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8154049: DualPivot sorting calculates incorrect runs for nearly sorted arrays

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Reviewed-by: shade
This commit is contained in:
Paul Sandoz 2016-05-16 07:01:26 +02:00
parent c139d55758
commit 00883c0dc9
2 changed files with 253 additions and 89 deletions
jdk
src/java.base/share/classes/java/util
DualPivotQuicksort.java
test/java/util/Arrays
SortingNearlySortedPrimitive.java

146
jdk/src/java.base/share/classes/java/util/DualPivotQuicksort.java

@ -1,5 +1,5 @@
/*
* Copyright (c) 2009, 2015, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2009, 2016, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
@ -146,12 +146,26 @@ final class DualPivotQuicksort {
}
}
// Check special cases
// Implementation note: variable "right" is increased by 1.
if (run[count] == right++) { // The last run contains one element
run[++count] = right;
} else if (count <= 1) { // The array is already sorted
// These invariants should hold true:
// run[0] = 0
// run[<last>] = right + 1; (terminator)
if (count == 0) {
// A single equal run
return;
} else if (count == 1 && run[count] > right) {
// Either a single ascending or a transformed descending run.
// Always check that a final run is a proper terminator, otherwise
// we have an unterminated trailing run, to handle downstream.
return;
}
right++;
if (run[count] < right) {
// Corner case: the final run is not a terminator. This may happen
// if a final run is an equals run, or there is a single-element run
// at the end. Fix up by adding a proper terminator at the end.
// Note that we terminate with (right + 1), incremented earlier.
run[++count] = right;
}
// Determine alternation base for merge
@ -598,12 +612,26 @@ final class DualPivotQuicksort {
}
}
// Check special cases
// Implementation note: variable "right" is increased by 1.
if (run[count] == right++) { // The last run contains one element
run[++count] = right;
} else if (count <= 1) { // The array is already sorted
// These invariants should hold true:
// run[0] = 0
// run[<last>] = right + 1; (terminator)
if (count == 0) {
// A single equal run
return;
} else if (count == 1 && run[count] > right) {
// Either a single ascending or a transformed descending run.
// Always check that a final run is a proper terminator, otherwise
// we have an unterminated trailing run, to handle downstream.
return;
}
right++;
if (run[count] < right) {
// Corner case: the final run is not a terminator. This may happen
// if a final run is an equals run, or there is a single-element run
// at the end. Fix up by adding a proper terminator at the end.
// Note that we terminate with (right + 1), incremented earlier.
run[++count] = right;
}
// Determine alternation base for merge
@ -1086,12 +1114,26 @@ final class DualPivotQuicksort {
}
}
// Check special cases
// Implementation note: variable "right" is increased by 1.
if (run[count] == right++) { // The last run contains one element
run[++count] = right;
} else if (count <= 1) { // The array is already sorted
// These invariants should hold true:
// run[0] = 0
// run[<last>] = right + 1; (terminator)
if (count == 0) {
// A single equal run
return;
} else if (count == 1 && run[count] > right) {
// Either a single ascending or a transformed descending run.
// Always check that a final run is a proper terminator, otherwise
// we have an unterminated trailing run, to handle downstream.
return;
}
right++;
if (run[count] < right) {
// Corner case: the final run is not a terminator. This may happen
// if a final run is an equals run, or there is a single-element run
// at the end. Fix up by adding a proper terminator at the end.
// Note that we terminate with (right + 1), incremented earlier.
run[++count] = right;
}
// Determine alternation base for merge
@ -1574,12 +1616,26 @@ final class DualPivotQuicksort {
}
}
// Check special cases
// Implementation note: variable "right" is increased by 1.
if (run[count] == right++) { // The last run contains one element
run[++count] = right;
} else if (count <= 1) { // The array is already sorted
// These invariants should hold true:
// run[0] = 0
// run[<last>] = right + 1; (terminator)
if (count == 0) {
// A single equal run
return;
} else if (count == 1 && run[count] > right) {
// Either a single ascending or a transformed descending run.
// Always check that a final run is a proper terminator, otherwise
// we have an unterminated trailing run, to handle downstream.
return;
}
right++;
if (run[count] < right) {
// Corner case: the final run is not a terminator. This may happen
// if a final run is an equals run, or there is a single-element run
// at the end. Fix up by adding a proper terminator at the end.
