need to lock the mutex state around adding

progressbar.go

@@ -248,20 +248,20 @@ func (p *ProgressBar) Finish() error {
 	return p.Add(0)
 }
 
-// Add with increase the current count on the progress bar
-func (p *ProgressBar) Set(num int) error {
-	return p.Set64(int64(num))
+// Add will add the specified amount to the progressbar
+func (p *ProgressBar) Add(num int) error {
+	return p.Add64(int64(num))
 }
 
-// Add with increase the current count on the progress bar
-func (p *ProgressBar) Set64(num int64) error {
+// Add64 will add the specified amount to the progressbar
+func (p *ProgressBar) Add64(num int64) error {
 	p.lock.Lock()
 	defer p.lock.Unlock()
 
 	if p.config.max == 0 {
 		return errors.New("max must be greater than 0")
 	}
-	p.state.currentNum = num
+	p.state.currentNum += num
 	percent := float64(p.state.currentNum) / float64(p.config.max)
 	p.state.currentSaucerSize = int(percent * float64(p.config.width))
 	p.state.currentPercent = int(percent * 100)
@@ -281,16 +281,6 @@ func (p *ProgressBar) Set64(num int64) error {
 	return nil
 }
 
-// Add will add the specified amount to the progressbar
-func (p *ProgressBar) Add(num int) error {
-	return p.Add64(int64(num))
-}
-
-// Add64 will add the specified amount to the progressbar
-func (p *ProgressBar) Add64(num int64) error {
-	return p.Set64(p.state.currentNum + num)
-}
-
 // Clear erases the progress bar from the current line
 func (p *ProgressBar) Clear() error {
 	return clearProgressBar(p.config, p.state)
@@ -468,7 +458,6 @@ type Reader struct {
 	bar *ProgressBar
 }
 
-
 // Read will read the data and add the number of bytes to the progressbar
 func (r *Reader) Read(p []byte) (n int, err error) {
 	n, err = r.Reader.Read(p)

progressbar_test.go

@@ -11,6 +11,7 @@ import (
 	"net/http"
 	"os"
 	"strings"
+	"sync"
 	"testing"
 	"time"
 
@@ -209,6 +210,26 @@ func TestReaderToFile(t *testing.T) {
 	assert.Nil(t, os.Remove("croc_v4.1.4_Windows-64bit_GUI.zip"))
 }
 
+func TestConcurrency(t *testing.T) {
+	buf := strings.Builder{}
+	bar := NewOptions(
+		1000,
+		OptionSetWriter(&buf),
+	)
+	var wg sync.WaitGroup
+	for i := 0; i < 900; i++ {
+		wg.Add(1)
+		go func(b *ProgressBar, wg *sync.WaitGroup) {
+			bar.Add(1)
+			wg.Done()
+		}(bar, &wg)
+	}
+	wg.Wait()
+	result := bar.state.currentNum
+	expect := int64(900)
+	assert.Equal(t, expect, result)
+}
+
 func md5sum(filePath string) (result string, err error) {
 	file, err := os.Open(filePath)
 	if err != nil {