// go run v4.go -- $PWD
// GORACE="log_path=/tmp/v4.race_log" go run -race v4.go -- /usr/bin
// http://golang.org/doc/articles/race_detector.html
package main

import (
	"bufio"
	"flag"
	"fmt"
	"os"
	"path/filepath"
	"sync"
)

// START global OMIT
var (
	globalLineCount int
	wg              sync.WaitGroup // HLwg
)

// END global OMIT

func lineCount(path string) (int, error) {
	f, err := os.Open(path)
	if err != nil {
		return 0, err
	}
	defer f.Close()
	r := bufio.NewReader(f)
	var lc int
	for err == nil {
		_, err = r.ReadString('\n')
		if err == nil {
			lc++
		}
	}
	return lc, nil
}

func visit(path string, fi os.FileInfo, err error) error {
	if err != nil {
		return err
	}
	if !fi.Mode().IsRegular() {
		return nil
	}
	// START visit OMIT
	wg.Add(1) // HLwg
	go func() {
		lc, err := lineCount(path)
		if err != nil {
			fmt.Errorf("%s", err)
		}
		globalLineCount += lc // HL50
		fmt.Printf("%d\t%s\n", lc, path)
		wg.Done() // HLwg
	}()
	// END visit OMIT
	return nil
}

func main() {
	flag.Parse()
	root := flag.Arg(0)
	err := filepath.Walk(root, visit)
	if err != nil {
		fmt.Errorf("%s", err)
		os.Exit(1)
	}
	// START main OMIT
	wg.Wait() // HLwg
	fmt.Printf("%d\ttotal\n", globalLineCount)
	// END main OMIT
}