refactoring SHA directory, goroutines pool

shadirconcurrent/main.go

@@ -8,63 +8,55 @@ import "os"
 import "path/filepath"
 import "sync"
 
-var chan_hash chan string
+func sha256File(path string) (string, error) {
-var wg sync.WaitGroup
-
-func walk(path string, info os.FileInfo, err error) error {
-	if err != nil {
-		log.Fatalln(err)
-		return err
-	}
-
-	if info.IsDir() {
-		return nil
-	} else {
-		wg.Add(1)
-		go hash(info.Name(), path)
-	}
-	return nil
-}
-
-func hash(name string, path string) {
-	h, err := sha256File(path)
-	if err != nil {
-		log.Fatalln(err)
-	}
-	chan_hash <- fmt.Sprintf("SHA256 (%s) =  %x", name, h)
-}
-
-func sha256File(path string) ([]byte, error) {
 	f, err := os.Open(path)
 	if err != nil {
-		log.Fatalln(err)
+		return "", err
-		return nil, err
 	}
 	defer f.Close()
 	h := sha256.New()
 	io.Copy(h, f)
-	return h.Sum(nil), nil
+	return fmt.Sprintf("SHA256 (%s) =  %x", path, h.Sum(nil)), nil
-}
-
-func printer() {
-	for {
-		select {
-		case str := <-chan_hash:
-			fmt.Println(str)
-			wg.Done()
-		}
-	}
 }
 
 func main() {
 	if len(os.Args) < 2 {
 		log.Fatalln("Usage shadir file")
 	}
-	chan_hash = make(chan string)
 
-	go printer()
+	var wg sync.WaitGroup
-	if err := filepath.Walk(os.Args[1], walk); err != nil {
+	chan_hash, chan_path := make(chan string), make(chan string)
-		panic(err)
+
+	for i := 0; i < 100; i++ {
+		go func() {
+			for {
+				path := <-chan_path
+				if h, err := sha256File(path); err != nil {
+					wg.Done()
+					log.Print("Error "+path, err)
+				} else {
+					chan_hash <- h
+				}
+			}
+		}()
+	}
+
+	go func() {
+		for {
+			fmt.Println(<-chan_hash)
+			wg.Done()
+		}
+	}()
+
+	err := filepath.Walk(os.Args[1], func(path string, info os.FileInfo, err error) error {
+		if err != nil && !info.IsDir() {
+			wg.Add(1)
+			chan_path <- path
+		}
+		return err
+	})
+	if err != nil {
+		log.Fatalln(err)
 	}
 	wg.Wait()
 }