forked from mirrors/gecko-dev
989d33f031
Until now we used our own, well-aged C-style implementation of quick sort, based on code from 1992/93. Apart from being old (which is not bad as such), this code had some disadvantages, namely: - It was not typesafe and invocations could not be optimized by inlining. - [Quick Sort](https://en.wikipedia.org/wiki/Quicksort) has a worst case performance of O(n<sup>2</sup>). - Quick Sort can recurse deeply and thus cause stack overflows. - On Windows, [Control Flow Guard](https://learn.microsoft.com/en-us/windows/win32/secbp/control-flow-guard) inspects any function invocation via function pointers to check if the called function was known at compile time. This comes with a [notable overhead](https://bugzilla.mozilla.org/show_bug.cgi?id=1842079) when calling the compare function repeatedly. `std::sort` and `std::stable_sort` are preferred and have an optimal, guaranteed worst case performance. Differential Revision: https://phabricator.services.mozilla.com/D181339
47 lines
1.6 KiB
C++
47 lines
1.6 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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/* We need this because Solaris' version of qsort is broken and
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* causes array bounds reads.
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*/
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#ifndef nsQuickSort_h___
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#define nsQuickSort_h___
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#include "nscore.h"
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#ifdef __cplusplus
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extern "C" {
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#endif
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/**
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* You most probably want to not use this but std::sort or std::stable_sort
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* It will be removed eventually from the tree, see bug 1839052.
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*
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* Quicksort is recursive without limits and thus may make overflow the stack.
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* And while being close to optimal for randomized data for some edge cases
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* it can reach quadratic performance O(n*n) instead of O(n*log(n)).
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*
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* Parameters:
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* 1. the array to sort
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* 2. the number of elements in the array
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* 3. the size of each array element
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* 4. comparison function taking two elements and parameter #5 and
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* returning an integer:
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* + less than zero if the first element should be before the second
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* + 0 if the order of the elements does not matter
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* + greater than zero if the second element should be before the first
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* 5. extra data to pass to comparison function
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*/
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[[deprecated("Use std::sort or std::make/sort_heap instead.")]] void
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NS_QuickSort(void*, unsigned int, unsigned int,
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int (*)(const void*, const void*, void*), void*);
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#ifdef __cplusplus
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}
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#endif
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#endif /* nsQuickSort_h___ */
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