Merge pull request #710 from wallyqs/godoc-context-example

Add godoc example for JS context functions

example_test.go

@@ -774,3 +774,40 @@ func ExamplePullOpt() {
 		msg.Ack()
 	}
 }
+
+func ExampleContext() {
+	nc, err := nats.Connect("localhost")
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	js, _ := nc.JetStream()
+
+	// Base context
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	// nats.Context option implements context.Context interface, so can be used
+	// to create a new context from top level one.
+	nctx := nats.Context(ctx)
+
+	// JetStreamManager functions all can use context.
+	js.AddStream(&nats.StreamConfig{
+		Name:     "FOO",
+		Subjects: []string{"foo"},
+	}, nctx)
+
+	// Custom context with timeout
+	tctx, tcancel := context.WithTimeout(nctx, 2*time.Second)
+	defer tcancel()
+
+	// Set a timeout for publishing using context.
+	deadlineCtx := nats.Context(tctx)
+
+	js.Publish("foo", []byte("Hello JS!"), deadlineCtx)
+	sub, _ := js.SubscribeSync("foo")
+	msg, _ := sub.NextMsgWithContext(deadlineCtx)
+
+	// Acks can also use a context to await for a response.
+	msg.Ack(deadlineCtx)
+}

js.go

@@ -775,7 +775,8 @@ func (ctx ContextOpt) configureAck(opts *ackOpts) error {
 	return nil
 }
 
-// Context returns an option that can be used to configure a context.
+// Context returns an option that can be used to configure a context for APIs
+// that are context aware such as those part of the JetStream interface.
 func Context(ctx context.Context) ContextOpt {
 	return ContextOpt{ctx}
 }