[exporterhelper] Add span links across batcher when merging multiple requests

.chloggen/merged_context.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: enhancement
+
+# 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: Link batcher context to all batched request's span contexts.
+
+# One or more tracking issues or pull requests related to the change
+issues: [12212, 8122]
+
+# (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: [user]

exporter/exporterhelper/internal/obs_report_sender.go

@@ -14,6 +14,7 @@ import (
 	"go.opentelemetry.io/collector/component"
 	"go.opentelemetry.io/collector/exporter"
 	"go.opentelemetry.io/collector/exporter/exporterhelper/internal/metadata"
+	"go.opentelemetry.io/collector/exporter/exporterhelper/internal/queuebatch"
 	"go.opentelemetry.io/collector/exporter/exporterhelper/internal/request"
 	"go.opentelemetry.io/collector/exporter/exporterhelper/internal/sender"
 	"go.opentelemetry.io/collector/pipeline"
@@ -96,7 +97,10 @@ func (ors *obsReportSender[K]) Send(ctx context.Context, req K) error {
 // StartOp creates the span used to trace the operation. Returning
 // the updated context and the created span.
 func (ors *obsReportSender[K]) startOp(ctx context.Context) context.Context {
-	ctx, _ = ors.tracer.Start(ctx, ors.spanName, ors.spanAttrs)
+	ctx, _ = ors.tracer.Start(ctx,
+		ors.spanName,
+		ors.spanAttrs,
+		trace.WithLinks(queuebatch.LinksFromContext(ctx)...))
 	return ctx
 }
 

exporter/exporterhelper/internal/queuebatch/batch_context.go

@@ -0,0 +1,40 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package queuebatch // import "go.opentelemetry.io/collector/exporter/exporterhelper/internal/queuebatch"
+
+import (
+	"context"
+
+	"go.opentelemetry.io/otel/trace"
+)
+
+type traceContextKeyType int
+
+const batchSpanLinksKey traceContextKeyType = iota
+
+// LinksFromContext returns a list of trace links registered in the context.
+func LinksFromContext(ctx context.Context) []trace.Link {
+	if ctx == nil {
+		return []trace.Link{}
+	}
+	if links, ok := ctx.Value(batchSpanLinksKey).([]trace.Link); ok {
+		return links
+	}
+	return []trace.Link{}
+}
+
+func parentsFromContext(ctx context.Context) []trace.Link {
+	if spanCtx := trace.SpanContextFromContext(ctx); spanCtx.IsValid() {
+		return []trace.Link{{SpanContext: spanCtx}}
+	}
+	return LinksFromContext(ctx)
+}
+
+func contextWithMergedLinks(ctx1 context.Context, ctx2 context.Context) context.Context {
+	return context.WithValue(
+		context.Background(),
+		batchSpanLinksKey,
+		append(parentsFromContext(ctx1), parentsFromContext(ctx2)...),
+	)
+}

exporter/exporterhelper/internal/queuebatch/batch_context_test.go

@@ -0,0 +1,39 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package queuebatch
+
+import (
+	"context"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+	"go.opentelemetry.io/otel/trace"
+
+	"go.opentelemetry.io/collector/component/componenttest"
+)
+
+func TestBatchContextLink(t *testing.T) {
+	tracerProvider := componenttest.NewTelemetry().NewTelemetrySettings().TracerProvider
+	tracer := tracerProvider.Tracer("go.opentelemetry.io/collector/exporter/exporterhelper")
+
+	ctx1 := context.Background()
+
+	ctx2, span2 := tracer.Start(ctx1, "span2")
+	defer span2.End()
+
+	ctx3, span3 := tracer.Start(ctx1, "span3")
+	defer span3.End()
+
+	ctx4, span4 := tracer.Start(ctx1, "span4")
+	defer span4.End()
+
+	batchContext := contextWithMergedLinks(ctx2, ctx3)
+	batchContext = contextWithMergedLinks(batchContext, ctx4)
+
+	actualLinks := LinksFromContext(batchContext)
+	require.Len(t, actualLinks, 3)
+	require.Equal(t, trace.SpanContextFromContext(ctx2), actualLinks[0].SpanContext)
+	require.Equal(t, trace.SpanContextFromContext(ctx3), actualLinks[1].SpanContext)
+	require.Equal(t, trace.SpanContextFromContext(ctx4), actualLinks[2].SpanContext)
+}

exporter/exporterhelper/internal/queuebatch/default_batcher.go

@@ -125,9 +125,10 @@ func (qb *defaultBatcher) Consume(ctx context.Context, req request.Request, done
 	// - Last result may not have enough data to be flushed.
 
 	// Logic on how to deal with the current batch:
-	// TODO: Deal with merging Context.
 	qb.currentBatch.req = reqList[0]
 	qb.currentBatch.done = append(qb.currentBatch.done, done)
+	qb.currentBatch.ctx = contextWithMergedLinks(qb.currentBatch.ctx, ctx)
+
 	// Save the "currentBatch" if we need to flush it, because we want to execute flush without holding the lock, and
 	// cannot unlock and re-lock because we are not done processing all the responses.
 	var firstBatch *batch

exporter/exporterhelper/internal/queuebatch/obs_queue.go

@@ -8,6 +8,7 @@ import (
 
 	"go.opentelemetry.io/otel/attribute"
 	"go.opentelemetry.io/otel/metric"
+	"go.opentelemetry.io/otel/trace"
 