// Note that we terminate with (right + 1), incremented earlier.
run[++count] = right;
}
// Determine alternation base for merge
@ -2158,12 +2214,26 @@ final class DualPivotQuicksort {
}
}
// Check special cases
// Implementation note: variable "right" is increased by 1.
if (run[count] == right++) { // The last run contains one element
run[++count] = right;
} else if (count <= 1) { // The array is already sorted
// These invariants should hold true:
// run[0] = 0
// run[<last>] = right + 1; (terminator)
if (count == 0) {
// A single equal run
return;
} else if (count == 1 && run[count] > right) {
// Either a single ascending or a transformed descending run.
// Always check that a final run is a proper terminator, otherwise
// we have an unterminated trailing run, to handle downstream.
return;
}
right++;
if (run[count] < right) {
// Corner case: the final run is not a terminator. This may happen
// if a final run is an equals run, or there is a single-element run
// at the end. Fix up by adding a proper terminator at the end.
// Note that we terminate with (right + 1), incremented earlier.
run[++count] = right;
}
// Determine alternation base for merge
@ -2701,12 +2771,26 @@ final class DualPivotQuicksort {
}
}
// Check special cases
// Implementation note: variable "right" is increased by 1.
if (run[count] == right++) { // The last run contains one element
run[++count] = right;
} else if (count <= 1) { // The array is already sorted
// These invariants should hold true:
// run[0] = 0
// run[<last>] = right + 1; (terminator)
if (count == 0) {
// A single equal run
return;
} else if (count == 1 && run[count] > right) {
// Either a single ascending or a transformed descending run.
// Always check that a final run is a proper terminator, otherwise
// we have an unterminated trailing run, to handle downstream.
return;
}
right++;
if (run[count] < right) {
// Corner case: the final run is not a terminator. This may happen
// if a final run is an equals run, or there is a single-element run
// at the end. Fix up by adding a proper terminator at the end.
// Note that we terminate with (right + 1), incremented earlier.
run[++count] = right;
}
// Determine alternation base for merge

196
jdk/test/java/util/Arrays/SortingNearlySortedPrimitive.java

@ -1,6 +1,6 @@
/*
* Copyright 2015 Goldman Sachs.
* Copyright (c) 2015, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2015, 2016, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
@ -23,6 +23,7 @@
*/
/*
* @test
* @bug 8154049
* @summary Tests the sorting of a large array of sorted primitive values,
* predominently for cases where the array is nearly sorted. This tests
* code that detects patterns in the array to determine if it is nearly
@ -32,32 +33,117 @@
* @run testng SortingNearlySortedPrimitive
*/
import org.testng.Assert;
import org.testng.annotations.DataProvider;
import org.testng.annotations.Test;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.function.Supplier;
import java.util.List;
import java.util.StringJoiner;
import java.util.function.IntFunction;
import java.util.stream.IntStream;
import java.util.stream.Stream;
public class SortingNearlySortedPrimitive {
private static final int ARRAY_SIZE = 1_000_000;
@DataProvider(name = "arrays")
public Object[][] createData() {
return new Object[][]{
{"hiZeroLowTest", (Supplier<int[]>) this::hiZeroLowData},
{"endLessThanTest", (Supplier<int[]>) this::endLessThanData},
{"highFlatLowTest", (Supplier<int[]>) this::highFlatLowData},
{"identicalTest", (Supplier<int[]>) this::identicalData},
{"sortedReversedSortedTest", (Supplier<int[]>) this::sortedReversedSortedData},
{"pairFlipTest", (Supplier<int[]>) this::pairFlipData},
{"zeroHiTest", (Supplier<int[]>) this::zeroHiData},
};
static final int BASE = 3;
static final int WIDTH = 4;
// Should be > DualPivotQuicksort.QUICKSORT_THRESHOLD
static final int PAD = 300;
Stream<int[]> createCombinations() {
// Create all combinations for the BASE value and double the WIDTH
// elements
// This is create various combinations of ascending, descending and
// equal runs to exercise the nearly sorted code paths
return IntStream.range(0, (int) Math.pow(BASE, 2 * WIDTH)).
