Merge pull request AndrewBurian#5 from lithium3141/http2-skip-keepalive-header

Don't send Connection: keep-alive header to HTTP/2 clients

Author: AndrewBurian

README.md

@@ -83,13 +83,13 @@ Fine! The `Stream` object is entirely convenience. It runs no background routine
 You betcha.
 
 ## Create my own clients
-Clients have to be created off an `http.ResponseWriter` that supports the `http.Flusher` and `http.CloseNotifier` interfaces.
+Clients have to be created off an `http.ResponseWriter` that supports the `http.Flusher` and `http.CloseNotifier` interfaces. When creating a client, callers can optionally also pass the original `http.Request` being served, which helps determine which headers are appropriate to send in response.
 
 `NewClient` _does_ kick off a background routine to handle sending events, so constructing an object literal will not work. This is done because it's assumed you will likely be calling `NewClient` on an http handler routine, and will likely not be doing any interesting work on that routine.
 
 ```go
 func ServeHTTP(w http.ResponseWriter, r *http.Request) {
-  client := eventsource.NewClient(w)
+  client := eventsource.NewClient(w, r)
   if client == nil {
     http.Error(...)
     return

client.go

@@ -20,8 +20,11 @@ type Client struct {
 // NewClient creates a client wrapping a response writer.
 // The response writer must support http.Flusher and http.CloseNotifier
 // interfaces.
+// When writing, the client will automatically send some headers. Passing the
+// original http.Request helps determine which headers, but the request it is
+// optional.
 // Returns nil on error.
-func NewClient(w http.ResponseWriter) *Client {
+func NewClient(w http.ResponseWriter, req *http.Request) *Client {
 	c := &Client{
 		events: make(chan *Event, 1),
 		write:  w,
@@ -44,7 +47,9 @@ func NewClient(w http.ResponseWriter) *Client {
 	// Send the initial headers
 	w.Header().Set("Content-Type", "text/event-stream")
 	w.Header().Set("Cache-Control", "no-cache")
-	w.Header().Set("Connection", "keep-alive")
+	if req == nil || req.ProtoMajor < 2 {
+		w.Header().Set("Connection", "keep-alive")
+	}
 	flush.Flush()
 
 	// start the sending thread

stream.go

@@ -161,7 +161,7 @@ func (s *Stream) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	}
 
 	// create the client
-	c := NewClient(w)
+	c := NewClient(w, r)
 	if c == nil {
 		http.Error(w, "EventStream not supported for this connection", http.StatusInternalServerError)
 		return
@@ -188,7 +188,7 @@ func (s *Stream) TopicHandler(topics []string) http.HandlerFunc {
 		}
 
 		// create the client
-		c := NewClient(w)
+		c := NewClient(w, r)
 		if c == nil {
 			http.Error(w, "EventStream not supported for this connection", http.StatusInternalServerError)
 			return