MergingIterator.java 文件源码

@Override
protected Generation.Entry<K, V> computeNext() {
    if (heap.isEmpty()) {
        return endOfData();
    }

    PeekingIterator<EntryAndGenerationId<K,V>> first = heap.poll();
    EntryAndGenerationId<K,V> ret = first.next();
    if (first.hasNext()) {
        temp.add(first);
    }
    while (!heap.isEmpty() && keyComparator.compare(ret.entry.getKey(), heap.peek().peek().entry.getKey()) == 0) {
        PeekingIterator<EntryAndGenerationId<K, V>> iter = heap.poll();
        iter.next();
        if (iter.hasNext()) {
            temp.add(iter);
        }
    }
    heap.addAll(temp);
    temp.clear();
    return ret.entry;
}