Merge pull request #48356 from sharwell/perf-1224834

Implement low-hanging performance improvements from feedback investigation

src/CodeStyle/Core/CodeFixes/LanguageServices/SemanticModelWorkspaceService/SemanticModelWorkspaceServiceFactory.SemanticModelWorkspaceService.cs

@@ -17,7 +17,7 @@ public SemanticModelReuseWorkspaceService(Workspace _)
             {
             }
 
-            public Task<SemanticModel> ReuseExistingSpeculativeModelAsync(Document document, SyntaxNode node, CancellationToken cancellationToken)
+            public ValueTask<SemanticModel> ReuseExistingSpeculativeModelAsync(Document document, SyntaxNode node, CancellationToken cancellationToken)
             {
                 // TODO: port the GetSemanticModelForNodeAsync implementation from Workspaces layer,
                 // which currently relies on a bunch of internal APIs.

src/Compilers/Core/CodeAnalysisTest/InternalUtilities/ConcurrentDictionaryExtensionsTests.cs

@@ -0,0 +1,39 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System;
+using System.Collections.Concurrent;
+using Roslyn.Utilities;
+using Xunit;
+
+namespace Microsoft.CodeAnalysis.UnitTests.InternalUtilities
+{
+    public class ConcurrentDictionaryExtensionsTests
+    {
+        [Fact]
+        public void TestAdd()
+        {
+            var dictionary = new ConcurrentDictionary<int, int>();
+            dictionary.Add(0, 0);
+            Assert.Equal(0, dictionary[0]);
+
+            Assert.Throws<ArgumentException>(() => dictionary.Add(0, 0));
+        }
+
+        [Fact]
+        public void TestGetOrAdd()
+        {
+            var first = new object();
+            var second = new object();
+
+            var dictionary = new ConcurrentDictionary<int, object>();
+            Assert.Same(first, dictionary.GetOrAdd(0, static (key, arg) => arg, first));
+            Assert.Same(first, dictionary[0]);
+            Assert.Single(dictionary);
+            Assert.Same(first, dictionary.GetOrAdd(0, static (key, arg) => arg, second));
+            Assert.Same(first, dictionary[0]);
+            Assert.Single(dictionary);
+        }
+    }
+}

src/Compilers/Core/Portable/InternalUtilities/ConcurrentDictionaryExtensions.cs

@@ -2,7 +2,9 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+using System;
 using System.Collections.Concurrent;
+using Microsoft.CodeAnalysis.PooledObjects;
 
 namespace Roslyn.Utilities
 {
@@ -19,8 +21,22 @@ public static void Add<K, V>(this ConcurrentDictionary<K, V> dict, K key, V valu
         {
             if (!dict.TryAdd(key, value))
             {
-                throw new System.ArgumentException("adding a duplicate");
+                throw new ArgumentException("adding a duplicate", nameof(key));
             }
         }
+
+        public static TValue GetOrAdd<TKey, TArg, TValue>(this ConcurrentDictionary<TKey, TValue> dictionary, TKey key, Func<TKey, TArg, TValue> valueFactory, TArg factoryArgument)
+            where TKey : notnull
+        {
+#if NETCOREAPP
+            return dictionary.GetOrAdd(key, valueFactory, factoryArgument);
+#else
+            if (dictionary.TryGetValue(key, out var value))
+                return value;
+
+            using var _ = PooledDelegates.GetPooledFunction(valueFactory, factoryArgument, out var boundFunction);
+            return dictionary.GetOrAdd(key, boundFunction);
+#endif
+        }
     }
 }

src/EditorFeatures/TestUtilities/ChangeSignature/AddedParameterOrExistingIndex.cs

@@ -61,7 +61,7 @@ public override string ToString()
 
         internal AddedParameter GetAddedParameter(Document document)
         {
-            var semanticModel = document.GetRequiredSemanticModelAsync(CancellationToken.None).Result;
+            var semanticModel = document.GetRequiredSemanticModelAsync(CancellationToken.None).AsTask().Result;
 
             var type = document.Project.Language switch
             {

src/Features/Core/Portable/ChangeSignature/DelegateInvokeMethodReferenceFinder.cs

@@ -71,7 +71,7 @@ protected override Task<ImmutableArray<Document>> DetermineDocumentsToSearchAsyn
             return Task.FromResult(project.Documents.ToImmutableArray());
         }
 
-        protected override async Task<ImmutableArray<FinderLocation>> FindReferencesInDocumentAsync(
+        protected override async ValueTask<ImmutableArray<FinderLocation>> FindReferencesInDocumentAsync(
             IMethodSymbol methodSymbol,
             Document document,
             SemanticModel semanticModel,

src/Features/Core/Portable/Completion/Providers/ImportCompletionProvider/ExtensionMethodImportCompletionHelper.ExtensionMethodSymbolComputer.cs

