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package main
import (
"sync/atomic"
"github.com/kataras/iris"
"github.com/kataras/iris/websocket"
)
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.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 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.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() {
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
// 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())
}
})
}