finetune view waiting

blockstore/splitstore/splitstore.go

@@ -150,6 +150,7 @@ type SplitStore struct {
 	txnViewsMx      sync.Mutex
 	txnViewsCond    sync.Cond
 	txnViews        int
+	txnViewsWaiting bool
 	txnActive       bool
 	txnProtect      MarkSet
 	txnRefsMx       sync.Mutex
@@ -651,7 +652,7 @@ func (s *SplitStore) viewDone() {
 	defer s.txnViewsMx.Unlock()
 
 	s.txnViews--
-	if s.txnViews == 0 {
+	if s.txnViews == 0 && s.txnViewsWaiting {
 		s.txnViewsCond.Signal()
 	}
 }
@@ -660,9 +661,11 @@ func (s *SplitStore) viewWait() {
 	s.txnViewsMx.Lock()
 	defer s.txnViewsMx.Unlock()
 
+	s.txnViewsWaiting = true
 	for s.txnViews > 0 {
 		s.txnViewsCond.Wait()
 	}
+	s.txnViewsWaiting = false
 }
 
 // transactionally protect a reference to an object