@NotNull
 private Set<VirtualFile> pollFilesToResolve() {
   Set<VirtualFile> set;
   synchronized (filesToResolve) {
     int queuedSize = filesToResolve.size();
     set = new LinkedHashSet<VirtualFile>(queuedSize);
     // someone might have cleared this bit to mark file as processed
     for (VirtualFile file : filesToResolve) {
       if (fileIsInQueue.clear(getAbsId(file))) {
         set.add(file);
       }
     }
     filesToResolve.clear();
   }
   return countAndMarkUnresolved(set, false);
 }
 @Override
 public int getQueueSize() {
   synchronized (filesToResolve) {
     return filesToResolve.size();
   }
 }