BoundedFrequencyRunner: fix tests

The tests were using a fake timer that only ticked when the test cases
told it to, so it would only be correctly testing the
BoundedFrequencyRunner functionality if the test cases made it tick
whenever the BFR timer was supposed to expire, and didn't make it tick
at any other time. But they didn't do that. Fix it to tick
automatically at the correct times, and update the test cases
accordingly (including adding a new helper method for asserting that
the runner did nothing in cases when it's expected to have done
nothing).

Also fix two unrelated minor bugs in fakeTimer.

pkg/util/async/bounded_frequency_runner_test.go

@@ -54,6 +54,7 @@ type fakeTimer struct {
 
 	lock    sync.Mutex
 	now     time.Time
+	timeout time.Time
 	active  bool
 
 	updated chan timerUpdate
@@ -61,7 +62,7 @@ type fakeTimer struct {
 
 func newFakeTimer() *fakeTimer {
 	ft := &fakeTimer{
-		now:     time.Date(2000, 0, 0, 0, 0, 0, 0, time.UTC),
+		now:     time.Date(2000, 1, 1, 0, 0, 0, 0, time.UTC),
 		c:       make(chan time.Time),
 		updated: make(chan timerUpdate),
 	}
@@ -78,6 +79,7 @@ func (ft *fakeTimer) Reset(in time.Duration) bool {
 
 	was := ft.active
 	ft.active = true
+	ft.timeout = ft.now.Add(in)
 	ft.updated <- timerUpdate{
 		active: true,
 		next:   in,
@@ -112,9 +114,7 @@ func (ft *fakeTimer) Since(t time.Time) time.Duration {
 }
 
 func (ft *fakeTimer) Sleep(d time.Duration) {
-	ft.lock.Lock()
-	defer ft.lock.Unlock()
-
+	// ft.advance grabs ft.lock
 	ft.advance(d)
 }
 
@@ -124,15 +124,10 @@ func (ft *fakeTimer) advance(d time.Duration) {
 	defer ft.lock.Unlock()
 
 	ft.now = ft.now.Add(d)
-}
-
-// send a timer tick.
-func (ft *fakeTimer) tick() {
-	ft.lock.Lock()
-	defer ft.lock.Unlock()
-
+	if ft.active && !ft.now.Before(ft.timeout) {
 		ft.active = false
-	ft.c <- ft.now
+		ft.c <- ft.timeout
+	}
 }
 
 // return the calling line number (for printing)
@@ -177,6 +172,17 @@ func waitForDefer(name string, t *testing.T, timer *fakeTimer, obj *receiver, ex
 	waitForReset(name, t, timer, obj, false, expectNext)
 }
 
+func waitForNothing(name string, t *testing.T, timer *fakeTimer, obj *receiver) {
+	select {
+	case <-timer.c:
+		t.Fatalf("%s: unexpected timer tick", name)
+	case upd := <-timer.updated:
+		t.Fatalf("%s: unexpected timer update %v", name, upd)
+	default:
+	}
+	checkReceiver(name, t, obj, false)
+}
+
 func Test_BoundedFrequencyRunnerNoBurst(t *testing.T) {
 	obj := &receiver{}
 	timer := newFakeTimer()
@@ -206,13 +212,11 @@ func Test_BoundedFrequencyRunnerNoBurst(t *testing.T) {
 	runner.Run()
 	waitForDefer("still too soon after first", t, timer, obj, 1*time.Millisecond)
 
-	// Run again, once minInterval has passed (race with timer).
+	// Do the deferred run
 	timer.advance(1 * time.Millisecond) // rel=1000ms
-	runner.Run()
 	waitForRun("second run", t, timer, obj)
 
-	// Run again, before minInterval expires.
-	// rel=0ms
+	// Try again immediately
 	runner.Run()
 	waitForDefer("too soon after second", t, timer, obj, 1*time.Second)
 
