f087d03eb2
Make a few changes to memory usage throughout the application to reduce transient allocations from the `big.txt` test from ~213,000 to ~53,000. ## PR Checklist * [x] Supports #3075 * [x] I work here. * [x] Tested manually and WPR'd. Test suite should still pass. * [x] Am core contributor ## Detailed Description of the Pull Request / Additional comments Transient allocations are those that are new'd, used, then delete'd. Going back and forth to the system allocator for things we're just going to throw away or use rapidly again is a performance detriment. Not only is it a bunch of time to go ask the system with a syscall, it also hits a whole bunch of locks on the allocators. This PR identifies a few places where we were accidentally allocating and didn't mean to or were allocating and freeing just to turn around and allocate again. I chose other strategies to avoid this. ## Validation Steps Performed - Ran `big.txt` sample (~6MB file) before and after. Observed heap allocations with WPR.
81 lines
2 KiB
C++
81 lines
2 KiB
C++
/*++
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Copyright (c) Microsoft Corporation
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Licensed under the MIT license.
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Module Name:
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- AttrRowIterator.hpp
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Abstract:
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- iterator for ATTR_ROW to walk the TextAttributes of the run
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- read only iterator
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Author(s):
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- Austin Diviness (AustDi) 04-Jun-2018
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--*/
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#pragma once
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#include "TextAttribute.hpp"
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#include "TextAttributeRun.hpp"
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class ATTR_ROW;
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class AttrRowIterator final
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{
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public:
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using iterator_category = std::bidirectional_iterator_tag;
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using value_type = TextAttribute;
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using difference_type = std::ptrdiff_t;
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using pointer = TextAttribute*;
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using reference = TextAttribute&;
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static AttrRowIterator CreateEndIterator(const ATTR_ROW* const attrRow) noexcept;
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AttrRowIterator(const ATTR_ROW* const attrRow) noexcept;
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operator bool() const noexcept;
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bool operator==(const AttrRowIterator& it) const noexcept;
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bool operator!=(const AttrRowIterator& it) const noexcept;
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AttrRowIterator& operator++() noexcept
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{
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_increment(1);
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return *this;
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}
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AttrRowIterator operator++(int) noexcept
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{
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auto copy = *this;
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_increment(1);
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return copy;
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}
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AttrRowIterator& operator+=(const ptrdiff_t& movement);
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AttrRowIterator& operator-=(const ptrdiff_t& movement);
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AttrRowIterator& operator--() noexcept
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{
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_decrement(1);
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return *this;
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}
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AttrRowIterator operator--(int) noexcept
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{
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auto copy = *this;
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_decrement(1);
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return copy;
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}
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const TextAttribute* operator->() const;
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const TextAttribute& operator*() const;
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private:
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boost::container::small_vector_base<TextAttributeRun>::const_iterator _run;
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const ATTR_ROW* _pAttrRow;
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size_t _currentAttributeIndex; // index of TextAttribute within the current TextAttributeRun
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bool _exceeded;
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void _increment(size_t count) noexcept;
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void _decrement(size_t count) noexcept;
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void _setToEnd() noexcept;
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};
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