quickSort.cpp

/*
 * Copyright (c) 2011, 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
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 *
 */

#include "precompiled.hpp"
#include "utilities/quickSort.hpp"

#ifndef PRODUCT

// Unit tests

#include "runtime/os.hpp"
#include <stdlib.h>

static int test_comparator(int a, int b) {
  if (a == b) {
    return 0;
  }
  if (a < b) {
    return -1;
  }
  return 1;
}

static int test_even_odd_comparator(int a, int b) {
  bool a_is_odd = (a % 2) == 1;
  bool b_is_odd = (b % 2) == 1;
  if (a_is_odd == b_is_odd) {
    return 0;
  }
  if (a_is_odd) {
    return -1;
  }
  return 1;
}

extern "C" {
  static int test_stdlib_comparator(const void* a, const void* b) {
    int ai = *(int*)a;
    int bi = *(int*)b;
    if (ai == bi) {
      return 0;
    }
    if (ai < bi) {
      return -1;
    }
    return 1;
  }
}

void QuickSort::print_array(const char* prefix, int* array, int length) {
  tty->print("%s:", prefix);
  for (int i = 0; i < length; i++) {
    tty->print(" %d", array[i]);
  }
  tty->print_cr("");
}

bool QuickSort::compare_arrays(int* actual, int* expected, int length) {
  for (int i = 0; i < length; i++) {
    if (actual[i] != expected[i]) {
      print_array("Sorted array  ", actual, length);
      print_array("Expected array", expected, length);
      return false;
    }
  }
  return true;
}

template <class C>
bool QuickSort::sort_and_compare(int* arrayToSort, int* expectedResult, int length, C comparator, bool idempotent) {
  sort<int, C>(arrayToSort, length, comparator, idempotent);
  return compare_arrays(arrayToSort, expectedResult, length);
}

