设置内置的HTTP请求超时的最佳方法是什么？

huangapple
go评论192阅读模式
英文:

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

问题

设置内置http.NewRequest的超时时间的最佳方法是什么？目前，我正在使用http.Client的Timeout属性，它覆盖整个请求过程，但是否有更好的方法，例如使用context.WithDeadline或context.WithTimeout？如果有，它是如何工作的？如何为http.NewRequest设置context.WithDeadline解决方案？

以下是我目前的解决方案：

  1. func (c *Client) post(resource string, data url.Values, timeout time.Duration) ([]byte, error) {
  2.     url := c.getURL(resource)
  3.     client := &http.Client{
  4.         Timeout: timeout * time.Millisecond,
  5.     }
  6.     req, err := http.NewRequest("POST", url, strings.NewReader(data.Encode()))
  7.     if err != nil {
  8.         return nil, err
  9.     }
  10.     req.Header.Add("Content-Type", "application/x-www-form-urlencoded")
  11.     resp, err := client.Do(req)
  12.     if err != nil {
  13.         return nil, err
  14.     }
  15.     return ioutil.ReadAll(resp.Body)
  16. }

请注意，这是一个示例代码，你可以根据自己的需求进行调整。

英文:

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:

  1. func (c *Client) post(resource string, data url.Values, timeout time.Duration) ([]byte, error) {
  2. 	url := c.getURL(resource)
  3. 	client := &http.Client{
  4. 		Timeout: timeout * time.Millisecond,
  5. 	}
  6. 	req, err := http.NewRequest("POST", url, strings.NewReader(data.Encode()))
  7. 	if err != nil {
  8. 		return nil, err
  9. 	}
  10. 	req.Header.Add("Content-Type", "application/x-www-form-urlencoded")
  11. 	resp, err := client.Do(req)
  12. 	if err != nil {
  13. 		return nil, err
  14. 	}
  15. 	return ioutil.ReadAll(resp.Body)
  16. }

答案1

得分: 1

从context.WithDeadline中获取新的上下文。请参阅文档。
WithTimeout只是返回WithDeadline(parent, time.Now().Add(timeout))。

  1. package main
  3. import (
  4. 	"context"
  5. 	"io"
  6. 	"log"
  7. 	"net/http"
  8. 	"os"
  9. 	"time"
  10. )
  12. func getContent(ctx context.Context) {
  13. 	req, err := http.NewRequest("GET", "http://example.com", nil)
  14. 	if err != nil {
  15. 		log.Fatal(err)
  16. 	}
  17. 	ctx, cancel := context.WithDeadline(ctx, time.Now().Add(3 * time.Second))
  18. 	defer cancel()
  20. 	req.WithContext(ctx)
  22. 	resp, err := http.DefaultClient.Do(req)
  23. 	if err != nil {
  24. 		log.Fatal(err)
  25. 	}
  26. 	defer resp.Body.Close()
  27. 	io.Copy(os.Stdout, resp.Body)
  28. }
  30. func main() {
  31. 	ctx := context.Background()
  32. 	getContent(ctx)
  33. }

如果你想在main函数中触发取消操作：

  1. func main() {
  2. 	ctx := context.Background()
  3. 	ctx, cancel := context.WithCancel(ctx)
  5. 	sc := make(chan os.Signal, 1)
  6. 	signal.Notify(sc, os.Interrupt)
  7. 	go func(){
  8. 	    <-sc
  9. 		cancel()
  10. 	}()
  12. 	getContent(ctx)
  13. }
英文:

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

  1. package main
  3. import (
  4. 	&quot;context&quot;
  5. 	&quot;io&quot;
  6. 	&quot;log&quot;
  7. 	&quot;net/http&quot;
  8. 	&quot;os&quot;
  9. 	&quot;time&quot;
  10. )
  12. func getContent(ctx context.Context) {
  13. 	req, err := http.NewRequest(&quot;GET&quot;, &quot;http://example.com&quot;, nil)
  14. 	if err != nil {
  15. 		log.Fatal(err)
  16. 	}
  17. 	ctx, cancel := context.WithDeadline(ctx, time.Now().Add(3 * time.Second))
  18. 	defer cancel()
  20. 	req.WithContext(ctx)
  22. 	resp, err := http.DefaultClient.Do(req)
  23. 	if err != nil {
  24. 		log.Fatal(err)
  25. 	}
  26. 	defer resp.Body.Close()
  27. 	io.Copy(os.Stdout, resp.Body)
  28. }
  30. func main() {
  31. 	ctx := context.Background()
  32. 	getContent(ctx)
  33. }

If you want to make cancel trigger on main:

  1. func main() {
  2. 	ctx := context.Background()
  3. 	ctx, cancel := context.WithCancel(ctx)
  5. 	sc := make(chan os.Signal, 1)
  6. 	signal.Notify(sc, os.Interrupt)
  7. 	go func(){
  8. 	    &lt;-sc
  9. 		cancel()
  10. 	}()
  12. 	getContent(ctx)
  13. }

huangapple
  • 本文由 发表于 2017年7月5日 01:49:14
  • 转载请务必保留本文链接：https://go.coder-hub.com/44911726.html
  • go
  • timeout
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