Avoid allocating zero size slices (#13764)

Signed-off-by: Bogdan Drutu <bogdandrutu@gmail.com>

Signed-off-by: Bogdan Drutu <bogdandrutu@gmail.com>

exporter/alibabacloudlogserviceexporter/logsdata_to_logservice.go

@@ -42,7 +42,7 @@ const (
 )
 
 func logDataToLogService(ld plog.Logs) []*sls.Log {
-	slsLogs := make([]*sls.Log, 0)
+	var slsLogs []*sls.Log
 	rls := ld.ResourceLogs()
 	for i := 0; i < rls.Len(); i++ {
 		rl := rls.At(i)

exporter/awscloudwatchlogsexporter/exporter.go

@@ -144,7 +144,7 @@ func logsToCWLogs(logger *zap.Logger, ld plog.Logs) ([]*cloudwatchlogs.InputLogE
 	}
 
 	var dropped int
-	out := make([]*cloudwatchlogs.InputLogEvent, 0) // TODO(jbd): set a better capacity
+	var out []*cloudwatchlogs.InputLogEvent
 
 	rls := ld.ResourceLogs()
 	for i := 0; i < rls.Len(); i++ {

exporter/awsemfexporter/config.go

@@ -90,7 +90,7 @@ type MetricDescriptor struct {
 
 // Validate filters out invalid metricDeclarations and metricDescriptors
 func (config *Config) Validate() error {
-	validDeclarations := []*MetricDeclaration{}
+	var validDeclarations []*MetricDeclaration
 	for _, declaration := range config.MetricDeclarations {
 		err := declaration.init(config.logger)
 		if err != nil {
@@ -101,7 +101,7 @@ func (config *Config) Validate() error {
 	}
 	config.MetricDeclarations = validDeclarations
 
-	validDescriptors := []MetricDescriptor{}
+	var validDescriptors []MetricDescriptor
 	for _, descriptor := range config.MetricDescriptors {
 		if descriptor.metricName == "" {
 			continue

exporter/awsemfexporter/config_test.go

@@ -60,13 +60,10 @@ func TestLoadConfig(t *testing.T) {
 				Region:                "us-west-2",
 				RoleARN:               "arn:aws:iam::123456789:role/monitoring-EKS-NodeInstanceRole",
 			},
-			LogGroupName:                    "",
-			LogStreamName:                   "",
-			DimensionRollupOption:           "ZeroAndSingleDimensionRollup",
-			OutputDestination:               "cloudwatch",
-			ParseJSONEncodedAttributeValues: make([]string, 0),
-			MetricDeclarations:              []*MetricDeclaration{},
-			MetricDescriptors:               []MetricDescriptor{},
+			LogGroupName:          "",
+			LogStreamName:         "",
+			DimensionRollupOption: "ZeroAndSingleDimensionRollup",
+			OutputDestination:     "cloudwatch",
 		}, r1)
 
 	r2 := cfg.Exporters[config.NewComponentIDWithName(typeStr, "resource_attr_to_label")].(*Config)
@@ -84,14 +81,11 @@ func TestLoadConfig(t *testing.T) {
 				Region:                "",
 				RoleARN:               "",
 			},
-			LogGroupName:                    "",
-			LogStreamName:                   "",
-			DimensionRollupOption:           "ZeroAndSingleDimensionRollup",
-			OutputDestination:               "cloudwatch",
-			ResourceToTelemetrySettings:     resourcetotelemetry.Settings{Enabled: true},
-			ParseJSONEncodedAttributeValues: make([]string, 0),
-			MetricDeclarations:              []*MetricDeclaration{},
-			MetricDescriptors:               []MetricDescriptor{},
+			LogGroupName:                "",
+			LogStreamName:               "",
+			DimensionRollupOption:       "ZeroAndSingleDimensionRollup",
+			OutputDestination:           "cloudwatch",
+			ResourceToTelemetrySettings: resourcetotelemetry.Settings{Enabled: true},
 		})
 }
 

exporter/awsemfexporter/emf_exporter.go

@@ -210,7 +210,7 @@ func (emf *emfExporter) listPushers() []cwlogs.Pusher {
 	emf.pusherMapLock.Lock()
 	defer emf.pusherMapLock.Unlock()
 
