}
SorterTemplate sorter = new DocValueSorterTemplate(docs, comparator);
// It can be common to sort a reader, add docs, sort it again, ... and in
// that case timSort can save a lot of time
sorter.timSort(0, docs.length - 1); // docs is now the newToOld mapping
// The reason why we use MonotonicAppendingLongBuffer here is that it
// wastes very little memory if the index is in random order but can save
// a lot of memory if the index is already "almost" sorted
final MonotonicAppendingLongBuffer newToOld = new MonotonicAppendingLongBuffer();