Request pipeline techniques and application examples of http.Transport in Go language

http.Transport in the Go language is a high-performance HTTP client library. It provides functions such as connection pooling, retry, and timeout control, and can facilitate HTTP requests. In actual application scenarios, we often need to send a large number of HTTP requests concurrently, and http.Transport's request pipeline technology can help us improve request speed and efficiency.

Request pipelining means that in the process of sending HTTP requests, you do not have to wait for the response of each request to return before sending the next request. Instead, you send multiple requests at the same time and process the response after the response returns. . This can make full use of network bandwidth and improve the concurrent processing capabilities of requests. Below we use a specific example to illustrate how to use http.Transport to implement request pipeline.

First, we need to create an http.Client instance and set its Transport property to a custom http.Transport object. Then, send multiple requests through that http.Client and use a goroutine to handle each response. The specific code is as follows:

package main

import (
    "fmt"
    "io/ioutil"
    "net/http"
    "sync"
    "time"
)

type PipelineTransport struct {
    Transport http.Transport
    RWMutex   sync.RWMutex
    Channels  map[string]chan string
}

func (t *PipelineTransport) RoundTrip(req *http.Request) (*http.Response, error) {
    // 获取请求的URL
    url := req.URL.String()

    t.RWMutex.Lock()
    // 如果该URL对应的通道不存在，则新建一个通道
    if _, ok := t.Channels[url]; !ok {
        t.Channels[url] = make(chan string)
    }
    c := t.Channels[url] // 获取通道
    t.RWMutex.Unlock()

    // 向通道发送请求
    go func() {
        resp, err := t.Transport.RoundTrip(req)
        if err != nil {
            c <- err.Error()
            return
        }

        defer resp.Body.Close()
        body, _ := ioutil.ReadAll(resp.Body)
        c <- string(body)
    }()

    return &http.Response{}, nil
}

func main() {
    // 创建一个自定义的http.Transport对象
    transport := PipelineTransport{
        Transport: http.Transport{
            MaxIdleConns:        100,
            MaxIdleConnsPerHost: 100,
            IdleConnTimeout:     30 * time.Second,
        },
        Channels: make(map[string]chan string),
    }

    // 创建一个http.Client对象
    client := http.Client{
        Transport: &transport,
    }

    // 构建并发发送的HTTP请求
    reqs := []*http.Request{
        &http.Request{
            Method: "GET",
            URL:    &url.URL{Scheme: "http", Host: "example.com", Path: "/1"},
        },
        &http.Request{
            Method: "GET",
            URL:    &url.URL{Scheme: "http", Host: "example.com", Path: "/2"},
        },
        &http.Request{
            Method: "GET",
            URL:    &url.URL{Scheme: "http", Host: "example.com", Path: "/3"},
        },
    }

    // 发送并发请求
    var wg sync.WaitGroup
    for _, req := range reqs {
        wg.Add(1)
        go func(r *http.Request) {
            resp, err := client.Do(r)
            if err != nil {
                fmt.Println(err)
                return
            }
            defer resp.Body.Close()

            body, _ := ioutil.ReadAll(resp.Body)
            fmt.Println(string(body))
            wg.Done()
        }(req)
    }

    wg.Wait()
}

In the above code, we created a custom PipelineTransport type, which implements the RoundTrip method of http.Transport. In the RoundTrip method, we first obtain the requested URL and use read-write locks to ensure the concurrency safety of multiple goroutines. Then, we check whether the channel corresponding to the URL exists, and if it does not exist, create a new channel. Next, we use a goroutine to send the request and write the response to the channel. In the main function, we create a custom http.Transport object and http.Client object. We then constructed several HTTP requests sent concurrently and used goroutine and sync.WaitGroup to handle the responses.

Through the above examples, we can see how to use http.Transport to send HTTP requests concurrently, and use request pipeline techniques to improve request speed and efficiency. In actual applications, we can flexibly adjust the code according to needs and add functions such as error handling, request retry, and timeout control to meet specific business needs.

To sum up, using the http.Transport request pipeline technique in the Go language, we can better handle concurrent HTTP requests and improve system performance and response speed. I hope this article helps you understand and apply this technique.

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