refactor (stdoutlog): implement self-observability metrics following contributing guidelines

Signed-off-by: Praful Khanduri <holiodin@gmail.com>

added chloggen

Signed-off-by: Praful Khanduri <holiodin@gmail.com>

fix: return err

Signed-off-by: Praful Khanduri <holiodin@gmail.com>

Author: Horiodino

CHANGELOG.md

@@ -10,6 +10,8 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 
 ### Added
 
+- Add experimental self-observability log exporter metrics in `go.opentelemetry.io/otel/exporters/stdout/stdoutlog`.
+  Check the `go.opentelemetry.io/otel/exporters/stdout/stdoutlog/internal/x` package documentation for more information.
 - Add `WithInstrumentationAttributeSet` option to `go.opentelemetry.io/otel/log`, `go.opentelemetry.io/otel/metric`, and `go.opentelemetry.io/otel/trace` packages.
   This provides a concurrent-safe and performant alternative to `WithInstrumentationAttributes` by accepting a pre-constructed `attribute.Set`. (#7287)
 

exporters/stdout/stdoutlog/config.go

@@ -38,7 +38,6 @@ func newConfig(options []Option) config {
 	for _, opt := range options {
 		cfg = opt.apply(cfg)
 	}
-
 	return cfg
 }
 

exporters/stdout/stdoutlog/exporter.go

@@ -6,19 +6,21 @@ package stdoutlog // import "go.opentelemetry.io/otel/exporters/stdout/stdoutlog
 import (
 	"context"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"sync"
 	"sync/atomic"
 	"time"
 
 	"go.opentelemetry.io/otel"
 	"go.opentelemetry.io/otel/attribute"
+	"go.opentelemetry.io/otel/exporters/stdout/stdoutlog/internal/counter"
 	"go.opentelemetry.io/otel/exporters/stdout/stdoutlog/internal/x"
 	"go.opentelemetry.io/otel/metric"
 	"go.opentelemetry.io/otel/sdk"
 	"go.opentelemetry.io/otel/sdk/log"
-	semconv "go.opentelemetry.io/otel/semconv/v1.36.0"
-	"go.opentelemetry.io/otel/semconv/v1.36.0/otelconv"
+	semconv "go.opentelemetry.io/otel/semconv/v1.37.0"
+	"go.opentelemetry.io/otel/semconv/v1.37.0/otelconv"
 )
 
 // otelComponentType is a name identifying the type of the OpenTelemetry component.
@@ -29,12 +31,12 @@ var _ log.Exporter = &Exporter{}
 // Exporter writes JSON-encoded log records to an [io.Writer] ([os.Stdout] by default).
 // Exporter must be created with [New].
 type Exporter struct {
-	encoder           atomic.Pointer[json.Encoder]
-	timestamps        bool
-	selfObservability *selfObservability
+	encoder    atomic.Pointer[json.Encoder]
+	timestamps bool
+	inst       *instrumentationImpl
 }
 
-type selfObservability struct {
+type instrumentationImpl struct {
 	attrs                   []attribute.KeyValue
 	inflightMetric          otelconv.SDKExporterLogInflight
 	exportedMetric          otelconv.SDKExporterLogExported
@@ -54,23 +56,23 @@ func New(options ...Option) (*Exporter, error) {
 		timestamps: cfg.Timestamps,
 	}
 	e.encoder.Store(enc)
-	selfObs, err := newSelfObservability()
+	selfObs, err := newInstrumentation()
 	if err != nil {
 		return nil, err
 	}
-	e.selfObservability = selfObs
+	e.inst = selfObs
 
 	return &e, nil
 }
 
-func newSelfObservability() (*selfObservability, error) {
+func newInstrumentation() (*instrumentationImpl, error) {
 	if !x.SelfObservability.Enabled() {
 		return nil, nil
 	}
 
-	selfObservability := &selfObservability{
+	inst := &instrumentationImpl{
 		attrs: []attribute.KeyValue{
-			semconv.OTelComponentName(fmt.Sprintf("%s/%d", otelComponentType, nextExporterID())),
+			semconv.OTelComponentName(fmt.Sprintf("%s/%d", otelComponentType, counter.NextExporterID())),
 			semconv.OTelComponentTypeKey.String(otelComponentType),
 		},
 	}
@@ -81,24 +83,23 @@ func newSelfObservability() (*selfObservability, error) {
 		metric.WithSchemaURL(semconv.SchemaURL),
 	)
 
