| /* |
| * 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.lucene.util; |
| |
| |
| import java.util.LinkedList; |
| import java.util.List; |
| |
| import org.apache.lucene.util.LuceneTestCase.Nightly; |
| import org.apache.lucene.util.packed.PackedInts; |
| |
| import com.carrotsearch.randomizedtesting.generators.RandomNumbers; |
| |
| @Nightly |
| public class TestTimSorterWorstCase extends LuceneTestCase { |
| |
| public void testWorstCaseStackSize() { |
| // we need large arrays to be able to reproduce this bug |
| // but not so big we blow up available heap. |
| final int length; |
| if (TEST_NIGHTLY) { |
| length = RandomNumbers.randomIntBetween(random(), 140000000, 400000000); |
| } else { |
| length = RandomNumbers.randomIntBetween(random(), 140000000, 200000000); |
| } |
| final PackedInts.Mutable arr = generateWorstCaseArray(length); |
| new TimSorter(0) { |
| |
| @Override |
| protected void swap(int i, int j) { |
| final long tmp = arr.get(i); |
| arr.set(i, arr.get(j)); |
| arr.set(j, tmp); |
| } |
| |
| @Override |
| protected int compare(int i, int j) { |
| return Long.compare(arr.get(i), arr.get(j)); |
| } |
| |
| @Override |
| protected void save(int i, int len) { |
| throw new UnsupportedOperationException(); |
| } |
| |
| @Override |
| protected void restore(int i, int j) { |
| throw new UnsupportedOperationException(); |
| } |
| |
| @Override |
| protected void copy(int src, int dest) { |
| arr.set(dest, arr.get(src)); |
| } |
| |
| @Override |
| protected int compareSaved(int i, int j) { |
| throw new UnsupportedOperationException(); |
| } |
| }.sort(0, length); |
| } |
| |
| /** Create an array for the given list of runs. */ |
| private static PackedInts.Mutable createArray(int length, List<Integer> runs) { |
| PackedInts.Mutable array = PackedInts.getMutable(length, 1, 0); |
| int endRun = -1; |
| for (long len : runs) { |
| array.set(endRun += len, 1); |
| } |
| array.set(length - 1, 0); |
| return array; |
| } |
| |
| /** Create an array that triggers a worst-case sequence of run lens. */ |
| public static PackedInts.Mutable generateWorstCaseArray(int length) { |
| final int minRun = TimSorter.minRun(length); |
| final List<Integer> runs = runsWorstCase(length, minRun); |
| return createArray(length, runs); |
| } |
| |
| // |
| // Code below is borrowed from https://github.com/abstools/java-timsort-bug/blob/master/TestTimSort.java |
| // |
| |
| /** |
| * Fills <code>runs</code> with a sequence of run lengths of the form<br> |
| * Y_n x_{n,1} x_{n,2} ... x_{n,l_n} <br> |
| * Y_{n-1} x_{n-1,1} x_{n-1,2} ... x_{n-1,l_{n-1}} <br> |
| * ... <br> |
| * Y_1 x_{1,1} x_{1,2} ... x_{1,l_1}<br> |
| * The Y_i's are chosen to satisfy the invariant throughout execution, |
| * but the x_{i,j}'s are merged (by <code>TimSort.mergeCollapse</code>) |
| * into an X_i that violates the invariant. |
| */ |
| private static List<Integer> runsWorstCase(int length, int minRun) { |
| List<Integer> runs = new LinkedList<>(); |
| |
| int runningTotal = 0, Y=minRun+4, X=minRun; |
| |
| while((long) runningTotal+Y+X <= length) { |
| runningTotal += X + Y; |
| generateWrongElem(X, minRun, runs); |
| runs.add(0,Y); |
| |
| // X_{i+1} = Y_i + x_{i,1} + 1, since runs.get(1) = x_{i,1} |
| X = Y + runs.get(1) + 1; |
| |
| // Y_{i+1} = X_{i+1} + Y_i + 1 |
| Y += X + 1; |
| } |
| |
| if((long) runningTotal + X <= length) { |
| runningTotal += X; |
| generateWrongElem(X, minRun, runs); |
| } |
| |
| runs.add(length-runningTotal); |
| return runs; |
| } |
| |
| /** |
| * Adds a sequence x_1, ..., x_n of run lengths to <code>runs</code> such that:<br> |
| * 1. X = x_1 + ... + x_n <br> |
| * 2. x_j >= minRun for all j <br> |
| * 3. x_1 + ... + x_{j-2} < x_j < x_1 + ... + x_{j-1} for all j <br> |
| * These conditions guarantee that TimSort merges all x_j's one by one |
| * (resulting in X) using only merges on the second-to-last element. |
| * @param X The sum of the sequence that should be added to runs. |
| */ |
| private static void generateWrongElem(int X, int minRun, List<Integer> runs) { |
| for(int newTotal; X >= 2*minRun+1; X = newTotal) { |
| //Default strategy |
| newTotal = X/2 + 1; |
| |
| //Specialized strategies |
| if(3*minRun+3 <= X && X <= 4*minRun+1) { |
| // add x_1=MIN+1, x_2=MIN, x_3=X-newTotal to runs |
| newTotal = 2*minRun+1; |
| } else if(5*minRun+5 <= X && X <= 6*minRun+5) { |
| // add x_1=MIN+1, x_2=MIN, x_3=MIN+2, x_4=X-newTotal to runs |
| newTotal = 3*minRun+3; |
| } else if(8*minRun+9 <= X && X <= 10*minRun+9) { |
| // add x_1=MIN+1, x_2=MIN, x_3=MIN+2, x_4=2MIN+2, x_5=X-newTotal to runs |
| newTotal = 5*minRun+5; |
| } else if(13*minRun+15 <= X && X <= 16*minRun+17) { |
| // add x_1=MIN+1, x_2=MIN, x_3=MIN+2, x_4=2MIN+2, x_5=3MIN+4, x_6=X-newTotal to runs |
| newTotal = 8*minRun+9; |
| } |
| runs.add(0, X-newTotal); |
| } |
| runs.add(0, X); |
| } |
| |
| } |