Another new feature: websocket controller, for real

Former-commit-id: c1a59b86733e890709b52446e22427a17d87f5fc

_examples/mvc/singleton/main.go

@@ -0,0 +1,33 @@
+package main
+
+import (
+	"fmt"
+	"sync/atomic"
+
+	"github.com/kataras/iris"
+	"github.com/kataras/iris/mvc"
+)
+
+func main() {
+	app := iris.New()
+	mvc.New(app.Party("/")).Register(new(globalVisitorsController))
+
+	// http://localhost:8080
+	app.Run(iris.Addr(":8080"))
+}
+
+type globalVisitorsController struct {
+	// When a singleton controller is used then concurent safe access is up to the developers, because
+	// all clients share the same controller instance instead. Note that any controller's methods
+	// are per-client, but the struct's field can be shared accross multiple clients if the structure
+	// does not have any dynamic struct field depenendies that depend on the iris.Context,
+	// this declares a Singleton, note that you don't have to write a single line of code to do this, Iris is smart enough.
+	//
+	// see `Get`.
+	visits uint64
+}
+
+func (c *globalVisitorsController) Get() string {
+	count := atomic.AddUint64(&c.visits, 1)
+	return fmt.Sprintf("Total visitors: %d", count)
+}