[#1] mclock: Fix time based scheduling

Signed-off-by: Dmitrii Stepanov <d.stepanov@yadro.com>

scheduling/mclock_test.go

@@ -79,14 +79,17 @@ func TestMClockSharesScheduling(t *testing.T) {
 var _ clock = &noopClock{}
 
 type noopClock struct {
-	v float64
+	v          float64
+	runAtValue *float64
 }
 
 func (n *noopClock) now() float64 {
 	return n.v
 }
 
-func (n *noopClock) runAt(ts float64, f func()) {}
+func (n *noopClock) runAt(ts float64, f func()) {
+	n.runAtValue = &ts
+}
 
 func (n *noopClock) close() {}
 
@@ -457,3 +460,36 @@ func (q *MClock) waitingCount() int {
 
 	return q.sharesQueue.Len()
 }
+
+func TestMClockTimeBasedSchedule(t *testing.T) {
+	t.Parallel()
+	limit := 1.0 // 1 request per second allowed
+	cl := &noopClock{v: float64(1.5)}
+	q, err := NewMClock(100, math.MaxUint64, map[string]TagInfo{
+		"class1": {Shares: 1, Limit: &limit},
+	}, 100)
+	require.NoError(t, err)
+	defer q.Close()
+	q.clock = cl
+
+	running := make(chan struct{})
+	checked := make(chan struct{})
+	eg, ctx := errgroup.WithContext(context.Background())
+	eg.Go(func() error {
+		release, err := q.RequestArrival(ctx, "class1")
+		require.NoError(t, err)
+		defer release()
+		close(running)
+		<-checked
+		return nil
+	})
+
+	<-running
+	// request must be scheduled at 2.0
+	_, _, err = q.pushRequest("class1")
+	require.NoError(t, err)
+	require.NotNil(t, cl.runAtValue)
+	require.Equal(t, cl.v+1.0/limit, *cl.runAtValue)
+	close(checked)
+	require.NoError(t, eg.Wait())
+}