Fix events timeout errorsv0.11.22

Resetting the timeout doesn't fully cut it, as it may timeout after we
got an event and be delivered later. This should fix it well enough for
the moment. https://github.com/golang/go/issues/11513

2 files changed, 18 insertions, 3 deletions

diff --git a/lib/events/events.go b/lib/events/events.go
index 78c1d692f..9f7c53522 100644
--- a/lib/events/events.go
+++ b/lib/events/events.go
@@ -182,12 +182,19 @@ func (s *Subscription) Poll(timeout time.Duration) (Event, error) {
 		dl.Debugln("poll", timeout)
 	}
 
-	s.timeout.Reset(timeout)
+	if !s.timeout.Reset(timeout) {
+		select {
+		case <-s.timeout.C:
+		default:
+		}
+	}
+
 	select {
 	case e, ok := <-s.events:
 		if !ok {
 			return e, ErrClosed
 		}
+		s.timeout.Stop()
 		return e, nil
 	case <-s.timeout.C:
 		return Event{}, ErrTimeout
diff --git a/lib/events/events_test.go b/lib/events/events_test.go
index 982953d94..2f91dafea 100644
--- a/lib/events/events_test.go
+++ b/lib/events/events_test.go
@@ -14,7 +14,7 @@ import (
 	"github.com/syncthing/syncthing/lib/events"
 )
 
-var timeout = 100 * time.Millisecond
+const timeout = 100 * time.Millisecond
 
 func TestNewLogger(t *testing.T) {
 	l := events.NewLogger()
@@ -26,6 +26,7 @@ func TestNewLogger(t *testing.T) {
 func TestSubscriber(t *testing.T) {
 	l := events.NewLogger()
 	s := l.Subscribe(0)
+	defer l.Unsubscribe(s)
 	if s == nil {
 		t.Fatal("Unexpected nil Subscription")
 	}
@@ -34,6 +35,7 @@ func TestSubscriber(t *testing.T) {
 func TestTimeout(t *testing.T) {
 	l := events.NewLogger()
 	s := l.Subscribe(0)
+	defer l.Unsubscribe(s)
 	_, err := s.Poll(timeout)
 	if err != events.ErrTimeout {
 		t.Fatal("Unexpected non-Timeout error:", err)
@@ -45,6 +47,7 @@ func TestEventBeforeSubscribe(t *testing.T) {
 
 	l.Log(events.DeviceConnected, "foo")
 	s := l.Subscribe(0)
+	defer l.Unsubscribe(s)
 
 	_, err := s.Poll(timeout)
 	if err != events.ErrTimeout {
@@ -56,6 +59,7 @@ func TestEventAfterSubscribe(t *testing.T) {
 	l := events.NewLogger()
 
 	s := l.Subscribe(events.AllEvents)
+	defer l.Unsubscribe(s)
 	l.Log(events.DeviceConnected, "foo")
 
 	ev, err := s.Poll(timeout)
@@ -80,6 +84,7 @@ func TestEventAfterSubscribeIgnoreMask(t *testing.T) {
 	l := events.NewLogger()
 
 	s := l.Subscribe(events.DeviceDisconnected)
+	defer l.Unsubscribe(s)
 	l.Log(events.DeviceConnected, "foo")
 
 	_, err := s.Poll(timeout)
@@ -91,7 +96,8 @@ func TestEventAfterSubscribeIgnoreMask(t *testing.T) {
 func TestBufferOverflow(t *testing.T) {
 	l := events.NewLogger()
 
-	_ = l.Subscribe(events.AllEvents)
+	s := l.Subscribe(events.AllEvents)
+	defer l.Unsubscribe(s)
 
 	t0 := time.Now()
 	for i := 0; i < events.BufferSize*2; i++ {
@@ -126,6 +132,7 @@ func TestIDs(t *testing.T) {
 	l := events.NewLogger()
 
 	s := l.Subscribe(events.AllEvents)
+	defer l.Unsubscribe(s)
 	l.Log(events.DeviceConnected, "foo")
 	l.Log(events.DeviceConnected, "bar")
 
@@ -154,6 +161,7 @@ func TestBufferedSub(t *testing.T) {
 	l := events.NewLogger()
 
 	s := l.Subscribe(events.AllEvents)
+	defer l.Unsubscribe(s)
 	bs := events.NewBufferedSubscription(s, 10*events.BufferSize)
 
 	go func() {