[exporterhelper] fix bug with queue size and capacity metrics (open-t…

…elemetry#8716)

This change ensures the queue_size and queue_capacity metrics are
available when using OpenTelemetry for the collector's internal metrics.

Fixes open-telemetry#8682

---------

Signed-off-by: Alex Boten <aboten@lightstep.com>
Co-authored-by: Dmitrii Anoshin <anoshindx@gmail.com>

.chloggen/codeboten_fix-queue-size-metric.yaml

@@ -0,0 +1,25 @@
+# Use this changelog template to create an entry for release notes.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: bug_fix
+
+# The name of the component, or a single word describing the area of concern, (e.g. otlpreceiver)
+component: exporterhelper
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: fix bug with queue size and capacity metrics
+
+# One or more tracking issues or pull requests related to the change
+issues: [8682]
+
+# (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:
+
+# 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: []

exporter/exporterhelper/queue_sender.go

@@ -11,18 +11,24 @@ import (
 
 	"go.opencensus.io/metric/metricdata"
 	"go.opentelemetry.io/otel/attribute"
+	otelmetric "go.opentelemetry.io/otel/metric"
 	"go.opentelemetry.io/otel/trace"
+	"go.uber.org/multierr"
 	"go.uber.org/zap"
 
 	"go.opentelemetry.io/collector/component"
 	"go.opentelemetry.io/collector/exporter"
 	"go.opentelemetry.io/collector/exporter/exporterhelper/internal"
+	"go.opentelemetry.io/collector/internal/obsreportconfig"
 	"go.opentelemetry.io/collector/internal/obsreportconfig/obsmetrics"
 )
 
 const defaultQueueSize = 1000
 
-var errSendingQueueIsFull = errors.New("sending_queue is full")
+var (
+	errSendingQueueIsFull = errors.New("sending_queue is full")
+	scopeName             = "go.opentelemetry.io/collector/exporterhelper"
+)
 
 // QueueSettings defines configuration for queueing batches before sending to the consumerSender.
 type QueueSettings struct {
@@ -74,6 +80,9 @@ type queueSender struct {
 	traceAttribute   attribute.KeyValue
 	logger           *zap.Logger
 	requeuingEnabled bool
+
+	metricCapacity otelmetric.Int64ObservableGauge
+	metricSize     otelmetric.Int64ObservableGauge
 }
 
 func newQueueSender(id component.ID, signal component.DataType, queue internal.ProducerConsumerQueue, logger *zap.Logger) *queueSender {
@@ -131,8 +140,44 @@ func (qs *queueSender) start(ctx context.Context, host component.Host, set expor
 		return err
 	}
 
+	if obsreportconfig.UseOtelForInternalMetricsfeatureGate.IsEnabled() {
+		return qs.recordWithOtel(set.MeterProvider.Meter(scopeName))
+	}
+	return qs.recordWithOC()
+}
+
+func (qs *queueSender) recordWithOtel(meter otelmetric.Meter) error {
+	var err, errs error
+
+	attrs := otelmetric.WithAttributeSet(attribute.NewSet(attribute.String(obsmetrics.ExporterKey, qs.fullName)))
+
+	qs.metricSize, err = meter.Int64ObservableGauge(
+		obsmetrics.ExporterKey+"/queue_size",
+		otelmetric.WithDescription("Current size of the retry queue (in batches)"),
+		otelmetric.WithUnit("1"),
+		otelmetric.WithInt64Callback(func(_ context.Context, o otelmetric.Int64Observer) error {
+			o.Observe(int64(qs.queue.Size()), attrs)
+			return nil
+		}),
+	)
+	errs = multierr.Append(errs, err)
+
+	qs.metricCapacity, err = meter.Int64ObservableGauge(
+		obsmetrics.ExporterKey+"/queue_capacity",
+		otelmetric.WithDescription("Fixed capacity of the retry queue (in batches)"),
+		otelmetric.WithUnit("1"),
+		otelmetric.WithInt64Callback(func(_ context.Context, o otelmetric.Int64Observer) error {
+			o.Observe(int64(qs.queue.Capacity()), attrs)
+			return nil
+		}))
+
+	errs = multierr.Append(errs, err)
+	return errs
+}
+
+func (qs *queueSender) recordWithOC() error {
 	// Start reporting queue length metric
-	err = globalInstruments.queueSize.UpsertEntry(func() int64 {
+	err := globalInstruments.queueSize.UpsertEntry(func() int64 {
 		return int64(qs.queue.Size())
 	}, metricdata.NewLabelValue(qs.fullName))
 	if err != nil {

exporter/exporterhelper/queue_sender_test.go

@@ -19,6 +19,8 @@ import (
 	"go.opentelemetry.io/collector/exporter"
 	"go.opentelemetry.io/collector/exporter/exporterhelper/internal"
 	"go.opentelemetry.io/collector/exporter/exportertest"
+	"go.opentelemetry.io/collector/featuregate"
+	"go.opentelemetry.io/collector/internal/obsreportconfig"
 	"go.opentelemetry.io/collector/internal/testdata"
 	"go.opentelemetry.io/collector/obsreport/obsreporttest"
 )
@@ -132,11 +134,24 @@ func TestQueuedRetryHappyPath(t *testing.T) {
 	ocs.checkDroppedItemsCount(t, 0)
 }
 
