Add cache to TagHelperDocumentContext

TagHelperBinders are expensive to create, and Razor often creates them for the same set of tag helpers. This change introduces a cache to avoid creating a new TagHelperDocumentContext (and therefore, a new TagHelperBinder) for the same TagHelperCollection.

Note: This requires adding some deduping logic to Rename, which started creating duplicate ranges with this change.

Author: DustinCampbell

src/Compiler/Microsoft.AspNetCore.Razor.Language/test/RazorCodeDocumentExtensionsTest.cs

@@ -52,7 +52,7 @@ public void GetAndSetTagHelperContext_ReturnsTagHelperContext()
         // Arrange
         var codeDocument = TestRazorCodeDocument.CreateEmpty();
 
-        var expected = TagHelperDocumentContext.Create(tagHelpers: []);
+        var expected = TagHelperDocumentContext.GetOrCreate(tagHelpers: []);
         codeDocument.SetTagHelperContext(expected);
 
         // Act

src/Compiler/Microsoft.CodeAnalysis.Razor.Compiler/src/Language/DefaultRazorTagHelperContextDiscoveryPhase.cs

@@ -51,7 +51,7 @@ protected override void ExecuteCore(RazorCodeDocument codeDocument, Cancellation
         // This will always be null for a component document.
         var tagHelperPrefix = visitor.TagHelperPrefix;
 
-        var context = TagHelperDocumentContext.Create(tagHelperPrefix, visitor.GetResults());
+        var context = TagHelperDocumentContext.GetOrCreate(tagHelperPrefix, visitor.GetResults());
         codeDocument.SetTagHelperContext(context);
         codeDocument.SetPreTagHelperSyntaxTree(syntaxTree);
     }

src/Compiler/Microsoft.CodeAnalysis.Razor.Compiler/src/Language/TagHelperDocumentContext.cs

@@ -1,14 +1,18 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+using Microsoft.AspNetCore.Razor.Utilities;
+
 namespace Microsoft.AspNetCore.Razor.Language;
 
 /// <summary>
 /// The binding information for Tag Helpers resulted to a <see cref="RazorCodeDocument"/>. Represents the
 /// Tag Helper information after processing by directives.
 /// </summary>
 internal sealed class TagHelperDocumentContext
-{
+{  
+    private static readonly CleanableWeakCache<(string? Prefix, Checksum), TagHelperDocumentContext> s_cache = new(cleanUpThreshold: 20);
+
     public string? Prefix { get; }
     public TagHelperCollection TagHelpers { get; }
 
@@ -20,22 +24,19 @@ private TagHelperDocumentContext(string? prefix, TagHelperCollection tagHelpers)
         TagHelpers = tagHelpers;
     }
 
-    public static TagHelperDocumentContext Create(TagHelperCollection tagHelpers)
-    {
-        ArgHelper.ThrowIfNull(tagHelpers);
-
-        return new(prefix: null, tagHelpers);
-    }
+    public static TagHelperDocumentContext GetOrCreate(TagHelperCollection tagHelpers)
+        => GetOrCreate(prefix: null, tagHelpers);
 
-    public static TagHelperDocumentContext Create(string? prefix, TagHelperCollection tagHelpers)
+    public static TagHelperDocumentContext GetOrCreate(string? prefix, TagHelperCollection tagHelpers)
     {
         ArgHelper.ThrowIfNull(tagHelpers);
 
-        return new(prefix, tagHelpers);
+        return s_cache.GetOrAdd(
+            key: (prefix, tagHelpers.Checksum),
+            arg: (prefix, tagHelpers),
+            arg => new(arg.prefix, arg.tagHelpers));
     }
 
     public TagHelperBinder GetBinder()
-    {
-        return _binder ?? InterlockedOperations.Initialize(ref _binder, new TagHelperBinder(Prefix, TagHelpers));
-    }
+        => _binder ?? InterlockedOperations.Initialize(ref _binder, new TagHelperBinder(Prefix, TagHelpers));
 }

src/Razor/benchmarks/Microsoft.AspNetCore.Razor.Microbenchmarks/LanguageServer/TagHelperCompletionBenchmark.cs

