Int2IntMap () { final Int2IntMap histo = new Int2IntOpenHashMap(); for (int i = 0; i < pages.length(); i++) { final PageImpl page = pages.get(i); if (page != null) { final int probingLength = probingSequenceLengthFor(pages, page.pageIndex()); histo.mergeInt(probingLength, 1, Integer::sum); } } return histo; }