+// Force the state of feature gate for a test
+func setFeatureGateForTest(t testing.TB, gate *featuregate.Gate, enabled bool) func() {
+	originalValue := gate.IsEnabled()
+	require.NoError(t, featuregate.GlobalRegistry().Set(gate.ID(), enabled))
+	return func() {
+		require.NoError(t, featuregate.GlobalRegistry().Set(gate.ID(), originalValue))
+	}
+}
+
 func TestQueuedRetry_QueueMetricsReported(t *testing.T) {
+	tt, err := obsreporttest.SetupTelemetry(defaultID)
+	require.NoError(t, err)
+
 	qCfg := NewDefaultQueueSettings()
 	qCfg.NumConsumers = 0 // to make every request go straight to the queue
 	rCfg := NewDefaultRetrySettings()
-	be, err := newBaseExporter(defaultSettings, "", false, nil, nil, newObservabilityConsumerSender, WithRetry(rCfg), WithQueue(qCfg))
+	set := exporter.CreateSettings{ID: defaultID, TelemetrySettings: tt.TelemetrySettings, BuildInfo: component.NewDefaultBuildInfo()}
+	be, err := newBaseExporter(set, "", false, nil, nil, newObservabilityConsumerSender, WithRetry(rCfg), WithQueue(qCfg))
 	require.NoError(t, err)
 	require.NoError(t, be.Start(context.Background(), componenttest.NewNopHost()))
 
@@ -150,6 +165,31 @@ func TestQueuedRetry_QueueMetricsReported(t *testing.T) {
 	checkValueForGlobalManager(t, defaultExporterTags, int64(0), "exporter/queue_size")
 }
 
+func TestQueuedRetry_QueueMetricsReportedUsingOTel(t *testing.T) {
+	resetFlag := setFeatureGateForTest(t, obsreportconfig.UseOtelForInternalMetricsfeatureGate, true)
+	defer resetFlag()
+
+	tt, err := obsreporttest.SetupTelemetry(defaultID)
+	require.NoError(t, err)
+
+	qCfg := NewDefaultQueueSettings()
+	qCfg.NumConsumers = 0 // to make every request go straight to the queue
+	rCfg := NewDefaultRetrySettings()
+	set := exporter.CreateSettings{ID: defaultID, TelemetrySettings: tt.TelemetrySettings, BuildInfo: component.NewDefaultBuildInfo()}
+	be, err := newBaseExporter(set, "", false, nil, nil, newObservabilityConsumerSender, WithRetry(rCfg), WithQueue(qCfg))
+	require.NoError(t, err)
+	require.NoError(t, be.Start(context.Background(), componenttest.NewNopHost()))
+
+	require.NoError(t, tt.CheckExporterMetricGauge("exporter_queue_capacity", int64(defaultQueueSize)))
+
+	for i := 0; i < 7; i++ {
+		require.NoError(t, be.send(newErrorRequest(context.Background())))
+	}
+	require.NoError(t, tt.CheckExporterMetricGauge("exporter_queue_size", int64(7)))
+
+	assert.NoError(t, be.Shutdown(context.Background()))
+}
+
 func TestNoCancellationContext(t *testing.T) {
 	deadline := time.Now().Add(1 * time.Second)
 	ctx, cancelFunc := context.WithDeadline(context.Background(), deadline)

obsreport/obsreporttest/obsreporttest.go

@@ -78,6 +78,10 @@ func (tts *TestTelemetry) CheckExporterLogs(sentLogRecords, sendFailedLogRecords
 	return tts.prometheusChecker.checkExporterLogs(tts.id, sentLogRecords, sendFailedLogRecords)
 }
 
+func (tts *TestTelemetry) CheckExporterMetricGauge(metric string, val int64) error {
+	return tts.prometheusChecker.checkExporterMetricGauge(tts.id, metric, val)
+}
+
 // CheckProcessorTraces checks that for the current exported values for trace exporter metrics match given values.
 // When this function is called it is required to also call SetupTelemetry as first thing.
 func (tts *TestTelemetry) CheckProcessorTraces(acceptedSpans, refusedSpans, droppedSpans int64) error {

obsreport/obsreporttest/otelprometheuschecker.go

@@ -101,6 +101,24 @@ func (pc *prometheusChecker) checkExporterEnqueueFailed(exporter component.ID, d
 	return pc.checkCounter(fmt.Sprintf("exporter_enqueue_failed_%s", datatype), enqueueFailed, exporterAttrs)
 }
 
+func (pc *prometheusChecker) checkExporterMetricGauge(exporter component.ID, metric string, val int64) error {
+	exporterAttrs := attributesForExporterMetrics(exporter)
+	// Forces a flush for the opencensus view data.
+	_, _ = view.RetrieveData(metric)
+
+	ts, err := pc.getMetric(metric, io_prometheus_client.MetricType_GAUGE, exporterAttrs)
+	if err != nil {
+		return err
+	}
+
+	expected := float64(val)
+	if math.Abs(ts.GetGauge().GetValue()-expected) > 0.0001 {
+		return fmt.Errorf("values for metric '%s' did not match, expected '%f' got '%f'", metric, expected, ts.GetGauge().GetValue())
+	}
+
+	return nil
+}
+
 func (pc *prometheusChecker) checkCounter(expectedMetric string, value int64, attrs []attribute.KeyValue) error {
 	// Forces a flush for the opencensus view data.
 	_, _ = view.RetrieveData(expectedMetric)