WIP: move error out of function signature

component/componenttest/nop_telemetry.go

@@ -21,8 +21,7 @@ func NewNopTelemetrySettings() component.TelemetrySettings {
 		MeterProvider:  noopmetric.NewMeterProvider(),
 		MetricsLevel:   configtelemetry.LevelNone,
 		Resource:       pcommon.NewResource(),
-		ReportComponentStatus: func(*component.StatusEvent) error {
-			return nil
+		ReportComponentStatus: func(*component.StatusEvent) {
 		},
 	}
 }

component/telemetry.go

@@ -37,13 +37,6 @@ type TelemetrySettings struct {
 
 	// ReportComponentStatus allows a component to report runtime changes in status. The service
 	// will automatically report status for a component during startup and shutdown. Components can
-	// use this method to report status after start and before shutdown. ReportComponentStatus
-	// will only return errors if the API used incorrectly. The two scenarios where an error will
-	// be returned are:
-	//
-	//   - An illegal state transition
-	//   - Calling this method before component startup
-	//
-	// If the API is being used properly, these errors are safe to ignore.
-	ReportComponentStatus func(*StatusEvent) error
+	// use this method to report status after start and before shutdown.
+	ReportComponentStatus func(*StatusEvent)
 }

service/extensions/extensions.go

@@ -37,18 +37,18 @@ func (bes *Extensions) Start(ctx context.Context, host component.Host) error {
 		extLogger.Info("Extension is starting...")
 		instanceID := bes.instanceIDs[extID]
 		ext := bes.extMap[extID]
-		_ = bes.telemetry.Status.ReportComponentStatus(
+		bes.telemetry.Status.ReportComponentStatus(
 			instanceID,
 			component.NewStatusEvent(component.StatusStarting),
 		)
 		if err := ext.Start(ctx, components.NewHostWrapper(host, extLogger)); err != nil {
-			_ = bes.telemetry.Status.ReportComponentStatus(
+			bes.telemetry.Status.ReportComponentStatus(
 				instanceID,
 				component.NewPermanentErrorEvent(err),
 			)
 			return err
 		}
-		_ = bes.telemetry.Status.ReportComponentOKIfStarting(instanceID)
+		bes.telemetry.Status.ReportComponentOKIfStarting(instanceID)
 		extLogger.Info("Extension started.")
 	}
 	return nil
@@ -62,19 +62,19 @@ func (bes *Extensions) Shutdown(ctx context.Context) error {
 		extID := bes.extensionIDs[i]
 		instanceID := bes.instanceIDs[extID]
 		ext := bes.extMap[extID]
-		_ = bes.telemetry.Status.ReportComponentStatus(
+		bes.telemetry.Status.ReportComponentStatus(
 			instanceID,
 			component.NewStatusEvent(component.StatusStopping),
 		)
 		if err := ext.Shutdown(ctx); err != nil {
-			_ = bes.telemetry.Status.ReportComponentStatus(
+			bes.telemetry.Status.ReportComponentStatus(
 				instanceID,
 				component.NewPermanentErrorEvent(err),
 			)
 			errs = multierr.Append(errs, err)
 			continue
 		}
-		_ = bes.telemetry.Status.ReportComponentStatus(
+		bes.telemetry.Status.ReportComponentStatus(
 			instanceID,
 			component.NewStatusEvent(component.StatusStopped),
 		)

service/extensions/extensions_test.go

@@ -434,6 +434,8 @@ func TestStatusReportedOnStartupShutdown(t *testing.T) {
 			var actualStatuses []*component.StatusEvent
 			rep := status.NewReporter(func(id *component.InstanceID, ev *component.StatusEvent) {
 				actualStatuses = append(actualStatuses, ev)
+			}, func(err error) {
+				require.NoError(t, err)
 			})
 			extensions.telemetry.Status = rep
 			rep.Ready()

service/internal/graph/graph.go

@@ -388,20 +388,20 @@ func (g *Graph) StartAll(ctx context.Context, host component.Host) error {
 		}
 
 		instanceID := g.instanceIDs[node.ID()]
-		_ = g.telemetry.Status.ReportComponentStatus(
+		g.telemetry.Status.ReportComponentStatus(
 			instanceID,
 			component.NewStatusEvent(component.StatusStarting),
 		)
 
 		if compErr := comp.Start(ctx, host); compErr != nil {
-			_ = g.telemetry.Status.ReportComponentStatus(
+			g.telemetry.Status.ReportComponentStatus(
 				instanceID,
 				component.NewPermanentErrorEvent(compErr),
 			)
 			return compErr
 		}
 
