otlplog: document Exporter concurrency guarantees

CHANGELOG.md

@@ -20,6 +20,7 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 - Document a compatibility regression introduced in `go.opentelemetry.io/otel` v1.47.0 that breaks compilation with `go.opentelemetry.io/otel/bridge/opentracing` v1.46.0 and earlier.
   Include instructions for upgrading the bridge to v1.47.0.
   See the [bridge version compatibility documentation](bridge/opentracing/README.md#version-compatibility). (#9209)
+- Document the concurrency guarantees of the `Exporter` in `go.opentelemetry.io/otel/exporters/otlp/otlplog/otlploggrpc` and `go.opentelemetry.io/otel/exporters/otlp/otlplog/otlploghttp`. (#9244)
 
 ### Deprecated
 

exporters/otlp/otlplog/otlploggrpc/exporter.go

@@ -58,6 +58,8 @@ var transformResourceLogs = transform.ResourceLogs
 //
 // This method returns [log.ErrExporterShutdown] if called after Shutdown.
 // This method returns an error if the method is canceled by the passed context.
+//
+// This method is safe to call concurrently.
 func (e *Exporter) Export(ctx context.Context, records []log.Record) error {
 	if e.stopped.Load() {
 		return log.ErrExporterShutdown
@@ -79,6 +81,11 @@ func (e *Exporter) Export(ctx context.Context, records []log.Record) error {
 
 // Shutdown shuts down the Exporter. Calls to Export after Shutdown return
 // [log.ErrExporterShutdown]. Calls to ForceFlush perform no operation.
+//
+// Calling Shutdown more than once is safe: subsequent calls do nothing and
+// return nil.
+//
+// This method is safe to call concurrently.
 func (e *Exporter) Shutdown(ctx context.Context) error {
 	if e.stopped.Swap(true) {
 		return nil
@@ -93,6 +100,8 @@ func (e *Exporter) Shutdown(ctx context.Context) error {
 }
 
 // ForceFlush does nothing. The Exporter holds no state.
+//
+// This method is safe to call concurrently.
 func (*Exporter) ForceFlush(context.Context) error {
 	return nil
 }

exporters/otlp/otlplog/otlploghttp/exporter.go

@@ -46,6 +46,8 @@ var transformResourceLogs = transform.ResourceLogs
 
 // Export transforms and transmits log records to an OTLP receiver. It returns
 // [log.ErrExporterShutdown] if called after Shutdown.
+//
+// This method is safe to call concurrently.
 func (e *Exporter) Export(ctx context.Context, records []log.Record) error {
 	if e.stopped.Load() {
 		return log.ErrExporterShutdown
@@ -64,6 +66,12 @@ func (e *Exporter) Export(ctx context.Context, records []log.Record) error {
 
 // Shutdown shuts down the Exporter. Calls to Export after Shutdown return
 // [log.ErrExporterShutdown]. Calls to ForceFlush perform no operation.
+//
+// Shutdown does not wait for or cancel in-flight Export calls.
+// Calling Shutdown more than once is safe: subsequent calls do nothing and
+// return nil.
+//
+// This method is safe to call concurrently.
 func (e *Exporter) Shutdown(context.Context) error {
 	if e.stopped.Swap(true) {
 		return nil
@@ -74,6 +82,8 @@ func (e *Exporter) Shutdown(context.Context) error {
 }
 
 // ForceFlush does nothing. The Exporter holds no state.
+//
+// This method is safe to call concurrently.
 func (*Exporter) ForceFlush(context.Context) error {
 	return nil
 }