saving periodically and loading state from file

.gitignore

@@ -131,3 +131,5 @@ dmypy.json
 
 # Pyre type checker
 .pyre/
+go/state.json
+python/logo.png

go/server.go

@@ -3,8 +3,11 @@ package main
 import (
 	"encoding/json"
 	"flag"
+	"fmt"
+	"io/ioutil"
 	"log"
 	"net/http"
+	"os"
 	"strconv"
 	"time"
 
@@ -44,17 +47,17 @@ func get(w http.ResponseWriter, r *http.Request) {
 
 	defer c.Close()
 	ticker := time.NewTicker(1 * time.Second)
-	var tmpImage = GetImage(img.width, img.height)
+	var tmpImage = GetImage(img.Width, img.Height)
 
 	for range ticker.C {
 
 		diff := tmpImage.GetDiff(&img)
-		for i := 0; i < int(diff.width*diff.height); i++ {
-			pix := diff.pixels[i]
-			if pix.pixel.UserID != 0 {
-				x := i / int(diff.width)
-				y := i % int(diff.height)
-				msg := Message{X: uint32(x), Y: uint32(y), Timestamp: pix.pixel.Timestamp, UserID: pix.pixel.UserID, Color: pix.pixel.Color}
+		for i := 0; i < int(diff.Width*diff.Height); i++ {
+			pix := diff.Pixels[i]
+			if pix.Pixel.UserID != 0 {
+				x := i / int(diff.Width)
+				y := i % int(diff.Height)
+				msg := Message{X: uint32(x), Y: uint32(y), Timestamp: pix.Pixel.Timestamp, UserID: pix.Pixel.UserID, Color: pix.Pixel.Color}
 				marshalMsg, err := json.Marshal(msg)
 				if err != nil {
 					log.Println("error while writing image", err)
@@ -68,7 +71,7 @@ func get(w http.ResponseWriter, r *http.Request) {
 		if err := c.WriteMessage(websocket.PingMessage, []byte{}); err != nil {
 			return
 		}
-		copy(tmpImage.pixels, img.pixels)
+		copy(tmpImage.Pixels, img.Pixels)
 	}
 }
 
@@ -79,7 +82,6 @@ func set(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 	c.SetReadLimit(maxMessageSize)
-
 	c.SetPongHandler(func(string) error { c.SetReadDeadline(time.Now().Add(pongWait)); return nil })
 
 	defer c.Close()
@@ -100,12 +102,49 @@ func set(w http.ResponseWriter, r *http.Request) {
 	}
 }
 
+func loadState(img *image, path string) {
+	stateJSON, err := os.Open(path)
+	if err != nil {
+		fmt.Println(err)
+		return
+	}
+	defer stateJSON.Close()
+	byteValue, _ := ioutil.ReadAll(stateJSON)
+
+	json.Unmarshal(byteValue, &img)
+}
+
+func saveState(img *image, path string) {
+	ticker := time.NewTicker(1 * time.Second)
+
+	for range ticker.C {
+		imgJSON, _ := json.Marshal(img)
+		file, err := os.Create(path)
+
+		if err != nil {
+			return
+		}
+		defer file.Close()
+		file.WriteString(string(imgJSON))
+		if err != nil {
+			fmt.Println("Could not save state")
+			fmt.Println(err)
+		}
+	}
+}
+
 func main() {
 	var addr = flag.String("addr", "localhost:8080", "http service address")
 
 	flag.Parse()
 	log.SetFlags(0)
 	log.Println("starting server on", *addr)
+
+	cachePath := "./state.json"
+
+	loadState(&img, cachePath)
+	go saveState(&img, cachePath)
+
 	http.HandleFunc("/get", get)
 	http.HandleFunc("/set", set)
 

go/util.go

@@ -20,36 +20,36 @@ type pixel struct {
 }
 
 type pixelContainer struct {
-	pixel pixel
+	Pixel pixel `json:"pixel"`
 	Mutex sync.Mutex
 }
 
 type image struct {
-	width  uint32
-	height uint32
-	pixels []pixelContainer
+	Width  uint32           `json:"Width"`
+	Height uint32           `json:"Height"`
+	Pixels []pixelContainer `json:"Pixels"`
 }
 