-	var err error
-	if selfObservability.inflightMetric, err = otelconv.NewSDKExporterLogInflight(m); err != nil {
-		return nil, err
-	}
-	if selfObservability.exportedMetric, err = otelconv.NewSDKExporterLogExported(m); err != nil {
-		return nil, err
-	}
-	if selfObservability.operationDurationMetric, err = otelconv.NewSDKExporterOperationDuration(m); err != nil {
-		return nil, err
-	}
+	var err, e error
+	inst.inflightMetric, e = otelconv.NewSDKExporterLogInflight(m)
+	err = errors.Join(err, e)
+
+	inst.exportedMetric, e = otelconv.NewSDKExporterLogExported(m)
+	err = errors.Join(err, e)
+
+	inst.operationDurationMetric, e = otelconv.NewSDKExporterOperationDuration(m)
+	err = errors.Join(err, e)
 
-	return selfObservability, nil
+	return inst, err
 }
 
 // Export exports log records to writer.
 func (e *Exporter) Export(ctx context.Context, records []log.Record) error {
 	var err error
-	if e.selfObservability != nil && x.SelfObservability.Enabled() {
+	if e.inst != nil && x.SelfObservability.Enabled() {
 		err = e.exportWithSelfObservability(ctx, records)
 	} else {
 		err = e.exportWithoutSelfObservability(ctx, records)
@@ -108,7 +109,7 @@ func (e *Exporter) Export(ctx context.Context, records []log.Record) error {
 
 const bufferSize = 4
 
-var selfObservabilityBuffer = sync.Pool{
+var attrPool = sync.Pool{
 	New: func() any {
 		buf := make([]attribute.KeyValue, 0, bufferSize)
 		return &buf
@@ -120,31 +121,34 @@ func (e *Exporter) exportWithSelfObservability(ctx context.Context, records []lo
 	count := int64(len(records))
 	start := time.Now()
 
-	e.selfObservability.inflightMetric.Add(ctx, count, e.selfObservability.attrs...)
+	e.inst.inflightMetric.Add(ctx, count, e.inst.attrs...)
 
+	bufPtrAny := attrPool.Get()
+	bufPtr, ok := bufPtrAny.(*[]attribute.KeyValue)
+	if !ok || bufPtr == nil {
+		bufPtr = &[]attribute.KeyValue{}
+	}
 	defer func() {
-		bufPtrAny := selfObservabilityBuffer.Get()
-		bufPtr, ok := bufPtrAny.(*[]attribute.KeyValue)
-		if !ok || bufPtr == nil {
-			bufPtr = &[]attribute.KeyValue{}
-		}
+		*bufPtr = (*bufPtr)[:0]
+		attrPool.Put(bufPtr)
+	}()
 
+	defer func() {
 		addAttrs := (*bufPtr)[:0]
-		addAttrs = append(addAttrs, e.selfObservability.attrs...)
+		addAttrs = append(addAttrs, e.inst.attrs...)
 
 		if err != nil {
 			addAttrs = append(addAttrs, semconv.ErrorType(err))
 		}
-		e.selfObservability.exportedMetric.Add(ctx, count, addAttrs...)
-		e.selfObservability.inflightMetric.Add(ctx, -count, e.selfObservability.attrs...)
-		e.selfObservability.operationDurationMetric.Record(ctx, time.Since(start).Seconds(), addAttrs...)
+		e.inst.exportedMetric.Add(ctx, count, addAttrs...)
+		e.inst.inflightMetric.Add(ctx, -count, e.inst.attrs...)
+		e.inst.operationDurationMetric.Record(ctx, time.Since(start).Seconds(), addAttrs...)
 
