可以将Go通道终止到一个接收（sink）的goroutine吗？

huangapple
go评论121阅读模式
英文:

Is it possible to terminate a Go channel to a sink goroutine?

问题

我有一个goroutine，它以块的形式读取文件，并通过通道传递给另一个goroutine，该goroutine为文件计算校验和。消费goroutine是通道的终点。

在所有字节从通道接收完毕后，是否可能让消费者返回校验和字符串，或者必须使用字符串流来返回值？对于前者，我遇到了死锁问题，但我没有使用任何waitgroup；不确定如何在这种情况下应用它们。

我很感谢您的意见，谢谢您的帮助。

  1. // main()
  2. var done = make(chan bool)
  3. defer close(done)
  4. checksum := FileCheckSum(ReadFileToChannel("mydata4.bin", done), done)
  5. fmt.Println("Final Checksum: ", checksum)
  1. // FileCheckSum()
  2. import (
  3. 	"crypto/sha256"
  4. 	"encoding/hex"
  5. 	"log"
  6. )
  8. func FileCheckSum(cin <-chan []byte, done <-chan bool) string {
  10. 	chunkStream := make(chan []byte)
  11. 	checksum := func(in <-chan []byte, done <-chan bool) string {
  12. 		defer close(chunkStream)
  14. 		hasher := sha256.New()
  16. 		for chunk := range in {
  17. 			_, err := hasher.Write(chunk[:len(chunk)])
  19. 			if err != nil {
  20. 				log.Fatal(err)
  21. 			}
  23. 			select {
  24. 			case <-done:
  25. 				return ""
  26. 			}
  27. 		}
  29. 		return hex.EncodeToString(hasher.Sum(nil))
  30. 	}(cin, done)
  31. 	return checksum
  32. }
英文:

I have a goroutine that reads a file in chunks and passes them through a channel to another goroutine that calculates a checksum for the file. The consuming goroutine is kind of a sink for the channel.

Is it possible to have the consumer return the checksum string after all of the bytes have been received from the channel, or must I use a string stream to return the value? For the former, I get a deadlock, but I am not using any waitgroups; Not sure how to apply them in this case.

I'd appreciate your comments and thank you for your help.

  1. // main()
  2. 	var done = make(chan bool)
  3. 	defer close(done)
  4. 	checksum := FileCheckSum(ReadFileToChannel(&quot;mydata4.bin&quot;, done), done)
  5. 	fmt.Println(&quot;Final Checksum: &quot;, checksum)
  1. // FileCheckSum()
  2. import (
  3. 	&quot;crypto/sha256&quot;
  4. 	&quot;encoding/hex&quot;
  5. 	&quot;log&quot;
  6. )
  8. func FileCheckSum(cin &lt;-chan []byte, done &lt;-chan bool) string {
  10. 	chunkStream := make(chan []byte)
  11. 	checksum := func(in &lt;-chan []byte, done &lt;-chan bool) string {
  12. 		defer close(chunkStream)
  13. 		
  14. 		hasher := sha256.New()
  16. 		for chunk := range in {
  17. 			_, err := hasher.Write(chunk[:len(chunk)])
  19. 			if err != nil {
  20. 				log.Fatal(err)
  21. 			}
  23. 			select {
  24. 			case &lt;-done:
  25. 				return &quot;&quot;
  26. 			}
  27. 		}
  29. 		return hex.EncodeToString(hasher.Sum(nil))
  30. 	}(cin, done)
  31. 	return checksum
  32. }

答案1

得分: 1

是的，让我简化你的代码，并阅读以下代码中的注释。请尝试这个链接：

  1. package main
  3. import (
  4. 	"crypto/rand"
  5. 	"crypto/sha256"
  6. 	"encoding/hex"
  7. 	"fmt"
  8. 	"log"
  9. )
  11. func FileCheckSum(cin <-chan []byte) string {
  12. 	h := sha256.New()
  14. 	for buf := range cin {
  15. 		_, err := h.Write(buf)
  16. 		if err != nil {
  17. 			log.Fatal(err)
  18. 		}
  19. 	}
  21. 	return hex.EncodeToString(h.Sum(nil))
  22. }
  24. func ReadFileToChannel(filename string) chan []byte {
  25. 	gen := make(chan []byte)
  26. 	go func() { // goroutine
  27. 		defer close(gen)          // signal end of reading file
  28. 		for i := 0; i < 10; i++ { // e.g. read from file
  29. 			b := make([]byte, 16)  // make new slice every time
  30. 			_, err := rand.Read(b) // fill it
  31. 			if err != nil {
  32. 				log.Fatal(err)
  33. 			}
  34. 			gen <- b // send it
  35. 		}
  36. 	}()
  37. 	return gen
  38. }
  40. func main() {
  41. 	ch := ReadFileToChannel("mydata4.bin")
  42. 	crc := FileCheckSum(ch)
  43. 	fmt.Println("Final Checksum: ", crc)
  44. }

输出结果：

  1. Final Checksum: 1e0ad2ec11bfe77833af670c6de296f530c2217d18aa1b8e600feddf6998fb95

注意：
你的代码需要进行代码审查，你可以前往这里进行代码审查。

英文:

Yes, and let me simplify your code - and read comments inside the following code.
Try this:

  1. package main
  3. import (
  4. 	&quot;crypto/rand&quot;
  5. 	&quot;crypto/sha256&quot;
  6. 	&quot;encoding/hex&quot;
  7. 	&quot;fmt&quot;
  8. 	&quot;log&quot;
  9. )
  11. func FileCheckSum(cin &lt;-chan []byte) string {
  12. 	h := sha256.New()
  14. 	for buf := range cin {
  15. 		_, err := h.Write(buf)
  16. 		if err != nil {
  17. 			log.Fatal(err)
  18. 		}
  19. 	}
  21. 	return hex.EncodeToString(h.Sum(nil))
  22. }
  24. func ReadFileToChannel(filename string) chan []byte {
  25. 	gen := make(chan []byte)
  26. 	go func() { // goroutine
  27. 		defer close(gen)          // signal end of reading file
  28. 		for i := 0; i &lt; 10; i++ { // e.g. read from file
  29. 			b := make([]byte, 16)  // make new slice every time
  30. 			_, err := rand.Read(b) // fill it
  31. 			if err != nil {
  32. 				log.Fatal(err)
  33. 			}
  34. 			gen &lt;- b // send it
  35. 		}
  36. 	}()
  37. 	return gen
  38. }
  40. func main() {
  41. 	ch := ReadFileToChannel(&quot;mydata4.bin&quot;)
  42. 	crc := FileCheckSum(ch)
  43. 	fmt.Println(&quot;Final Checksum: &quot;, crc)
  44. }

Output:

  1. Final Checksum:  1e0ad2ec11bfe77833af670c6de296f530c2217d18aa1b8e600feddf6998fb95

Note

Your code needs a code review, you may head over here for the code review.

huangapple
  • 本文由 发表于 2022年1月29日 13:28:42
  • 转载请务必保留本文链接：https://go.coder-hub.com/70902556.html
  • concurrency
  • go
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