-	pushers := []cwlogs.Pusher{}
+	var pushers []cwlogs.Pusher
 	for _, pusherMap := range emf.groupStreamToPusherMap {
 		for _, pusher := range pusherMap {
 			pushers = append(pushers, pusher)

exporter/awsemfexporter/factory.go

@@ -41,17 +41,14 @@ func NewFactory() component.ExporterFactory {
 // CreateDefaultConfig creates the default configuration for exporter.
 func createDefaultConfig() config.Exporter {
 	return &Config{
-		ExporterSettings:                config.NewExporterSettings(config.NewComponentID(typeStr)),
-		AWSSessionSettings:              awsutil.CreateDefaultSessionConfig(),
-		LogGroupName:                    "",
-		LogStreamName:                   "",
-		Namespace:                       "",
-		DimensionRollupOption:           "ZeroAndSingleDimensionRollup",
-		ParseJSONEncodedAttributeValues: make([]string, 0),
-		MetricDeclarations:              make([]*MetricDeclaration, 0),
-		MetricDescriptors:               make([]MetricDescriptor, 0),
-		OutputDestination:               "cloudwatch",
-		logger:                          nil,
+		ExporterSettings:      config.NewExporterSettings(config.NewComponentID(typeStr)),
+		AWSSessionSettings:    awsutil.CreateDefaultSessionConfig(),
+		LogGroupName:          "",
+		LogStreamName:         "",
+		Namespace:             "",
+		DimensionRollupOption: "ZeroAndSingleDimensionRollup",
+		OutputDestination:     "cloudwatch",
+		logger:                nil,
 	}
 }
 

exporter/awsemfexporter/metric_translator.go

@@ -250,7 +250,7 @@ func groupedMetricToCWMeasurementsWithFilters(groupedMetric *groupedMetric, conf
 	// If the whole batch of metrics don't match any metric declarations, drop them
 	if len(metricDeclarations) == 0 {
 		labelsStr, _ := json.Marshal(labels)
-		metricNames := make([]string, 0)
+		var metricNames []string
 		for metricName := range groupedMetric.metrics {
 			metricNames = append(metricNames, metricName)
 		}

exporter/awsemfexporter/util.go

@@ -131,7 +131,7 @@ func dedupDimensions(dimensions [][]string) (deduped [][]string) {
 // The returned dimensions are sorted in alphabetical order within each dimension set
 func dimensionRollup(dimensionRollupOption string, labels map[string]string) [][]string {
 	var rollupDimensionArray [][]string
-	dimensionZero := make([]string, 0)
+	var dimensionZero []string
 
 	instrLibName, hasOTelKey := labels[oTellibDimensionKey]
 	if hasOTelKey {

exporter/awsxrayexporter/internal/translator/cause.go

@@ -60,7 +60,7 @@ func makeCause(span ptrace.Span, attributes map[string]pcommon.Value, resource p
 			language = val.StringVal()
 		}
 
-		exceptions := make([]awsxray.Exception, 0)
+		var exceptions []awsxray.Exception
 		for i := 0; i < span.Events().Len(); i++ {
 			event := span.Events().At(i)
 			if event.Name() == ExceptionEventName {
@@ -202,7 +202,7 @@ func fillJavaStacktrace(stacktrace string, exceptions []awsxray.Exception) []aws
 		return exceptions
 	}
 
