implement otel.sdk.span.processor.queue_capacity and otel.sdk.span.processor.spans_processed self-observability metrics

Author: dashpole

sdk/trace/batch_span_processor.go

@@ -69,9 +69,16 @@ type batchSpanProcessor struct {
 	e SpanExporter
 	o BatchSpanProcessorOptions
 
-	queue                chan ReadOnlySpan
-	dropped              uint32
-	callbackRegistration metric.Registration
+	queue   chan ReadOnlySpan
+	dropped uint32
+
+	callbackRegistration      metric.Registration
+	spansProcessedCounter     metric.Int64Counter
+	successAttributes         metric.MeasurementOption
+	alreadyShutdownAttributes metric.MeasurementOption
+	noExporterAttributes      metric.MeasurementOption
+	notSampledAttributes      metric.MeasurementOption
+	queueFullAttributes       metric.MeasurementOption
 
 	batch      []ReadOnlySpan
 	batchMutex sync.Mutex
@@ -130,6 +137,15 @@ func NewBatchSpanProcessor(exporter SpanExporter, options ...BatchSpanProcessorO
 	return bsp
 }
 
+var processorID atomic.Uint64
+
+// nextProcessorID returns an identifier for this batch span processor,
+// starting with 0 and incrementing by 1 each time it is called.
+func nextProcessorID() int64 {
+	return int64(processorID.Add(1) - 1)
+}
+
+// configureSelfObservability configures metrics for the batch span processor.
 func (bsp *batchSpanProcessor) configureSelfObservability() {
 	mp := otel.GetMeterProvider()
 	if !x.SelfObservability.Enabled() {
@@ -140,23 +156,44 @@ func (bsp *batchSpanProcessor) configureSelfObservability() {
 		metric.WithInstrumentationVersion(version()),
 	)
 
-	queueSizeCounter, err := meter.Int64ObservableUpDownCounter("otel.sdk.span.processor.queue_size",
+	queueCapacityUpDownCounter, err := meter.Int64ObservableUpDownCounter("otel.sdk.span.processor.queue_capacity",
+		metric.WithUnit("{span}"),
+		metric.WithDescription("The maximum number of spans the queue of a given instance of an SDK span processor can hold."),
+	)
+	if err != nil {
+		otel.Handle(err)
+	}
+	queueSizeUpDownCounter, err := meter.Int64ObservableUpDownCounter("otel.sdk.span.processor.queue_size",
 		metric.WithUnit("{span}"),
 		metric.WithDescription("The number of spans in the queue of a given instance of an SDK span processor."),
 	)
 	if err != nil {
 		otel.Handle(err)
 	}
-
-	attrsOpt := metric.WithAttributes(
-		attribute.String("otel.sdk.component.name", fmt.Sprintf("batching_span_processor/%p", bsp)),
+	bsp.spansProcessedCounter, err = meter.Int64Counter("otel.sdk.span.processor.spans_processed",
+		metric.WithUnit("{span}"),
+		metric.WithDescription("The number of spans for which the processing has finished, either successful or failed."),
 	)
+	if err != nil {
+		otel.Handle(err)
+	}
+
+	componentTypeAttr := attribute.String("otel.sdk.component.type", "batching_span_processor")
+	componentNameAttr := attribute.String("otel.sdk.component.name", fmt.Sprintf("batching_span_processor/%d", nextProcessorID()))
+	bsp.successAttributes = metric.WithAttributes(componentNameAttr, componentTypeAttr, attribute.String("error.type", ""))
+	bsp.alreadyShutdownAttributes = metric.WithAttributes(componentNameAttr, componentTypeAttr, attribute.String("error.type", "already_shutdown"))
+	bsp.noExporterAttributes = metric.WithAttributes(componentNameAttr, componentTypeAttr, attribute.String("error.type", "no_exporter"))
+	bsp.notSampledAttributes = metric.WithAttributes(componentNameAttr, componentTypeAttr, attribute.String("error.type", "not_sampled"))
+	bsp.queueFullAttributes = metric.WithAttributes(componentNameAttr, componentTypeAttr, attribute.String("error.type", "queue_full"))
+	callabckAttributesOpt := metric.WithAttributes(componentNameAttr, componentTypeAttr)
 	bsp.callbackRegistration, err = meter.RegisterCallback(
 		func(ctx context.Context, o metric.Observer) error {
-			o.ObserveInt64(queueSizeCounter, int64(len(bsp.queue)), attrsOpt)
+			o.ObserveInt64(queueSizeUpDownCounter, int64(len(bsp.queue)), callabckAttributesOpt)
+			o.ObserveInt64(queueCapacityUpDownCounter, int64(bsp.o.MaxQueueSize), callabckAttributesOpt)
+			// TODO: can we track the number of spans batched, but not exported?
 			return nil
 		},
-		queueSizeCounter)
+		queueSizeUpDownCounter, queueCapacityUpDownCounter)
 	if err != nil {
 		otel.Handle(err)
 	}
@@ -167,13 +204,16 @@ func (bsp *batchSpanProcessor) OnStart(parent context.Context, s ReadWriteSpan)
 
