[Prototype] log: Events support with minimal non-breaking changes

log/logger.go

@@ -28,9 +28,6 @@ type Logger interface {
 	//
 	// Implementations of this method need to be safe for a user to call
 	// concurrently.
-	//
-	// Notice: Emit is intended to be used by log bridges.
-	// Is should not be used for writing instrumentation.
 	Emit(ctx context.Context, record Record)
 
 	// Enabled returns whether the Logger emits for the given context and
@@ -53,9 +50,6 @@ type Logger interface {
 	//
 	// Implementations of this method need to be safe for a user to call
 	// concurrently.
-	//
-	// Notice: Enabled is intended to be used by log bridges.
-	// Is should not be used for writing instrumentation.
 	Enabled(ctx context.Context, param EnabledParameters) bool
 }
 
@@ -138,5 +132,6 @@ func WithSchemaURL(schemaURL string) LoggerOption {
 
 // EnabledParameters represents payload for [Logger]'s Enabled method.
 type EnabledParameters struct {
-	Severity Severity
+	EventName string
+	Severity  Severity
 }

log/record.go

@@ -15,10 +15,13 @@ import (
 const attributesInlineCount = 5
 
 // Record represents a log record.
+// A log record with non-empty event name is interpreted as an event record.
 type Record struct {
 	// Ensure forward compatibility by explicitly making this not comparable.
 	noCmp [0]func() //nolint: unused  // This is indeed used.
 
+	eventName string
+
 	timestamp         time.Time
 	observedTimestamp time.Time
 	severity          Severity
@@ -44,6 +47,18 @@ type Record struct {
 	back []KeyValue
 }
 
+// Event returns the event name.
+// A log record with non-empty event name is interpreted as an event record.
+func (r *Record) EventName() string {
+	return r.eventName
+}
+
+// SetEventName sets the event name.
+// A log record with non-empty event name is interpreted as an event record.
+func (r *Record) SetEventName(s string) {
+	r.eventName = s
+}
+
 // Timestamp returns the time when the log record occurred.
 func (r *Record) Timestamp() time.Time {
 	return r.timestamp

log/record_test.go

@@ -15,6 +15,14 @@ import (
 
 var y2k = time.Date(2000, time.January, 1, 0, 0, 0, 0, time.UTC)
 
+func TestRecordEventName(t *testing.T) {
+	const text = "testing text"
+
+	var r log.Record
+	r.SetEventName(text)
+	assert.Equal(t, text, r.EventName())
+}
+
 func TestRecordTimestamp(t *testing.T) {
 	var r log.Record
 	r.SetTimestamp(y2k)

sdk/log/logger.go

@@ -73,6 +73,8 @@ func (l *logger) newRecord(ctx context.Context, r log.Record) Record {
 	sc := trace.SpanContextFromContext(ctx)
 
 	newRecord := Record{
+		eventName: r.EventName(),
+
 		timestamp:         r.Timestamp(),
 		observedTimestamp: r.ObservedTimestamp(),
 		severity:          r.Severity(),

sdk/log/logger_test.go

@@ -33,6 +33,7 @@ func TestLoggerEmit(t *testing.T) {
 	p2WithError.Err = errors.New("error")
 
 	r := log.Record{}
+	r.SetEventName("testing.name")
 	r.SetTimestamp(time.Date(2000, time.January, 1, 0, 0, 0, 0, time.UTC))
 	r.SetBody(log.StringValue("testing body value"))
 	r.SetSeverity(log.SeverityInfo)
@@ -78,6 +79,7 @@ func TestLoggerEmit(t *testing.T) {
 			record: r,
 			expectedRecords: []Record{
 				{
+					eventName:                 r.EventName(),
 					timestamp:                 r.Timestamp(),
 					body:                      r.Body(),
 					severity:                  r.Severity(),
@@ -118,6 +120,7 @@ func TestLoggerEmit(t *testing.T) {
 			record: r,
 			expectedRecords: []Record{
 				{
+					eventName:                 r.EventName(),
 					timestamp:                 r.Timestamp(),
 					body:                      r.Body(),
 					severity:                  r.Severity(),
@@ -151,6 +154,7 @@ func TestLoggerEmit(t *testing.T) {
 			record: r,
 			expectedRecords: []Record{
 				{
+					eventName:                 r.EventName(),
 					timestamp:                 r.Timestamp(),
 					body:                      r.Body(),
 					severity:                  r.Severity(),
@@ -181,6 +185,7 @@ func TestLoggerEmit(t *testing.T) {
 			record: rWithNoObservedTimestamp,
 			expectedRecords: []Record{
 				{
+					eventName:                 rWithNoObservedTimestamp.EventName(),
 					timestamp:                 rWithNoObservedTimestamp.Timestamp(),
 					body:                      rWithNoObservedTimestamp.Body(),
 					severity:                  rWithNoObservedTimestamp.Severity(),

sdk/log/record.go

@@ -42,6 +42,7 @@ func putIndex(index map[string]int) {
 }
 
 // Record is a log record emitted by the Logger.
+// A log record with non-empty event name is interpreted as an event record.
 //
 // Do not create instances of Record on your own in production code.
 // You can use [go.opentelemetry.io/otel/sdk/log/logtest.RecordFactory]
@@ -50,6 +51,8 @@ type Record struct {
 	// Do not embed the log.Record. Attributes need to be overwrite-able and
 	// deep-copying needs to be possible.
 
+	eventName string
+
 	timestamp         time.Time
 	observedTimestamp time.Time
 	severity          log.Severity
@@ -104,6 +107,18 @@ func (r *Record) setDropped(n int) {
 	r.dropped = n
 }
 
+// Event returns the event name.
+// A log record with non-empty event name is interpreted as an event record.
+func (r *Record) EventName() string {
+	return r.eventName
+}
+
+// SetEventName sets the event name.
+// A log record with non-empty event name is interpreted as an event record.
+func (r *Record) SetEventName(s string) {
+	r.eventName = s
+}
+
 // Timestamp returns the time when the log record occurred.
 func (r *Record) Timestamp() time.Time {
 	return r.timestamp