Initial QSfera import

Server/services/invitations/pkg/service/v0/instrument.go

@@ -0,0 +1,38 @@
+package service
+
+import (
+	"context"
+
+	"github.com/qsfera/server/services/invitations/pkg/invitations"
+	"github.com/qsfera/server/services/invitations/pkg/metrics"
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+// NewInstrument returns a service that instruments metrics.
+func NewInstrument(next Service, metrics *metrics.Metrics) Service {
+	return instrument{
+		next:    next,
+		metrics: metrics,
+	}
+}
+
+type instrument struct {
+	next    Service
+	metrics *metrics.Metrics
+}
+
+// Invite implements the Service interface.
+func (i instrument) Invite(ctx context.Context, invitation *invitations.Invitation) (*invitations.Invitation, error) {
+	timer := prometheus.NewTimer(prometheus.ObserverFunc(func(v float64) {
+		us := v * 1000000
+
+		i.metrics.Latency.WithLabelValues().Observe(us)
+		i.metrics.Duration.WithLabelValues().Observe(v)
+	}))
+
+	defer timer.ObserveDuration()
+
+	i.metrics.Counter.WithLabelValues().Inc()
+
+	return i.next.Invite(ctx, invitation)
+}