Reduce allocations on file-discovery and markdown hot paths - #783
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SimonCropp merged 1 commit intoJul 7, 2026
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Three behavior-preserving allocation reductions on always-on paths. Each was
measured with GC.GetAllocatedBytesForCurrentThread and produces byte-identical
output; the full snapshot suite stays green.
- GetLanguageFromPath: span-based Path.GetExtension + a single lowercasing
string.Create, replacing GetExtension + TrimStart('.') + ToLowerInvariant
(3 string allocations -> 1). 71.2 -> 28.8 B/call. Called for every file
during discovery and again per snippet source file.
- MarkdownProcessor toc checks: line.Current.TrimStart() == "toc" ->
span SequenceEqual, dropping a trimmed-string allocation on every indented
line.
- Line.LeadingWhitespace: computed lazily. Only snippet / web-snippet lines
ever read it, but the ctor allocated a leading-whitespace substring for every
indented line in the document.
Wins 2 and 3 together cut ~13.5% of the allocations when applying an
indentation-heavy document. Adds OptimizationBenchmarks3 (#11
GetLanguageFromPath, #12 indented Apply) to the existing benchmark suite.
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Three behavior-preserving allocation reductions on always-on paths. Each was measured with GC.GetAllocatedBytesForCurrentThread and produces byte-identical output; the full snapshot suite stays green.
GetLanguageFromPath: span-based Path.GetExtension + a single lowercasing string.Create, replacing GetExtension + TrimStart('.') + ToLowerInvariant (3 string allocations -> 1). 71.2 -> 28.8 B/call. Called for every file during discovery and again per snippet source file.
MarkdownProcessor toc checks: line.Current.TrimStart() == "toc" ->
span SequenceEqual, dropping a trimmed-string allocation on every indented line.
Line.LeadingWhitespace: computed lazily. Only snippet / web-snippet lines ever read it, but the ctor allocated a leading-whitespace substring for every indented line in the document.
Wins 2 and 3 together cut ~13.5% of the allocations when applying an indentation-heavy document. Adds OptimizationBenchmarks3 (#11 GetLanguageFromPath, #12 indented Apply) to the existing benchmark suite.