Golang implements broadcast

Golang is an efficient programming language, which is a language developed by Google. In the modern Internet field, Golang is undoubtedly a very important programming language. Its excellent performance and high scalability of applications are very suitable for building large-scale and high-performance network applications. Here we will introduce how to use Golang to implement the broadcast function.

Broadcasting is a method of publishing messages to multiple clients. In communication protocols, broadcast is the transmission of an information packet to a specific address on the network so that the packet is captured by all computers in the vicinity of the address. Usually, broadcasts are used to notify everyone of the occurrence of events.

In Golang, broadcast implementation can realize the broadcast function by sending data to multiple connections at the same time. We can use a list of multiple client connections and send the message to each client. Goroutine and channel are used here to implement broadcasting.

First, we need to create a connection list:

type Client struct {
    conn net.Conn
    name string
}

type ConnectionList struct {
    clients map[*Client]bool
    broadcast chan string
    addClient  chan *Client
    removeClient chan *Client
}

In the above code, the Client structure saves the information about connecting the client, and the ConnectionList structure saves the client connection list, including Channels for broadcasting messages and channels for adding and deleting connections.

The following are the add and remove functions for connections:

func (list *ConnectionList) add(client *Client) {
    list.clients[client] = true
}

func (list *ConnectionList) remove(client *Client) {
    if _, ok := list.clients[client]; ok {
        delete(list.clients, client)
        close(client.conn)
    }
}

Next, we will create more goroutines and channels to handle the connections and broadcast messages to all connected clients:

func handleConnection(conn net.Conn, list *ConnectionList) {
    client := &Client{conn: conn}

    list.addClient <- client
    defer func() {
        list.removeClient <- client
    }()

    for {
        message := make([]byte, 4096)
        length, err := conn.Read(message)

        if err != nil || length == 0 {
            break
        }

        data := strings.TrimSpace(string(message[:length]))

        if len(data) > 0 {
            list.broadcast <- data
        }
    }
}

func (list *ConnectionList) broadcastMessage() {
    for {
        message := <-list.broadcast
        for client := range list.clients {
            _, err := client.conn.Write([]byte(message + "
"))

            if err != nil {
                list.removeClient <- client
            }
        }
    }
}

func (list *ConnectionList) handleClients() {
    for {
        select {
        case client := <-list.addClient:
            list.add(client)
        case client := <-list.removeClient:
            list.remove(client)
        case <-time.After(60 * time.Second):
            fmt.Println("Keep alive.")
        }
    }
}

The handleConnection function handles the connection request and, if it exists, is added to the connection list. Broadcast messages are processed through the broadcastMessage function. Finally, the handleClients function runs forever so that the list of connections remains active for a long time.

Combining methods together:

func main() {
    list := &ConnectionList{
        clients: make(map[*Client]bool),
        broadcast: make(chan string),
        addClient:  make(chan *Client),
        removeClient: make(chan *Client),
    }

    go list.broadcastMessage()
    go list.handleClients()

    listen, err := net.Listen("tcp", ":6000")
    if err != nil {
        fmt.Println(err)
        return
    }

    defer listen.Close()

    for {
        conn, err := listen.Accept()
        if err != nil {
            fmt.Println(err)
            continue
        }

        go handleConnection(conn, list)
    }
}

In this simple example, we can use Golang to implement the function of broadcast messages. As you can see, Golang is efficient, reliable, and flexible, making it an ideal choice for building high-performance distributed applications.

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