reorganization of _examples and add some new examples such as iris+groupcache+mysql+docker

Former-commit-id: ed635ee95de7160cde11eaabc0c1dcb0e460a620

_examples/websocket/online-visitors/main.go

@@ -0,0 +1,173 @@
+package main
+
+import (
+	"fmt"
+	"sync/atomic"
+
+	"github.com/kataras/iris/v12"
+
+	"github.com/kataras/iris/v12/websocket"
+)
+
+var events = websocket.Namespaces{
+	"default": websocket.Events{
+		websocket.OnRoomJoined: onRoomJoined,
+		websocket.OnRoomLeft:   onRoomLeft,
+	},
+}
+
+func main() {
+	// init the web application instance
+	// app := iris.New()
+	app := iris.Default()
+
+	// load templates
+	app.RegisterView(iris.HTML("./templates", ".html").Reload(true))
+	// setup the websocket server
+	ws := websocket.New(websocket.DefaultGorillaUpgrader, events)
+
+	app.Get("/my_endpoint", websocket.Handler(ws))
+
+	// register static assets request path and system directory
+	app.HandleDir("/js", "./static/assets/js")
+
+	h := func(ctx iris.Context) {
+		ctx.ViewData("", page{PageID: "index page"})
+		ctx.View("index.html")
+	}
+
+	h2 := func(ctx iris.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.Listen(":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() {
+	atomic.AddUint64(&v.count, ^uint64(0))
+}
+
+func (v *pageView) getCount() uint64 {
+	return atomic.LoadUint64(&v.count)
+}
+
+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
+
+func viewsCountBytes(viewsCount uint64) []byte {
+	// * there are other methods to convert uint64 to []byte
+	return []byte(fmt.Sprintf("%d", viewsCount))
+}
+
+func onRoomJoined(ns *websocket.NSConn, msg websocket.Message) error {
+	// the roomName here is the source.
+	pageSource := string(msg.Room)
+
+	v.Add(pageSource)
+
+	viewsCount := v.Get(pageSource).getCount()
+	if viewsCount == 0 {
+		viewsCount++ // count should be always > 0 here
+	}
+
+	// fire the "onNewVisit" client event
+	// on each connection joined to this room (source page)
+	// and notify of the new visit,
+	// including this connection (see nil on first input arg).
+	ns.Conn.Server().Broadcast(nil, websocket.Message{
+		Namespace: msg.Namespace,
+		Room:      pageSource,
+		Event:     "onNewVisit", // fire the "onNewVisit" client event.
+		Body:      viewsCountBytes(viewsCount),
+	})
+
+	return nil
+}
+
+func onRoomLeft(ns *websocket.NSConn, msg websocket.Message) error {
+	// the roomName here is the source.
+	pageV := v.Get(msg.Room)
+	if pageV == nil {
+		return nil // for any case that this room is not a pageView source
+	}
+	// decrement -1 the specific counter for this page source.
+	pageV.decrement()
+
+	// fire the "onNewVisit" client event
+	// on each connection joined to this room (source page)
+	// and notify of the new, decremented by one, visits count.
+	ns.Conn.Server().Broadcast(nil, websocket.Message{
+		Namespace: msg.Namespace,
+		Room:      msg.Room,
+		Event:     "onNewVisit",
+		Body:      viewsCountBytes(pageV.getCount()),
+	})
+
+	return nil
+}