Add a Shutdown method to sdk TraceProvider (#1227)

* Add a Shutdown method to api TraceProvider

- sdktraceprovider shutdown span processors
- In examples, replace processosr shutdown with
  traceprovider's shutdown

Signed-off-by: Hui Kang <kangh@us.ibm.com>

* remove shutdown in the api provider interface

* Add context in parameter and return error

* handle error in shutdown

* Update CHANGELOG.md

Co-authored-by: Tyler Yahn <MrAlias@users.noreply.github.com>

CHANGELOG.md

@@ -52,6 +52,7 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 - OTLP Metric exporter supports Histogram aggregation. (#1209)
 - The `Code` struct from the `go.opentelemetry.io/otel/codes` package now supports JSON marshaling and unmarshaling as well as implements the `Stringer` interface. (#1214)
 - A Baggage API to implement the OpenTelemetry specification. (#1217)
+- Add Shutdown method to sdk/trace/provider, shutdown processors in the order they were registered. (#1227)
 
 ### Changed
 

example/basic/main.go

@@ -46,8 +46,8 @@ func main() {
 	}
 
 	bsp := sdktrace.NewBatchSpanProcessor(exporter)
-	defer bsp.Shutdown()
 	tp := sdktrace.NewTracerProvider(sdktrace.WithSpanProcessor(bsp))
+	defer func() { _ = tp.Shutdown(context.Background()) }()
 	pusher := push.New(
 		basic.New(
 			simple.NewWithExactDistribution(),

example/namedtracer/main.go

@@ -35,12 +35,12 @@ var (
 var tp *sdktrace.TracerProvider
 
 // initTracer creates and registers trace provider instance.
-func initTracer() func() {
+func initTracer() {
 	var err error
 	exp, err := stdout.NewExporter(stdout.WithPrettyPrint())
 	if err != nil {
 		log.Panicf("failed to initialize stdout exporter %v\n", err)
-		return nil
+		return
 	}
 	bsp := sdktrace.NewBatchSpanProcessor(exp)
 	tp = sdktrace.NewTracerProvider(
@@ -52,17 +52,16 @@ func initTracer() func() {
 		sdktrace.WithSpanProcessor(bsp),
 	)
 	global.SetTracerProvider(tp)
-	return bsp.Shutdown
 }
 
 func main() {
 	// initialize trace provider.
-	shutdown := initTracer()
+	initTracer()
-	defer shutdown()
 
 	// Create a named tracer with package path as its name.
 	tracer := tp.Tracer("example/namedtracer/main")
 	ctx := context.Background()
+	defer func() { _ = tp.Shutdown(ctx) }()
 	ctx = otel.ContextWithBaggageValues(ctx, fooKey.String("foo1"), barKey.String("bar1"))
 
 	var span otel.Span

example/otel-collector/main.go

@@ -80,7 +80,7 @@ func initProvider() func() {
 	pusher.Start()
 
 	return func() {
-		bsp.Shutdown() // shutdown the processor
+		handleErr(tracerProvider.Shutdown(context.Background()), "failed to shutdown provider")
 		handleErr(exp.Shutdown(context.Background()), "failed to stop exporter")
 		pusher.Stop() // pushes any last exports to the receiver
 	}

exporters/otlp/otlp_integration_test.go

@@ -492,6 +492,7 @@ func TestNewExporter_withMultipleAttributeTypes(t *testing.T) {
 			sdktrace.WithMaxExportBatchSize(10),
 		),
 	)
+	defer func() { _ = tp.Shutdown(context.Background()) }()
 
 	tr := tp.Tracer("test-tracer")
 	testKvs := []label.KeyValue{

sdk/trace/provider.go

@@ -15,6 +15,7 @@
 package trace
 
 import (
+	"context"
 	"sync"
 	"sync/atomic"
 
@@ -180,6 +181,21 @@ func (p *TracerProvider) ApplyConfig(cfg Config) {
 	p.config.Store(&c)
 }
 
+// Shutdown shuts down the span processors in the order they were registered
+func (p *TracerProvider) Shutdown(ctx context.Context) error {
+	spss, ok := p.spanProcessors.Load().(spanProcessorStates)
+	if !ok || len(spss) == 0 {
+		return nil
+	}
+
+	for _, sps := range spss {
+		sps.state.Do(func() {
+			sps.sp.Shutdown()
+		})
+	}
+	return nil
+}
+
 // WithSyncer registers the exporter with the TracerProvider using a
 // SimpleSpanProcessor.
 func WithSyncer(e export.SpanExporter) TracerProviderOption {

sdk/trace/provider_test.go

@@ -0,0 +1,48 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package trace
+
+import (
+	"context"
+	"testing"
+
+	export "go.opentelemetry.io/otel/sdk/export/trace"
+)
+
+type basicSpanProcesor struct {
+	running bool
+}
+
+func (t *basicSpanProcesor) Shutdown() {
+	t.running = false
+}
+
+func (t *basicSpanProcesor) OnStart(s *export.SpanData) {}
+func (t *basicSpanProcesor) OnEnd(s *export.SpanData)   {}
+func (t *basicSpanProcesor) ForceFlush()                {}
+
+func TestShutdownTraceProvider(t *testing.T) {
+	stp := NewTracerProvider()
+	sp := &basicSpanProcesor{}
+	stp.RegisterSpanProcessor(sp)
+
+	sp.running = true
+
+	_ = stp.Shutdown(context.Background())
+
+	if sp.running != false {
+		t.Errorf("Error shutdown basicSpanProcesor\n")
+	}
+}