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widgets/spinner: fix Spinner.frame race

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It's accessed by the goroutine which increments it and the goroutine that draws
the widget at the same time. Use atomic instead.

    Write at 0x00c00000ebc0 by goroutine 7:
      git.sr.ht/~sircmpwn/aerc2/widgets.(*Spinner).Start.func1()
          /home/simon/src/aerc2/widgets/spinner.go:50 +0x169

    Previous read at 0x00c00000ebc0 by main goroutine:
      [failed to restore the stack]

    Goroutine 7 (running) created at:
      git.sr.ht/~sircmpwn/aerc2/widgets.(*Spinner).Start()
          /home/simon/src/aerc2/widgets/spinner.go:44 +0x8b
      git.sr.ht/~sircmpwn/aerc2/widgets.NewDirectoryList()
          /home/simon/src/aerc2/widgets/dirlist.go:37 +0x286
      git.sr.ht/~sircmpwn/aerc2/widgets.NewAccountView()
          /home/simon/src/aerc2/widgets/account.go:50 +0x5ca
      git.sr.ht/~sircmpwn/aerc2/widgets.NewAerc()
          /home/simon/src/aerc2/widgets/aerc.go:60 +0x800
      main.main()
          /home/simon/src/aerc2/aerc.go:65 +0x33e
This commit is contained in:
Simon Ser 2019-04-27 15:09:59 +00:00 committed by Drew DeVault
parent e72574c308
commit 2159eb876e
1 changed files with 15 additions and 12 deletions
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27
widgets/spinner.go
View file

@ -1,6 +1,7 @@
package widgets package widgets
import ( import (
"sync/atomic"
"time" "time"
"github.com/gdamore/tcell" "github.com/gdamore/tcell"
@ -22,14 +23,14 @@ var (
) )
type Spinner struct { type Spinner struct {
frame int frame int64 // access via atomic
onInvalidate func(d ui.Drawable) onInvalidate func(d ui.Drawable)
stop chan interface{} stop chan struct{}
} }
func NewSpinner() *Spinner { func NewSpinner() *Spinner {
spinner := Spinner{ spinner := Spinner{
stop: make(chan interface{}), stop: make(chan struct{}),
frame: -1, frame: -1,
} }
return &spinner return &spinner
@ -40,17 +41,17 @@ func (s *Spinner) Start() {
return return
} }
s.frame = 0 atomic.StoreInt64(&s.frame, 0)
go func() { go func() {
for { for {
select { select {
case <-s.stop: case <-s.stop:
atomic.StoreInt64(&s.frame, -1)
s.stop <- struct{}{}
return return
case <-time.After(200 * time.Millisecond): case <-time.After(200 * time.Millisecond):
s.frame++ atomic.AddInt64(&s.frame, 1)
if s.frame >= len(frames) {
s.frame = 0
}
s.Invalidate() s.Invalidate()
} }
} }
@ -62,13 +63,13 @@ func (s *Spinner) Stop() {
return return
} }
s.stop <- nil s.stop <- struct{}{}
s.frame = -1 <-s.stop
s.Invalidate() s.Invalidate()
} }
func (s *Spinner) IsRunning() bool { func (s *Spinner) IsRunning() bool {
return s.frame != -1 return atomic.LoadInt64(&s.frame) != -1
} }
func (s *Spinner) Draw(ctx *ui.Context) { func (s *Spinner) Draw(ctx *ui.Context) {
@ -76,9 +77,11 @@ func (s *Spinner) Draw(ctx *ui.Context) {
s.Start() s.Start()
} }
cur := int(atomic.LoadInt64(&s.frame) % int64(len(frames)))
ctx.Fill(0, 0, ctx.Width(), ctx.Height(), ' ', tcell.StyleDefault) ctx.Fill(0, 0, ctx.Width(), ctx.Height(), ' ', tcell.StyleDefault)
col := ctx.Width()/2 - len(frames[0])/2 + 1 col := ctx.Width()/2 - len(frames[0])/2 + 1
ctx.Printf(col, 0, tcell.StyleDefault, "%s", frames[s.frame]) ctx.Printf(col, 0, tcell.StyleDefault, "%s", frames[cur])
} }
func (s *Spinner) OnInvalidate(onInvalidate func(d ui.Drawable)) { func (s *Spinner) OnInvalidate(onInvalidate func(d ui.Drawable)) {