Discuss how to use Golang to implement long-round training

Golang is an efficient and powerful language that has a wide range of applications in the field of network programming. Long rotation training is a widely used technology that can achieve instant messaging, chat and other functions by maintaining a connection for a long time. In this article, we will discuss how to implement long-round training using Golang.

1. What is long rotation training

Long rotation training is a WEB technology, which is closely related to the HTTP protocol. The core idea of ​​long-round training is to maintain a connection between the client and the server for a period of time in order to transmit data in real time. This implementation method is not like the traditional HTTP request method, which requires the client to actively send a request to the server. Instead, the server sends data to the client in its free time.

Long rotation training can be used to implement real-time chat, online games and other applications because it can provide real-time notification and data transmission functions without interruption. In Golang, you can use goroutine and channel to implement long-round training function.

2. Golang long rotation training implementation

1. Server-side implementation

First, we need to create an HTTP server so that the client can connect to it and Do long rotations. It is very simple to implement an HTTP server using Golang's net/http package:

package main

import (
    "fmt"
    "log"
    "net/http"
)

func main() {
    http.HandleFunc("/longpolling", longPollingHandler)
    log.Fatal(http.ListenAndServe(":8080", nil))
}

func longPollingHandler(w http.ResponseWriter, r *http.Request) {
    // 实现长轮训逻辑
}

Next, we need to implement the long-round training logic. Here we use two goroutines, one to handle client requests and the other to send data to the client.

func longPollingHandler(w http.ResponseWriter, r *http.Request) {
    // 首先，我们创建一个通道用于接收数据
    ch := make(chan string)

    // 开启一个goroutine用于处理客户端请求
    go func() {
        for {
            // 阻塞等待，直到有数据可读
            data := <-ch
            fmt.Fprint(w, data)
            return
        }
    }()

    // 开启一个goroutine用于发送数据到客户端
    go func() {
        for {
            // 模拟发送数据到客户端
            data := "long polling data"
            ch <- data
        }
    }()
}

The above code implements the long-round training logic. The specific idea is: first create a channel to receive data, continuously send data to the channel in a goroutine; in another goroutine, block and wait. If there is data in the channel, the data will be returned to the client.

2. Client implementation

On the client side, we implement long-round training through HTTP requests. We need to first send a request to the server and then wait for the server's response:

function longPolling() {
  $.ajax({
    url: "/longpolling",
    success: function(data) {
      console.log(data);
      longPolling();
    },
    timeout: 30000
  });
}

longPolling();

In the above code, we use jQuery's $.ajax function, which will send a HTTP request and execute a callback function after receiving the response. In the callback function, we will get the data sent by the server, and call the longPolling function again after outputting the data to wait for the next response.

We use a timeout option to define the timeout. If the waiting time exceeds 30 seconds, the client will automatically disconnect and resend the request.

3. Summary

In this article, we introduced how to use Golang to implement the long rotation training function. Long rotation is a great technique that allows real-time data transfer between different applications. In Golang, it is very convenient to use goroutine and channels to implement the long-round training function. For client code, we use jQuery’s $.ajax function to send HTTP requests. I hope this article will help you learn and master long rotation training.

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