Revert "ae: restore previous pause/resume behavior"

This reverts commit 126046be23.

agent/ae/ae.go

@@ -77,7 +77,7 @@ type StateSyncer struct {
 
 	// paused stores whether sync runs are temporarily disabled.
 	pauseLock sync.Mutex
-	paused    int
+	paused    bool
 }
 
 func NewStateSyner(state State, intv time.Duration, shutdownCh chan struct{}, logger *log.Logger) *StateSyncer {
@@ -180,7 +180,7 @@ FullSync:
 func (s *StateSyncer) ifNotPausedRun(f func() error) error {
 	s.pauseLock.Lock()
 	defer s.pauseLock.Unlock()
-	if s.paused != 0 {
+	if s.paused {
 		return errPaused
 	}
 	return f()
@@ -189,7 +189,10 @@ func (s *StateSyncer) ifNotPausedRun(f func() error) error {
 // Pause temporarily disables sync runs.
 func (s *StateSyncer) Pause() {
 	s.pauseLock.Lock()
-	s.paused++
+	if s.paused {
+		panic("pause while paused")
+	}
+	s.paused = true
 	s.pauseLock.Unlock()
 }
 
@@ -197,18 +200,16 @@ func (s *StateSyncer) Pause() {
 func (s *StateSyncer) Paused() bool {
 	s.pauseLock.Lock()
 	defer s.pauseLock.Unlock()
-	return s.paused != 0
+	return s.paused
 }
 
 // Resume re-enables sync runs.
 func (s *StateSyncer) Resume() {
 	s.pauseLock.Lock()
-	s.paused--
-	if s.paused < 0 {
-		panic("unbalanced pause/resume")
-	}
-	if s.paused == 0 {
-		s.SyncChanges.Trigger()
+	if !s.paused {
+		panic("resume while not paused")
 	}
+	s.paused = false
 	s.pauseLock.Unlock()
+	s.SyncChanges.Trigger()
 }