-	exception.Stack = make([]awsxray.StackFrame, 0)
+	exception.Stack = nil
 	for {
 		if strings.HasPrefix(line, "\tat ") {
 			parenIdx := strings.IndexByte(line, '(')
@@ -260,7 +260,7 @@ func fillJavaStacktrace(stacktrace string, exceptions []awsxray.Exception) []aws
 				ID:      aws.String(newSegmentID().HexString()),
 				Type:    aws.String(causeType),
 				Message: aws.String(causeMessage),
-				Stack:   make([]awsxray.StackFrame, 0),
+				Stack:   nil,
 			})
 			// when append causes `exceptions` to outgrow its existing
 			// capacity, re-allocation will happen so the place
@@ -299,7 +299,7 @@ func fillPythonStacktrace(stacktrace string, exceptions []awsxray.Exception) []a
 	line := lines[lineIdx]
 	exception := &exceptions[0]
 
-	exception.Stack = make([]awsxray.StackFrame, 0)
+	exception.Stack = nil
 	for {
 		if strings.HasPrefix(line, "  File ") {
 			parts := strings.Split(line, ",")
@@ -355,7 +355,6 @@ func fillPythonStacktrace(stacktrace string, exceptions []awsxray.Exception) []a
 				ID:      aws.String(newSegmentID().HexString()),
 				Type:    aws.String(causeType),
 				Message: aws.String(causeMessage),
-				Stack:   make([]awsxray.StackFrame, 0),
 			})
 			// when append causes `exceptions` to outgrow its existing
 			// capacity, re-allocation will happen so the place
@@ -396,7 +395,7 @@ func fillJavaScriptStacktrace(stacktrace string, exceptions []awsxray.Exception)
 		return exceptions
 	}
 
-	exception.Stack = make([]awsxray.StackFrame, 0)
+	exception.Stack = nil
 	for {
 		if strings.HasPrefix(line, "    at ") {
 			parenIdx := strings.IndexByte(line, '(')
@@ -455,7 +454,7 @@ func fillDotnetStacktrace(stacktrace string, exceptions []awsxray.Exception) []a
 		return exceptions
 	}
 
-	exception.Stack = make([]awsxray.StackFrame, 0)
+	exception.Stack = nil
 	for {
 		if strings.HasPrefix(line, "\tat ") {
 			index := strings.Index(line, " in ")
@@ -532,7 +531,7 @@ func fillGoStacktrace(stacktrace string, exceptions []awsxray.Exception) []awsxr
 		return exceptions
 	}
 
-	exception.Stack = make([]awsxray.StackFrame, 0)
+	exception.Stack = nil
 	for {
 		match := re.Match([]byte(line))
 		if match {

exporter/datadogexporter/internal/metrics/consumer_test.go

@@ -72,7 +72,7 @@ func TestRunningMetrics(t *testing.T) {
 	consumer := NewConsumer()
 	assert.NoError(t, tr.MapMetrics(ctx, ms, consumer))
 
-	runningHostnames := []string{}
+	var runningHostnames []string
 	for _, metric := range consumer.runningMetrics(0, component.BuildInfo{}) {
 		if metric.Host != nil {
 			runningHostnames = append(runningHostnames, *metric.Host)
@@ -117,8 +117,8 @@ func TestTagsMetrics(t *testing.T) {
 	assert.NoError(t, tr.MapMetrics(ctx, ms, consumer))
 
 	runningMetrics := consumer.runningMetrics(0, component.BuildInfo{})
-	runningTags := []string{}
-	runningHostnames := []string{}
+	var runningTags []string
+	var runningHostnames []string
 	for _, metric := range runningMetrics {
 		runningTags = append(runningTags, metric.Tags...)
 		if metric.Host != nil {

exporter/dynatraceexporter/metrics_exporter.go

@@ -43,7 +43,7 @@ const (
 
 // NewExporter exports to a Dynatrace Metrics v2 API
 func newMetricsExporter(params component.ExporterCreateSettings, cfg *config.Config) *exporter {
-	confDefaultDims := []dimensions.Dimension{}
+	var confDefaultDims []dimensions.Dimension
 	for key, value := range cfg.DefaultDimensions {
 		confDefaultDims = append(confDefaultDims, dimensions.NewDimension(key, value))
 	}
@@ -82,7 +82,7 @@ type exporter struct {
 
