go-tour: render tour just once at startup

R=golang-dev, campoy
CC=golang-dev
https://codereview.appspot.com/7331046

gotour/appengine.go

@@ -26,11 +26,14 @@ func init() {
 	if err != nil {
 		panic(err)
 	}
+	if err := initTour("."); err != nil {
+		panic(err)
+	}
 }
 
 func rootHandler(w http.ResponseWriter, r *http.Request) {
 	c := appengine.NewContext(r)
-	if err := renderTour(w, "."); err != nil {
+	if err := renderTour(w); err != nil {
 		c.Criticalf("template render: %v", err)
 	}
 }

gotour/local.go

@@ -89,14 +89,30 @@ func main() {
 
 	log.Println("Serving content from", root)
 
+	host, port, err := net.SplitHostPort(*httpListen)
+	if err != nil {
+		log.Fatal(err)
+	}
+	if host == "" {
+		host = "localhost"
+	}
+	if host != "127.0.0.1" && host != "localhost" {
+		log.Print(localhostWarning)
+	}
+	httpAddr = host + ":" + port
+
+	if err := initTour(root); err != nil {
+		log.Fatal(err)
+	}
+
 	fs := http.FileServer(http.Dir(root))
 	http.Handle("/favicon.ico", fs)
 	http.Handle("/static/", fs)
 	http.Handle("/talks/", fs)
 
 	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
 		if r.URL.Path == "/" {
-			if err := renderTour(w, root); err != nil {
+			if err := renderTour(w); err != nil {
 				log.Println(err)
 			}
 			return
@@ -111,18 +127,6 @@ func main() {
 		log.Fatal(err)
 	}
 
-	host, port, err := net.SplitHostPort(*httpListen)
-	if err != nil {
-		log.Fatal(err)
-	}
-	if host == "" {
-		host = "localhost"
-	}
-	if host != "127.0.0.1" && host != "localhost" {
-		log.Print(localhostWarning)
-	}
-
-	httpAddr = host + ":" + port
 	go func() {
 		url := "http://" + httpAddr
 		if waitServer(url) && *openBrowser && startBrowser(url) {

gotour/tour.go

@@ -22,9 +22,11 @@ func init() {
 	present.PlayEnabled = true
 }
 
-// renderTour loads tour.article and the relevant HTML templates from the given
-// tour root, and renders the template to the provided writer.
-func renderTour(w io.Writer, root string) error {
+var tourContent []byte
+
+// initTour loads tour.article and the relevant HTML templates from the given
+// tour root, and renders the template to the tourContent global variable.
+func initTour(root string) error {
 	// Open and parse source file.
 	source := filepath.Join(root, "tour.article")
 	f, err := os.Open(source)
@@ -47,7 +49,21 @@ func renderTour(w io.Writer, root string) error {
 	}
 
 	// Render.
-	return doc.Render(w, t)
+	buf := new(bytes.Buffer)
+	if err := doc.Render(buf, t); err != nil {
+		return err
+	}
+	tourContent = buf.Bytes()
+	return nil
+}
+
+// renderTour writes the tour content to the provided Writer.
+func renderTour(w io.Writer) error {
+	if tourContent == nil {
+		panic("renderTour called before successful initTour")
+	}
+	_, err := w.Write(tourContent)
+	return err
 }
 
 // nocode returns true if the provided Section contains