@@ -84,7 +84,7 @@ public Task PopulateIndicesAsync(CancellationToken cancellationToken)
                 foreach (var peReference in GetAllRelevantPeReferences())
                 {
                     tasks.Add(Task.Run(()
-                        => SymbolTreeInfo.GetInfoForMetadataReferenceAsync(Solution, peReference, loadOnly: false, cancellationToken), cancellationToken));
+                        => SymbolTreeInfo.GetInfoForMetadataReferenceAsync(Solution, peReference, loadOnly: false, cancellationToken).AsTask(), cancellationToken));
                 }
 
                 return Task.WhenAll(tasks.ToImmutable());
@@ -100,7 +100,7 @@ public Task PopulateIndicesAsync(CancellationToken cancellationToken)
                     tasks.Add(Task.Run(() => GetExtensionMethodSymbolsFromPeReferenceAsync(
                         peReference,
                         forceIndexCreation,
-                        cancellationToken), cancellationToken));
+                        cancellationToken).AsTask(), cancellationToken));
                 }
 
                 foreach (var project in GetAllRelevantProjects())
@@ -184,7 +184,7 @@ private ImmutableArray<PortableExecutableReference> GetAllRelevantPeReferences()
                     : GetExtensionMethodsForSymbolsFromDifferentCompilation(matchingMethodSymbols, cancellationToken);
             }
 
-            private async Task<ImmutableArray<IMethodSymbol>?> GetExtensionMethodSymbolsFromPeReferenceAsync(
+            private async ValueTask<ImmutableArray<IMethodSymbol>?> GetExtensionMethodSymbolsFromPeReferenceAsync(
                 PortableExecutableReference peReference,
                 bool forceIndexCreation,
                 CancellationToken cancellationToken)

src/Features/Core/Portable/IncrementalCaches/SymbolTreeInfoCacheService.cs

@@ -29,7 +29,7 @@ public SymbolTreeInfoCacheService(
                 _metadataIdToInfo = metadataIdToInfo;
             }
 
-            public async Task<SymbolTreeInfo> TryGetMetadataSymbolTreeInfoAsync(
+            public async ValueTask<SymbolTreeInfo> TryGetMetadataSymbolTreeInfoAsync(
                 Solution solution,
                 PortableExecutableReference reference,
                 CancellationToken cancellationToken)

src/VisualStudio/Core/Def/Implementation/AbstractEditorFactory.cs

@@ -321,7 +321,7 @@ private void FormatDocumentCreatedFromTemplate(IVsHierarchy hierarchy, uint item
 
             // Organize using directives
             addedDocument = ThreadHelper.JoinableTaskFactory.Run(() => OrganizeUsingsCreatedFromTemplateAsync(addedDocument, cancellationToken));
-            rootToFormat = ThreadHelper.JoinableTaskFactory.Run(() => addedDocument.GetRequiredSyntaxRootAsync(cancellationToken));
+            rootToFormat = ThreadHelper.JoinableTaskFactory.Run(() => addedDocument.GetRequiredSyntaxRootAsync(cancellationToken).AsTask());
 
             // Format document
             var unformattedText = addedDocument.GetTextSynchronously(cancellationToken);

src/VisualStudio/Core/Def/Implementation/ChangeSignature/AddParameterDialogViewModel.cs

@@ -27,7 +27,7 @@ internal class AddParameterDialogViewModel : AbstractNotifyPropertyChanged
         public AddParameterDialogViewModel(Document document, int positionForTypeBinding)
         {
             _notificationService = document.Project.Solution.Workspace.Services.GetService<INotificationService>();
-            _semanticModel = document.GetRequiredSemanticModelAsync(CancellationToken.None).WaitAndGetResult_CanCallOnBackground(CancellationToken.None);
+            _semanticModel = document.GetRequiredSemanticModelAsync(CancellationToken.None).AsTask().WaitAndGetResult_CanCallOnBackground(CancellationToken.None);
 
             TypeIsEmptyImage = Visibility.Visible;
             TypeBindsImage = Visibility.Collapsed;

src/Workspaces/Core/Portable/ExternalAccess/Pythia/Api/PythiaDocumentExtensions.cs

