wsdashdemo/main.go

package main

import (
	"encoding/csv"
	"github.com/gorilla/websocket"
	"io"
	"log"
	"net/http"
	"os"
	"strconv"
	"time"
)

type dashData struct {
	RPM   int     `json:"rpm"`
	Speed int     `json:"speed"`
	PSI   float64 `json:"psi"`
}

// Process the data log at startup
func load_data(filename string) []dashData {
	var d []dashData
	f, err := os.Open(filename)
	if err != nil {
		log.Fatal(err)
	}
	r := csv.NewReader(f)
	for {
		row, err := r.Read()
		if err == io.EOF {
			break
		}
		if err != nil {
			log.Fatal(err)
		}
		var e dashData
		e.RPM, _ = strconv.Atoi(row[0])
		e.Speed, _ = strconv.Atoi(row[2])
		e.PSI, _ = strconv.ParseFloat(row[1], 64)
		d = append(d, e)
	}
	return d
}

var upgrader = websocket.Upgrader{
	CheckOrigin: func(r *http.Request) bool {
		return true
	},
}

func main() {
	http.HandleFunc("/ws", subscribe)
	log.Fatal(http.ListenAndServe("localhost:9888", nil))
}

func subscribe(w http.ResponseWriter, r *http.Request) {
	c, err := upgrader.Upgrade(w, r, nil)
	if err != nil {
		log.Print("upgrade:", err)
		return
	}
	defer c.Close()
	// Load data set
	d := load_data("fin.csv")
	iterator := 0
	for {
		if iterator == len(d) {
			iterator = 0
		}
		err := c.WriteJSON(d[iterator])
		if err != nil {
			// Conection dropped or otherwise
			log.Printf("Connection failed.")
			return
		}
		time.Sleep(100 * time.Millisecond)
		iterator++
	}

}