Add Pusher() function for support http2 server push (#1273)

gin already support http2, while previously not support server push. Add Pusher() function to extend the ResponseWriter interface. ```golang // get http.Pusher if pusher := c.Writer.Pusher(); pusher != nil { // use pusher.Push() to do server push } ``` <img width="881" alt="screen shot 2018-03-07 at 11 20 49 pm" src="https://user-images.githubusercontent.com/16014993/37100619-680c00c6-225e-11e8-9352-76ec3bd62894.png">
gin-gonic · Jun 21, 2018 · bf85b32 · bf85b32
1 parent 87d536c
commit bf85b32
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diff --git a/README.md b/README.md
@@ -54,6 +54,7 @@ Gin is a web framework written in Go (Golang). It features a martini-like API wi
     - [Build a single binary with templates](#build-a-single-binary-with-templates)
     - [Bind form-data request with custom struct](#bind-form-data-request-with-custom-struct)
     - [Try to bind body into different structs](#try-to-bind-body-into-different-structs)
+    - [http2 server push](#http2-server-push)
 - [Testing](#testing)
 - [Users](#users--)
 
@@ -1656,6 +1657,55 @@ enough to call binding at once.
 can be called by `c.ShouldBind()` multiple times without any damage to
 performance (See [#1341](https://github.com/gin-gonic/gin/pull/1341)).
 
+### http2 server push
+
+http.Pusher is supported only **go1.8+**. See the [golang blog](https://blog.golang.org/h2push) for detail information.
+
+[embedmd]:# (examples/http-pusher/main.go go)
+```go
+package main
+
+import (
+	"html/template"
+	"log"
+
+	"github.com/gin-gonic/gin"
+)
+
+var html = template.Must(template.New("https").Parse(`
+<html>
+<head>
+  <title>Https Test</title>
+  <script src="/assets/app.js"></script>
+</head>
+<body>
+  <h1 style="color:red;">Welcome, Ginner!</h1>
+</body>
+</html>
+`))
+
+func main() {
+	r := gin.Default()
+	r.Static("/assets", "./assets")
+	r.SetHTMLTemplate(html)
+
+	r.GET("/", func(c *gin.Context) {
+		if pusher := c.Writer.Pusher(); pusher != nil {
+			// use pusher.Push() to do server push
+			if err := pusher.Push("/assets/app.js", nil); err != nil {
+				log.Printf("Failed to push: %v", err)
+			}
+		}
+		c.HTML(200, "https", gin.H{
+			"status": "success",
+		})
+	})
+
+	// Listen and Server in https://127.0.0.1:8080
+	r.RunTLS(":8080", "./testdata/server.pem", "./testdata/server.key")
+}
+```
+
 ## Testing
 
 The `net/http/httptest` package is preferable way for HTTP testing.

diff --git a/examples/http-pusher/assets/app.js b/examples/http-pusher/assets/app.js
@@ -0,0 +1 @@
+console.log("http2 pusher");
diff --git a/examples/http-pusher/main.go b/examples/http-pusher/main.go
@@ -0,0 +1,41 @@
+package main
+
+import (
+	"html/template"
+	"log"
+
+	"github.com/gin-gonic/gin"
+)
+
+var html = template.Must(template.New("https").Parse(`
+<html>
+<head>
+  <title>Https Test</title>
+  <script src="/assets/app.js"></script>
+</head>
+<body>
+  <h1 style="color:red;">Welcome, Ginner!</h1>
+</body>
+</html>
+`))
+
+func main() {
+	r := gin.Default()
+	r.Static("/assets", "./assets")
+	r.SetHTMLTemplate(html)
+
+	r.GET("/", func(c *gin.Context) {
+		if pusher := c.Writer.Pusher(); pusher != nil {
+			// use pusher.Push() to do server push
+			if err := pusher.Push("/assets/app.js", nil); err != nil {
+				log.Printf("Failed to push: %v", err)
+			}
+		}
+		c.HTML(200, "https", gin.H{
+			"status": "success",
+		})
+	})
+
+	// Listen and Server in https://127.0.0.1:8080
+	r.RunTLS(":8080", "./testdata/server.pem", "./testdata/server.key")
+}
diff --git a/examples/http-pusher/testdata/ca.pem b/examples/http-pusher/testdata/ca.pem
@@ -0,0 +1,15 @@
+-----BEGIN CERTIFICATE-----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+-----END CERTIFICATE-----
diff --git a/examples/http-pusher/testdata/server.key b/examples/http-pusher/testdata/server.key
@@ -0,0 +1,16 @@
+-----BEGIN PRIVATE KEY-----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+-----END PRIVATE KEY-----
diff --git a/examples/http-pusher/testdata/server.pem b/examples/http-pusher/testdata/server.pem
@@ -0,0 +1,16 @@
+-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----
diff --git a/response_writer.go b/response_writer.go
@@ -16,7 +16,7 @@ const (
 	defaultStatus = 200
 )
 
-type ResponseWriter interface {
+type responseWriterBase interface {
 	http.ResponseWriter
 	http.Hijacker
 	http.Flusher

diff --git a/response_writer_1.7.go b/response_writer_1.7.go
@@ -0,0 +1,12 @@
+// +build !go1.8
+
+// Copyright 2018 Gin Core Team.  All rights reserved.
+// Use of this source code is governed by a MIT style
+// license that can be found in the LICENSE file.
+
+package gin
+
+// ResponseWriter ...
+type ResponseWriter interface {
+	responseWriterBase
+}
diff --git a/response_writer_1.8.go b/response_writer_1.8.go
@@ -0,0 +1,25 @@
+// +build go1.8
+
+// Copyright 2018 Gin Core Team.  All rights reserved.
+// Use of this source code is governed by a MIT style
+// license that can be found in the LICENSE file.
+
+package gin
+
+import (
+	"net/http"
+)
+
+// ResponseWriter ...
+type ResponseWriter interface {
+	responseWriterBase
+	// get the http.Pusher for server push
+	Pusher() http.Pusher
+}
+
+func (w *responseWriter) Pusher() (pusher http.Pusher) {
+	if pusher, ok := w.ResponseWriter.(http.Pusher); ok {
+		return pusher
+	}
+	return nil
+}