Go websocket test acting strange - go

So basically I'm writing a go test for my chat application and for some reason the if I write Test_saveMessage function in the top of this file my tests go through and they work fine, however if I write the Test_InitRouter in the top of this file - my server opens and the test doesn't finish. As if it would be listening for more requests. Does anyone know the reason of why this could be happening? Here is the that does not work code:
package messenger
import (
"fmt"
"github.com/gorilla/websocket"
"github.com/stretchr/testify/assert"
"net/http/httptest"
"strings"
"testing"
)
var testMessage = Message{
Username: "Name",
Message: "Test message"}
//Tests InitRouter both sending and receiving messages
func Test_InitRouter(t *testing.T) {
var receivedMessage Message
//Create test server with the InitRouter handler
s := httptest.NewServer(InitRouter())
defer s.Close()
// Convert URL from http to ws
u := "ws" + strings.TrimPrefix(s.URL, "http")
fmt.Println(u)
// Connect to the test server
ws, _, err := websocket.DefaultDialer.Dial(u, nil)
if err != nil {
t.Fatalf("%v", err)
}
defer ws.Close()
//Send message to the server read received message and see if it's the same
if err != ws.WriteJSON(testMessage) {
t.Fatalf("%v", err)
}
err = ws.ReadJSON(&receivedMessage)
if err != nil {
t.Fatalf("%v", err)
}
if receivedMessage != testMessage {
t.Fatalf("%v", err)
}
}
//Test for the saveMessage function
func Test_saveMessage(t *testing.T) {
saveMessage(testMessage)
assert.Equal(t, 1, len(messages), "Expected to have 1 message")
}
As soon as I move the Test_saveMessage function to the top it starts working properly.
Here is the code for the handler:
package messenger
import (
"fmt"
"github.com/go-chi/chi"
"github.com/gorilla/websocket"
log "github.com/sirupsen/logrus"
"net/http"
)
func InitRouter() http.Handler {
r := chi.NewRouter()
r.Get("/", GetWebsocket)
return r
}
var clients = make(map[*websocket.Conn]bool) // connected clients
var broadcast = make(chan Message) // broadcast channel
var messages = []Message{}
func GetWebsocket(w http.ResponseWriter, r *http.Request) {
// Upgrade initial GET request to a websocket
upgrader := websocket.Upgrader{}
ws, err := upgrader.Upgrade(w, r, nil)
if err != nil {
log.Error(err)
}
// Close the connection when the function returns
defer ws.Close()
// Register our new client and send him the chat history
clients[ws] = true
serveInitialMessages(ws)
//initialize message sending logic
sendMessages(ws)
}
// Sends messages from a particular websocket to the channel
func sendMessages(ws *websocket.Conn){
for {
var msg Message
// Read in a new message as JSON and map it to a Message object
err := ws.ReadJSON(&msg)
if err != nil {
log.Info(err)
delete(clients, ws)
break
}
// Send the newly received message to the broadcast channel
broadcast <- msg
saveMessage(msg)
}
}
func HandleMessages() {
for {
// Grab the next message from the broadcast channel
msg := <-broadcast
fmt.Println(msg)
// Send it out to every client that is currently connected
for client := range clients {
err := client.WriteJSON(msg)
if err != nil {
log.Printf("error: %v", err)
client.Close()
delete(clients, client)
}
}
}
}
func saveMessage(m Message) {
if len(messages) >= 50 {
messages = messages[1:]
}
messages = append(messages, m)
}
func serveInitialMessages(ws *websocket.Conn) {
for _, m := range messages {
err := ws.WriteJSON(m)
if err != nil {
log.Error(err)
}
}
}