@@ -11,6 +11,6 @@ namespace Microsoft.CodeAnalysis.ExternalAccess.Pythia.Api
     internal static class PythiaDocumentExtensions
     {
         public static Task<SemanticModel> GetSemanticModelForNodeAsync(this Document document, SyntaxNode? node, CancellationToken cancellationToken)
-            => DocumentExtensions.ReuseExistingSpeculativeModelAsync(document, node, cancellationToken);
+            => DocumentExtensions.ReuseExistingSpeculativeModelAsync(document, node, cancellationToken).AsTask();
     }
 }

src/Workspaces/Core/Portable/FindSymbols/FindReferences/FindReferenceCache.cs

@@ -12,6 +12,7 @@
 using System.Linq;
 using System.Threading;
 using Microsoft.CodeAnalysis.LanguageServices;
+using Microsoft.CodeAnalysis.PooledObjects;
 using Microsoft.CodeAnalysis.Shared.Extensions;
 using Microsoft.CodeAnalysis.Text;
 using Roslyn.Utilities;
@@ -32,7 +33,7 @@ public static SymbolInfo GetSymbolInfo(SemanticModel model, SyntaxNode node, Can
                 return model.GetSymbolInfo(node, cancellationToken);
             }
 
-            return nodeCache.GetOrAdd(node, n => model.GetSymbolInfo(n, cancellationToken));
+            return nodeCache.GetOrAdd(node, static (n, arg) => arg.model.GetSymbolInfo(n, arg.cancellationToken), (model, cancellationToken));
         }
 
         public static IAliasSymbol GetAliasInfo(
@@ -84,25 +85,34 @@ public static ImmutableArray<SyntaxToken> GetIdentifierOrGlobalNamespaceTokensWi
                     syntaxFacts, root, sourceText, key, cancellationToken));
         }
 
+        [PerformanceSensitive("https://devdiv.visualstudio.com/DevDiv/_workitems/edit/1224834", AllowCaptures = false)]
         private static ImmutableArray<SyntaxToken> GetIdentifierOrGlobalNamespaceTokensWithText(
             ISyntaxFactsService syntaxFacts, SyntaxNode root, SourceText sourceText,
             string text, CancellationToken cancellationToken)
         {
-            // identifier is not escaped
             if (sourceText != null)
             {
-                return GetTokensFromText(syntaxFacts, root, sourceText, text, IsCandidate, cancellationToken);
+                // identifier is not escaped
+                Func<SyntaxToken, ISyntaxFactsService, string, bool> isCandidate = static (t, syntaxFacts, text) => IsCandidate(t, syntaxFacts, text);
+                return GetTokensFromText(syntaxFacts, root, sourceText, text, isCandidate, cancellationToken);
             }
+            else
+            {
+                // identifier is escaped
+                using var _ = PooledDelegates.GetPooledFunction<SyntaxToken, (ISyntaxFactsService syntaxFacts, string text), bool>(
+                    static (t, arg) => IsCandidate(t, arg.syntaxFacts, arg.text),
+                    (syntaxFacts, text),
+                    out var isCandidate);
 
-            // identifier is escaped
-            return root.DescendantTokens(descendIntoTrivia: true).Where(IsCandidate).ToImmutableArray();
+                return root.DescendantTokens(descendIntoTrivia: true).Where(isCandidate).ToImmutableArray();
+            }
 
-            bool IsCandidate(SyntaxToken t)
+            static bool IsCandidate(SyntaxToken t, ISyntaxFactsService syntaxFacts, string text)
                 => syntaxFacts.IsGlobalNamespaceKeyword(t) || (syntaxFacts.IsIdentifier(t) && syntaxFacts.TextMatch(t.ValueText, text));
         }
 
         private static ImmutableArray<SyntaxToken> GetTokensFromText(
-            ISyntaxFactsService syntaxFacts, SyntaxNode root, SourceText content, string text, Func<SyntaxToken, bool> candidate, CancellationToken cancellationToken)
+            ISyntaxFactsService syntaxFacts, SyntaxNode root, SourceText content, string text, Func<SyntaxToken, ISyntaxFactsService, string, bool> candidate, CancellationToken cancellationToken)
         {
             if (text.Length == 0)
             {
@@ -120,7 +130,7 @@ private static ImmutableArray<SyntaxToken> GetTokensFromText(
 
                 var token = root.FindToken(index, findInsideTrivia: true);
                 var span = token.Span;
-                if (!token.IsMissing && span.Start == index && span.Length == text.Length && candidate(token))
+                if (!token.IsMissing && span.Start == index && span.Length == text.Length && candidate(token, syntaxFacts, text))
                 {
                     result.Add(token);
                 }

src/Workspaces/Core/Portable/FindSymbols/FindReferences/Finders/AbstractMemberScopedReferenceFinder.cs

@@ -47,7 +47,7 @@ protected override Task<ImmutableArray<Document>> DetermineDocumentsToSearchAsyn
             return Task.FromResult(ImmutableArray.Create(document));
         }
 
