examples: Replace context.Background with context.WithTimeout (#1877)

examples/gotutorial.md

@@ -313,7 +313,7 @@ Now let's look at how we call our service methods. Note that in gRPC-Go, RPCs op
 Calling the simple RPC `GetFeature` is nearly as straightforward as calling a local method.
 
 ```go
-feature, err := client.GetFeature(context.Background(), &pb.Point{409146138, -746188906})
+feature, err := client.GetFeature(ctx, &pb.Point{409146138, -746188906})
 if err != nil {
         ...
 }
@@ -331,7 +331,7 @@ Here's where we call the server-side streaming method `ListFeatures`, which retu
 
 ```go
 rect := &pb.Rectangle{ ... }  // initialize a pb.Rectangle
-stream, err := client.ListFeatures(context.Background(), rect)
+stream, err := client.ListFeatures(ctx, rect)
 if err != nil {
     ...
 }
@@ -364,7 +364,7 @@ for i := 0; i < pointCount; i++ {
 	points = append(points, randomPoint(r))
 }
 log.Printf("Traversing %d points.", len(points))
-stream, err := client.RecordRoute(context.Background())
+stream, err := client.RecordRoute(ctx)
 if err != nil {
 	log.Fatalf("%v.RecordRoute(_) = _, %v", client, err)
 }
@@ -387,7 +387,7 @@ The `RouteGuide_RecordRouteClient` has a `Send()` method that we can use to send
 Finally, let's look at our bidirectional streaming RPC `RouteChat()`. As in the case of `RecordRoute`, we only pass the method a context object and get back a stream that we can use to both write and read messages. However, this time we return values via our method's stream while the server is still writing messages to *their* message stream.
 
 ```go
-stream, err := client.RouteChat(context.Background())
+stream, err := client.RouteChat(ctx)
 waitc := make(chan struct{})
 go func() {
 	for {

examples/helloworld/greeter_client/main.go

@@ -21,6 +21,7 @@ package main
 import (
 	"log"
 	"os"
+	"time"
 
 	"golang.org/x/net/context"
 	"google.golang.org/grpc"
@@ -46,7 +47,9 @@ func main() {
 	if len(os.Args) > 1 {
 		name = os.Args[1]
 	}
-	r, err := c.SayHello(context.Background(), &pb.HelloRequest{Name: name})
+	ctx, cancel := context.WithTimeout(context.Background(), time.Second)
+	defer cancel()
+	r, err := c.SayHello(ctx, &pb.HelloRequest{Name: name})
 	if err != nil {
 		log.Fatalf("could not greet: %v", err)
 	}

examples/helloworld/mock_helloworld/hw_mock_test.go

@@ -21,6 +21,7 @@ package mock_helloworld_test
 import (
 	"fmt"
 	"testing"
+	"time"
 
 	"github.com/golang/mock/gomock"
 	"github.com/golang/protobuf/proto"
@@ -59,7 +60,9 @@ func TestSayHello(t *testing.T) {
 }
 
 func testSayHello(t *testing.T, client helloworld.GreeterClient) {
-	r, err := client.SayHello(context.Background(), &helloworld.HelloRequest{Name: "unit_test"})
+	ctx, cancel := context.WithTimeout(context.Background(), time.Second)
+	defer cancel()
+	r, err := client.SayHello(ctx, &helloworld.HelloRequest{Name: "unit_test"})
 	if err != nil || r.Message != "Mocked Interface" {
 		t.Errorf("mocking failed")
 	}

examples/route_guide/client/client.go

@@ -46,7 +46,9 @@ var (
 // printFeature gets the feature for the given point.
 func printFeature(client pb.RouteGuideClient, point *pb.Point) {
 	log.Printf("Getting feature for point (%d, %d)", point.Latitude, point.Longitude)
-	feature, err := client.GetFeature(context.Background(), point)
+	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+	defer cancel()
+	feature, err := client.GetFeature(ctx, point)
 	if err != nil {
 		log.Fatalf("%v.GetFeatures(_) = _, %v: ", client, err)
 	}
@@ -56,7 +58,9 @@ func printFeature(client pb.RouteGuideClient, point *pb.Point) {
 // printFeatures lists all the features within the given bounding Rectangle.
 func printFeatures(client pb.RouteGuideClient, rect *pb.Rectangle) {
 	log.Printf("Looking for features within %v", rect)
-	stream, err := client.ListFeatures(context.Background(), rect)
+	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+	defer cancel()
+	stream, err := client.ListFeatures(ctx, rect)
 	if err != nil {
 		log.Fatalf("%v.ListFeatures(_) = _, %v", client, err)
 	}
@@ -82,7 +86,9 @@ func runRecordRoute(client pb.RouteGuideClient) {
 		points = append(points, randomPoint(r))
 	}
 	log.Printf("Traversing %d points.", len(points))
-	stream, err := client.RecordRoute(context.Background())
+	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+	defer cancel()
+	stream, err := client.RecordRoute(ctx)
 	if err != nil {
 		log.Fatalf("%v.RecordRoute(_) = _, %v", client, err)
 	}
@@ -108,7 +114,9 @@ func runRouteChat(client pb.RouteGuideClient) {
 		{Location: &pb.Point{Latitude: 0, Longitude: 2}, Message: "Fifth message"},
 		{Location: &pb.Point{Latitude: 0, Longitude: 3}, Message: "Sixth message"},
 	}
-	stream, err := client.RouteChat(context.Background())
+	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+	defer cancel()
+	stream, err := client.RouteChat(ctx)
 	if err != nil {
 		log.Fatalf("%v.RouteChat(_) = _, %v", client, err)
 	}

examples/route_guide/mock_routeguide/rg_mock_test.go

@@ -21,6 +21,7 @@ package mock_routeguide_test
 import (
 	"fmt"
 	"testing"
+	"time"
 
 	"github.com/golang/mock/gomock"
 	"github.com/golang/protobuf/proto"
@@ -59,7 +60,9 @@ func TestRouteChat(t *testing.T) {
 }
 
 func testRouteChat(client rgpb.RouteGuideClient) error {
-	stream, err := client.RouteChat(context.Background())
+	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+	defer cancel()
+	stream, err := client.RouteChat(ctx)
 	if err != nil {
 		return err
 	}