 func GetImage(w uint32, h uint32) image {
-	pixels := make([]pixelContainer, w*h)
+	Pixels := make([]pixelContainer, w*h)
 	for i := 0; i < int(w*h); i++ {
-		pixels[i] = pixelContainer{pixel: pixel{Color: 0, Timestamp: 0, UserID: 0}, Mutex: sync.Mutex{}}
+		Pixels[i] = pixelContainer{Pixel: pixel{Color: 0, Timestamp: 0, UserID: 0}, Mutex: sync.Mutex{}}
 	}
-	return image{width: w, height: h, pixels: pixels}
+	return image{Width: w, Height: h, Pixels: Pixels}
 }
 
 func (p *pixelContainer) setColor(color uint8, timestamp int64, userid uint64) {
 	p.Mutex.Lock()
 	defer p.Mutex.Unlock()
-	if timestamp > p.pixel.Timestamp {
-		p.pixel.Color = color
-		p.pixel.Timestamp = timestamp
-		p.pixel.UserID = userid
+	if timestamp > p.Pixel.Timestamp {
+		p.Pixel.Color = color
+		p.Pixel.Timestamp = timestamp
+		p.Pixel.UserID = userid
 	}
 }
 
 func (img *image) SetPixel(message Message) int {
-	if message.X >= img.width || message.Y >= img.height || message.X < 0 || message.Y < 0 {
+	if message.X >= img.Width || message.Y >= img.Height || message.X < 0 || message.Y < 0 {
 		fmt.Printf("User %d tried accessing out of bounds \n", message.UserID)
 		return 1
 	}
@@ -57,24 +57,24 @@ func (img *image) SetPixel(message Message) int {
 		fmt.Printf("User %d tried setting non existent color \n", message.UserID)
 		return 1
 	}
-	pos := uint32(message.X)*uint32(img.width) + uint32(message.Y)
-	img.pixels[pos].setColor(message.Color, message.Timestamp, message.UserID)
+	pos := uint32(message.X)*uint32(img.Width) + uint32(message.Y)
+	img.Pixels[pos].setColor(message.Color, message.Timestamp, message.UserID)
 	return 0
 }
 
 func comparePixels(pixel1 *pixelContainer, pixel2 *pixelContainer) bool {
-	return pixel1.pixel.Color == pixel2.pixel.Color &&
-		pixel1.pixel.Timestamp == pixel2.pixel.Timestamp &&
-		pixel1.pixel.UserID == pixel2.pixel.UserID
+	return pixel1.Pixel.Color == pixel2.Pixel.Color &&
+		pixel1.Pixel.Timestamp == pixel2.Pixel.Timestamp &&
+		pixel1.Pixel.UserID == pixel2.Pixel.UserID
 }
 
 func (img *image) GetDiff(img2 *image) image {
-	diff := GetImage(img.width, img.height)
-	for i := 0; i < int(img.width*img.height); i++ {
-		if !comparePixels(&img.pixels[i], &img2.pixels[i]) {
-			diff.pixels[i].pixel.Color = img2.pixels[i].pixel.Color
-			diff.pixels[i].pixel.UserID = img2.pixels[i].pixel.UserID
-			diff.pixels[i].pixel.Timestamp = img2.pixels[i].pixel.Timestamp
+	diff := GetImage(img.Width, img.Height)
+	for i := 0; i < int(img.Width*img.Height); i++ {
+		if !comparePixels(&img.Pixels[i], &img2.Pixels[i]) {
+			diff.Pixels[i].Pixel.Color = img2.Pixels[i].Pixel.Color
+			diff.Pixels[i].Pixel.UserID = img2.Pixels[i].Pixel.UserID
+			diff.Pixels[i].Pixel.Timestamp = img2.Pixels[i].Pixel.Timestamp
 		}
 	}
 	return diff

python/clients.py

@@ -57,7 +57,6 @@ async def client():
             #image[x.x][x.y] = ([y*255 for y in colors[x.color]])
             image[x.x][x.y] = ((x.color, x.color, x.color))
             if i% 1000 == 0:
-                print("showing")
                 cv2.imshow("changes x", image)
                 cv2.waitKey(10) & 0XFF
             await websocket.send("1")