 // for backwards-compatibility with deprecated `Tags` config option
 func dimensionsFromTags(tags []string) dimensions.NormalizedDimensionList {
-	dims := []dimensions.Dimension{}
+	var dims []dimensions.Dimension
 	for _, tag := range tags {
 		parts := strings.SplitN(tag, "=", 2)
 		if len(parts) == 2 {
@@ -120,7 +120,7 @@ func (e *exporter) PushMetricsData(ctx context.Context, md pmetric.Metrics) erro
 }
 
 func (e *exporter) serializeMetrics(md pmetric.Metrics) []string {
-	lines := make([]string, 0)
+	var lines []string
 
 	resourceMetrics := md.ResourceMetrics()
 

exporter/instanaexporter/exporter.go

@@ -51,7 +51,7 @@ func (e *instanaExporter) start(_ context.Context, host component.Host) error {
 
 func (e *instanaExporter) pushConvertedTraces(ctx context.Context, td ptrace.Traces) error {
 	converter := converter.NewConvertAllConverter(e.settings.Logger)
-	spans := make([]model.Span, 0)
+	var spans []model.Span
 
 	hostID := ""
 	resourceSpans := td.ResourceSpans()

exporter/instanaexporter/internal/converter/model/bundle.go

@@ -24,7 +24,7 @@ type Bundle struct {
 
 func NewBundle() Bundle {
 	return Bundle{
-		Spans: make([]Span, 0),
+		Spans: []Span{},
 	}
 }
 

exporter/instanaexporter/internal/converter/model/util.go

@@ -22,37 +22,13 @@ import (
 )
 
 func convertTraceID(traceID pcommon.TraceID) string {
-	const byteLength = 16
-
 	bytes := traceID.Bytes()
-	traceBytes := make([]byte, 0)
-
-	for (len(traceBytes) + len(bytes)) < byteLength {
-		traceBytes = append(traceBytes, 0)
-	}
-
-	for _, byte := range bytes {
-		traceBytes = append(traceBytes, byte)
-	}
-
-	return hex.EncodeToString(traceBytes)
+	return hex.EncodeToString(bytes[:])
 }
 
 func convertSpanID(spanID pcommon.SpanID) string {
-	const byteLength = 8
-
 	bytes := spanID.Bytes()
-	spanBytes := make([]byte, 0)
-
-	for (len(spanBytes) + len(bytes)) < byteLength {
-		spanBytes = append(spanBytes, 0)
-	}
-
-	for _, byte := range bytes {
-		spanBytes = append(spanBytes, byte)
-	}
-
-	return hex.EncodeToString(spanBytes)
+	return hex.EncodeToString(bytes[:])
 }
 
 func otelKindToInstanaKind(otelKind ptrace.SpanKind) (string, bool) {

exporter/instanaexporter/internal/converter/span_converter.go

@@ -43,8 +43,6 @@ func (c *SpanConverter) AcceptsSpans(attributes pcommon.Map, spanSlice ptrace.Sp
 
 func (c *SpanConverter) ConvertSpans(attributes pcommon.Map, spanSlice ptrace.SpanSlice) model.Bundle {
 	bundle := model.NewBundle()
-	spans := make([]model.Span, 0)
-
 	fromS := model.FromS{}
 
 	hostIDValue, ex := attributes.Get(backend.AttributeInstanaHostID)
@@ -76,11 +74,9 @@ func (c *SpanConverter) ConvertSpans(attributes pcommon.Map, spanSlice ptrace.Sp
 			continue
 		}
 
-		spans = append(spans, instanaSpan)
+		bundle.Spans = append(bundle.Spans, instanaSpan)
 	}
 
