539a5dc0af
I was looking at conhost/OpenConsole and noticed it was being pretty inefficient with allocations due to some usages of std::deque and std::vector that didn't need to be done quite that way. So this uses std::vector for the TextBuffer's storage of ROW objects, which allows one allocation to contiguously reserve space for all the ROWs - on Desktop this is 9001 ROW objects which means it saves 9000 allocations that the std::deque would have done. Plus it has the benefit of increasing locality of the ROW objects since deque is going to chase pointers more often with its data structure. Then, within each ROW there are CharRow and ATTR_ROW objects that use std::vector today. This changes them to use Boost's small_vector, which is a variation of vector that allows for the so-called "small string optimization." Since we know the typical size of these vectors, we can pre-reserve the right number of elements directly in the CharRow/ATTR_ROW instances, avoiding any heap allocations at all for constructing these objects. There are a ton of variations on this "small_vector" concept out there in the world - this one in Boost, LLVM has one called SmallVector, Electronic Arts' STL has a small_vector, Facebook's folly library has one...there are a silly number of these out there. But Boost seems like it's by far the easiest to consume in terms of integration into this repo, the CI/CD pipeline, licensing, and stuff like that, so I went with the boost version. In terms of numbers, I measured the startup path of OpenConsole.exe on my dev box for Release x64 configuration. My box is an i7-6700k @ 4 Ghz, with 32 GB RAM, not that I think machine config matters much here: | | Allocation count | Allocated bytes | CPU usage (ms) | | ------ | ------------------- | ------------------ | -------------- | | Before | 29,461 | 4,984,640 | 103 | | After | 2,459 (-91%) | 4,853,931 (-2.6%) | 96 (-7%) | Along the way, I also fixed a dynamic initializer I happened to spot in the registry code, and updated some docs. ## Validation Steps Performed - Ran "runut", "runft" and "runuia" locally and confirmed results are the same as the main branch - Profiled the before/after numbers in the Visual Studio profiler, for the numbers shown in the table Co-authored-by: Austin Lamb <austinl@microsoft.com>
51 lines
1.4 KiB
C++
51 lines
1.4 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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- TextAttributeRun.hpp
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Abstract:
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- contains data structure for run-length-encoding of text attribute data
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Author(s):
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- Michael Niksa (miniksa) 10-Apr-2014
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- Paul Campbell (paulcam) 10-Apr-2014
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Revision History:
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- From components of output.h/.c
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by Therese Stowell (ThereseS) 1990-1991
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- Pulled into its own file from textBuffer.hpp/cpp (AustDi, 2017)
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--*/
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#pragma once
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#include "TextAttribute.hpp"
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class TextAttributeRun final
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{
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public:
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TextAttributeRun() = default;
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TextAttributeRun(const size_t cchLength, const TextAttribute attr) noexcept :
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_cchLength(gsl::narrow<unsigned int>(cchLength))
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{
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SetAttributes(attr);
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}
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size_t GetLength() const noexcept { return _cchLength; }
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void SetLength(const size_t cchLength) noexcept { _cchLength = gsl::narrow<unsigned int>(cchLength); }
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void IncrementLength() noexcept { _cchLength++; }
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void DecrementLength() noexcept { _cchLength--; }
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const TextAttribute& GetAttributes() const noexcept { return _attributes; }
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void SetAttributes(const TextAttribute textAttribute) noexcept { _attributes = textAttribute; }
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private:
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unsigned int _cchLength{ 0 };
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TextAttribute _attributes{ 0 };
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#ifdef UNIT_TESTING
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friend class AttrRowTests;
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#endif
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};
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