-		_ = g.telemetry.Status.ReportComponentOKIfStarting(instanceID)
+		g.telemetry.Status.ReportComponentOKIfStarting(instanceID)
 	}
 	return nil
 }
@@ -427,21 +427,21 @@ func (g *Graph) ShutdownAll(ctx context.Context) error {
 		}
 
 		instanceID := g.instanceIDs[node.ID()]
-		_ = g.telemetry.Status.ReportComponentStatus(
+		g.telemetry.Status.ReportComponentStatus(
 			instanceID,
 			component.NewStatusEvent(component.StatusStopping),
 		)
 
 		if compErr := comp.Shutdown(ctx); compErr != nil {
 			errs = multierr.Append(errs, compErr)
-			_ = g.telemetry.Status.ReportComponentStatus(
+			g.telemetry.Status.ReportComponentStatus(
 				instanceID,
 				component.NewPermanentErrorEvent(compErr),
 			)
 			continue
 		}
 
-		_ = g.telemetry.Status.ReportComponentStatus(
+		g.telemetry.Status.ReportComponentStatus(
 			instanceID,
 			component.NewStatusEvent(component.StatusStopped),
 		)

service/internal/graph/graph_test.go

@@ -2337,6 +2337,8 @@ func TestStatusReportedOnStartupShutdown(t *testing.T) {
 			actualStatuses := make(map[*component.InstanceID][]*component.StatusEvent)
 			rep := status.NewReporter(func(id *component.InstanceID, ev *component.StatusEvent) {
 				actualStatuses[id] = append(actualStatuses[id], ev)
+			}, func(err error) {
+				require.NoError(t, err)
 			})
 
 			pg.telemetry.Status = rep

service/internal/servicetelemetry/nop_telemetry_settings.go

@@ -22,6 +22,6 @@ func NewNopTelemetrySettings() TelemetrySettings {
 		MeterProvider:  noopmetric.NewMeterProvider(),
 		MetricsLevel:   configtelemetry.LevelNone,
 		Resource:       pcommon.NewResource(),
-		Status:         status.NewReporter(func(*component.InstanceID, *component.StatusEvent) {}),
+		Status:         status.NewReporter(func(*component.InstanceID, *component.StatusEvent) {}, func(err error) {}),
 	}
 }

service/internal/servicetelemetry/nop_telemetry_settings_test.go

@@ -26,11 +26,10 @@ func TestNewNopSettings(t *testing.T) {
 	require.Equal(t, noopmetric.NewMeterProvider(), set.MeterProvider)
 	require.Equal(t, configtelemetry.LevelNone, set.MetricsLevel)
 	require.Equal(t, pcommon.NewResource(), set.Resource)
-	require.NoError(t,
-		set.Status.ReportComponentStatus(
-			&component.InstanceID{},
-			component.NewStatusEvent(component.StatusStarting),
-		),
+	set.Status.ReportComponentStatus(
+		&component.InstanceID{},
+		component.NewStatusEvent(component.StatusStarting),
 	)
-	require.NoError(t, set.Status.ReportComponentOKIfStarting(&component.InstanceID{}))
+	set.Status.ReportComponentOKIfStarting(&component.InstanceID{})
+
 }

service/internal/servicetelemetry/telemetry_settings_test.go

@@ -24,17 +24,17 @@ func TestSettings(t *testing.T) {
 		MeterProvider:  noopmetric.NewMeterProvider(),
 		MetricsLevel:   configtelemetry.LevelNone,
 		Resource:       pcommon.NewResource(),
-		Status:         status.NewReporter(func(*component.InstanceID, *component.StatusEvent) {}),
+		Status: status.NewReporter(
+			func(*component.InstanceID, *component.StatusEvent) {},
+			func(err error) { require.NoError(t, err) }),
 	}
 	set.Status.Ready()
-	require.NoError(t,
-		set.Status.ReportComponentStatus(
-			&component.InstanceID{},
-			component.NewStatusEvent(component.StatusStarting),
-		),
+	set.Status.ReportComponentStatus(
+		&component.InstanceID{},
+		component.NewStatusEvent(component.StatusStarting),
 	)
-	require.NoError(t, set.Status.ReportComponentOKIfStarting(&component.InstanceID{}))
+	set.Status.ReportComponentOKIfStarting(&component.InstanceID{})
 
 	compSet := set.ToComponentTelemetrySettings(&component.InstanceID{})
-	require.NoError(t, compSet.ReportComponentStatus(component.NewStatusEvent(component.StatusStarting)))
+	compSet.ReportComponentStatus(component.NewStatusEvent(component.StatusStarting))
 }

service/internal/status/status.go

@@ -86,26 +86,31 @@ func newFSM(onTransition onTransitionFunc) *fsm {
 // NotifyStatusFunc is the receiver of status events after successful state transitions
 type NotifyStatusFunc func(*component.InstanceID, *component.StatusEvent)
 