Related

Sending Websocket messages to new clients

I am creating a chat API using Go and Gorilla websocket. I would like my users to receive the last 10 messages on establishing a websocket connection. However I can't find a simple way to do that. I would just like to send every message from my messages array to the new client. Is there a simple way to edit my code without hubs? Here is my code:
package messenger
import (
"../config"
"fmt"
"github.com/go-chi/chi"
"github.com/gorilla/websocket"
log "github.com/sirupsen/logrus"
"net/http"
)
func InitRouter() http.Handler {
r := chi.NewRouter()
r.Get("/", getWebsocket)
return r
}
var clients = make(map[*websocket.Conn]bool) // connected clients
var broadcast = make(chan Message) // broadcast channel
var messages = []Message{}
// Configure the upgrader
var upgrader = websocket.Upgrader{}
func getWebsocket(w http.ResponseWriter, r *http.Request) {
// Upgrade initial GET request to a websocket
ws, err := upgrader.Upgrade(w, r, nil)
if err != nil {
log.Fatal(err)
}
// Make sure we close the connection when the function returns
defer ws.Close()
// Register our new client
clients[ws] = true
for {
var msg Message
// Read in a new message as JSON and map it to a Message object
err := ws.ReadJSON(&msg)
if err != nil {
log.Printf("error: %v", err)
delete(clients, ws)
break
}
// Send the newly received message to the broadcast channel
broadcast <- msg
saveMessage(msg)
}
}
func HandleMessages() {
for {
// Grab the next message from the broadcast channel
msg := <-broadcast
// Send it out to every client that is currently connected
for client := range clients {
err := client.WriteJSON(msg)
if err != nil {
log.Printf("error: %v", err)
client.Close()
delete(clients, client)
}
}
}
}
func saveMessage(m Message) {
if len(messages) >= config.Conf.MessageAmount {
messages = messages[1:]
}
messages = append(messages, m)
fmt.Println(messages)
}
Okay looks like I did it. I just created a new function and called it fromgetWebsocket function passing the newly created Websocket. Here is the new function:
func serveInitialMessages(ws *websocket.Conn) {
for _, m := range messages {
fmt.Println(m)
err := ws.WriteJSON(m)
if err != nil {
fmt.Println(err)
}
}
}

