private void calculateRoots() { final ModuleManager moduleManager = ModuleManager.getInstance(myProject); // assertion for read access inside final Module[] modules = ApplicationManager.getApplication() .runReadAction( new Computable<Module[]>() { public Module[] compute() { return moduleManager.getModules(); } }); final TreeSet<VirtualFile> checkSet = new TreeSet<VirtualFile>(FilePathComparator.getInstance()); myRoots = new HashSet<VirtualFile>(); myRoots.addAll(myInitialRoots); checkSet.addAll(myInitialRoots); for (Module module : modules) { final VirtualFile[] files = ModuleRootManager.getInstance(module).getContentRoots(); for (VirtualFile file : files) { final VirtualFile floor = checkSet.floor(file); if (floor != null) { myModulesSet.put(file, module.getName()); myRoots.add(file); } } } }