+// InvalidTransitionFunc is the receiver of invalid transition errors
+type InvalidTransitionFunc func(error)
+
 // ServiceStatusFunc is the expected type of ReportComponentStatus for servicetelemetry.Settings
-type ServiceStatusFunc func(*component.InstanceID, *component.StatusEvent) error
+type ServiceStatusFunc func(*component.InstanceID, *component.StatusEvent)
 
 // errStatusNotReady is returned when trying to report status before service start
 var errStatusNotReady = errors.New("report component status is not ready until service start")
 
 // Reporter handles component status reporting
 type Reporter struct {
-	mu             sync.Mutex
-	ready          bool
-	fsmMap         map[*component.InstanceID]*fsm
-	onStatusChange NotifyStatusFunc
+	mu                  sync.Mutex
+	ready               bool
+	fsmMap              map[*component.InstanceID]*fsm
+	onStatusChange      NotifyStatusFunc
+	onInvalidTransition InvalidTransitionFunc
 }
 
 // NewReporter returns a reporter that will invoke the NotifyStatusFunc when a component's status
 // has changed.
-func NewReporter(onStatusChange NotifyStatusFunc) *Reporter {
+func NewReporter(onStatusChange NotifyStatusFunc, onInvalidTransition InvalidTransitionFunc) *Reporter {
 	return &Reporter{
-		fsmMap:         make(map[*component.InstanceID]*fsm),
-		onStatusChange: onStatusChange,
+		fsmMap:              make(map[*component.InstanceID]*fsm),
+		onStatusChange:      onStatusChange,
+		onInvalidTransition: onInvalidTransition,
 	}
 }
 
@@ -120,27 +125,31 @@ func (r *Reporter) Ready() {
 func (r *Reporter) ReportComponentStatus(
 	id *component.InstanceID,
 	ev *component.StatusEvent,
-) error {
+) {
 	r.mu.Lock()
 	defer r.mu.Unlock()
 	if !r.ready {
-		return errStatusNotReady
+		r.onInvalidTransition(errStatusNotReady)
+	} else {
+		if err := r.componentFSM(id).transition(ev); err != nil {
+			r.onInvalidTransition(err)
+		}
 	}
-	return r.componentFSM(id).transition(ev)
 }
 
 // ReportComponentOkIfStarting reports StatusOK if the component's current status is Starting
-func (r *Reporter) ReportComponentOKIfStarting(id *component.InstanceID) error {
+func (r *Reporter) ReportComponentOKIfStarting(id *component.InstanceID) {
 	r.mu.Lock()
 	defer r.mu.Unlock()
 	if !r.ready {
-		return errStatusNotReady
+		r.onInvalidTransition(errStatusNotReady)
 	}
 	fsm := r.componentFSM(id)
 	if fsm.current.Status() == component.StatusStarting {
-		return fsm.transition(component.NewStatusEvent(component.StatusOK))
+		if err := fsm.transition(component.NewStatusEvent(component.StatusOK)); err != nil {
+			r.onInvalidTransition(err)
+		}
 	}
-	return nil
 }
 
 // Note: a lock must be acquired before calling this method.
@@ -159,8 +168,8 @@ func (r *Reporter) componentFSM(id *component.InstanceID) *fsm {
 func NewComponentStatusFunc(
 	id *component.InstanceID,
 	srvStatus ServiceStatusFunc,
-) func(*component.StatusEvent) error {
-	return func(ev *component.StatusEvent) error {
-		return srvStatus(id, ev)
+) func(*component.StatusEvent) {
+	return func(ev *component.StatusEvent) {
+		srvStatus(id, ev)
 	}
 }

service/internal/status/status_test.go

@@ -208,17 +208,20 @@ func TestStatusFuncs(t *testing.T) {
 		id2: statuses2,
 	}
 
