@Override
    public void truncate() {
        truncateToEntries(0);
    }
@Test
    public void testTruncate() {
        appendEntries(maxEntries - 1);
        idx.truncate();
        assertEquals(0, idx.entries());

        appendEntries(maxEntries - 1);
        idx.truncateTo(10 + baseOffset);
        assertEquals(0, idx.entries());
    }