mapToObj(this::createArray);
}
@Test(dataProvider = "arrays")
public void runTests(String testName, Supplier<int[]> dataMethod) throws Exception {
int[] intSourceArray = dataMethod.get();
// Create an array which at either end is filled with -ve and +ve elements
// according to the base value and padded with zeros in between
int[] createArray(int v) {
int[] a = new int[WIDTH + PAD + WIDTH];
// Fill head of array
for (int j = 0; j < WIDTH; j++) {
a[j] = (v % BASE) - (BASE / 2);
v /= BASE;
}
// Fill tail of array
for (int j = 0; j < WIDTH; j++) {
a[WIDTH + PAD + j] = (v % BASE) - (BASE / 2);
v /= BASE;
}
return a;
}
@Test
public void testCombination() {
createCombinations().forEach(a -> {
try {
// Clone source array to ensure it is not modified
this.sortAndAssert(a.clone());
this.sortAndAssert(floatCopyFromInt(a));
this.sortAndAssert(doubleCopyFromInt(a));
this.sortAndAssert(longCopyFromInt(a));
this.sortAndAssert(shortCopyFromInt(a));
this.sortAndAssert(charCopyFromInt(a));
} catch (AssertionError sae) {
AssertionError ae = new AssertionError("Sort failed for " + arrayToString(a));
ae.addSuppressed(sae);
throw ae;
}
});
}
String arrayToString(int[] a) {
int[] l = Arrays.copyOfRange(a, 0, WIDTH + 2);
int[] r = Arrays.copyOfRange(a, a.length - (WIDTH + 2), a.length);
StringJoiner sj = new StringJoiner(",", "[", "]");
for (int i : l) {
sj.add(Integer.toString(i));
}
sj.add("...");
for (int i : r) {
sj.add(Integer.toString(i));
}
return sj.toString();
}
@DataProvider(name = "shapes")
public Object[][] createShapes() {
Stream<List<Object>> baseCases = Stream.of(
List.of("hiZeroLowTest", (IntFunction<int[]>) this::hiZeroLowData),
List.of("endLessThanTest", (IntFunction<int[]>) this::endLessThanData),
List.of("highFlatLowTest", (IntFunction<int[]>) this::highFlatLowData),
List.of("identicalTest", (IntFunction<int[]>) this::identicalData),
List.of("sortedReversedSortedTest", (IntFunction<int[]>) this::sortedReversedSortedData),
List.of("pairFlipTest", (IntFunction<int[]>) this::pairFlipData),
List.of("zeroHiTest", (IntFunction<int[]>) this::zeroHiData)
);
// Ensure the following inequality holds for certain sizes
// DualPivotQuicksort.QUICKSORT_THRESHOLD <= size - 1
// < DualPivotQuicksort.COUNTING_SORT_THRESHOLD_FOR_SHORT_OR_CHAR
// This guarantees that code paths are taken for checking nearly sorted
// arrays for all primitive types
List<Integer> sizes = List.of(100, 1_000, 10_000, 1_000_000);
return baseCases.
flatMap(l -> sizes.stream().map(s -> append(l, s))).
toArray(Object[][]::new);
}
Object[] append(List<Object> l, Object value) {
List<Object> nl = new ArrayList<>(l);
nl.add(value);
return nl.toArray();
}
@Test(dataProvider = "shapes")
public void testShapes(String testName, IntFunction<int[]> dataMethod, int size) {
int[] intSourceArray = dataMethod.apply(size);
// Clone source array to ensure it is not modified
this.sortAndAssert(intSourceArray.clone());
@ -110,73 +196,67 @@ public class SortingNearlySortedPrimitive {
private void sortAndAssert(int[] array) {
Arrays.sort(array);
for (int i = 1; i < ARRAY_SIZE; i++) {
for (int i = 1; i < array.length; i++) {
if (array[i] < array[i - 1]) {
throw new AssertionError("not sorted");
}
}
Assert.assertEquals(ARRAY_SIZE, array.length);
}
private void sortAndAssert(char[] array) {
Arrays.sort(array);
for (int i = 1; i < ARRAY_SIZE; i++) {
for (int i = 1; i < array.length; i++) {
if (array[i] < array[i - 1]) {
throw new AssertionError("not sorted");
}
}
Assert.assertEquals(ARRAY_SIZE, array.length);
}
private void sortAndAssert(short[] array) {
Arrays.sort(array);
for (int i = 1; i < ARRAY_SIZE; i++) {
for (int i = 1; i < array.length; i++) {
if (array[i] < array[i - 1]) {
throw new AssertionError("not sorted");
}
}
