Data inconsistency introduced in 3.0.7 due to performance fix

[byte0ne]

Hi there,
The change introduced in commit b2acf69b51cec80393f13e8f280c83cc181e0bb9 may lead to a IndexOutOfBoundsException when the grid is for example used as an assignment component where items get added/removed between different grids.
This happens above all when the cell is double-clicked/clicked multiple times or is part of a TestBench test.

The IndexOutOfBoundsException happens at com.vaadin.componentfactory.selectiongrid.SelectionGrid#obtainNewSelectedItems:
newSelectedItems.add(dataCommunicator.getItem(i));

[TatuLund]

Do you have example code that reproduces this problem. It would significantly help to debug and fix.

[byte0ne]

Sure, here's an example based on the SimpleView from the demo:

public class SimpleView extends HorizontalLayout {
    private List<Person> dataProviderLeft;
    private Grid<Person> gridLeft;
    private List<Person> dataProviderRight;
    private Grid<Person> gridRight;

    private final Runnable assign = () -> {
        final Set<Person> selectedItems = gridLeft.getSelectedItems();

        dataProviderRight.addAll(selectedItems);
        dataProviderLeft.removeAll(selectedItems);

        gridRight.asMultiSelect().setValue(selectedItems);
        gridLeft.deselectAll();

        gridLeft.getDataProvider().refreshAll();
        gridRight.getDataProvider().refreshAll();
    };

    public SimpleView() {
        final Button assignButton = new Button(">>");
        assignButton.addClickListener(buttonClickEvent -> assign.run());

        dataProviderLeft = getItems();
        gridLeft = new SelectionGrid<>();
        gridLeft.setItems(dataProviderLeft);
        gridLeft.addColumn(Person::getFirstName).setHeader("First Name");
        gridLeft.addColumn(Person::getAge).setHeader("Age");
        gridLeft.setSelectionMode(Grid.SelectionMode.MULTI);

        dataProviderRight = new ArrayList<>();
        gridRight = new SelectionGrid<>();
        gridRight.setItems(dataProviderRight);
        gridRight.addColumn(Person::getFirstName).setHeader("First Name");
        gridRight.addColumn(Person::getAge).setHeader("Age");
        gridRight.setSelectionMode(Grid.SelectionMode.MULTI);

        gridLeft.addItemClickListener(event -> {
            if (event.getClickCount() == 2) {
                assign.run();
            }
        });

        add(gridLeft, gridRight, assignButton);
    }

    private List<Person> getItems() {
        PersonService personService = new PersonService();
        return personService.fetch(1, 2); // fetch only a small set of persons
    }
}

Note: there two possibilities to make an assignment (from the left grid to the right grid) – whereas the option via ">>"-button works, but the "doubleclick-assignement" not.