Improve performance and memory usage of TagHelperBinder #11671
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Don't expose the Mappings dictionary. Instead, expose a GetBoundRules(...) method and update each access.
This change uses a single HashSet<TagHelperDescriptor> to ensure that there are no duplicates. This avoids needing to use a HashSet<TagHelperDescriptor> per rule.
Instead of creating a new Dictionary with an arbitrary capacity, use a pooled Dictionary to build the initial map and copy the results to a new Dictionary with the precise capacity.
This avoids an extra Dictionary lookup for '*' during binding.
Frozen dictionaries are expensive to construct and should be avoided in binding. Instead, this change updates TagHelperBinding to store all bound rules as an array of TagHelperBoundRulesInfo, which is a struct containing the mapping of TagHelperDescriptor to bound rules.
A common pattern is to iterate over TagHelperBinding.Descriptors, call GetBoundRules for each descriptor and iterate over the rules. Because TagHelperBinding no longer contains a Dictionary, these double-loops are now O(n^2). Fortunately, it's easy to just iterate over AllBoundRules, which is what these cases are really trying to do.
- Store TagHelperDocumentContext in a field on RazorCodeDocument rather than in ItemCollection. - Move the GetTagHelperDocumentContext() extension method to RazorCodeDocument. - Move the SetTagHelperDocumentContext() extension method to RazorCodeDocument. - Add RazorCodeDocument.TryGetTagHelperDocumentContext(...) method. - Audit and update uses of GetTagHelperDocumentContext() Important note: This change includes a nullability change to one of the Legacy Editor shim's APIs. This change makes the API correct and I verified that Web Tools already handles null for this API.
jjonescz
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Mar 31, 2025
src/Compiler/Microsoft.CodeAnalysis.Razor.Compiler/src/Language/TagHelperBinder.cs
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src/Razor/src/Microsoft.VisualStudio.LegacyEditor.Razor/Parsing/VisualStudioRazorParser.cs
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src/Compiler/Microsoft.CodeAnalysis.Razor.Compiler/src/Language/TagHelperBinder.cs
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jjonescz
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Mar 31, 2025
333fred
approved these changes
Mar 31, 2025
src/Compiler/Microsoft.CodeAnalysis.Razor.Compiler/src/Language/TagHelperBinder.cs
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This code can be simplified, since the null check will be performed on our behalf.
This was referenced Apr 11, 2025
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While working on #11655, I noticed that
TagHelperBinderaccounts for a surprising amount of memory. This pull request aims to clean it up, reduce the amount of memory it holds onto, and improve the performance of binding operations. I recommend reviewing commit-by-commit as most commits have descriptions to aid reviewers.CI Build: https://dev.azure.com/dnceng/internal/_build/results?buildId=2675893&view=results
Test Insertion: https://dev.azure.com/devdiv/DevDiv/_git/VS/pullrequest/623866