@@ -31,7 +31,7 @@ public object GetAttributeCompletions()
     {
         var tagHelperCompletionService = new TagHelperCompletionService();
         var context = new AttributeCompletionContext(
-            TagHelperDocumentContext.Create([.. CommonResources.TelerikTagHelpers]),
+            TagHelperDocumentContext.GetOrCreate([.. CommonResources.TelerikTagHelpers]),
             existingCompletions: [],
             currentTagName: "PageTitle",
             currentAttributeName: null,
@@ -48,7 +48,7 @@ public object GetElementCompletions()
     {
         var tagHelperCompletionService = new TagHelperCompletionService();
         var context = new ElementCompletionContext(
-            TagHelperDocumentContext.Create([.. CommonResources.TelerikTagHelpers]),
+            TagHelperDocumentContext.GetOrCreate([.. CommonResources.TelerikTagHelpers]),
             existingCompletions: s_existingElementCompletions,
             containingTagName: null,
             attributes: [],

src/Razor/benchmarks/Microsoft.AspNetCore.Razor.Microbenchmarks/Serialization/CompletionListSerializationBenchmark.cs

@@ -66,7 +66,7 @@ private CompletionList GenerateCompletionList(string documentContent, int queryI
         var sourceDocument = RazorSourceDocument.Create(documentContent, RazorSourceDocumentProperties.Default);
         var codeDocument = RazorCodeDocument.Create(sourceDocument);
         var syntaxTree = RazorSyntaxTree.Parse(sourceDocument);
-        var tagHelperDocumentContext = TagHelperDocumentContext.Create([.. CommonResources.LegacyTagHelpers]);
+        var tagHelperDocumentContext = TagHelperDocumentContext.GetOrCreate([.. CommonResources.LegacyTagHelpers]);
 
         var owner = syntaxTree.Root.FindInnermostNode(queryIndex, includeWhitespace: true, walkMarkersBack: true);
         var context = new RazorCompletionContext(codeDocument, queryIndex, owner, syntaxTree, tagHelperDocumentContext);

src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/Completion/TagHelperCompletionProvider.cs

@@ -116,7 +116,7 @@ private ImmutableArray<RazorCompletionItem> GetAttributeCompletions(
         var ancestors = containingAttribute.Parent.Ancestors();
         var nonDirectiveAttributeTagHelpers = tagHelperDocumentContext.TagHelpers.Where(
             static tagHelper => !tagHelper.BoundAttributes.Any(static attribute => attribute.IsDirectiveAttribute));
-        var filteredContext = TagHelperDocumentContext.Create(tagHelperDocumentContext.Prefix, nonDirectiveAttributeTagHelpers);
+        var filteredContext = TagHelperDocumentContext.GetOrCreate(tagHelperDocumentContext.Prefix, nonDirectiveAttributeTagHelpers);
         var (ancestorTagName, ancestorIsTagHelper) = TagHelperFacts.GetNearestAncestorTagInfo(ancestors);
         var attributeCompletionContext = new AttributeCompletionContext(
             filteredContext,

src/Razor/test/Microsoft.CodeAnalysis.Razor.Workspaces.Test/Completion/DefaultRazorCompletionFactsServiceTest.cs

@@ -18,7 +18,7 @@ public void GetDirectiveCompletionItems_AllProvidersCompletionItems()
         var sourceDocument = RazorSourceDocument.Create("", RazorSourceDocumentProperties.Default);
         var codeDocument = RazorCodeDocument.Create(sourceDocument);
         var syntaxTree = RazorSyntaxTree.Parse(TestRazorSourceDocument.Create());
-        var tagHelperDocumentContext = TagHelperDocumentContext.Create(tagHelpers: []);
+        var tagHelperDocumentContext = TagHelperDocumentContext.GetOrCreate(tagHelpers: []);
 
         var completionItem1 = RazorCompletionItem.CreateDirective(
             displayText: "displayText1",

src/Razor/test/Microsoft.CodeAnalysis.Razor.Workspaces.Test/Completion/DirectiveAttributeCompletionItemProviderTest.AttributeNames.cs

