[Spanmetrics] - Add exemplars to events_total metric (open-telemetry#29090)

**Description:** Add exemplars to events_total metric for spanmetrics

Author: aishyandapalli

.chloggen/add-exemplars-to-events-total-metric.yaml

@@ -0,0 +1,27 @@
+# Use this changelog template to create an entry for release notes.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: enhancement
+
+# The name of the component, or a single word describing the area of concern, (e.g. filelogreceiver)
+component: spanmetricsconnector
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Add exemplars to sum metric
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [27451]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext:
+
+# If your change doesn't affect end users or the exported elements of any package,
+# you should instead start your pull request title with [chore] or use the "Skip Changelog" label.
+# Optional: The change log or logs in which this entry should be included.
+# e.g. '[user]' or '[user, api]'
+# Include 'user' if the change is relevant to end users.
+# Include 'api' if there is a change to a library API.
+# Default: '[user]'
+change_logs: []

connector/spanmetricsconnector/connector.go

@@ -361,6 +361,9 @@ func (p *connectorImp) aggregateMetrics(traces ptrace.Traces) {
 							p.metricKeyToDimensions.Add(eKey, eAttributes)
 						}
 						e := events.GetOrCreate(eKey, eAttributes)
+						if p.config.Exemplars.Enabled && !span.TraceID().IsEmpty() {
+							e.AddExemplar(span.TraceID(), span.SpanID(), duration)
+						}
 						e.Add(1)
 					}
 				}

connector/spanmetricsconnector/connector_test.go

@@ -413,6 +413,19 @@ func enabledExemplarsConfig() ExemplarsConfig {
 	}
 }
 
+func enabledEventsConfig() EventsConfig {
+	return EventsConfig{
+		Enabled:    true,
+		Dimensions: []Dimension{{Name: "exception.type"}},
+	}
+}
+
+func disabledEventsConfig() EventsConfig {
+	return EventsConfig{
+		Enabled: false,
+	}
+}
+
 func explicitHistogramsConfig() HistogramConfig {
 	return HistogramConfig{
 		Unit: defaultUnit,
@@ -586,7 +599,7 @@ func TestConcurrentShutdown(t *testing.T) {
 	ticker := mockClock.NewTicker(time.Nanosecond)
 
 	// Test
-	p := newConnectorImp(t, new(consumertest.MetricsSink), nil, explicitHistogramsConfig, disabledExemplarsConfig, cumulative, logger, ticker)
+	p := newConnectorImp(t, new(consumertest.MetricsSink), nil, explicitHistogramsConfig, disabledExemplarsConfig, disabledEventsConfig, cumulative, logger, ticker)
 	err := p.Start(ctx, componenttest.NewNopHost())
 	require.NoError(t, err)
 
@@ -666,7 +679,7 @@ func TestConsumeMetricsErrors(t *testing.T) {
 	}
 	mockClock := clock.NewMock(time.Now())
 	ticker := mockClock.NewTicker(time.Nanosecond)
-	p := newConnectorImp(t, mcon, nil, explicitHistogramsConfig, disabledExemplarsConfig, cumulative, logger, ticker)
+	p := newConnectorImp(t, mcon, nil, explicitHistogramsConfig, disabledExemplarsConfig, disabledEventsConfig, cumulative, logger, ticker)
 
 	ctx := metadata.NewIncomingContext(context.Background(), nil)
 	err := p.Start(ctx, componenttest.NewNopHost())
@@ -828,7 +841,7 @@ func TestConsumeTraces(t *testing.T) {
 			mockClock := clock.NewMock(time.Now())
 			ticker := mockClock.NewTicker(time.Nanosecond)
 
-			p := newConnectorImp(t, mcon, stringp("defaultNullValue"), tc.histogramConfig, tc.exemplarConfig, tc.aggregationTemporality, zaptest.NewLogger(t), ticker)
+			p := newConnectorImp(t, mcon, stringp("defaultNullValue"), tc.histogramConfig, tc.exemplarConfig, disabledEventsConfig, tc.aggregationTemporality, zaptest.NewLogger(t), ticker)
 
 			ctx := metadata.NewIncomingContext(context.Background(), nil)
 			err := p.Start(ctx, componenttest.NewNopHost())
@@ -854,7 +867,7 @@ func TestConsumeTraces(t *testing.T) {
 func TestMetricKeyCache(t *testing.T) {
 	mcon := consumertest.NewNop()
 
