Golang Bufio 编写器不写入 TCP 连接

Question

我正在开发一个用 Golang 编写的小型服务器。我正在查看以下示例:

https://gist.github.com/kenshinx/5796276

当尝试从 Bufio 包中实现 Reader 和 Writer 时，只能从连接中读取。看起来它没有写任何东西(好吧，我没有收到客户端的任何东西)，而且它也没有给出错误。但是，使用实际连接而不是 bufio.Writer 进行写入工作正常。

这是代码。

package main

import (
    "fmt"
    "net"
    "os"
    "bufio"
    "strings"
)

const (
    CONN_HOST = "localhost"
    CONN_TYPE = "tcp"
    CONN_PORT = "3333"
)

type Client struct{
    name string
    reader *bufio.Reader
    writer *bufio.Writer
    connection net.Conn
}

type Clients [] Client

var lobby Clients

func main() {
    c, err := net.Listen(CONN_TYPE, CONN_HOST+":"+CONN_PORT)

    if err != nil {
        fmt.Println("Error listening:", err.Error())
        os.Exit(1)
    }

    defer c.Close()
    fmt.Println("Server listening on port " + CONN_PORT)

    go matchmaking()

    for {
        conn, err := c.Accept()
        if err != nil {
            fmt.Println("Error accepting: ", err.Error())
            os.Exit(1)
        }

        if conn != nil {
            go handleRequest(conn)
        }
    }
}

func handleRequest(conn net.Conn) {
    client := &Client{
        reader: bufio.NewReader(conn),
        writer: bufio.NewWriter(conn),
        connection:conn,
    }

    client.name, _ = client.reader.ReadString('\n') // Works fine
    client.name = strings.TrimSpace(client.name)

    lobby = append(lobby, *client)
    fmt.Println("Client connected: " + client.name)
}

func matchmaking(){
    fmt.Println("Matchmaker started!")
    for {
        for i := range lobby {
            if len(lobby) >= 2 {
                go startMatch(lobby[i], lobby[i+1] )
                lobby = append(lobby[:i], lobby[i+1:]...) // Remove from lobby
                lobby = append(lobby[:i], lobby[i+1:]...)
            }
        }
    }
}

func startMatch(client1 Client, client2 Client){
    client1.writer.WriteString("found\n") // Doens't work?
    client2.writer.WriteString("found\n") // Doens't work?

    //client1.writer.Write([]byte("found\n")) => Doensn't work either
    //client1.connection.Write([]byte("found\n")) => this works fine..?

    fmt.Println("Starting match with: " + client1.name + " and " + client2.name)
    fmt.Println("Current lobby size is: ", len(lobby))
}

正如标题所说，为什么 bufio.Writer 不写入已连接的客户端？

Answer 1

缓冲的写入器已经缓冲了数据。要进一步插入它，请调用 writer.Flush .

func startMatch(client1 Client, client2 Client){
    _, err := client1.writer.WriteString("found\n")
    // handle error here
    err = client1.writer.Flush()
    // handle error here
    _, err = client2.writer.WriteString("found\n")
    // handle error here
    err = client2.writer.Flush()
    // handle error here

    fmt.Println("Starting match with: " + client1.name + " and " + client2.name)
    fmt.Println("Current lobby size is: ", len(lobby))
}

处理刷新操作中的错误也变得很重要，因为此时潜在的编写器错误可能会冒出来。