koyachi · December 9, 2012 09:26
diff --git a/wstail_2.go b/wstail_2.go
 package main

 // Usage:
 // % go run wstail.go a.txt
 //   or
 // % go build wstail.go
 // % wstail a.txt

 import (
 	"code.google.com/p/go.net/websocket"
 	"fmt"
 	"io"
 	"net/http"
 	"os"
 	"os/exec"
 )

 func indexHandler(w http.ResponseWriter, req *http.Request) {
 	io.WriteString(w, `<html>
 <head>
  <style>
    body
      { color: #1a2c37;
        font-family: 'Helvetica', sans-serif; font-size: 86%;
        padding: 2em; }
    #info
      { font-size: 120%;
        font-weight: bold; }
    #tail
      { border: 1px solid #ccc;
        height: 300px;
        padding: 0.5em;
        overflow: hidden;
        position: relative;
        overflow-y: scroll; }
  </style>
  <script type="text/javascript">
 var header = "[wstail]"
 var ws;
 function init() {
   console.log("init");
   if (ws != null) {
     ws.close();
     ws = null;
   }
   path = "/tail";
   console.log("path:" + path);
   var div = document.getElementById("tail");
   div.innerText = div.innerText + header + "path:" + path + "\n";
   ws = new WebSocket("ws://localhost:23456" + path);
   ws.onopen = function () {
      div.innerText = div.innerText + header + "opened\n";
   };
   ws.onmessage = function (e) {
      console.log(e.data);
      div.innerText = div.innerText + e.data;
      if (e.data instanceof ArrayBuffer) {
        s = "ArrayBuffer: " + e.data.byteLength + "[";
        var view = new Uint8Array(e.data);
        for (var i = 0; i < view.length; ++i) {
          s += " " + view[i];
        }
        s += "]";
        div.innerText = div.innerText + s + "\n";
      }
   };
   ws.onclose = function (e) {
      div.innerText = div.innerText + header + "closed\n";
   };
   console.log("init");
   div.innerText = div.innerText + header + "init\n";
 };
  </script>
  <body onLoad="init();">
    <pre id="info"></pre>
    <pre id="tail"></pre>
 </html>
 `)
 }

 func startTail(file string, ch chan string) error {
 	tail := exec.Command("tail", "-f", file)
 	stdout, err := tail.StdoutPipe()
 	if err != nil {
 		return err
 	}
 	if err := tail.Start(); err != nil {
 		return err
 	}
 	go func() {
 		buf := make([]byte, 4*1024)
 		for {
 			//buf := make([]byte, 100)
 			n, err := stdout.Read(buf)
 			if err != nil {
 				panic("reader.ReadString(): " + err.Error())
 				return
 			}
 			line := string(buf[0:n])
 			fmt.Printf("read[%v:%v]\n", n, line)
 			ch <- line
 		}
 	}()
 	return nil
 }

 func makeWebsocketHandlerWithChannel(ch chan string, f func(chan string, *websocket.Conn)) func(*websocket.Conn) {
 	return func(ws *websocket.Conn) {
 		f(ch, ws)
 	}
 }

 func websocketTailHandler(ch chan string, ws *websocket.Conn) {
 	fmt.Printf("tailHandler %v\n", ws)
 	for {
 		line := <-ch
 		if err := websocket.Message.Send(ws, line); err != nil {
 			fmt.Println("ERR:websoket.Message.Send(): " + err.Error())
 		}
 		fmt.Printf("tailHandler write[%v]\n", line)
 	}
 	fmt.Println("tailHandler finished")
 }

 // for debug
 func pseudoSubscriber(ch chan string) {
 	for {
 		line := <-ch
 		fmt.Println("[sub]: " + line)
 	}
 }

 func main() {
 	ch := make(chan string)
 	http.Handle("/tail", websocket.Handler(makeWebsocketHandlerWithChannel(ch, websocketTailHandler)))
 	http.HandleFunc("/", indexHandler)

 	if err := startTail(os.Args[1], ch); err != nil {
 		panic(err)
 	}

 	fmt.Println("start wstail...")
 	err := http.ListenAndServe(":23456", nil)
 	if err != nil {
 		panic("ListenAndServe: " + err.Error())
 	}
 	//pseudoSubscriber(ch)
 }
	package main

