Update grpc example to allow long runs (#835)

* Update grpc example to allow long runs

* Trigger Build

* Update sample to allow indefinite span generation

example/trace/otlpgrpc/example.go

@@ -17,6 +17,7 @@ package main
 
 import (
 	"context"
+	"flag"
 	"fmt"
 	"log"
 	"time"
@@ -31,6 +32,8 @@ import (
 	"google.golang.org/grpc/credentials/oauth"
 )
 
+var keepRunning = flag.Bool("keepRunning", false, "Set to true for generating spans at a fixed rate indefinitely. Default is false.")
+
 func initTracer() (func(), error) {
 	ctx := context.Background()
 
@@ -62,7 +65,28 @@ func initTracer() (func(), error) {
 	}, nil
 }
 
+func generateTestSpan(ctx context.Context, tr trace.Tracer, description string) {
+	fmt.Println("starting span...")
+	_, span := tr.Start(ctx, description, trace.WithAttributes(semconv.PeerServiceKey.String("ExampleService")))
+	defer span.End()
+	defer fmt.Println("ending span.")
+
+	time.Sleep(3 * time.Second)
+}
+
+func generateSpansAtFixedRate(ctx context.Context, tr trace.Tracer) {
+	fmt.Println("Generating 1 test span every 10 seconds indefinitely")
+	ticker := time.NewTicker(10 * time.Second)
+	defer ticker.Stop()
+
+	for tick := range ticker.C {
+		go generateTestSpan(ctx, tr, fmt.Sprintf("span-%s", tick))
+	}
+	fmt.Println("Span generation complete.")
+}
+
 func main() {
+	flag.Parse()
 	shutdown, err := initTracer()
 	if err != nil {
 		log.Fatal(err)
@@ -71,10 +95,9 @@ func main() {
 	tr := otel.Tracer("cloudtrace/example/client")
 
 	ctx := context.Background()
-	fmt.Println("starting span...")
-	_, span := tr.Start(ctx, "test span", trace.WithAttributes(semconv.PeerServiceKey.String("ExampleService")))
-	defer span.End()
-	defer fmt.Println("ending span.")
-
-	time.Sleep(3 * time.Second)
+	if *keepRunning {
+		generateSpansAtFixedRate(ctx, tr)
+	} else {
+		generateTestSpan(ctx, tr, "test span")
+	}
 }