Wrap the error used in concurrentbatchprocessor (#235)

A missing `func (_) Unwrap() error` makes the receiver not able to
unwrap the exporter errors.

Fixes #234.

CHANGELOG.md

@@ -8,6 +8,7 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 
 ## Unreleased
 
+- Wrap concurrentbatchprocessor errors [#235](https://github.com/open-telemetry/otel-arrow/pull/235)
 - Update to OTel-Collector v0.105.0, which includes the OTel-Arrow components. [#233](https://github.com/open-telemetry/otel-arrow/pull/233)
 - Remove the primary exporter/receiver components, update references and documentation. [#230](https://github.com/open-telemetry/otel-arrow/pull/230)
 - Update to Arrow v17. [#231](https://github.com/open-telemetry/otel-arrow/pull/231)

collector/processor/concurrentbatchprocessor/batch_processor.go

@@ -154,6 +154,10 @@ func (ce countedError) Error() string {
 	return fmt.Sprintf("batch error: %s", ce.err.Error())
 }
 
+func (ce countedError) Unwrap() error {
+	return ce.err
+}
+
 var _ consumer.Traces = (*batchProcessor)(nil)
 var _ consumer.Metrics = (*batchProcessor)(nil)
 var _ consumer.Logs = (*batchProcessor)(nil)

collector/processor/concurrentbatchprocessor/batch_processor_test.go

@@ -37,6 +37,21 @@ import (
 	"go.opentelemetry.io/otel/sdk/trace/tracetest"
 )
 
+type testError struct{}
+
+func (testError) Error() string {
+	return "test"
+}
+
+func TestErrorWrapping(t *testing.T) {
+	e := countedError{
+		err: fmt.Errorf("oops: %w", testError{}),
+	}
+	require.Error(t, e)
+	require.Contains(t, e.Error(), "oops: test")
+	require.ErrorIs(t, e, testError{})
+}
+
 func TestProcessorShutdown(t *testing.T) {
 	factory := NewFactory()
 
@@ -1697,3 +1712,40 @@ func TestBatchProcessorEmptyBatch(t *testing.T) {
 	wg.Wait()
 	require.NoError(t, batcher.Shutdown(context.Background()))
 }
+
+type errorSink struct {
+	err error
+}
+
+var _ consumer.Logs = errorSink{}
+
+func (es errorSink) Capabilities() consumer.Capabilities {
+	return consumer.Capabilities{}
+}
+
+func (es errorSink) ConsumeLogs(ctx context.Context, ld plog.Logs) error {
+	return es.err
+}
+
+func TestErrorPropagation(t *testing.T) {
+	for _, proto := range []error{
+		testError{},
+		fmt.Errorf("womp"),
+	} {
+		sink := errorSink{err: proto}
+
+		creationSet := processortest.NewNopSettings()
+		creationSet.MetricsLevel = configtelemetry.LevelDetailed
+		cfg := createDefaultConfig().(*Config)
+		batcher, err := newBatchLogsProcessor(creationSet, sink, cfg)
+
+		require.NoError(t, err)
+		require.NoError(t, batcher.Start(context.Background(), componenttest.NewNopHost()))
+
+		ld := testdata.GenerateLogs(1)
+		err = batcher.ConsumeLogs(context.Background(), ld)
+		assert.Error(t, err)
+		assert.ErrorIs(t, err, proto)
+		assert.Contains(t, err.Error(), proto.Error())
+	}
+}