The best way to set the timeout on built-in HTTP request

PumpkinSeed Published at

PumpkinSeed :

What is the best way to setup a timeout on built-in http NewRequest? Currently, I'm using http.Client.Timeout which is cover the entire exchange, but is there something better for example context.WithDeadline or context.WithTimeout. If yes how is it working, how can I setup a context.WithDeadline solution for the http.NewRequest?

There is my current solution:

func (c *Client) post(resource string, data url.Values, timeout time.Duration) ([]byte, error) {
    url := c.getURL(resource)
    client := &http.Client{
        Timeout: timeout * time.Millisecond,
    }
    req, err := http.NewRequest("POST", url, strings.NewReader(data.Encode()))
    if err != nil {
        return nil, err
    }
    req.Header.Add("Content-Type", "application/x-www-form-urlencoded")
    resp, err := client.Do(req)
    if err != nil {
        return nil, err
    }
    return ioutil.ReadAll(resp.Body)
}

mattn :

Get new context from context.WithDeadline. See documentation. WithTimeout just returns WithDeadline(parent, time.Now().Add(timeout)).

package main

import (
    "context"
    "io"
    "log"
    "net/http"
    "os"
    "time"
)

func getContent(ctx context.Context) {
    req, err := http.NewRequest("GET", "http://example.com", nil)
    if err != nil {
        log.Fatal(err)
    }
    ctx, cancel := context.WithDeadline(ctx, time.Now().Add(3 * time.Second))
    defer cancel()

    req.WithContext(ctx)

    resp, err := http.DefaultClient.Do(req)
    if err != nil {
        log.Fatal(err)
    }
    defer resp.Body.Close()
    io.Copy(os.Stdout, resp.Body)
}

func main() {
    ctx := context.Background()
    getContent(ctx)
}

If you want to make cancel trigger on main:

func main() {
    ctx := context.Background()
    ctx, cancel := context.WithCancel(ctx)

    sc := make(chan os.Signal, 1)
    signal.Notify(sc, os.Interrupt)
    go func(){
        <-sc
        cancel()
    }()

    getContent(ctx)
}

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