bool QuickSort::test_quick_sort() {
  tty->print_cr("test_quick_sort\n");
  {
    int* test_array = NULL;
    int* expected_array = NULL;
    assert(sort_and_compare(test_array, expected_array, 0, test_comparator), "Empty array not handled");
  }
  {
    int test_array[] = {3};
    int expected_array[] = {3};
    assert(sort_and_compare(test_array, expected_array, 1, test_comparator), "Single value array not handled");
  }
  {
    int test_array[] = {3,2};
    int expected_array[] = {2,3};
    assert(sort_and_compare(test_array, expected_array, 2, test_comparator), "Array with 2 values not correctly sorted");
  }
  {
    int test_array[] = {3,2,1};
    int expected_array[] = {1,2,3};
    assert(sort_and_compare(test_array, expected_array, 3, test_comparator), "Array with 3 values not correctly sorted");
  }
  {
    int test_array[] = {4,3,2,1};
    int expected_array[] = {1,2,3,4};
    assert(sort_and_compare(test_array, expected_array, 4, test_comparator), "Array with 4 values not correctly sorted");
  }
  {
    int test_array[] = {7,1,5,3,6,9,8,2,4,0};
    int expected_array[] = {0,1,2,3,4,5,6,7,8,9};
    assert(sort_and_compare(test_array, expected_array, 10, test_comparator), "Array with 10 values not correctly sorted");
  }
  {
    int test_array[] = {4,4,1,4};
    int expected_array[] = {1,4,4,4};
    assert(sort_and_compare(test_array, expected_array, 4, test_comparator), "3 duplicates not sorted correctly");
  }
  {
    int test_array[] = {0,1,2,3,4,5,6,7,8,9};
    int expected_array[] = {0,1,2,3,4,5,6,7,8,9};
    assert(sort_and_compare(test_array, expected_array, 10, test_comparator), "Already sorted array not correctly sorted");
  }
  {
    // one of the random arrays that found an issue in the partion method.
    int test_array[] = {76,46,81,8,64,56,75,11,51,55,11,71,59,27,9,64,69,75,21,25,39,40,44,32,7,8,40,41,24,78,24,74,9,65,28,6,40,31,22,13,27,82};
    int expected_array[] = {6,7,8,8,9,9,11,11,13,21,22,24,24,25,27,27,28,31,32,39,40,40,40,41,44,46,51,55,56,59,64,64,65,69,71,74,75,75,76,78,81,82};
    assert(sort_and_compare(test_array, expected_array, 42, test_comparator), "Not correctly sorted");
  }
  {
    int test_array[] = {2,8,1,4};
    int expected_array[] = {1,4,2,8};
    assert(sort_and_compare(test_array, expected_array, 4, test_even_odd_comparator), "Even/odd not sorted correctly");
  }
  {  // Some idempotent tests
    {
      // An array of lenght 3 is only sorted by find_pivot. Make sure that it is idempotent.
      int test_array[] = {1,4,8};
      int expected_array[] = {1,4,8};
      assert(sort_and_compare(test_array, expected_array, 3, test_even_odd_comparator, true), "Even/odd not idempotent");
    }
    {
      int test_array[] = {1,7,9,4,8,2};
      int expected_array[] = {1,7,9,4,8,2};
      assert(sort_and_compare(test_array, expected_array, 6, test_even_odd_comparator, true), "Even/odd not idempotent");
    }
    {
      int test_array[] = {1,9,7,4,2,8};
      int expected_array[] = {1,9,7,4,2,8};
      assert(sort_and_compare(test_array, expected_array, 6, test_even_odd_comparator, true), "Even/odd not idempotent");
    }
    {
      int test_array[] = {7,9,1,2,8,4};
      int expected_array[] = {7,9,1,2,8,4};
      assert(sort_and_compare(test_array, expected_array, 6, test_even_odd_comparator, true), "Even/odd not idempotent");
    }
    {
      int test_array[] = {7,1,9,2,4,8};
      int expected_array[] = {7,1,9,2,4,8};
      assert(sort_and_compare(test_array, expected_array, 6, test_even_odd_comparator, true), "Even/odd not idempotent");
    }
    {
      int test_array[] = {9,1,7,4,8,2};
      int expected_array[] = {9,1,7,4,8,2};
      assert(sort_and_compare(test_array, expected_array, 6, test_even_odd_comparator, true), "Even/odd not idempotent");
    }
    {
      int test_array[] = {9,7,1,4,2,8};
      int expected_array[] = {9,7,1,4,2,8};
      assert(sort_and_compare(test_array, expected_array, 6, test_even_odd_comparator, true), "Even/odd not idempotent");
    }
  }

  // test sorting random arrays
  for (int i = 0; i < 1000; i++) {
    int length = os::random() % 100;
    int* test_array = new int[length];
    int* expected_array = new int[length];
    for (int j = 0; j < length; j++) {
        // Choose random values, but get a chance of getting duplicates
        test_array[j] = os::random() % (length * 2);
        expected_array[j] = test_array[j];
    }

    // Compare sorting to stdlib::qsort()
    qsort(expected_array, length, sizeof(int), test_stdlib_comparator);
    assert(sort_and_compare(test_array, expected_array, length, test_comparator), "Random array not correctly sorted");

    // Make sure sorting is idempotent.
    // Both test_array and expected_array are sorted by the test_comparator.
    // Now sort them once with the test_even_odd_comparator. Then sort the
    // test_array one more time with test_even_odd_comparator and verify that
    // it is idempotent.
    sort(expected_array, length, test_even_odd_comparator, true);
    sort(test_array, length, test_even_odd_comparator, true);
    assert(compare_arrays(test_array, expected_array, length), "Sorting identical arrays rendered different results");
    sort(test_array, length, test_even_odd_comparator, true);
    assert(compare_arrays(test_array, expected_array, length), "Sorting already sorted array changed order of elements - not idempotent");

    delete[] test_array;
    delete[] expected_array;
  }
  return true;
}

#endif