github.com/EngineerKamesh/gofullstack@v0.0.0-20180609171605-d41341d7d4ee/volume3/section1/intermediate/gwsc/gwsc.go (about)

     1  // Copyright 2015 The Gorilla WebSocket Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package main
     6  
     7  import (
     8  	"flag"
     9  	"log"
    10  	"net/url"
    11  	"os"
    12  	"os/signal"
    13  	"time"
    14  
    15  	"github.com/gorilla/websocket"
    16  )
    17  
    18  var addr = flag.String("addr", "localhost:8080", "http service address")
    19  
    20  func main() {
    21  	flag.Parse()
    22  	log.SetFlags(0)
    23  
    24  	interrupt := make(chan os.Signal, 1)
    25  	signal.Notify(interrupt, os.Interrupt)
    26  
    27  	u := url.URL{Scheme: "ws", Host: *addr, Path: "/echo"}
    28  	log.Printf("connecting to %s", u.String())
    29  
    30  	c, _, err := websocket.DefaultDialer.Dial(u.String(), nil)
    31  	if err != nil {
    32  		log.Fatal("dial:", err)
    33  	}
    34  	defer c.Close()
    35  
    36  	done := make(chan struct{})
    37  
    38  	go func() {
    39  		defer c.Close()
    40  		defer close(done)
    41  		for {
    42  			_, message, err := c.ReadMessage()
    43  			if err != nil {
    44  				log.Println("read:", err)
    45  				return
    46  			}
    47  			log.Printf("recv: %s", message)
    48  		}
    49  	}()
    50  
    51  	ticker := time.NewTicker(time.Second)
    52  	defer ticker.Stop()
    53  
    54  	for {
    55  		select {
    56  		case t := <-ticker.C:
    57  			err := c.WriteMessage(websocket.TextMessage, []byte(t.String()))
    58  			if err != nil {
    59  				log.Println("write:", err)
    60  				return
    61  			}
    62  		case <-interrupt:
    63  			log.Println("interrupt")
    64  			// To cleanly close a connection, a client should send a close
    65  			// frame and wait for the server to close the connection.
    66  			err := c.WriteMessage(websocket.CloseMessage, websocket.FormatCloseMessage(websocket.CloseNormalClosure, ""))
    67  			if err != nil {
    68  				log.Println("write close:", err)
    69  				return
    70  			}
    71  			select {
    72  			case <-done:
    73  			case <-time.After(time.Second):
    74  			}
    75  			c.Close()
    76  			return
    77  		}
    78  	}
    79  }