Function main

ch8/du3/main.go:26–75

!+

()

//!+
func main() {
	// ...determine roots...

	//!-
	flag.Parse()

	// Determine the initial directories.
	roots := flag.Args()
	if len(roots) == 0 {
		roots = []string{"."}
	}

	//!+
	// Traverse each root of the file tree in parallel.
	fileSizes := make(chan int64)
	var n sync.WaitGroup
	for _, root := range roots {
		n.Add(1)
		go walkDir(root, &n, fileSizes)
	}
	go func() {
		n.Wait()
		close(fileSizes)
	}()
	//!-

	// Print the results periodically.
	var tick <-chan time.Time
	if *vFlag {
		tick = time.Tick(500 * time.Millisecond)
	}
	var nfiles, nbytes int64
loop:
	for {
		select {
		case size, ok := <-fileSizes:
			if !ok {
				break loop // fileSizes was closed
			}
			nfiles++
			nbytes += size
		case <-tick:
			printDiskUsage(nfiles, nbytes)
		}
	}

	printDiskUsage(nfiles, nbytes) // final totals
	//!+
	// ...select loop...
}

//!-