WebSocket Server that feeds messages to clients in a round robin fashion

I have a websocket server in Go using the Gorilla websocket package. At this stage, I will have only one server serving 5 clients. I am getting some messages from upstream into the WebSocket server. My intention is to NOT BROADCAST all the messages to the connected clients. I would like to send only one copy of the message to the connected clients in a round robin fashion. It doesn't matter which client gets it as long as there is only one that gets it.
My attempted solution
I have a simple Go server, created a Pool of clients (websocket connections) that I am receiving. However, I do not see any options to round robin the messages as I mentioned above. All my clients are getting the message. How can I send only one copy of the message to the connected clients instead of broadcasting to all.
Discalimer
The code I have is taken from online sources and modified to my requirement. I am relatively new to Go and Websockets. Is this something even possible using Websockets?
main.go
package main
import (
"fmt"
"net/http"
"github.com/realtime-chat-go-react/backend/pkg/websocket"
)
func serveWs(pool *websocket.Pool, w http.ResponseWriter, r *http.Request) {
fmt.Println("WebSocket Endpoint Hit")
conn, err := websocket.Upgrade(w, r)
if err != nil {
fmt.Fprintf(w, "%+v\n", err)
}
client := &websocket.Client{
Conn: conn,
Pool: pool,
}
pool.Register <- client
client.Read()
}
func setupRoutes() {
pool := websocket.NewPool()
go pool.Start()
http.HandleFunc("/ws", func(w http.ResponseWriter, r *http.Request) {
serveWs(pool, w, r)
})
}
func main() {
setupRoutes()
err := http.ListenAndServe(":8080",nil)
if err != nil {
fmt.Println(err)
}
}
websocket.go
package websocket
import (
"log"
"net/http"
"github.com/gorilla/websocket"
)
var upgrader = websocket.Upgrader{
ReadBufferSize: 1024,
WriteBufferSize: 1024,
}
var wsList []*websocket.Conn
func Upgrade(w http.ResponseWriter, r *http.Request) (*websocket.Conn, error) {
upgrader.CheckOrigin = func(r *http.Request) bool { return true }
conn, err := upgrader.Upgrade(w, r, nil)
wsList = append(wsList, conn) //Creating a list here to store all websocket clients.
if err != nil {
log.Println(err)
return nil, err
}
return conn, nil
}
pool.go
package websocket
import "fmt"
type Pool struct {
Register chan *Client
Unregister chan *Client
Clients map[*Client]bool
Broadcast chan Message
}
func NewPool() *Pool {
return &Pool{
Register: make(chan *Client),
Unregister: make(chan *Client),
Clients: make(map[*Client]bool),
Broadcast: make(chan Message),
}
}
func (pool *Pool) Start() {
for {
select {
case client := <-pool.Register:
pool.Clients[client] = true
fmt.Println("Size of Connection Pool: ", len(pool.Clients))
for client, _ := range pool.Clients {
fmt.Println(client)
client.Conn.WriteJSON(Message{Type: 1, Body: "New User Joined..."})
}
break
case client := <-pool.Unregister:
delete(pool.Clients, client)
fmt.Println("Size of Connection Pool: ", len(pool.Clients))
for client, _ := range pool.Clients {
client.Conn.WriteJSON(Message{Type: 1, Body: "User Disconnected..."})
}
break
case message := <-pool.Broadcast: //This is where I need to modify the code but not sure how
fmt.Println("Sending message to all clients in Pool")
for client, _ := range pool.Clients {
if err := client.Conn.WriteJSON(message); err != nil {
fmt.Println(err)
return
}
}
}
}
}
client.go
package websocket
import (
"fmt"
"log"
"sync"
"github.com/gorilla/websocket"
)
type Client struct {
ID string
Conn *websocket.Conn
Pool *Pool
mu sync.Mutex
}
type Message struct {
Type int `json:"type"`
Body string `json:"body"`
}
func (c *Client) Read() {
defer func() {
c.Pool.Unregister <- c
c.Conn.Close()
}()
for {
messageType, p, err := c.Conn.ReadMessage()
if err != nil {
log.Println(err)
return
}
message := Message{Type: messageType, Body: string(p)}
c.Pool.Broadcast <- message
fmt.Printf("Message Received: %+v\n", message)
}
}
Modify the pool to store clients in a slice instead of a map. Add field to record index of the previous client used.
type Pool struct {
Register chan *Client
Unregister chan *Client
Clients []*Client
Broadcast chan Message
PrevClientIndex int
}
Round robin instead of broadcasting:
case message := <-pool.Broadcast:
if len(pool.Clients) == 0 {
continue
}
pool.PrevClientIndex++
if pool.PrevClientIndex >= len(pool.Clients) {
pool.PrevClientIndex = 0
}
client := pool.Clients[pool.PrevClientIndex]
if err := client.Conn.WriteJSON(message); err != nil {
// handle error
...
Register appends to the slice:
case client := <-pool.Register:
pool.Clients = append(pool.Clients, client)
...
Unregister removes the client from the slice:
case client := <-pool.Unregister:
j := 0
for _, c := range pool.Clients {
if c != client {
c.Clients[j] = c
j++
}
}
pool.Clients = pool.Clients[:j]
...

