cloudfoundry-samples · crhntr · Sep 29, 2021 · Sep 29, 2021 · Oct 1, 2021 · Oct 1, 2021
diff --git a/cf_logo.png → assets/cf_logo.png b/cf_logo.png → assets/cf_logo.png
diff --git a/assets/index.gohtml b/assets/index.gohtml
@@ -0,0 +1,19 @@
+{{- /*gotype: github.com/gerg/http2_tile_demo.TemplateArgs*/ -}}
+<!DOCTYPE html>
+<html lang="en">
+<head>
+    <title>HTTP/2 Image Tile Demo</title>
+</head>
+<body>
+    <h1>HTTP/2 Image Tile Demo</h1>
+    <div>App HTTP Version: {{.HttpVersion}}</div>
+    <div>Browser HTTP Version: <span id="http"></span></div>
+    <div>Load Time: <span id="time"></span></div>
+    {{range .ImageFingerprints}}
+        <img src="/images/test_{{.}}.png" alt="Test Image {{.}}" height="20" />
+    {{end}}
+    <script>
+        {{.Script}}
+    </script>
+</body>
+</html>
diff --git a/assets/load_time.js b/assets/load_time.js
@@ -0,0 +1,6 @@
+document.getElementById("http").innerHTML = performance.getEntries()[0]?.nextHopProtocol;
+window.addEventListener("load", function() {
+    window.setTimeout(function() {
+        document.getElementById("time").innerHTML = (window.performance.timing.loadEventEnd - window.performance.timing.navigationStart);
+    }, 0);
+});
diff --git a/go.mod b/go.mod
@@ -2,4 +2,7 @@ module github.com/gerg/http2_tile_demo
 
 go 1.16
 
-require golang.org/x/net v0.0.0-20210716203947-853a461950ff
+require (
+	golang.org/x/net v0.0.0-20210929193557-e81a3d93ecf6
+	golang.org/x/text v0.3.7 // indirect
+)
diff --git a/go.sum b/go.sum
@@ -1,8 +1,9 @@
-golang.org/x/net v0.0.0-20210716203947-853a461950ff h1:j2EK/QoxYNBsXI4R7fQkkRUk8y6wnOBI+6hgPdP/6Ds=
-golang.org/x/net v0.0.0-20210716203947-853a461950ff/go.mod h1:9nx3DQGgdP8bBQD5qxJ1jj9UTztislL4KSBs9R2vV5Y=
+golang.org/x/net v0.0.0-20210929193557-e81a3d93ecf6 h1:Z04ewVs7JhXaYkmDhBERPi41gnltfQpMWDnTnQbaCqk=
+golang.org/x/net v0.0.0-20210929193557-e81a3d93ecf6/go.mod h1:9nx3DQGgdP8bBQD5qxJ1jj9UTztislL4KSBs9R2vV5Y=
 golang.org/x/sys v0.0.0-20201119102817-f84b799fce68/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20210423082822-04245dca01da/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
-golang.org/x/text v0.3.6 h1:aRYxNxv6iGQlyVaZmk6ZgYEDa+Jg18DxebPSrd6bg1M=
 golang.org/x/text v0.3.6/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
+golang.org/x/text v0.3.7 h1:olpwvP2KacW1ZWvsR7uQhoyTYvKAupfQrRGBFM352Gk=
+golang.org/x/text v0.3.7/go.mod h1:u+2+/6zg+i71rQMx5EYifcz6MCKuco9NR6JIITiCfzQ=
 golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
diff --git a/main.go b/main.go
@@ -2,15 +2,19 @@ package main
 
 import (
 	"bytes"
+	_ "embed"
 	"fmt"
 	"html/template"
 	"io"
+	"log"
 	"math"
 	"math/rand"
 	"net/http"
 	"os"
+	"strconv"
 	"strings"
 
+	"golang.org/x/net/html"
 	"golang.org/x/net/http2"
 	"golang.org/x/net/http2/h2c"
 )
@@ -22,66 +26,117 @@ func handleErr(message string, err error) {
 	}
 }
 
-func serveImgFactory() func(http.ResponseWriter, *http.Request) {
-	img, err := os.Open("cf_logo.png")
-	handleErr("Opening image", err)
-	defer img.Close()
-	imgContents, err := io.ReadAll(img)
-	handleErr("Copy image", err)
-	return func(w http.ResponseWriter, r *http.Request) {
-		w.Header().Set("Content-Type", "image/jpeg")
-		w.Header().Set("X-Http-Version", r.Proto)
-		_, err = io.Copy(w, bytes.NewBuffer(imgContents))
-		handleErr("Writing image", err)
-	}
-}
+var (
+	//go:embed assets/cf_logo.png
+	imgContents []byte
+)
 
-type TemplateArgs map[string]interface{}
+func serveImg(w http.ResponseWriter, r *http.Request) {
+	w.Header().Set("Content-Type", "image/jpeg")
+	w.Header().Set("X-Http-Version", r.Proto)
+	_, err := io.Copy(w, bytes.NewBuffer(imgContents))
+	handleErr("Writing image", err)
+}
 
-func generateImage() string {
-	fingerprint := rand.Int63n(math.MaxInt64)
-	return fmt.Sprintf(`<img src="/images/test_%d.png" height="20" />`, fingerprint)
+type TemplateArgs struct {
+	HttpVersion       string
+	ImageFingerprints []int
+	Script            template.JS
 }
 
-func generateImages(quantity int) string {
-	var sb strings.Builder
-	for i := 0; i < quantity; i++ {
-		sb.WriteString(generateImage())
+func generateImageFingerprints(n int) []int {
+	result := make([]int, n)
+	for i := range result {
+		result[i] = rand.Intn(math.MaxInt64)
 	}
-	return sb.String()
+	return result
 }
 
