def METHOD_NAME(self):
    # we keep track of dirty reports so we just have to update the tree
    # instead of reconstructing it
    reports = []
    for c in self._mgr.getFirstClassCaches():
        r = MemInfoNode()
        c.generateReport(r)
        reports.append(r)
    self._root.handleChildrenReports(reports, root=self.tree.invisibleRootItem())