Assert.assertEquals(ARRAY_SIZE, array.length);
}
private void sortAndAssert(double[] array) {
Arrays.sort(array);
for (int i = 1; i < ARRAY_SIZE; i++) {
for (int i = 1; i < array.length; i++) {
if (array[i] < array[i - 1]) {
throw new AssertionError("not sorted");
}
}
Assert.assertEquals(ARRAY_SIZE, array.length);
}
private void sortAndAssert(float[] array) {
Arrays.sort(array);
for (int i = 1; i < ARRAY_SIZE; i++) {
for (int i = 1; i < array.length; i++) {
if (array[i] < array[i - 1]) {
throw new AssertionError("not sorted");
}
}
Assert.assertEquals(ARRAY_SIZE, array.length);
}
private void sortAndAssert(long[] array) {
Arrays.sort(array);
for (int i = 1; i < ARRAY_SIZE; i++) {
for (int i = 1; i < array.length; i++) {
if (array[i] < array[i - 1]) {
throw new AssertionError("not sorted");
}
}
Assert.assertEquals(ARRAY_SIZE, array.length);
}
private int[] zeroHiData() {
int[] array = new int[ARRAY_SIZE];
private int[] zeroHiData(int size) {
int[] array = new int[size];
int threeQuarters = (int) (ARRAY_SIZE * 0.75);
int threeQuarters = (int) (size * 0.75);
for (int i = 0; i < threeQuarters; i++) {
array[i] = 0;
}
int k = 1;
for (int i = threeQuarters; i < ARRAY_SIZE; i++) {
for (int i = threeQuarters; i < size; i++) {
array[i] = k;
k++;
}
@ -184,10 +264,10 @@ public class SortingNearlySortedPrimitive {
return array;
}
private int[] hiZeroLowData() {
int[] array = new int[ARRAY_SIZE];
private int[] hiZeroLowData(int size) {
int[] array = new int[size];
int oneThird = ARRAY_SIZE / 3;
int oneThird = size / 3;
for (int i = 0; i < oneThird; i++) {
array[i] = i;
}
@ -195,16 +275,16 @@ public class SortingNearlySortedPrimitive {
for (int i = oneThird; i < twoThirds; i++) {
array[i] = 0;
}
for (int i = twoThirds; i < ARRAY_SIZE; i++) {
for (int i = twoThirds; i < size; i++) {
array[i] = oneThird - i + twoThirds;
}
return array;
}
private int[] highFlatLowData() {
int[] array = new int[ARRAY_SIZE];
private int[] highFlatLowData(int size) {
int[] array = new int[size];
int oneThird = ARRAY_SIZE / 3;
int oneThird = size / 3;
for (int i = 0; i < oneThird; i++) {
array[i] = i;
}
@ -213,57 +293,57 @@ public class SortingNearlySortedPrimitive {
for (int i = oneThird; i < twoThirds; i++) {
array[i] = constant;
}
for (int i = twoThirds; i < ARRAY_SIZE; i++) {
for (int i = twoThirds; i < size; i++) {
array[i] = constant - i + twoThirds;
}
return array;
}
private int[] identicalData() {
int[] array = new int[ARRAY_SIZE];
private int[] identicalData(int size) {
int[] array = new int[size];
int listNumber = 24;
for (int i = 0; i < ARRAY_SIZE; i++) {
for (int i = 0; i < size; i++) {
array[i] = listNumber;
}
return array;
}
private int[] endLessThanData() {
int[] array = new int[ARRAY_SIZE];
private int[] endLessThanData(int size) {
int[] array = new int[size];
for (int i = 0; i < ARRAY_SIZE - 1; i++) {
for (int i = 0; i < size - 1; i++) {
array[i] = 3;
}
array[ARRAY_SIZE - 1] = 1;
array[size - 1] = 1;
return array;
}
private int[] sortedReversedSortedData() {
int[] array = new int[ARRAY_SIZE];
private int[] sortedReversedSortedData(int size) {
int[] array = new int[size];
for (int i = 0; i < ARRAY_SIZE / 2; i++) {
for (int i = 0; i < size / 2; i++) {
array[i] = i;
}
int num = 0;
for (int i = ARRAY_SIZE / 2; i < ARRAY_SIZE; i++) {
array[i] = ARRAY_SIZE - num;
for (int i = size / 2; i < size; i++) {
array[i] = size - num;
num++;
}
return array;
}
private int[] pairFlipData() {
int[] array = new int[ARRAY_SIZE];
private int[] pairFlipData(int size) {
int[] array = new int[size];
for (int i = 0; i < ARRAY_SIZE; i++) {
for (int i = 0; i < size; i++) {
array[i] = i;
}
for (int i = 0; i < ARRAY_SIZE; i += 2) {
for (int i = 0; i < size; i += 2) {
int temp = array[i];
array[i] = array[i + 1];
array[i + 1] = temp;