cache: improved queue performance and stability

app/threading/threadticket.cpp

@@ -48,6 +48,12 @@ QVariant RenderTicket::Get()
   return result_;
 }
 
+bool RenderTicket::HasStarted()
+{
+  QMutexLocker locker(&lock_);
+  return started_;
+}
+
 bool RenderTicket::IsFinished(bool lock)
 {
   if (lock) {

app/threading/threadticket.h

@@ -52,6 +52,8 @@ public:
 
   QVariant Get();
 
+  bool HasStarted();
+
   bool IsFinished(bool lock = true);
 
   bool WasCancelled();

app/threading/threadticketwatcher.cpp

@@ -70,6 +70,15 @@ bool RenderTicketWatcher::IsFinished()
   }
 }
 
+bool RenderTicketWatcher::HasStarted()
+{
+  if (ticket_) {
+    return ticket_->HasStarted();
+  } else {
+    return false;
+  }
+}
+
 void RenderTicketWatcher::WaitForFinished()
 {
   if (ticket_) {

app/threading/threadticketwatcher.h

@@ -44,6 +44,8 @@ public:
 
   bool IsFinished();
 
+  bool HasStarted();
+
   void WaitForFinished();
 
   QVariant Get();