make progress output optional

cmd/cachectl/main.go

@@ -19,7 +19,7 @@ import (
 )
 
 var (
-	version string
+	progress bool
 )
 
 const gib = 1024 * 1024 * 1024
@@ -72,9 +72,13 @@ remove file (uses `+srcKey+`):
 
   rm file:///mnt/nfs /buzz.txt
 
+options
+  -p  show copy progress
+
 `)
 		os.Exit(1)
 	}
+	flag.BoolVar(&progress, "p", false, "show copy progress")
 	flag.Parse()
 
 	args := flag.Args()
@@ -180,18 +184,24 @@ func cp(args []string) (err error) {
 		return
 	}
 	defer df.Close()
+	if progress {
 		fi, err := sf.Stat()
 		if err != nil {
-		return
+			return err
 		}
 		r := &progressReader{
 			f:    sf,
 			done: make(chan struct{}),
 			size: fi.Size(),
 		}
-	go r.PrintProgress()
+		go r.Progress()
 		_, err = io.Copy(df, r)
 		close(r.done)
+		r.Print()
+		fmt.Println()
+	} else {
+		_, err = io.Copy(df, sf)
+	}
 	return
 }
 
@@ -214,19 +224,21 @@ func (p *progressReader) ReadAt(b []byte, off int64) (n int, err error) {
 	return
 }
 
-func (p *progressReader) PrintProgress() {
+func (p *progressReader) Print() {
-	for {
-		select {
-		case <-p.done:
-			fmt.Println()
-			return
-		case <-time.After(time.Millisecond * 500):
-		}
 	n := atomic.LoadInt64(&p.n)
 	percent := int(math.Round(float64(n) / float64(p.size) * 100))
 	fmt.Printf("progress: %d / %d %d%%\r", n, p.size, percent)
 }
+
+func (p *progressReader) Progress() {
+	for {
+		select {
+		case <-p.done:
 			return
+		case <-time.After(time.Millisecond * 500):
+		}
+		p.Print()
+	}
 }
 
 func rm(args []string) (err error) {