Add handler for the gRPC server in Golang

I have the following server/server.go definition for my gRPC server:
package main
import (
"flag"
"github.com/golang/glog"
pb "github.com/go-grpc-tutorial/pb"
"golang.org/x/net/context"
"google.golang.org/grpc"
"net"
)
// Implements of EchoServiceServer
type echoServer struct{}
func newEchoServer() pb.EchoServiceServer {
return new(echoServer)
}
func (s *echoServer) Echo(ctx context.Context, msg *pb.Message) (*pb.Message, error) {
glog.Info(msg)
return msg, nil
}
func Run() error {
listen, err := net.Listen("tcp", ":50051")
if err != nil {
return err
}
server := grpc.NewServer()
pb.RegisterEchoServiceServer(server, newEchoServer())
server.Serve(listen)
return nil
}
func main() {
flag.Parse()
defer glog.Flush()
if err := Run(); err != nil {
glog.Fatal(err)
}
}
I want the server to listen from a Kinesis stream, so whenever a message is posted to the Kinesis stream, it will consume that message and send it to the Echo() method.
So, I'm envisioning something like:
func handleKinesis(s *echoServer) error {
// wait until a message is published to the kinesis stream
records, err := readFromKinesis() // not implemented here
if err != nil {
return err
}
for _, record := records {
message := string(record.Data)
_, _ = s.Echo(context.Background(), &pb.Message{msg: message})
}
}
And the handleKinesis would run in the background, just listening for new Kinesis messages, and then call the echoServer to process that message.
How can I accomplish that?

