Edits according to feedback

exporter/exporterhelper/exporterhelperprofiles/profiles_batch_test.go

@@ -12,11 +12,9 @@ import (
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 
-	"go.opentelemetry.io/collector/consumer"
 	"go.opentelemetry.io/collector/exporter/exporterbatcher"
 	"go.opentelemetry.io/collector/exporter/exporterhelper"
 	"go.opentelemetry.io/collector/pdata/pprofile"
-	"go.opentelemetry.io/collector/pdata/ptrace"
 	"go.opentelemetry.io/collector/pdata/testdata"
 )
 
@@ -30,7 +28,7 @@ func TestMergeProfiles(t *testing.T) {
 }
 
 func TestMergeProfilesInvalidInput(t *testing.T) {
-	pr1 := &tracesRequest{td: testdata.GenerateTraces(2)}
+	pr1 := &dummyRequest{}
 	pr2 := &profilesRequest{pd: testdata.GenerateProfiles(3)}
 	_, err := pr2.Merge(context.Background(), pr1)
 	assert.Error(t, err)
@@ -131,7 +129,7 @@ func TestMergeSplitProfiles(t *testing.T) {
 }
 
 func TestMergeSplitProfilesInvalidInput(t *testing.T) {
-	r1 := &tracesRequest{td: testdata.GenerateTraces(2)}
+	r1 := &dummyRequest{}
 	r2 := &profilesRequest{pd: testdata.GenerateProfiles(3)}
 	_, err := r2.MergeSplit(context.Background(), exporterbatcher.MaxSizeConfig{}, r1)
 	assert.Error(t, err)
@@ -146,25 +144,23 @@ func TestExtractProfiles(t *testing.T) {
 	}
 }
 
-type tracesRequest struct {
-	td     ptrace.Traces
-	pusher consumer.ConsumeTracesFunc
+// dummyRequest implements BatchRequest. It is for checking that merging two request types would fail
+type dummyRequest struct {
 }
 
-func (req *tracesRequest) Export(ctx context.Context) error {
-	return req.pusher(ctx, req.td)
+func (req *dummyRequest) Export(_ context.Context) error {
+	return nil
 }
 
-func (req *tracesRequest) ItemsCount() int {
-	return req.td.SpanCount()
+func (req *dummyRequest) ItemsCount() int {
+	return 1
 }
 
-func (req *tracesRequest) Merge(_ context.Context, _ exporterhelper.BatchRequest) (exporterhelper.BatchRequest, error) {
+func (req *dummyRequest) Merge(_ context.Context, _ exporterhelper.BatchRequest) (exporterhelper.BatchRequest, error) {
 	return nil, nil
 }
 
-// MergeSplit splits and/or merges the profiles into multiple requests based on the MaxSizeConfig.
-func (req *tracesRequest) MergeSplit(_ context.Context, _ exporterbatcher.MaxSizeConfig, _ exporterhelper.BatchRequest) (
+func (req *dummyRequest) MergeSplit(_ context.Context, _ exporterbatcher.MaxSizeConfig, _ exporterhelper.BatchRequest) (
 	[]exporterhelper.BatchRequest, error) {
 	return nil, nil
 }

exporter/exporterhelper/internal/batch_sender.go

@@ -5,6 +5,7 @@ package internal // import "go.opentelemetry.io/collector/exporter/exporterhelpe
 
 import (
 	"context"
+	"errors"
 	"sync"
 	"sync/atomic"
 	"time"
@@ -141,10 +142,15 @@ func (bs *BatchSender) Send(ctx context.Context, req internal.Request) error {
 		return bs.NextSender.Send(ctx, req)
 	}
 
+	batchReq, ok := req.(internal.BatchRequest)
+	if !ok {
+		errors.New("Incoming request does not implement BatchRequest interface.")
+	}
+
 	if bs.cfg.MaxSizeItems > 0 {
-		return bs.sendMergeSplitBatch(ctx, req.(internal.BatchRequest))
+		return bs.sendMergeSplitBatch(ctx, batchReq)
 	}
-	return bs.sendMergeBatch(ctx, req.(internal.BatchRequest))
+	return bs.sendMergeBatch(ctx, batchReq)
 }
 
 // sendMergeSplitBatch sends the request to the batch which may be split into multiple requests.

exporter/internal/request.go

@@ -27,7 +27,20 @@ type Request interface {
 // until https://github.com/open-telemetry/opentelemetry-collector/issues/8122 is resolved.
 type BatchRequest interface {
 	Request
+	// Merge() is a function that merges this request with another one into a single request.
+	// Do not mutate the requests passed to the function if error can be returned after mutation or if the exporter is
+	// marked as not mutable.
+	// Experimental: This API is at the early stage of development and may change without backward compatibility
+	// until https://github.com/open-telemetry/opentelemetry-collector/issues/8122 is resolved.
 	Merge(context.Context, BatchRequest) (BatchRequest, error)
+	// MergeSplit() is a function that merge and/or splits this request with another one into multiple requests based on the
+	// configured limit provided in MaxSizeConfig.
+	// All the returned requests MUST have a number of items that does not exceed the maximum number of items.
+	// Size of the last returned request MUST be less or equal than the size of any other returned request.
+	// The original request MUST not be mutated if error is returned after mutation or if the exporter is
+	// marked as not mutable. The length of the returned slice MUST not be 0.
+	// Experimental: This API is at the early stage of development and may change without backward compatibility
+	// until https://github.com/open-telemetry/opentelemetry-collector/issues/8122 is resolved.
 	MergeSplit(context.Context, exporterbatcher.MaxSizeConfig, BatchRequest) ([]BatchRequest, error)
 }