Add application handler result to metrics

service/adapters/prometheus/prometheus.go

@@ -13,6 +13,10 @@ const (
 	labelHandlerName          = "handlerName"
 	labelRelayDownloaderState = "state"
 	labelTopic                = "topic"
+
+	labelResult        = "result"
+	labelResultSuccess = "success"
+	labelResultError   = "error"
 )
 
 type Prometheus struct {
@@ -31,14 +35,14 @@ func NewPrometheus(logger logging.Logger) *Prometheus {
 				Name: "application_handler_calls_total",
 				Help: "Total number of calls to application handlers.",
 			},
-			[]string{labelHandlerName},
+			[]string{labelHandlerName, labelResult},
 		),
 		applicationHandlerCallDurationHistogram: promauto.NewHistogramVec(
 			prometheus.HistogramOpts{
 				Name: "application_handler_calls_duration",
 				Help: "Duration of calls to application handlers in seconds.",
 			},
-			[]string{labelHandlerName},
+			[]string{labelHandlerName, labelResult},
 		),
 		relayDownloaderStateGauge: promauto.NewGaugeVec(
 			prometheus.GaugeOpts{
@@ -87,14 +91,30 @@ func NewApplicationCall(p *Prometheus, handlerName string, logger logging.Logger
 	}
 }
 
-func (a *ApplicationCall) End() {
+func (a *ApplicationCall) End(err error) {
 	duration := time.Since(a.start)
 
 	a.logger.Debug().
 		WithField("handlerName", a.handlerName).
 		WithField("duration", duration).
+		WithError(err).
 		Message("application call")
 
-	a.p.applicationHandlerCallsCounter.With(prometheus.Labels{labelHandlerName: a.handlerName}).Inc()
-	a.p.applicationHandlerCallDurationHistogram.With(prometheus.Labels{labelHandlerName: a.handlerName}).Observe(duration.Seconds())
+	labels := a.getLabels(err)
+	a.p.applicationHandlerCallsCounter.With(labels).Inc()
+	a.p.applicationHandlerCallDurationHistogram.With(labels).Observe(duration.Seconds())
+}
+
+func (a *ApplicationCall) getLabels(err error) prometheus.Labels {
+	labels := prometheus.Labels{
+		labelHandlerName: a.handlerName,
+	}
+
+	if err == nil {
+		labels[labelResult] = labelResultSuccess
+	} else {
+		labels[labelResult] = labelResultError
+	}
+
+	return labels
 }

service/app/app.go

@@ -119,5 +119,5 @@ type Metrics interface {
 }
 
 type ApplicationCall interface {
-	End()
+	End(err error)
 }

service/app/handler_get_events.go

@@ -56,7 +56,7 @@ func NewGetEventsHandler(
 }
 
 func (h *GetEventsHandler) Handle(ctx context.Context, filters domain.Filters) <-chan EventOrEOSEOrError {
-	defer h.metrics.TrackApplicationCall("getEvents").End()
+	defer h.metrics.TrackApplicationCall("getEvents").End(nil)
 
 	ch := make(chan EventOrEOSEOrError)
 	go h.send(ctx, filters, ch)

service/app/handler_get_public_keys.go

@@ -22,8 +22,8 @@ func NewGetPublicKeysHandler(
 	}
 }
 
-func (h *GetPublicKeysHandler) Handle(ctx context.Context, relay domain.RelayAddress) ([]domain.PublicKey, error) {
-	defer h.metrics.TrackApplicationCall("getPublicKeys").End()
+func (h *GetPublicKeysHandler) Handle(ctx context.Context, relay domain.RelayAddress) (keys []domain.PublicKey, err error) {
+	defer func() { h.metrics.TrackApplicationCall("getPublicKeys").End(err) }()
 
 	var result []domain.PublicKey
 	if err := h.transactionProvider.Transact(ctx, func(ctx context.Context, adapters Adapters) error {

service/app/handler_get_relays.go

@@ -22,8 +22,8 @@ func NewGetRelaysHandler(
 	}
 }
 
-func (h *GetRelaysHandler) Handle(ctx context.Context) ([]domain.RelayAddress, error) {
-	defer h.metrics.TrackApplicationCall("getRelays").End()
+func (h *GetRelaysHandler) Handle(ctx context.Context) (addresses []domain.RelayAddress, err error) {
+	defer func() { h.metrics.TrackApplicationCall("getRelays").End(err) }()
 
 	var result []domain.RelayAddress
 	if err := h.transactionProvider.Transact(ctx, func(ctx context.Context, adapters Adapters) error {

service/app/handler_get_tokens.go

@@ -22,8 +22,8 @@ func NewGetTokensHandler(
 	}
 }
 
-func (h *GetTokensHandler) Handle(ctx context.Context, publicKey domain.PublicKey) ([]domain.APNSToken, error) {
-	defer h.metrics.TrackApplicationCall("getTokens").End()
+func (h *GetTokensHandler) Handle(ctx context.Context, publicKey domain.PublicKey) (tokens []domain.APNSToken, err error) {
+	defer func() { h.metrics.TrackApplicationCall("getTokens").End(err) }()
 
 	var result []domain.APNSToken
 	if err := h.transactionProvider.Transact(ctx, func(ctx context.Context, adapters Adapters) error {

service/app/handler_process_saved_event.go

@@ -47,8 +47,8 @@ func NewProcessSavedEventHandler(
 	}
 }
 
-func (h *ProcessSavedEventHandler) Handle(ctx context.Context, cmd ProcessSavedEvent) error {
-	defer h.metrics.TrackApplicationCall("processSavedEvent").End()
+func (h *ProcessSavedEventHandler) Handle(ctx context.Context, cmd ProcessSavedEvent) (err error) {
+	defer func() { h.metrics.TrackApplicationCall("processSavedEvent").End(err) }()
 
 	logger := h.logger.WithField("event.id", cmd.eventId.Hex())
 

service/app/handler_save_received_event.go

@@ -36,8 +36,8 @@ func NewSaveReceivedEventHandler(
 	}
 }
 
-func (h *SaveReceivedEventHandler) Handle(ctx context.Context, cmd SaveReceivedEvent) error {
-	defer h.metrics.TrackApplicationCall("saveReceivedEvent").End()
+func (h *SaveReceivedEventHandler) Handle(ctx context.Context, cmd SaveReceivedEvent) (err error) {
+	defer func() { h.metrics.TrackApplicationCall("saveReceivedEvent").End(err) }()
 
 	if !domain.ShouldDownloadEventKind(cmd.event.Kind()) {
 		return fmt.Errorf("event '%s' shouldn't have been downloaded", cmd.event.String())

service/app/handler_save_registration.go

@@ -33,8 +33,8 @@ func NewSaveRegistrationHandler(
 	}
 }
 
-func (h *SaveRegistrationHandler) Handle(ctx context.Context, cmd SaveRegistration) error {
-	defer h.metrics.TrackApplicationCall("saveRegistration").End()
+func (h *SaveRegistrationHandler) Handle(ctx context.Context, cmd SaveRegistration) (err error) {
+	defer func() { h.metrics.TrackApplicationCall("saveRegistration").End(err) }()
 
 	h.logger.Debug().
 		WithField("apnsToken", cmd.registration.APNSToken().Hex()).