+var (
+	//go:embed assets/load_time.js
+	loadTimeScript string
+
+	//go:embed assets/index.gohtml
+	indexHTML string
+)
+
 func serveHTML(w http.ResponseWriter, r *http.Request) {
+	n, err := intQueryParam(r, "n", 1000)
+	if err != nil {
+		http.Error(w, "failed to parse n (int)", http.StatusBadRequest)
+		return
+	}
 	w.Header().Set("Content-Type", "text/html")
-	loadTimeScript := template.JS(`
-document.getElementById("http").innerHTML = performance.getEntries()[0]?.nextHopProtocol;
-window.addEventListener("load", function() {
-	window.setTimeout(function() {
-		document.getElementById("time").innerHTML = (window.performance.timing.loadEventEnd - window.performance.timing.navigationStart);
-	}, 0);
-});`)
 	templateArgs := TemplateArgs{
-		"HttpVersion": r.Proto,
-		"Images":      template.HTML(generateImages(1000)),
-		"Script":      loadTimeScript,
+		HttpVersion:       r.Proto,
+		ImageFingerprints: generateImageFingerprints(n),
+		Script:            template.JS(loadTimeScript),
+	}
+	var buf bytes.Buffer
+	err = template.Must(template.New("").Parse(indexHTML)).Execute(&buf, templateArgs)
+	if err != nil {
+		http.Error(w, "failed to generate page", http.StatusInternalServerError)
+		return
+	}
+	if pusher, ok := w.(http.Pusher); ok {
+		ps := getURLs(&buf, n)
+		log.Printf("pushing %d frames", len(ps))
+		for _, p := range ps {
+			if err := pusher.Push(p, nil); err != nil {
+				log.Printf("Failed to push: %v", err)
+				break
+			}
+		}
+	} else {
+		log.Printf("w does not implement http.Pusher")
+	}
+
+	w.WriteHeader(http.StatusOK)
+	_, _ = io.Copy(w, &buf)
+}
+
+func intQueryParam(r *http.Request, name string, defaultValue int) (int, error) {
+	result := defaultValue
+	if nStr := r.URL.Query().Get(name); nStr != "" {
+		qn, err := strconv.Atoi(nStr)
+		if err != nil {
+			return defaultValue, err
+		}
+		result = qn
+	}
+	return result, nil
+}
+
+func getURLs(r io.Reader, max int) []string {
+	paths := make([]string, 0, max)
+	root, err := html.Parse(r)
+	if err != nil {
+		panic("failed to parse html")
+	}
+	var visit func(node *html.Node)
+	visit = func(node *html.Node) {
+		if node == nil || len(paths) >= max {
+			return
+		}
+		switch node.Type {
+		case html.ElementNode:
+			for _, attr := range node.Attr {
+				if attr.Key == "src" && strings.HasPrefix(attr.Val, "/") {
+					paths = append(paths, attr.Val)
+				}
+			}
+			for n := node.FirstChild; n != nil; n = n.NextSibling {
+				visit(n)
+			}
+			visit(node.NextSibling)
+		case html.DoctypeNode:
+			visit(node.NextSibling)
+		case html.DocumentNode:
+			visit(node.FirstChild)
+		}
 	}
-	templateString := `<!DOCTYPE html>
-<html>
-<title>HTTP/2 Image Tile Demo</title>
-<body>
-<h1>HTTP/2 Image Tile Demo</h1>
-<div>App HTTP Version: {{.HttpVersion}}</div>
-<div>Browser HTTP Version: <span id="http"></span></div>
-<div>Load Time: <span id="time"></span></div>
-{{.Images}}
-<script>
-{{.Script}}
-</script>
-</body>
-</html>`
-	renderableTemplate := template.Must(template.New("").Parse(templateString))
-	err := renderableTemplate.Execute(w, templateArgs)
-	handleErr("Writing HTML", err)
+	visit(root)
+	return paths
 }
 
 func serveHttp2(address string) {
@@ -107,7 +162,6 @@ func serveHttp1(address string) {
 
 func main() {
 	http.HandleFunc("/", serveHTML)
-	serveImg := serveImgFactory()
 	http.HandleFunc("/images/", serveImg)
 
 	proto := strings.ToLower(os.Getenv("PROTO"))

diff --git a/main_test.go b/main_test.go
@@ -0,0 +1,26 @@
+package main
+
+import (
+	"bytes"
+	"html/template"
+	"testing"
+)
+
+func TestTemplate_GetURLs(t *testing.T) {
+	var (
+		buf  bytes.Buffer
+		data = TemplateArgs{
+			HttpVersion:       "http",
+			ImageFingerprints: generateImageFingerprints(10),
+			Script:            template.JS(loadTimeScript),
+		}
+	)
+	err := template.Must(template.New("").Parse(indexHTML)).Execute(&buf, data)
+	if err != nil {
+		t.Fail()
+	}
+	urls := getURLs(&buf, 1000)
+	if len(urls) != 10 {
+		t.Fail()
+	}
+}
diff --git a/manifest.yml b/manifest.yml
@@ -7,6 +7,7 @@ applications:
     env:
       GOVERSION: go1.16
       PROTO: http1
+      GODEBUG: http2debug=1
     buildpacks:
       - go_buildpack
   - name: h2c
@@ -16,6 +17,7 @@ applications:
     env:
       GOVERSION: go1.16
       PROTO: h2c
+      GODEBUG: http2debug=1
     buildpacks:
       - go_buildpack
 
diff --git a/vendor/golang.org/x/net/html/atom/atom.go b/vendor/golang.org/x/net/html/atom/atom.go