add go implementation parallel walking the directory tree

go/fsearch-parallel-walk.go

+package main
+
+import (
+	"bufio"
+	"fmt"
+	"io"
+	"log"
+	"os"
+	"path/filepath"
+	"strings"
+	"sync"
+)
+
+var needle string
+
+var wg sync.WaitGroup
+
+func search(path string) {
+	defer wg.Done()
+
+	f, err := os.Open(path)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	defer f.Close()
+
+	r := bufio.NewReader(f)
+	b := make([]byte, 4096)
+	for {
+		n, err := r.Read(b)
+		if err != nil {
+			if err == io.EOF {
+				return
+			}
+
+			log.Fatal("Error reading file:", err)
+		}
+
+		s := string(b[0:n])
+		if strings.Contains(s, needle) {
+			fmt.Println(path)
+			return
+		}
+	}
+	return
+}
+
+func walk_dir(dir string) {
+	defer wg.Done()
+
+	var visit = func(path string, finfo os.FileInfo, err error) error {
+		if err != nil {
+			fmt.Printf("error %v at path %s\n", err, path)
+			return err
+		}
+
+		// ascent concurrently
+		if finfo.IsDir() && path != dir {
+			wg.Add(1)
+			go walk_dir(path)
+			return filepath.SkipDir
+		}
+
+		if finfo.Mode().IsRegular() {
+			wg.Add(1)
+			go search(path)
+		}
+
+		return nil
+	}
+
+	var err = filepath.Walk(dir, visit)
+
+	if err != nil {
+		log.Fatal("error walking the path %q: %v\n", dir, err)
+	}
+}
+
+func main() {
+	if len(os.Args) < 2 {
+		log.Fatalf("Usage: %q <needle>", os.Args[0])
+	}
+	needle = os.Args[1]
+
+	myDir, err := os.Getwd()
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	wg.Add(1)
+	walk_dir(myDir)
+	wg.Wait()
+}