 // OnEnd method enqueues a ReadOnlySpan for later processing.
 func (bsp *batchSpanProcessor) OnEnd(s ReadOnlySpan) {
+	ctx := context.Background()
 	// Do not enqueue spans after Shutdown.
 	if bsp.stopped.Load() {
+		bsp.spansProcessedCounter.Add(ctx, 1, bsp.alreadyShutdownAttributes)
 		return
 	}
 
 	// Do not enqueue spans if we are just going to drop them.
 	if bsp.e == nil {
+		bsp.spansProcessedCounter.Add(ctx, 1, bsp.noExporterAttributes)
 		return
 	}
 	bsp.enqueue(s)
@@ -315,6 +355,7 @@ func (bsp *batchSpanProcessor) exportSpans(ctx context.Context) error {
 
 	if l := len(bsp.batch); l > 0 {
 		global.Debug("exporting spans", "count", len(bsp.batch), "total_dropped", atomic.LoadUint32(&bsp.dropped))
+		bsp.spansProcessedCounter.Add(ctx, int64(len(bsp.batch)), bsp.successAttributes)
 		err := bsp.e.ExportSpans(ctx, bsp.batch)
 
 		// A new batch is always created after exporting, even if the batch failed to be exported.
@@ -416,19 +457,23 @@ func (bsp *batchSpanProcessor) enqueue(sd ReadOnlySpan) {
 
 func (bsp *batchSpanProcessor) enqueueBlockOnQueueFull(ctx context.Context, sd ReadOnlySpan) bool {
 	if !sd.SpanContext().IsSampled() {
+		bsp.spansProcessedCounter.Add(ctx, 1, bsp.notSampledAttributes)
 		return false
 	}
 
+	// TODO: Can we track the number of spans blocking on the queue?
 	select {
 	case bsp.queue <- sd:
 		return true
 	case <-ctx.Done():
+		bsp.spansProcessedCounter.Add(ctx, 1, bsp.queueFullAttributes)
 		return false
 	}
 }
 
-func (bsp *batchSpanProcessor) enqueueDrop(_ context.Context, sd ReadOnlySpan) bool {
+func (bsp *batchSpanProcessor) enqueueDrop(ctx context.Context, sd ReadOnlySpan) bool {
 	if !sd.SpanContext().IsSampled() {
+		bsp.spansProcessedCounter.Add(ctx, 1, bsp.notSampledAttributes)
 		return false
 	}
 
@@ -437,6 +482,7 @@ func (bsp *batchSpanProcessor) enqueueDrop(_ context.Context, sd ReadOnlySpan) b
 		return true
 	default:
 		atomic.AddUint32(&bsp.dropped, 1)
+		bsp.spansProcessedCounter.Add(ctx, 1, bsp.queueFullAttributes)
 	}
 	return false
 }