "err", err)
}()
return mw.next.Sum(ctx, a, b)
}
func (mw loggingMiddleware) Concat(ctx context.Context, a, b string) (v string, err error) {
defer func() {
mw.logger.Log("method", "Concat", "a", a, "b", b, "v", v, "err", err)
}()
return mw.next.Concat(ctx, a, b)
}
// InstrumentingMiddleware returns a service middleware that instruments
// the number of integers summed and characters concatenated over the lifetime of
// the service.
func InstrumentingMiddleware(ints, chars metrics.Counter) Middleware {
return func(next Service) Service {
return instrumentingMiddleware{
ints: ints,
chars: chars,
next: next,
}
}
}
type instrumentingMiddleware struct {
ints metrics.Counter
chars metrics.Counter
next Service
}
func (mw instrumentingMiddleware) Sum(ctx context.Context, a, b int) (int, error) {
v, err := mw.next.Sum(ctx, a, b)
mw.ints.Add(float64(v))
return v, err
}
func (mw instrumentingMiddleware) Concat(ctx context.Context, a, b string) (string, error) {
v, err := mw.next.Concat(ctx, a, b)
mw.chars.Add(float64(len(v)))
return v, err
}