Autogen README (new example)

Author: ant0ine

README.md

@@ -47,6 +47,7 @@ In fact the internal code of **go-json-rest** is itself implemented with Middlew
 	  - [Streaming](#streaming)
 	  - [Non JSON payload](#non-json-payload)
 	  - [API Versioning](#api-versioning)
+	  - [Statsd](#statsd)
 	  - [SPDY](#spdy)
 	  - [Google App Engine](#gae)
 	  - [Basic Auth Custom](#basic-auth-custom)
@@ -1125,6 +1126,98 @@ func main() {
 
 ```
 
+#### Statsd
+
+Demonstrate how to use OuterMiddlewares to do additional logging and reporting.
+
+Here `request.Env["STATUS_CODE"]` and `request.Env["ELAPSED_TIME"]` that are available to outer middlewares are used with the [g2s](https://github.com/peterbourgon/g2s) statsd client to send these metrics to statsd.
+
+The curl demo:
+``` sh
+# start statsd server
+# monitor network
+ngrep -d any port 8125
+
+curl -i http://127.0.0.1:8080/message
+curl -i http://127.0.0.1:8080/doesnotexist
+
+```
+
+Go code:
+``` go
+package main
+
+import (
+	"github.com/ant0ine/go-json-rest/rest"
+	"github.com/peterbourgon/g2s"
+	"log"
+	"net/http"
+	"strconv"
+	"time"
+)
+
+type StatsdMiddleware struct {
+	IpPort string
+	Prefix string
+}
+
+func (mw *StatsdMiddleware) MiddlewareFunc(handler rest.HandlerFunc) rest.HandlerFunc {
+
+	statsd, err := g2s.Dial("udp", mw.IpPort)
+	if err != nil {
+		panic(err)
+	}
+
+	keyBase := ""
+	if mw.Prefix != "" {
+		keyBase += mw.Prefix + "."
+	}
+	keyBase += "response."
+
+	return func(writer rest.ResponseWriter, request *rest.Request) {
+
+		handler(writer, request)
+
+		statusCode := request.Env["STATUS_CODE"].(int)
+		statsd.Counter(1.0, keyBase+"status_code."+strconv.Itoa(statusCode), 1)
+		log.Print(keyBase + "status_code." + strconv.Itoa(statusCode))
+
+		elapsedTime := request.Env["ELAPSED_TIME"].(*time.Duration)
+		statsd.Timing(1.0, keyBase+"elapsed_time", *elapsedTime)
+	}
+}
+
+type Message struct {
+	Body string
+}
+
+func main() {
+	handler := rest.ResourceHandler{
+		OuterMiddlewares: []rest.Middleware{
+			&StatsdMiddleware{
+				IpPort: "localhost:8125",
+			},
+		},
+	}
+	err := handler.SetRoutes(
+		&rest.Route{"GET", "/message", func(w rest.ResponseWriter, req *rest.Request) {
+
+			// take more than 1ms so statsd can report it
+			time.Sleep(100 * time.Millisecond)
+
+			w.WriteJson(&Message{
+				Body: "Hello World!",
+			})
+		}},
+	)
+	if err != nil {
+		log.Fatal(err)
+	}
+	log.Fatal(http.ListenAndServe(":8080", &handler))
+}
+
+```
+
 #### SPDY
 
 Demonstrate how to use SPDY with https://github.com/shykes/spdy-go