improved ledger account discovery

api/pkg/discovery/metrics.go

@@ -0,0 +1,65 @@
+package discovery
+
+import (
+	"errors"
+	"sync"
+	"time"
+
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/promauto"
+	"github.com/tech/sendico/pkg/merrors"
+)
+
+var (
+	metricsOnce sync.Once
+
+	eventLatency *prometheus.HistogramVec
+	eventStatus  *prometheus.CounterVec
+)
+
+func initMetrics() {
+	metricsOnce.Do(func() {
+		eventLatency = promauto.NewHistogramVec(prometheus.HistogramOpts{
+			Namespace: "sendico",
+			Subsystem: "discovery",
+			Name:      "event_latency_seconds",
+			Help:      "Latency distribution for discovery event handling.",
+			Buckets:   prometheus.DefBuckets,
+		}, []string{"event"})
+
+		eventStatus = promauto.NewCounterVec(prometheus.CounterOpts{
+			Namespace: "sendico",
+			Subsystem: "discovery",
+			Name:      "event_requests_total",
+			Help:      "Total number of discovery events handled, grouped by event and status.",
+		}, []string{"event", "status"})
+	})
+}
+
+func observeEvent(event string, err error, duration time.Duration) {
+	if eventLatency != nil {
+		eventLatency.WithLabelValues(event).Observe(duration.Seconds())
+	}
+	if eventStatus != nil {
+		eventStatus.WithLabelValues(event, statusLabel(err)).Inc()
+	}
+}
+
+func statusLabel(err error) string {
+	switch {
+	case err == nil:
+		return "ok"
+	case errors.Is(err, merrors.ErrInvalidArg):
+		return "invalid_argument"
+	case errors.Is(err, merrors.ErrNoData):
+		return "not_found"
+	case errors.Is(err, merrors.ErrDataConflict):
+		return "conflict"
+	case errors.Is(err, merrors.ErrAccessDenied):
+		return "denied"
+	case errors.Is(err, merrors.ErrInternal):
+		return "internal"
+	default:
+		return "error"
+	}
+}