TCP connection returns 'broken pipe' error when used multiple times

This question relates to go and its net package.
I wrote a simple tcp server handles some RPC. the client is using a chan net.Conn to manage all tcp connection on the client side. Server is running with a tcp listener.
here's the code:
client:
package server
import (
"errors"
"log"
"net"
)
var tcpPool chan net.Conn
func NewClient(connections int, address string) {
tcpPool = make(chan net.Conn, connections)
for i := 0; i < connections; i++ {
conn, err := net.Dial("tcp4", address)
if err != nil {
log.Panic(err)
}
tcpPool <- conn
}
}
func SendMessage(msg []byte) ([]byte, error) {
conn := getConn()
log.Println("check conn: ", conn)
log.Println("msg: ", msg)
defer releaseConn(conn)
// send message
n, err := conn.Write(msg)
if err != nil {
log.Panic(err)
} else if n < len(msg) {
log.Panic(errors.New("Message did not send in full"))
}
// receiving a message
inBytes := make([]byte, 0)
for {
// bufsize 1024, read bufsize bytes each time
b := make([]byte, bufSize)
res, err := conn.Read(b)
log.Println("server sends >>>>>>>>>>>>: ", res)
if err != nil {
b[0] = ReError
break
}
inBytes = append(inBytes, b[:res]...)
// message finished.
if res < bufSize {
break
}
}
// check replied message
if len(inBytes) == 0 {
return []byte{}, errors.New("empty buffer error")
}
log.Println("SendMessage gets: ", inBytes)
return inBytes, nil
}
func releaseConn(conn net.Conn) error {
log.Println("return conn to pool")
select {
case tcpPool <- conn:
return nil
}
}
func getConn() (conn net.Conn) {
log.Println("Take one from pool")
select {
case conn := <-tcpPool:
return conn
}
}
server
func StartTCPServer(network, addr string) error {
listener, err := net.Listen(network, addr)
if err != nil {
return errors.Wrapf(err, "Unable to listen on address %s\n", addr)
}
log.Println("Listen on", listener.Addr().String())
defer listener.Close()
for {
log.Println("Accept a connection request.")
conn, err := listener.Accept()
if err != nil {
log.Println("Failed accepting a connection request:", err)
continue
}
log.Println("Handle incoming messages.")
go onConn(conn)
}
}
//onConn recieves a tcp connection and waiting for incoming messages
func onConn(conn net.Conn) {
inBytes := make([]byte, 0)
defer func() {
if e := recover(); e != nil {
//later log
if err, ok := e.(error); ok {
println("recover", err.Error())
}
}
conn.Close()
}()
// load msg
for {
buf := make([]byte, bufSize)
res, err := conn.Read(buf)
log.Println("server reading: ", res)
inBytes = append(inBytes, buf[:res]...)
if err != nil || res < bufSize {
break
}
}
var req RPCRequest
err := json.Unmarshal(inBytes, &req)
if err != nil {
log.Panic(err)
}
log.Println("rpc request: ", req)
var query UserRequest
err = json.Unmarshal(req.Query, &query)
if err != nil {
log.Panic(err)
}
log.Println("rpc request query: ", query)
// call method to process request
// good now we can proceed to function call
// some actual function calls gets a output
// outBytes, err := json.Marshal(out)
conn.Write(outBytes)
}
I think this is very standard. but for some reason, I can only send message on the client side one, and then the follow 2nd and 3rd start to show some irregularity.
1st ---> success, gets response
2nd ---> client can send but nothing gets back, logs on server side shows no in coming message
3rd ---> if I send from client side one more time, it shows broken pipe error..
There are some bad handling way.
First, the flag to insure the msg from server finished is depending on io.EOF,not length
// message finished.
if res < 512 {
break
}
instead of this, reader returns an io.EOF is the only symbol that shows message finished.
Second, chan type has its property to block and not need to use select.by the way, you really need to start a goroutine to release. The same requirement for getConn
func releaseConn(conn net.Conn) {
go func(){
tcpPool <- conn
}()
}
func getConn() net.Conn {
con := <-tcpPool
return con
}
Third, listener should not be close, code below is bad
defer listener.Close()
The most important reason is
on the client side,
res, err := conn.Read(b) this receive the reply from the server.
when nothing reply ,it block rather than io.EOF, nor some error else.
It means ,you cann't box a lasting communicating part into a function send().
You can do a single thing to use sendmsg() to send, but never use sendmsg() to handle the reply.
you can handle reply like this
var receive chan string
func init() {
receive = make(chan string, 10)
}
func ReceiveMessage(con net.Conn) {
// receiving a message
inBytes := make([]byte, 0, 1000)
var b = make([]byte, 512)
for {
// bufsize 1024, read bufsize bytes each time
res, err := con.Read(b)
if err != nil {
if err == io.EOF {
break
}
fmt.Println(err.Error())
break
}
inBytes = append(inBytes, b[:res]...)
msg := string(inBytes)
fmt.Println("receive msg from server:" + msg)
receive <- msg
}
}
I found several problem in your code, but I can't tell which one leads your failure.
This is my code according to what you write and did some fixing.
client.go:
package main
import (
"fmt"
"io"
"log"
"net"
)
var tcpPool chan net.Conn
var receive chan string
func init() {
receive = make(chan string, 10)
}
func NewClient(connections int, address string) {
tcpPool = make(chan net.Conn, connections)
for i := 0; i < connections; i++ {
conn, err := net.Dial("tcp", address)
if err != nil {
log.Panic(err)
}
tcpPool <- conn
}
}
func SendMessage(con net.Conn, msg []byte) error {
// send message
_, err := con.Write(msg)
if err != nil {
log.Panic(err)
}
return nil
}
func ReceiveMessage(con net.Conn) {
// receiving a message
inBytes := make([]byte, 0, 1000)
var b = make([]byte, 512)
for {
// bufsize 1024, read bufsize bytes each time
res, err := con.Read(b)
if err != nil {
if err == io.EOF {
break
}
fmt.Println(err.Error())
break
}
inBytes = append(inBytes, b[:res]...)
msg := string(inBytes)
fmt.Println("receive msg from server:" + msg)
receive <- msg
}
}
func getConn() net.Conn {
con := <-tcpPool
return con
}
func main() {
NewClient(20, "localhost:8101")
con := <-tcpPool
e := SendMessage(con, []byte("hello, i am client"))
if e != nil {
fmt.Println(e.Error())
return
}
go ReceiveMessage(con)
var msg string
for {
select {
case msg = <-receive:
fmt.Println(msg)
}
}
}
server.go
package main
import (
"fmt"
"io"
"net"
)
func StartTCPServer(network, addr string) error {
listener, err := net.Listen(network, addr)
if err != nil {
return err
}
for {
conn, err := listener.Accept()
if err != nil {
fmt.Println(err.Error())
continue
}
onConn(conn)
}
}
//onConn recieves a tcp connection and waiting for incoming messages
func onConn(conn net.Conn) {
inBytes := make([]byte, 0)
// load msg
for {
buf := make([]byte, 512)
res, err := conn.Read(buf)
if err != nil {
if err == io.EOF {
return
}
fmt.Println(err.Error())
return
}
inBytes = append(inBytes, buf[:res]...)
fmt.Println("receive from client:" + string(inBytes))
conn.Write([]byte("hello"))
}
}
func main() {
if e := StartTCPServer("tcp", ":8101"); e != nil {
fmt.Println(e.Error())
return
}
}
this works and no error.
By the way, I can't see where either on the client side or the server side you do con.Close(). It's nessasary to close it.This means a connection once got from the pool, you don't put it back. When you think a connection is over, then close it and build a new connection to fill the pool rather than put it back,beause it's a fatal operation to put a closed con back to the pool.

