add performance enhancements #72
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feat(solution): add NestedProjects section to solution file chore: add commit message instructions to settings chore: create Justfile for build and benchmark commands chore: add Directory.Build.props for benchmark project
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Pull Request Overview
This PR implements significant performance enhancements to the HTTP User Agent Parser by replacing regex-based parsing with faster Span-based token matching for platform and browser detection. The changes demonstrate substantial performance improvements with up to 90% reduction in memory allocations.
- Replace regex-based platform and browser detection with optimized Span token matching
- Add fast-path token rules arrays for zero-allocation lookups while maintaining regex fallback compatibility
- Update copyright years across all license files and add development tooling configuration
Reviewed Changes
Copilot reviewed 16 out of 16 changed files in this pull request and generated 4 comments.
Show a summary per file
| File | Description |
|---|---|
| src/HttpUserAgentParser/HttpUserAgentParser.cs | Core optimization implementing Span-based parsing methods with aggressive inlining |
| src/HttpUserAgentParser/HttpUserAgentStatics.cs | Added fast-path token rule arrays and precompiled regex mappings for performance |
| src/HttpUserAgentParser/Providers/HttpUserAgentParserDefaultProvider.cs | Updated XML documentation reference to match method signature |
| LICENSE files | Updated copyright year from 2023 to 2025 |
| Benchmark/tooling files | Added development environment configuration and namespace corrections |
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| // Precompiled platform regex map to attach to PlatformInformation without per-call allocations | ||
| private static readonly Dictionary<string, Regex> s_platformRegexMap = s_platformRules |
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Could use FrozenDictionary on targets that support it.
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I totally forgot FrozenDictionary
| // Skip separators until we hit a digit | ||
| while (i < end) | ||
| { | ||
| char c = haystack[i]; |
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We could slice the haystack to avoid some bound checks here and below.
| while (i < end) | ||
| { | ||
| char c = haystack[i]; | ||
| if ((uint)(c - '0') <= 9) |
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Maybe it's worth to use a vectorized search here too?
IndexOf will be a method call, so potentially slower, but a simple self coded search for one vector length could be faster. Maybe in combination with a SWAR search.
I can try this later (September). But we cache that info later on, so is it worth it?
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Maybe it's worth to use a vectorized search here too?
Yes, but tbh vectorized search is way over my casual knowledge ☹
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So we merge this and create a new PR end sept?
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Yep, I'll file an issue and assign to me so I can't forget it.
Edit: #73
| /// Accepts digits and dots; skips common separators ('/', ' ', ':', '=') until first digit. | ||
| /// Returns false if no version-like token is found. | ||
| /// </summary> | ||
| private static bool TryExtractVersion(ReadOnlySpan<char> haystack, int startIndex, out Range range) |
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The startIndex isn't needed, as the ROS haystack can be sliced therefore to proper start.
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With your changes BenchmarkDotNet v0.14.0, Windows 10 (10.0.19045.6216/22H2/2022Update)
AMD Ryzen 9 9950X, 1 CPU, 32 logical and 16 physical cores
.NET SDK 10.0.100-preview.7.25380.108
[Host] : .NET 10.0.0 (10.0.25.38108), X64 RyuJIT AVX-512F+CD+BW+DQ+VL+VBMI
ShortRun : .NET 10.0.0 (10.0.25.38108), X64 RyuJIT AVX-512F+CD+BW+DQ+VL+VBMI
Job=ShortRun IterationCount=3 LaunchCount=1
WarmupCount=3
| Method | Categories | Data | Mean | Error | StdDev | Ratio | RatioSD | Gen0 | Gen1 | Gen2 | Allocated | Alloc Ratio |
|------------------- |----------- |------------- |----------------:|-----------------:|---------------:|----------:|---------:|---------:|---------:|---------:|-----------:|------------:|
| MyCSharp | Basic | Chrome Win10 | 867.96 ns | 67.366 ns | 3.693 ns | 1.00 | 0.01 | 0.0029 | - | - | 48 B | 1.00 |
| UAParser | Basic | Chrome Win10 | 8,915,044.79 ns | 619,314.743 ns | 33,946.731 ns | 10,271.42 | 50.86 | 656.2500 | 546.8750 | 109.3750 | 11523315 B | 240,069.06 |
| DeviceDetector.NET | Basic | Chrome Win10 | 5,314,358.33 ns | 7,521,345.077 ns | 412,270.305 ns | 6,122.91 | 411.98 | 296.8750 | 125.0000 | 31.2500 | 5002235 B | 104,213.23 |
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| MyCSharp | Basic | Google-Bot | 161.00 ns | 10.338 ns | 0.567 ns | 1.00 | 0.00 | - | - | - | - | NA |
| UAParser | Basic | Google-Bot | 9,464,732.81 ns | 4,726,277.375 ns | 259,063.212 ns | 58,789.19 | 1,404.99 | 671.8750 | 656.2500 | 109.3750 | 11877003 B | NA |
| DeviceDetector.NET | Basic | Google-Bot | 5,999,877.08 ns | 1,009,150.081 ns | 55,314.921 ns | 37,267.61 | 318.42 | 500.0000 | 62.5000 | - | 8817022 B | NA |
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| MyCSharp | Cached | Chrome Win10 | 24.86 ns | 2.335 ns | 0.128 ns | 1.00 | 0.01 | - | - | - | - | NA |
| UAParser | Cached | Chrome Win10 | 173,556.74 ns | 6,719.752 ns | 368.332 ns | 6,982.49 | 33.76 | 2.1973 | - | - | 37489 B | NA |
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| MyCSharp | Cached | Google-Bot | 17.48 ns | 1.317 ns | 0.072 ns | 1.00 | 0.01 | - | - | - | - | NA |
| UAParser | Cached | Google-Bot | 130,208.42 ns | 30,606.978 ns | 1,677.672 ns | 7,449.30 | 87.27 | 2.6855 | - | - | 45857 B | NA | |
| } | ||
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| int s = i; | ||
| haystack = haystack.Slice(i + 1); |
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We have a test for an invalid useragent. With this code it throws an ArgumentOutOfRangeException here
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Mozilla/ (iPhone; U; CPU iPhone OS like Mac OS X) AppleWebKit/ (KHTML, like Gecko) Version/ Mobile/ Safari/
We test for this UA.
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Wanted to add a test and create a pr by myself. But couldn't get the solution to build. (Have not installed .net10 preview on my machine)
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What does the user agent
Mozilla/ (iPhone; U; CPU iPhone OS like Mac OS X) AppleWebKit/ (KHTML, like Gecko) Version/ Mobile/ Safari/
stand for?
I couldn’t find any exact match online.
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Yeah that is a invalid one.
We have a test which tries to parse this one (can not remember how we came up with this one...)
We use it to test that we do not proceed when the ua is invalid.
I am ok to change my test, but the parser did not throw before and now throws an exception 🤷
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Okay, a invalid one.
I will take a look. It should not break tests.
I saw we're not using Span enough, so I made a test
I added span
out of interest I used span in public apis (I was aware of ToString)
so I used string again in public apis
results:
~90% less allocations (if not zero anyway)
~20% better performance