-	bundle.Spans = spans
-
 	return bundle
 }
 

exporter/loadbalancingexporter/resolver_static_test.go

@@ -69,7 +69,7 @@ func TestResolvedOnlyOnce(t *testing.T) {
 
 func TestFailOnMissingEndpoints(t *testing.T) {
 	// prepare
-	expected := []string{}
+	var expected []string
 
 	// test
 	res, err := newStaticResolver(expected)

exporter/logzioexporter/logger.go

@@ -111,7 +111,7 @@ func (l *hclog2ZapLogger) StandardLogger(opts *hclog.StandardLoggerOptions) *log
 }
 
 func argsToFields(args ...interface{}) []zapcore.Field {
-	fields := []zapcore.Field{}
+	var fields []zapcore.Field
 	for i := 0; i < len(args); i += 2 {
 		fields = append(fields, zap.String(args[i].(string), fmt.Sprintf("%v", args[i+1])))
 	}

exporter/lokiexporter/legacy_exporter_test.go

@@ -382,7 +382,7 @@ func TestExporter_logDataToLoki(t *testing.T) {
 		lr.SetTimestamp(ts)
 
 		pr, numDroppedLogs := exp.logDataToLoki(logs)
-		expectedPr := &logproto.PushRequest{Streams: make([]logproto.Stream, 0)}
+		expectedPr := &logproto.PushRequest{Streams: []logproto.Stream{}}
 		require.Equal(t, 1, numDroppedLogs)
 		require.Equal(t, expectedPr, pr)
 	})
@@ -468,7 +468,7 @@ func TestExporter_logDataToLoki(t *testing.T) {
 		lri.SetTimestamp(ts)
 
 		pr, numDroppedLogs := exp.logDataToLoki(logs)
-		expectedPr := &logproto.PushRequest{Streams: make([]logproto.Stream, 0)}
+		expectedPr := &logproto.PushRequest{Streams: []logproto.Stream{}}
 		require.Equal(t, 1, numDroppedLogs)
 		require.Equal(t, expectedPr, pr)
 	})

exporter/prometheusremotewriteexporter/exporter_test.go

@@ -263,7 +263,7 @@ func Test_export(t *testing.T) {
 		assert.Equal(t, "snappy", r.Header.Get("Content-Encoding"))
 		assert.Equal(t, "opentelemetry-collector/1.0", r.Header.Get("User-Agent"))
 		writeReq := &prompb.WriteRequest{}
-		unzipped := []byte{}
+		var unzipped []byte
 
 		dest, err := snappy.Decode(unzipped, body)
 		require.NoError(t, err)

exporter/prometheusremotewriteexporter/helper.go

@@ -38,7 +38,7 @@ func batchTimeSeries(tsMap map[string]*prompb.TimeSeries, maxBatchByteSize int)
 			wrapped := convertTimeseriesToRequest(tsArray)
 			requests = append(requests, wrapped)
 
-			tsArray = make([]prompb.TimeSeries, 0)
+			tsArray = nil
 			sizeOfCurrentBatch = 0
 		}
 

exporter/skywalkingexporter/logrecord_to_logdata.go

@@ -36,7 +36,7 @@ const (
 )
 
 func logRecordToLogData(ld plog.Logs) []*logpb.LogData {
-	lds := make([]*logpb.LogData, 0)
+	var lds []*logpb.LogData
 	rls := ld.ResourceLogs()
 	for i := 0; i < rls.Len(); i++ {
 		rl := rls.At(i)

exporter/skywalkingexporter/metricrecord_to_metricdata.go

@@ -221,7 +221,6 @@ func metricsRecordToMetricData(
 		service, serviceInstance := resourceToServiceInfo(resMetricSlice.Resource())
 		insMetricSlice := resMetricSlice.ScopeMetrics()
 		metrics = &metricpb.MeterDataCollection{}
-		metrics.MeterData = make([]*metricpb.MeterData, 0)
 		for j := 0; j < insMetricSlice.Len(); j++ {
 			insMetrics := insMetricSlice.At(j)
 			// ignore insMetrics.Scope()