Add notes for the new lead maintainer of the open-source iris project and align with @get-ion/ion by @hiveminded

Former-commit-id: da4f38eb9034daa49446df3ee529423b98f9b331

_examples/tutorial/online-visitors/main.go

@@ -0,0 +1,166 @@
+package main
+
+import (
+	"sync/atomic"
+
+	"github.com/kataras/iris"
+	"github.com/kataras/iris/context"
+
+	"github.com/kataras/iris/websocket"
+)
+
+func main() {
+	// init the web application instance
+	// app := iris.New()
+	app := iris.Default()
+
+	// load templaes
+	app.RegisterView(iris.HTML("./templates", ".html").Reload(true))
+	// setup the websocket server
+	ws := websocket.New(websocket.Config{})
+	ws.OnConnection(HandleWebsocketConnection)
+
+	app.Get("/my_endpoint", ws.Handler())
+	app.Any("/iris-ws.js", websocket.ClientHandler())
+
+	// register static assets request path and system directory
+	app.StaticWeb("/js", "./static/assets/js")
+
+	h := func(ctx context.Context) {
+		ctx.ViewData("", page{PageID: "index page"})
+		ctx.View("index.html")
+	}
+
+	h2 := func(ctx context.Context) {
+		ctx.ViewData("", page{PageID: "other page"})
+		ctx.View("other.html")
+	}
+
+	// Open some browser tabs/or windows
+	// and navigate to
+	// http://localhost:8080/ and http://localhost:8080/other multiple times.
+	// Each page has its own online-visitors counter.
+	app.Get("/", h)
+	app.Get("/other", h2)
+	app.Run(iris.Addr(":8080"))
+}
+
+type page struct {
+	PageID string
+}
+
+type pageView struct {
+	source string
+	count  uint64
+}
+
+func (v *pageView) increment() {
+	atomic.AddUint64(&v.count, 1)
+}
+
+func (v *pageView) decrement() {
+	oldCount := v.count
+	if oldCount > 0 {
+		atomic.StoreUint64(&v.count, oldCount-1)
+	}
+}
+
+func (v *pageView) getCount() uint64 {
+	val := atomic.LoadUint64(&v.count)
+	return val
+}
+
+type (
+	pageViews []pageView
+)
+
+func (v *pageViews) Add(source string) {
+	args := *v
+	n := len(args)
+	for i := 0; i < n; i++ {
+		kv := &args[i]
+		if kv.source == source {
+			kv.increment()
+			return
+		}
+	}
+
+	c := cap(args)
+	if c > n {
+		args = args[:n+1]
+		kv := &args[n]
+		kv.source = source
+		kv.count = 1
+		*v = args
+		return
+	}
+
+	kv := pageView{}
+	kv.source = source
+	kv.count = 1
+	*v = append(args, kv)
+}
+
+func (v *pageViews) Get(source string) *pageView {
+	args := *v
+	n := len(args)
+	for i := 0; i < n; i++ {
+		kv := &args[i]
+		if kv.source == source {
+			return kv
+		}
+	}
+	return nil
+}
+
+func (v *pageViews) Reset() {
+	*v = (*v)[:0]
+}
+
+var v pageViews
+
+// HandleWebsocketConnection handles the online viewers per example(gist source)
+func HandleWebsocketConnection(c websocket.Connection) {
+
+	c.On("watch", func(pageSource string) {
+		v.Add(pageSource)
+		// join the socket to a room linked with the page source
+		c.Join(pageSource)
+
+		viewsCount := v.Get(pageSource).getCount()
+		if viewsCount == 0 {
+			viewsCount++ // count should be always > 0 here
+		}
+		c.To(pageSource).Emit("watch", viewsCount)
+	})
+
+	c.OnLeave(func(roomName string) {
+		if roomName != c.ID() { // if the roomName  it's not the connection iself
+			// the roomName here is the source, this is the only room(except the connection's ID room) which we join the users to.
+			pageV := v.Get(roomName)
+			if pageV == nil {
+				return // for any case that this room is not a pageView source
+			}
+			// decrement -1 the specific counter for this page source.
+			pageV.decrement()
+			// 1. open 30 tabs.
+			// 2. close the browser.
+			// 3. re-open the browser
+			// 4. should be  v.getCount() = 1
+			// in order to achieve the previous flow we should decrement exactly when the user disconnects
+			// but emit the result a little after, on a goroutine
+			// getting all connections within this room and emit the online views one by one.
+			// note:
+			// we can also add a time.Sleep(2-3 seconds) inside the goroutine at the future if we don't need 'real-time' updates.
+			go func(currentConnID string) {
+				for _, conn := range c.Server().GetConnectionsByRoom(roomName) {
+					if conn.ID() != currentConnID {
+						conn.Emit("watch", pageV.getCount())
+					}
+
+				}
+			}(c.ID())
+		}
+
+	})
+}