@@ -221,30 +225,30 @@ func Test_BoundedFrequencyRunnerNoBurst(t *testing.T) {
 	runner.Run()
 	waitForDefer("still too soon after second", t, timer, obj, 999*time.Millisecond)
 
-	// Let the timer tick prematurely.
+	// Ensure that we don't run again early
 	timer.advance(998 * time.Millisecond) // rel=999ms
-	timer.tick()
-	waitForDefer("premature tick", t, timer, obj, 1*time.Millisecond)
+	waitForNothing("premature", t, timer, obj)
 
-	// Let the timer tick.
+	// Do the deferred run
 	timer.advance(1 * time.Millisecond) // rel=1000ms
-	timer.tick()
-	waitForRun("first tick", t, timer, obj)
+	waitForRun("third run", t, timer, obj)
 
-	// Let the timer tick.
-	timer.advance(10 * time.Second) // rel=10000ms
-	timer.tick()
-	waitForRun("second tick", t, timer, obj)
+	// Let minInterval pass, but there are no runs queued
+	timer.advance(1 * time.Second) // rel=1000ms
+	waitForNothing("minInterval", t, timer, obj)
+
+	// Let maxInterval pass
+	timer.advance(9 * time.Second) // rel=10000ms
+	waitForRun("maxInterval", t, timer, obj)
 
 	// Run again, before minInterval expires.
 	timer.advance(1 * time.Millisecond) // rel=1ms
 	runner.Run()
-	waitForDefer("too soon after tick", t, timer, obj, 999*time.Millisecond)
+	waitForDefer("too soon after maxInterval run", t, timer, obj, 999*time.Millisecond)
 
-	// Let the timer tick.
+	// Let minInterval pass
 	timer.advance(999 * time.Millisecond) // rel=1000ms
-	timer.tick()
-	waitForRun("third tick", t, timer, obj)
+	waitForRun("fourth run", t, timer, obj)
 
 	// Clean up.
 	stop <- struct{}{}
@@ -289,8 +293,10 @@ func Test_BoundedFrequencyRunnerBurst(t *testing.T) {
 	runner.Run()
 	waitForDefer("too soon after second 3", t, timer, obj, 500*time.Millisecond)
 
-	// Run again, once burst has replenished.
+	// Advance timer enough to replenish bursts, but not enough to be minInterval
+	// after the last run
 	timer.advance(499 * time.Millisecond) // abs=1000ms, rel=999ms
+	waitForNothing("not minInterval", t, timer, obj)
 	runner.Run()
 	waitForRun("third run", t, timer, obj)
 
@@ -304,9 +310,8 @@ func Test_BoundedFrequencyRunnerBurst(t *testing.T) {
 	runner.Run()
 	waitForDefer("too soon after third 2", t, timer, obj, 1*time.Millisecond)
 
-	// Run again, once burst has replenished.
+	// Advance and do the deferred run
 	timer.advance(1 * time.Millisecond) // abs=2000ms, rel=1000ms
-	runner.Run()
 	waitForRun("fourth run", t, timer, obj)
 
 	// Run again, once burst has fully replenished.
@@ -318,15 +323,13 @@ func Test_BoundedFrequencyRunnerBurst(t *testing.T) {
 	runner.Run()
 	waitForDefer("too soon after sixth", t, timer, obj, 1*time.Second)
 
-	// Let the timer tick.
+	// Wait until minInterval after the last run
 	timer.advance(1 * time.Second) // abs=5000ms, rel=1000ms
-	timer.tick()
-	waitForRun("first tick", t, timer, obj)
+	waitForRun("seventh run", t, timer, obj)
 
-	// Let the timer tick.
+	// Wait for maxInterval
 	timer.advance(10 * time.Second) // abs=15000ms, rel=10000ms
-	timer.tick()
-	waitForRun("second tick", t, timer, obj)
+	waitForRun("maxInterval", t, timer, obj)
 
 	// Clean up.
 	stop <- struct{}{}