| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you under the Apache License, Version 2.0 (the |
| * "License"); you may not use this file except in compliance |
| * with the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| package org.apache.hadoop.util; |
| |
| import org.apache.hadoop.classification.InterfaceAudience; |
| import org.apache.hadoop.classification.InterfaceStability; |
| |
| /** |
| * An implementation of the core algorithm of HeapSort. |
| */ |
| @InterfaceAudience.Private |
| @InterfaceStability.Unstable |
| public final class HeapSort implements IndexedSorter { |
| |
| public HeapSort() { } |
| |
| private static void downHeap(final IndexedSortable s, final int b, |
| int i, final int N) { |
| for (int idx = i << 1; idx < N; idx = i << 1) { |
| if (idx + 1 < N && s.compare(b + idx, b + idx + 1) < 0) { |
| if (s.compare(b + i, b + idx + 1) < 0) { |
| s.swap(b + i, b + idx + 1); |
| } else return; |
| i = idx + 1; |
| } else if (s.compare(b + i, b + idx) < 0) { |
| s.swap(b + i, b + idx); |
| i = idx; |
| } else return; |
| } |
| } |
| |
| /** |
| * Sort the given range of items using heap sort. |
| * {@inheritDoc} |
| */ |
| @Override |
| public void sort(IndexedSortable s, int p, int r) { |
| sort(s, p, r, null); |
| } |
| |
| @Override |
| public void sort(final IndexedSortable s, final int p, final int r, |
| final Progressable rep) { |
| final int N = r - p; |
| // build heap w/ reverse comparator, then write in-place from end |
| final int t = Integer.highestOneBit(N); |
| for (int i = t; i > 1; i >>>= 1) { |
| for (int j = i >>> 1; j < i; ++j) { |
| downHeap(s, p-1, j, N + 1); |
| } |
| if (null != rep) { |
| rep.progress(); |
| } |
| } |
| for (int i = r - 1; i > p; --i) { |
| s.swap(p, i); |
| downHeap(s, p - 1, 1, i - p + 1); |
| } |
| } |
| } |