 	"go.opentelemetry.io/collector/exporter/exporterhelper/internal/metadata"
 	"go.opentelemetry.io/collector/exporter/exporterhelper/internal/request"
@@ -28,6 +29,7 @@ type obsQueue[T request.Request] struct {
 	tb                *metadata.TelemetryBuilder
 	metricAttr        metric.MeasurementOption
 	enqueueFailedInst metric.Int64Counter
+	tracer            trace.Tracer
 }
 
 func newObsQueue[T request.Request](set Settings[T], delegate Queue[T]) (Queue[T], error) {
@@ -54,10 +56,13 @@ func newObsQueue[T request.Request](set Settings[T], delegate Queue[T]) (Queue[T
 		return nil, err
 	}
 
+	tracer := metadata.Tracer(set.Telemetry)
+
 	or := &obsQueue[T]{
 		Queue:      delegate,
 		tb:         tb,
 		metricAttr: metric.WithAttributeSet(attribute.NewSet(exporterAttr)),
+		tracer:     tracer,
 	}
 
 	switch set.Signal {
@@ -81,7 +86,11 @@ func (or *obsQueue[T]) Offer(ctx context.Context, req T) error {
 	// Have to read the number of items before sending the request since the request can
 	// be modified by the downstream components like the batcher.
 	numItems := req.ItemsCount()
+
+	ctx, span := or.tracer.Start(ctx, "exporter/enqueue")
 	err := or.Queue.Offer(ctx, req)
+	span.End()
+
 	// No metrics recorded for profiles, remove enqueueFailedInst check with nil when profiles metrics available.
 	if err != nil && or.enqueueFailedInst != nil {
 		or.enqueueFailedInst.Add(ctx, int64(numItems), or.metricAttr)

exporter/exporterhelper/internal/queuebatch/queue_batch_test.go

@@ -449,40 +449,6 @@ func TestQueueBatch_BatchBlocking(t *testing.T) {
 	require.NoError(t, qb.Shutdown(context.Background()))
 }
 
-// Validate that the batch is cancelled once the first request in the request is cancelled
-func TestQueueBatch_BatchCancelled(t *testing.T) {
-	sink := requesttest.NewSink()
-	cfg := newTestConfig()
-	cfg.WaitForResult = true
-	cfg.Batch.MinSize = 2
-	qb, err := NewQueueBatch(newFakeRequestSettings(), cfg, sink.Export)
-	require.NoError(t, err)
-	require.NoError(t, qb.Start(context.Background(), componenttest.NewNopHost()))
-
-	// send 2 blockOnOverflow requests
-	wg := sync.WaitGroup{}
-	ctx, cancel := context.WithCancel(context.Background())
-	wg.Add(1)
-	go func() {
-		defer wg.Done()
-		assert.ErrorIs(t, qb.Send(ctx, &requesttest.FakeRequest{Items: 1, Delay: 100 * time.Millisecond}), context.Canceled)
-	}()
-	wg.Add(1)
-	go func() {
-		defer wg.Done()
-		time.Sleep(100 * time.Millisecond) // ensure this call is the second
-		assert.ErrorIs(t, qb.Send(context.Background(), &requesttest.FakeRequest{Items: 1, Delay: 100 * time.Millisecond}), context.Canceled)
-	}()
-	cancel() // canceling the first request should cancel the whole batch
-	wg.Wait()
-
-	// nothing should be delivered
-	assert.Equal(t, 0, sink.RequestsCount())
-	assert.Equal(t, 0, sink.ItemsCount())
-
-	require.NoError(t, qb.Shutdown(context.Background()))
-}
-
 func TestQueueBatch_DrainActiveRequests(t *testing.T) {
 	sink := requesttest.NewSink()
 	cfg := newTestConfig()
@@ -514,47 +480,6 @@ func TestQueueBatch_DrainActiveRequests(t *testing.T) {
 	assert.Equal(t, 3, sink.ItemsCount())
 }
 
-func TestQueueBatchWithTimeout(t *testing.T) {
-	sink := requesttest.NewSink()
-	cfg := newTestConfig()
-	cfg.WaitForResult = true
-	cfg.Batch.MinSize = 10
-	qb, err := NewQueueBatch(newFakeRequestSettings(), cfg, sink.Export)
-	require.NoError(t, err)
-	require.NoError(t, qb.Start(context.Background(), componenttest.NewNopHost()))
-
-	ctx, cancel := context.WithTimeout(context.Background(), 50*time.Millisecond)
-	defer cancel()
-	// Send 3 concurrent requests that should be merged in one batch
-	wg := sync.WaitGroup{}
-	for i := 0; i < 3; i++ {
-		wg.Add(1)
-		go func() {
-			assert.NoError(t, qb.Send(ctx, &requesttest.FakeRequest{Items: 4}))
-			wg.Done()
-		}()
-	}
-	wg.Wait()
-	assert.Equal(t, 1, sink.RequestsCount())
-	assert.Equal(t, 12, sink.ItemsCount())
-
-	// 3 requests with a 90ms cumulative delay must be cancelled by the timeout sender
-	for i := 0; i < 3; i++ {
-		wg.Add(1)
-		go func() {
-			assert.Error(t, qb.Send(ctx, &requesttest.FakeRequest{Items: 4, Delay: 30 * time.Millisecond}))
-			wg.Done()
-		}()
-	}
-	wg.Wait()
-
-	require.NoError(t, qb.Shutdown(context.Background()))
-
-	// The sink should not change
-	assert.Equal(t, 1, sink.RequestsCount())
-	assert.Equal(t, 12, sink.ItemsCount())
-}
-
 func TestQueueBatchTimerResetNoConflict(t *testing.T) {
 	sink := requesttest.NewSink()
 	cfg := newTestConfig()