	// Usage:
	// % go run wstail.go a.txt
	// or
	// % go build wstail.go
	// % wstail a.txt

	import (
	"code.google.com/p/go.net/websocket"
	"fmt"
	"io"
	"net/http"
	"os"
	"os/exec"
	)

	func indexHandler(w http.ResponseWriter, req *http.Request) {
	io.WriteString(w, `<html>
	<head>
	<style>
	body
	{ color: #1a2c37;
	font-family: 'Helvetica', sans-serif; font-size: 86%;
	padding: 2em; }
	#info
	{ font-size: 120%;
	font-weight: bold; }
	#tail
	{ border: 1px solid #ccc;
	height: 300px;
	padding: 0.5em;
	overflow: hidden;
	position: relative;
	overflow-y: scroll; }
	</style>
	<script type="text/javascript">
	var header = "[wstail]"
	var ws;
	function init() {
	console.log("init");
	if (ws != null) {
	ws.close();
	ws = null;
	}
	path = "/tail";
	console.log("path:" + path);
	var div = document.getElementById("tail");
	div.innerText = div.innerText + header + "path:" + path + "\n";
	ws = new WebSocket("ws://localhost:23456" + path);
	ws.onopen = function () {
	div.innerText = div.innerText + header + "opened\n";
	};
	ws.onmessage = function (e) {
	console.log(e.data);
	div.innerText = div.innerText + e.data;
	if (e.data instanceof ArrayBuffer) {
	s = "ArrayBuffer: " + e.data.byteLength + "[";
	var view = new Uint8Array(e.data);
	for (var i = 0; i < view.length; ++i) {
	s += " " + view[i];
	}
	s += "]";
	div.innerText = div.innerText + s + "\n";
	}
	};
	ws.onclose = function (e) {
	div.innerText = div.innerText + header + "closed\n";
	};
	console.log("init");
	div.innerText = div.innerText + header + "init\n";
	};
	</script>
	<body onLoad="init();">
	<pre id="info"></pre>
	<pre id="tail"></pre>
	</html>
	`)
	}

	func startTail(file string, ch chan string) error {
	tail := exec.Command("tail", "-f", file)
	stdout, err := tail.StdoutPipe()
	if err != nil {
	return err
	}
	if err := tail.Start(); err != nil {
	return err
	}
	go func() {
	buf := make([]byte, 4*1024)
	for {
	//buf := make([]byte, 100)
	n, err := stdout.Read(buf)
	if err != nil {
	panic("reader.ReadString(): " + err.Error())
	return
	}
	line := string(buf[0:n])
	fmt.Printf("read[%v:%v]\n", n, line)
	ch <- line
	}
	}()
	return nil
	}

	func makeWebsocketHandlerWithChannel(ch chan string, f func(chan string, websocket.Conn)) func(websocket.Conn) {
	return func(ws *websocket.Conn) {
	f(ch, ws)
	}
	}

	func websocketTailHandler(ch chan string, ws *websocket.Conn) {
	fmt.Printf("tailHandler %v\n", ws)
	for {
	line := <-ch
	if err := websocket.Message.Send(ws, line); err != nil {
	fmt.Println("ERR:websoket.Message.Send(): " + err.Error())
	}
	fmt.Printf("tailHandler write[%v]\n", line)
	}
	fmt.Println("tailHandler finished")
	}

	// for debug
	func pseudoSubscriber(ch chan string) {
	for {
	line := <-ch
	fmt.Println("[sub]: " + line)
	}
	}

	func main() {
	ch := make(chan string)
	http.Handle("/tail", websocket.Handler(makeWebsocketHandlerWithChannel(ch, websocketTailHandler)))
	http.HandleFunc("/", indexHandler)

	if err := startTail(os.Args[1], ch); err != nil {
	panic(err)
	}

	fmt.Println("start wstail...")
	err := http.ListenAndServe(":23456", nil)
	if err != nil {
	panic("ListenAndServe: " + err.Error())
	}
	//pseudoSubscriber(ch)
	}