-	p := newConnectorImp(t, mcon, stringp("defaultNullValue"), explicitHistogramsConfig, disabledExemplarsConfig, cumulative, zaptest.NewLogger(t), nil)
+	p := newConnectorImp(t, mcon, stringp("defaultNullValue"), explicitHistogramsConfig, disabledExemplarsConfig, disabledEventsConfig, cumulative, zaptest.NewLogger(t), nil)
 	traces := buildSampleTrace()
 
 	// Test
@@ -885,7 +898,7 @@ func BenchmarkConnectorConsumeTraces(b *testing.B) {
 	// Prepare
 	mcon := consumertest.NewNop()
 
-	conn := newConnectorImp(nil, mcon, stringp("defaultNullValue"), explicitHistogramsConfig, disabledExemplarsConfig, cumulative, zaptest.NewLogger(b), nil)
+	conn := newConnectorImp(nil, mcon, stringp("defaultNullValue"), explicitHistogramsConfig, disabledExemplarsConfig, disabledEventsConfig, cumulative, zaptest.NewLogger(b), nil)
 
 	traces := buildSampleTrace()
 
@@ -899,7 +912,7 @@ func BenchmarkConnectorConsumeTraces(b *testing.B) {
 func TestExcludeDimensionsConsumeTraces(t *testing.T) {
 	mcon := consumertest.NewNop()
 	excludeDimensions := []string{"span.kind", "span.name", "totallyWrongNameDoesNotAffectAnything"}
-	p := newConnectorImp(t, mcon, stringp("defaultNullValue"), explicitHistogramsConfig, disabledExemplarsConfig, cumulative, zaptest.NewLogger(t), nil, excludeDimensions...)
+	p := newConnectorImp(t, mcon, stringp("defaultNullValue"), explicitHistogramsConfig, disabledExemplarsConfig, disabledEventsConfig, cumulative, zaptest.NewLogger(t), nil, excludeDimensions...)
 	traces := buildSampleTrace()
 
 	// Test
@@ -948,7 +961,7 @@ func TestExcludeDimensionsConsumeTraces(t *testing.T) {
 
 }
 
-func newConnectorImp(t *testing.T, mcon consumer.Metrics, defaultNullValue *string, histogramConfig func() HistogramConfig, exemplarsConfig func() ExemplarsConfig, temporality string, logger *zap.Logger, ticker *clock.Ticker, excludedDimensions ...string) *connectorImp {
+func newConnectorImp(t *testing.T, mcon consumer.Metrics, defaultNullValue *string, histogramConfig func() HistogramConfig, exemplarsConfig func() ExemplarsConfig, eventsConfig func() EventsConfig, temporality string, logger *zap.Logger, ticker *clock.Ticker, excludedDimensions ...string) *connectorImp {
 
 	cfg := &Config{
 		AggregationTemporality: temporality,
@@ -972,6 +985,7 @@ func newConnectorImp(t *testing.T, mcon consumer.Metrics, defaultNullValue *stri
 			// Add a resource attribute to test "process" attributes like IP, host, region, cluster, etc.
 			{regionResourceAttrName, nil},
 		},
+		Events: eventsConfig(),
 	}
 	c, err := newConnector(logger, cfg, ticker)
 	require.NoError(t, err)
@@ -1066,7 +1080,7 @@ func TestConnectorConsumeTracesEvictedCacheKey(t *testing.T) {
 	ticker := mockClock.NewTicker(time.Nanosecond)
 
 	// Note: default dimension key cache size is 2.
-	p := newConnectorImp(t, mcon, stringp("defaultNullValue"), explicitHistogramsConfig, disabledExemplarsConfig, cumulative, zaptest.NewLogger(t), ticker)
+	p := newConnectorImp(t, mcon, stringp("defaultNullValue"), explicitHistogramsConfig, disabledExemplarsConfig, disabledEventsConfig, cumulative, zaptest.NewLogger(t), ticker)
 
 	ctx := metadata.NewIncomingContext(context.Background(), nil)
 	err := p.Start(ctx, componenttest.NewNopHost())
@@ -1320,7 +1334,7 @@ func TestSpanMetrics_Events(t *testing.T) {
 }
 func TestExemplarsForSumMetrics(t *testing.T) {
 	mcon := consumertest.NewNop()
-	p := newConnectorImp(t, mcon, stringp("defaultNullValue"), explicitHistogramsConfig, enabledExemplarsConfig, cumulative, zaptest.NewLogger(t), nil)
+	p := newConnectorImp(t, mcon, stringp("defaultNullValue"), explicitHistogramsConfig, enabledExemplarsConfig, enabledEventsConfig, cumulative, zaptest.NewLogger(t), nil)
 	traces := buildSampleTrace()
 
 	// Test