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Dan committed Nov 7, 2020
1 parent 37b05bc commit 62bdbc9
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Showing 6 changed files with 284 additions and 0 deletions.
103 changes: 103 additions & 0 deletions client.go
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package main

import (
"bytes"
"log"
"net/http"
"time"

"github.com/gorilla/websocket"
)

const (
writeWait = 10 * time.Second
pongWait = 60 * time.Second
pingPeriod = (pongWait * 9) / 10
maxMessageSize = 512
)

var (
newLine = []byte{'\n'}
space = []byte{' '}
)

var upgrader = websocket.Upgrader{}

type Client struct {
hub *Hub
conn *websocket.Conn
send chan []byte
}

func (c *Client) readPump() {
defer func() {
c.hub.unregister <- c
c.conn.Close()
}()
c.conn.SetReadLimit(maxMessageSize)
c.conn.SetReadDeadline(time.Now().Add(pongWait))
c.conn.SetPongHandler(func(string) error { c.conn.SetReadDeadline(time.Now().Add(pongWait)); return nil })
for {
_, message, err := c.conn.ReadMessage()
if err != nil {
if websocket.IsUnexpectedCloseError(err, websocket.CloseGoingAway, websocket.CloseAbnormalClosure) {
log.Printf("error: %v", err)
}
break
}
message = bytes.TrimSpace(bytes.Replace(message, newLine, space, -1))
c.hub.broadcast <- message
}
}

func (c *Client) writePump() {
ticker := time.NewTicker(pingPeriod)
defer func() {
ticker.Stop()
c.conn.Close()
}()
for {
select {
case message, ok := <-c.send:
c.conn.SetWriteDeadline(time.Now().Add(writeWait))
if !ok {
c.conn.WriteMessage(websocket.CloseMessage, []byte{})
return
}

w, err := c.conn.NextWriter(websocket.TextMessage)
if err != nil {
return
}
w.Write(message)

n := len(c.send)
for i := 0; i < n; i++ {
w.Write(newLine)
w.Write(<-c.send)
}

if err := w.Close(); err != nil {
return
}
case <-ticker.C:
c.conn.SetWriteDeadline(time.Now().Add(writeWait))
if err := c.conn.WriteMessage(websocket.PingMessage, nil); err != nil {
return
}
}
}
}

func serveWs(hub *Hub, w http.ResponseWriter, r *http.Request) {
conn, err := upgrader.Upgrade(w, r, nil)
if err != nil {
log.Println(err)
return
}
client := &Client{hub: hub, conn: conn, send: make(chan []byte, 256)}
client.hub.register <- client

go client.writePump()
go client.readPump()
}
5 changes: 5 additions & 0 deletions go.mod
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module go-websocket-example

go 1.15

require github.com/gorilla/websocket v1.4.2 // indirect
2 changes: 2 additions & 0 deletions go.sum
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github.com/gorilla/websocket v1.4.2 h1:+/TMaTYc4QFitKJxsQ7Yye35DkWvkdLcvGKqM+x0Ufc=
github.com/gorilla/websocket v1.4.2/go.mod h1:YR8l580nyteQvAITg2hZ9XVh4b55+EU/adAjf1fMHhE=
40 changes: 40 additions & 0 deletions hub.go
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package main

type Hub struct {
clients map[*Client]bool
broadcast chan []byte
register chan *Client
unregister chan *Client
}

func newHub() *Hub {
return &Hub{
broadcast: make(chan []byte),
register: make(chan *Client),
unregister: make(chan *Client),
clients: make(map[*Client]bool),
}
}

func (h *Hub) run() {
for {
select {
case client := <-h.register:
h.clients[client] = true
case client := <-h.unregister:
if _, ok := h.clients[client]; ok {
delete(h.clients, client)
close(client.send)
}
case message := <-h.broadcast:
for client := range h.clients {
select {
case client.send <- message:
default:
close(client.send)
delete(h.clients, client)
}
}
}
}
}
98 changes: 98 additions & 0 deletions index.html
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<!DOCTYPE html>
<html lang="en">
<head>
<title>Chat Example</title>
<script type="text/javascript">
window.onload = function () {
var conn;
var msg = document.getElementById("msg");
var log = document.getElementById("log");

function appendLog(item) {
var doScroll = log.scrollTop > log.scrollHeight - log.clientHeight - 1;
log.appendChild(item);
if (doScroll) {
log.scrollTop = log.scrollHeight - log.clientHeight;
}
}

document.getElementById("form").onsubmit = function () {
if (!conn) {
return false;
}
if (!msg.value) {
return false;
}
conn.send(msg.value);
msg.value = "";
return false;
};

if (window["WebSocket"]) {
conn = new WebSocket("ws://" + document.location.host + "/ws");
conn.onclose = function (evt) {
var item = document.createElement("div");
item.innerHTML = "<b>Connection closed.</b>";
appendLog(item);
};
conn.onmessage = function (evt) {
var messages = evt.data.split('\n');
for (var i = 0; i < messages.length; i++) {
var item = document.createElement("div");
item.innerText = messages[i];
appendLog(item);
}
};
} else {
var item = document.createElement("div");
item.innerHTML = "<b>Your browser does not support WebSockets.</b>";
appendLog(item);
}
};
</script>
<style type="text/css">
html {
overflow: hidden;
}

body {
overflow: hidden;
padding: 0;
margin: 0;
width: 100%;
height: 100%;
background: gray;
}

#log {
background: white;
margin: 0;
padding: 0.5em 0.5em 0.5em 0.5em;
position: absolute;
top: 0.5em;
left: 0.5em;
right: 0.5em;
bottom: 3em;
overflow: auto;
}

#form {
padding: 0 0.5em 0 0.5em;
margin: 0;
position: absolute;
bottom: 1em;
left: 0px;
width: 100%;
overflow: hidden;
}

</style>
</head>
<body>
<div id="log"></div>
<form id="form">
<input type="submit" value="Send" />
<input type="text" id="msg" size="64" autofocus />
</form>
</body>
</html>
36 changes: 36 additions & 0 deletions main.go
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package main

import (
"flag"
"log"
"net/http"
)

var addr = flag.String("addr", ":8080", "http service address")

func serveIndex(w http.ResponseWriter, r *http.Request) {
log.Println(r.URL)
if r.URL.Path != "/" {
http.Error(w, "Not found", http.StatusNotFound)
return
}
if r.Method != "GET" {
http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
return
}
http.ServeFile(w, r, "index.html")
}

func main() {
flag.Parse()
hub := newHub()
go hub.run()
http.HandleFunc("/", serveIndex)
http.HandleFunc("/ws", func(w http.ResponseWriter, r *http.Request) {
serveWs(hub, w, r)
})
err := http.ListenAndServe(*addr, nil)
if err != nil {
log.Fatal("Liatend and serve: ", err)
}
}

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