@@ -180,7 +180,7 @@ public void GetCompletionItems_ExistingAttribute_Partial_ReturnsEmptyCollection(
     public void GetAttributeCompletions_NoDescriptorsForTag_ReturnsEmptyCollection()
     {
         // Arrange
-        var documentContext = TagHelperDocumentContext.Create(tagHelpers: []);
+        var documentContext = TagHelperDocumentContext.GetOrCreate(tagHelpers: []);
         var context = GetDefaultDirectivateAttributeCompletionContext("@bin");
 
         // Act
@@ -197,7 +197,7 @@ public void GetAttributeCompletions_NoDirectiveAttributesForTag_ReturnsEmptyColl
         var descriptor = TagHelperDescriptorBuilder.CreateTagHelper("CatchAll", "TestAssembly");
         descriptor.BoundAttributeDescriptor(boundAttribute => boundAttribute.Name = "Test");
         descriptor.TagMatchingRule(rule => rule.RequireTagName("*"));
-        var documentContext = TagHelperDocumentContext.Create([descriptor.Build()]);
+        var documentContext = TagHelperDocumentContext.GetOrCreate([descriptor.Build()]);
 
         var context = GetDefaultDirectivateAttributeCompletionContext("@bin");
 

src/Razor/test/Microsoft.CodeAnalysis.Razor.Workspaces.Test/Completion/DirectiveAttributeCompletionItemProviderTest.ParameterNames.cs

@@ -35,7 +35,7 @@ public void GetCompletionItems_OnDirectiveAttributeParameter_ReturnsCompletions(
     public void GetAttributeParameterCompletions_NoDescriptorsForTag_ReturnsEmptyCollection()
     {
         // Arrange
-        var documentContext = TagHelperDocumentContext.Create(tagHelpers: []);
+        var documentContext = TagHelperDocumentContext.GetOrCreate(tagHelpers: []);
         var context = GetDefaultDirectiveAttributeCompletionContext("@bin");
 
         // Act
@@ -52,7 +52,7 @@ public void GetAttributeParameterCompletions_NoDirectiveAttributesForTag_Returns
         var descriptor = TagHelperDescriptorBuilder.CreateTagHelper("CatchAll", "TestAssembly");
         descriptor.BoundAttributeDescriptor(boundAttribute => boundAttribute.Name = "Test");
         descriptor.TagMatchingRule(rule => rule.RequireTagName("*"));
-        var documentContext = TagHelperDocumentContext.Create([descriptor.Build()]);
+        var documentContext = TagHelperDocumentContext.GetOrCreate([descriptor.Build()]);
 
         var context = GetDefaultDirectiveAttributeCompletionContext("@bin");
 

src/Razor/test/Microsoft.CodeAnalysis.Razor.Workspaces.Test/Completion/DirectiveAttributeTransitionCompletionItemProviderTest.cs

@@ -13,7 +13,7 @@ namespace Microsoft.CodeAnalysis.Razor.Completion;
 
 public class DirectiveAttributeTransitionCompletionItemProviderTest(ITestOutputHelper testOutput) : ToolingTestBase(testOutput)
 {
-    private readonly TagHelperDocumentContext _tagHelperDocumentContext = TagHelperDocumentContext.Create(tagHelpers: []);
+    private readonly TagHelperDocumentContext _tagHelperDocumentContext = TagHelperDocumentContext.GetOrCreate(tagHelpers: []);
     private readonly DirectiveAttributeTransitionCompletionItemProvider _provider = new(TestLanguageServerFeatureOptions.Instance);
 
     [Fact]