尝试在Go语言中使用goroutines写文件。

huangapple
go评论110阅读模式
英文:

Trying to test write file from goroutines in Go

问题

好的，以下是翻译好的内容：

嗯，我的代码的一部分在没有使用方法的情况下工作，我正在尝试测试将文本追加到文件并从goroutine中读取，但我在尝试写入时卡住了。

有什么问题吗？文件已创建，但我无法将文本追加到其中，可能是一些明显的问题，但似乎我看不见，也许我在理解某些语言概念方面出错了...

  1. package main
  3. import (
  4. 	"bufio"
  5. 	"fmt"
  6. 	"os"
  7. 	"sync"
  8. 	"time"
  9. )
  11. var w sync.WaitGroup
  13. type Buffer struct {
  14. 	F *os.File
  15. }
  17. func (buff *Buffer) Open(pathName string) (err error) {
  18. 	buff.F, err = os.OpenFile(pathName, os.O_APPEND|os.O_CREATE, 0666)
  19. 	if err != nil {
  20. 		return
  21. 	}
  22. 	fmt.Println("Open() ok")
  23. 	return nil
  24. }
  25. func (buff *Buffer) Close() (err error) {
  26. 	err = buff.F.Close()
  27. 	if err != nil {
  28. 		return
  29. 	}
  30. 	fmt.Println("Close() ok")
  31. 	return nil
  32. }
  33. func (buff *Buffer) Push(data string) (err error) {
  34. 	w := bufio.NewWriter(buff.F)
  35. 	_, err = fmt.Fprintf(w, "data=%s", data)
  36. 	if err != nil {
  37. 		return
  38. 	}
  39. 	w.Flush()
  40. 	fmt.Println("Push() ok")
  41. 	return nil
  42. }
  43. func checkErr(err error) {
  44. 	if err != nil {
  45. 		fmt.Println(err.Error())
  46. 	}
  47. }
  48. func worker() {
  49. 	var err error
  50. 	buffer := new(Buffer)
  51. 	err = buffer.Open("test")
  52. 	checkErr(err)
  53. 	err = buffer.Push("data\n")
  54. 	checkErr(err)
  55. 	time.Sleep(5 * time.Second)
  56. 	err = buffer.Close()
  57. 	checkErr(err)
  58. 	w.Done()
  59. }
  60. func main() {
  61. 	w.Add(2)
  62. 	go worker()
  63. 	go worker()
  64. 	w.Wait()
  65. }

谢谢！

英文:

Well, part of my code was working without a method approach, I'm trying to test
append text to a file and reading from goroutines, but I'm stuck here trying to
write it.

What is wrong? the file is created, but I can't append text to it, maybe something obvious, but seems I'm blind, maybe I'm failing understanding some language concepts...

  1. package main
  2. import (
  3. "bufio"
  4. "fmt"
  5. "os"
  6. "sync"
  7. "time"
  8. )
  9. var w sync.WaitGroup
  10. type Buffer struct {
  11. F *os.File
  12. }
  13. func (buff *Buffer) Open(pathName string) (err error) {
  14. buff.F, err = os.OpenFile(pathName, os.O_APPEND|os.O_CREATE, 0666)
  15. if err != nil {
  16. return
  17. }
  18. fmt.Println("Open() ok")
  19. return nil
  20. }
  21. func (buff *Buffer) Close() (err error) {
  22. err = buff.F.Close()
  23. if err != nil {
  24. return
  25. }
  26. fmt.Println("Close() ok")
  27. return nil
  28. }
  29. func (buff *Buffer) Push(data string) (err error) {
  30. w := bufio.NewWriter(buff.F)
  31. _, err = fmt.Fprintf(w, "data=%s", data)
  32. if err != nil {
  33. return
  34. }
  35. w.Flush()
  36. fmt.Println("Push() ok")
  37. return nil
  38. }
  39. func checkErr(err error) {
  40. if err != nil {
  41. fmt.Println(err.Error())
  42. }
  43. }
  44. func worker() {
  45. var err error
  46. buffer := new(Buffer)
  47. err = buffer.Open("test")
  48. checkErr(err)
  49. err = buffer.Push("data\n")
  50. checkErr(err)
  51. time.Sleep(5 * time.Second)
  52. err = buffer.Close()
  53. checkErr(err)
  54. w.Done()
  55. }
  56. func main() {
  57. w.Add(2)
  58. go worker()
  59. go worker()
  60. w.Wait()
  61. }

Thanks

答案1

得分: 3

像这样打开文件：

  1. buff.F, err = os.OpenFile(pathName, os.O_WRONLY|os.O_APPEND|os.O_CREATE, 0666)

写入标志是必需的以便写入文件。

你错过了写入错误，因为忽略了从bufio Flush返回的值。将Push更改为：

  1. func (buff *Buffer) Push(data string) (err error) {
  2. w := bufio.NewWriter(buff.F)
  3. _, err = fmt.Fprintf(w, "data=%s", data)
  4. if err != nil {
  5. return
  6. }
  7. err = w.Flush()
  8. if err != nil {
  9. return err
  10. }
  11. fmt.Println("Push() ok")
  12. return nil
  13. }

为了在不与其他推送混合的情况下清晰地追加数据，必须使用单个调用文件的Write方法来写入数据。使用bytes.Buffer而不是bufio.Writer，以确保对文件的Write方法进行单个调用：

  1. func (buff *Buffer) Push(data string) (err error) {
  2. var b bytes.Buffer
  3. _, err = fmt.Fprintf(&b, "data=%s", data)
  4. if err != nil {
  5. return
  6. }
  7. _, err := buff.F.Write(b.Bytes())
  8. if err != nil {
  9. return err
  10. }
  11. fmt.Println("Push() ok")
  12. return nil
  13. }
英文:

Open the file like this:

  1. buff.F, err = os.OpenFile(pathName, os.O_WRONLY|os.O_APPEND|os.O_CREATE, 0666)

The write flag is required to write to the file.

You missed the write error because the return from bufio Flush is ignored. Change Push to:

  1. func (buff *Buffer) Push(data string) (err error) {
  2. w := bufio.NewWriter(buff.F)
  3. _, err = fmt.Fprintf(w, "data=%s", data)
  4. if err != nil {
  5. return
  6. }
  7. err = w.Flush()
  8. if err != nil {
  9. return err
  10. }
  11. fmt.Println("Push() ok")
  12. return nil
  13. }

To cleanly append data without intermixing with other pushes, the data must be written with a single call to the file Write method. Use a bytes.Buffer instead of a bufio.Writer to ensure a single call to the file Write method:

  1. func (buff *Buffer) Push(data string) (err error) {
  2. var b bytes.Buffer
  3. _, err = fmt.Fprintf(&b, "data=%s", data)
  4. if err != nil {
  5. return
  6. }
  7. _, err := buff.F.Write(b.Bytes())
  8. if err != nil {
  9. return err
  10. }
  11. fmt.Println("Push() ok")
  12. return nil
  13. }

huangapple
  • 本文由 发表于 2014年10月3日 08:58:41
  • 转载请务必保留本文链接：https://go.coder-hub.com/26171854.html
  • go
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