-	rep := NewReporter(statusFunc)
+	rep := NewReporter(statusFunc,
+		func(err error) {
+			require.NoError(t, err)
+		})
 	comp1Func := NewComponentStatusFunc(id1, rep.ReportComponentStatus)
 	comp2Func := NewComponentStatusFunc(id2, rep.ReportComponentStatus)
 	rep.Ready()
 
 	for _, st := range statuses1 {
-		require.NoError(t, comp1Func(component.NewStatusEvent(st)))
+		comp1Func(component.NewStatusEvent(st))
 	}
 
 	for _, st := range statuses2 {
-		require.NoError(t, comp2Func(component.NewStatusEvent(st)))
+		comp2Func(component.NewStatusEvent(st))
 	}
 
 	require.Equal(t, expectedStatuses, actualStatuses)
@@ -230,7 +233,10 @@ func TestStatusFuncsConcurrent(t *testing.T) {
 	statusFunc := func(id *component.InstanceID, ev *component.StatusEvent) {
 		count++
 	}
-	rep := NewReporter(statusFunc)
+	rep := NewReporter(statusFunc,
+		func(err error) {
+			require.NoError(t, err)
+		})
 	rep.Ready()
 
 	wg := sync.WaitGroup{}
@@ -240,10 +246,10 @@ func TestStatusFuncsConcurrent(t *testing.T) {
 		id := id
 		go func() {
 			compFn := NewComponentStatusFunc(id, rep.ReportComponentStatus)
-			_ = compFn(component.NewStatusEvent(component.StatusStarting))
+			compFn(component.NewStatusEvent(component.StatusStarting))
 			for i := 0; i < 1000; i++ {
-				_ = compFn(component.NewStatusEvent(component.StatusRecoverableError))
-				_ = compFn(component.NewStatusEvent(component.StatusOK))
+				compFn(component.NewStatusEvent(component.StatusRecoverableError))
+				compFn(component.NewStatusEvent(component.StatusOK))
 			}
 			wg.Done()
 		}()
@@ -255,15 +261,19 @@ func TestStatusFuncsConcurrent(t *testing.T) {
 
 func TestReporterReady(t *testing.T) {
 	statusFunc := func(*component.InstanceID, *component.StatusEvent) {}
-	rep := NewReporter(statusFunc)
+	var err error
+	rep := NewReporter(statusFunc,
+		func(e error) {
+			err = e
+		})
 	id := &component.InstanceID{}
 
-	err := rep.ReportComponentStatus(id, component.NewStatusEvent(component.StatusStarting))
+	rep.ReportComponentStatus(id, component.NewStatusEvent(component.StatusStarting))
 	require.ErrorIs(t, err, errStatusNotReady)
-
 	rep.Ready()
 
-	err = rep.ReportComponentStatus(id, component.NewStatusEvent(component.StatusStarting))
+	err = nil
+	rep.ReportComponentStatus(id, component.NewStatusEvent(component.StatusStarting))
 	require.NoError(t, err)
 }
 
@@ -324,18 +334,19 @@ func TestReportComponentOKIfStarting(t *testing.T) {
 				func(_ *component.InstanceID, ev *component.StatusEvent) {
 					receivedStatuses = append(receivedStatuses, ev.Status())
 				},
+				func(err error) {
+					require.NoError(t, err)
+				},
 			)
 			rep.Ready()
 
 			id := &component.InstanceID{}
 			for _, status := range tc.initialStatuses {
-				err := rep.ReportComponentStatus(id, component.NewStatusEvent(status))
-				require.NoError(t, err)
+				rep.ReportComponentStatus(id, component.NewStatusEvent(status))
 			}
 
-			err := rep.ReportComponentOKIfStarting(id)
+			rep.ReportComponentOKIfStarting(id)
 
-			require.NoError(t, err)
 			require.Equal(t, tc.expectedStatuses, receivedStatuses)
 		})
 	}

service/service.go

@@ -113,7 +113,9 @@ func New(ctx context.Context, set Settings, cfg Config) (*Service, error) {
 		MetricsLevel:   cfg.Telemetry.Metrics.Level,
 		// Construct telemetry attributes from build info and config's resource attributes.
 		Resource: pcommonRes,
-		Status:   status.NewReporter(srv.host.notifyComponentStatusChange),
+		Status: status.NewReporter(srv.host.notifyComponentStatusChange, func(err error) {
+			srv.telemetry.Logger().Warn("Invalid transition", zap.Error(err))
+		}),
 	}
 
 	if err = srv.telemetryInitializer.init(res, srv.telemetrySettings, cfg.Telemetry, set.AsyncErrorChannel); err != nil {