-		*bufPtr = addAttrs[:0]
-		selfObservabilityBuffer.Put(bufPtr)
+		*bufPtr = addAttrs
 	}()
 
 	err = e.exportWithoutSelfObservability(ctx, records)
-	return
+	return err
 }
 
 // exportWithoutSelfObservability exports logs without self-observability metrics.
@@ -178,11 +182,3 @@ func (e *Exporter) Shutdown(context.Context) error {
 func (*Exporter) ForceFlush(context.Context) error {
 	return nil
 }
-
-var exporterIDCounter atomic.Int64
-
-// nextExporterID returns a new unique ID for an exporter.
-// the starting value is 0, and it increments by 1 for each call.
-func nextExporterID() int64 {
-	return exporterIDCounter.Add(1) - 1
-}

exporters/stdout/stdoutlog/exporter_test.go

@@ -16,6 +16,7 @@ import (
 
 	"go.opentelemetry.io/otel"
 	"go.opentelemetry.io/otel/attribute"
+	"go.opentelemetry.io/otel/exporters/stdout/stdoutlog/internal/counter"
 	"go.opentelemetry.io/otel/log"
 	"go.opentelemetry.io/otel/sdk/instrumentation"
 	sdklog "go.opentelemetry.io/otel/sdk/log"
@@ -24,7 +25,7 @@ import (
 	"go.opentelemetry.io/otel/sdk/metric/metricdata"
 	"go.opentelemetry.io/otel/sdk/metric/metricdata/metricdatatest"
 	"go.opentelemetry.io/otel/sdk/resource"
-	"go.opentelemetry.io/otel/semconv/v1.36.0/otelconv"
+	"go.opentelemetry.io/otel/semconv/v1.37.0/otelconv"
 	"go.opentelemetry.io/otel/trace"
 )
 
@@ -932,7 +933,7 @@ func TestNewSelfObservability(t *testing.T) {
 
 			if ranOnce {
 				// Reset the global exporter ID counter for deterministic tests
-				exporterIDCounter.Store(0) // First call to nextExporterID() will return 0
+				counter.SetExporterID(0) // First call to NextExporterID() will return 0
 			}
 
 			prev := otel.GetMeterProvider()

exporters/stdout/stdoutlog/go.mod

@@ -6,21 +6,14 @@ go 1.24.0
 retract v0.12.0
 
 require (
-	github.com/stretchr/testify v1.10.0
-	go.opentelemetry.io/otel v1.37.0
-	go.opentelemetry.io/otel/log v0.13.0
-	go.opentelemetry.io/otel/metric v1.37.0
-	go.opentelemetry.io/otel/sdk v1.37.0
-	go.opentelemetry.io/otel/sdk/log v0.13.0
-	go.opentelemetry.io/otel/sdk/log/logtest v0.13.0
-	go.opentelemetry.io/otel/sdk/metric v1.37.0
-	go.opentelemetry.io/otel/trace v1.37.0
 	github.com/stretchr/testify v1.11.1
 	go.opentelemetry.io/otel v1.38.0
 	go.opentelemetry.io/otel/log v0.14.0
+	go.opentelemetry.io/otel/metric v1.38.0
 	go.opentelemetry.io/otel/sdk v1.38.0
 	go.opentelemetry.io/otel/sdk/log v0.14.0
 	go.opentelemetry.io/otel/sdk/log/logtest v0.14.0
+	go.opentelemetry.io/otel/sdk/metric v1.38.0
 	go.opentelemetry.io/otel/trace v1.38.0
 )
 
@@ -31,7 +24,6 @@ require (
 	github.com/google/uuid v1.6.0 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
 	go.opentelemetry.io/auto/sdk v1.1.0 // indirect
-	go.opentelemetry.io/otel/metric v1.38.0 // indirect
 	golang.org/x/sys v0.36.0 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect
 )

exporters/stdout/stdoutlog/internal/counter/counter.go

@@ -0,0 +1,9 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+// Package internal provides internal functionality for the stdoutlog
+// package.
+package internal // import "go.opentelemetry.io/otel/exporters/stdout/stdoutlog/internal"
+
+//go:generate gotmpl --body=../../../../internal/shared/counter/counter.go.tmpl "--data={ \"pkg\": \"go.opentelemetry.io/otel/exporters/stdout/stdoutlog/internal/counter\" }" --out=counter/counter.go
+//go:generate gotmpl --body=../../../../internal/shared/counter/counter_test.go.tmpl "--data={}" --out=counter/counter_test.go