go routine - why websocket reports the connection as closed?

I'm trying to create a client and a server using Go but for some reason the server reports the connection as "closed". As the code is trivial I can't think of anything wrong with my code. Any help is appreciated.
package main
import (
log "github.com/golang/glog"
"net/http"
"golang.org/x/net/websocket"
"time"
"flag"
)
type server struct {
payload chan string
}
// srv pushes the messages received via ws into srv.payload
func (srv *server) serve(ws *websocket.Conn) {
go func() {
var msg string
if err := websocket.Message.Receive(ws, &msg); err != nil {
log.Exit(err)
}
srv.payload <- msg
}()
return
}
// This example demonstrates a trivial client/ server.
func main() {
flag.Parse()
srv := server{payload: make(chan string, 10)}
http.Handle("/echo", websocket.Handler(srv.serve))
go func() {
err := http.ListenAndServe(":12345", nil)
if err != nil {
log.Errorf("ListenAndServe: " + err.Error())
}
}()
// give the server some time to start listening
time.Sleep(3 *time.Second)
//dial and test the response.
ws, err := websocket.Dial("ws://localhost:12345/echo", "", "http://localhost/?x=45")
if err != nil {
log.Exit(err)
}
ms := "test"
if err := websocket.Message.Send(ws, ms); err != nil {
log.Exit(err)
}
msg := <-srv.payload
if msg != ms{
log.Errorf("msg %v is not %v", ms)
}
}
Error
t.go:21] read tcp 127.0.0.1:12345->127.0.0.1:43135:
Edit:
After some try and error I've found that if I remove the go routine from the serve method it works but it doesn't make sense to me. Any idea why it doesn't work when websocket.Message.Receive is in a separate go routine?
package main
import (
log "github.com/golang/glog"
"net/http"
"golang.org/x/net/websocket"
"time"
"flag"
)
type server struct {
payload chan string
}
// srv pushes the messages received via ws into srv.payload
func (srv *server) serve(ws *websocket.Conn) {
var msg string
if err := websocket.Message.Receive(ws, &msg); err != nil {
log.Exit(err)
}
srv.payload <- msg
return
}
// This example demonstrates a trivial client/ server.
func main() {
flag.Parse()
srv := server{payload: make(chan string, 10)}
go func() {
http.Handle("/echo", websocket.Handler(srv.serve))
err := http.ListenAndServe(":12345", nil)
if err != nil {
log.Errorf("ListenAndServe: " + err.Error())
}
}()
// give the server some time to start listening
time.Sleep(3 *time.Second)
//dial and test the response.
ws, err := websocket.Dial("ws://localhost:12345/echo", "", "http://localhost/?x=45")
if err != nil {
log.Exit(err)
}
ms := "test"
if err := websocket.Message.Send(ws, ms); err != nil {
log.Exit(err)
}
msg := <-srv.payload
if msg != ms{
log.Errorf("msg %v is not %v", ms)
}
}
The websocket server closes the connection when the handler returns.
Removing the Go routine is the correct fix.

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