-        protected override async Task<ImmutableArray<FinderLocation>> FindReferencesInDocumentAsync(
+        protected override async ValueTask<ImmutableArray<FinderLocation>> FindReferencesInDocumentAsync(
             TSymbol symbol,
             Document document,
             SemanticModel semanticModel,

src/Workspaces/Core/Portable/FindSymbols/FindReferences/Finders/AbstractReferenceFinder.cs

@@ -34,7 +34,7 @@ public abstract Task<ImmutableArray<ISymbol>> DetermineCascadedSymbolsAsync(
         public abstract Task<ImmutableArray<Document>> DetermineDocumentsToSearchAsync(
             ISymbol symbol, Project project, IImmutableSet<Document> documents, FindReferencesSearchOptions options, CancellationToken cancellationToken);
 
-        public abstract Task<ImmutableArray<FinderLocation>> FindReferencesInDocumentAsync(
+        public abstract ValueTask<ImmutableArray<FinderLocation>> FindReferencesInDocumentAsync(
             ISymbol symbol, Document document, SemanticModel semanticModel, FindReferencesSearchOptions options, CancellationToken cancellationToken);
 
         protected static bool TryGetNameWithoutAttributeSuffix(
@@ -149,7 +149,7 @@ protected static Task<ImmutableArray<Document>> FindDocumentsAsync(
         protected static bool IdentifiersMatch(ISyntaxFactsService syntaxFacts, string name, SyntaxToken token)
             => syntaxFacts.IsIdentifier(token) && syntaxFacts.TextMatch(token.ValueText, name);
 
-        protected static Task<ImmutableArray<FinderLocation>> FindReferencesInDocumentUsingIdentifierAsync(
+        protected static ValueTask<ImmutableArray<FinderLocation>> FindReferencesInDocumentUsingIdentifierAsync(
             ISymbol symbol,
             string identifier,
             Document document,
@@ -161,7 +161,7 @@ protected static Task<ImmutableArray<FinderLocation>> FindReferencesInDocumentUs
                 cancellationToken: cancellationToken);
         }
 
-        protected static Task<ImmutableArray<FinderLocation>> FindReferencesInDocumentUsingIdentifierAsync(
+        protected static ValueTask<ImmutableArray<FinderLocation>> FindReferencesInDocumentUsingIdentifierAsync(
             ISymbol symbol,
             string identifier,
             Document document,
@@ -174,7 +174,7 @@ protected static Task<ImmutableArray<FinderLocation>> FindReferencesInDocumentUs
                 symbol, identifier, document, semanticModel, symbolsMatch, cancellationToken);
         }
 
-        protected static Task<ImmutableArray<FinderLocation>> FindReferencesInDocumentUsingIdentifierAsync(
+        protected static ValueTask<ImmutableArray<FinderLocation>> FindReferencesInDocumentUsingIdentifierAsync(
             ISymbol symbol,
             string identifier,
             Document document,
@@ -188,7 +188,8 @@ protected static Task<ImmutableArray<FinderLocation>> FindReferencesInDocumentUs
                 docCommentId, findInGlobalSuppressions, cancellationToken);
         }
 
-        protected static async Task<ImmutableArray<FinderLocation>> FindReferencesInDocumentUsingIdentifierAsync(
+        [PerformanceSensitive("https://devdiv.visualstudio.com/DevDiv/_workitems/edit/1224834", OftenCompletesSynchronously = true)]
+        protected static async ValueTask<ImmutableArray<FinderLocation>> FindReferencesInDocumentUsingIdentifierAsync(
             string identifier,
             Document document,
             SemanticModel semanticModel,
@@ -900,7 +901,7 @@ protected abstract Task<ImmutableArray<Document>> DetermineDocumentsToSearchAsyn
             TSymbol symbol, Project project, IImmutableSet<Document> documents,
             FindReferencesSearchOptions options, CancellationToken cancellationToken);
 
-        protected abstract Task<ImmutableArray<FinderLocation>> FindReferencesInDocumentAsync(
+        protected abstract ValueTask<ImmutableArray<FinderLocation>> FindReferencesInDocumentAsync(
             TSymbol symbol, Document document, SemanticModel semanticModel,
             FindReferencesSearchOptions options, CancellationToken cancellationToken);
 
@@ -920,13 +921,13 @@ public override Task<ImmutableArray<Document>> DetermineDocumentsToSearchAsync(
                 : SpecializedTasks.EmptyImmutableArray<Document>();
         }
 
-        public override Task<ImmutableArray<FinderLocation>> FindReferencesInDocumentAsync(
+        public override ValueTask<ImmutableArray<FinderLocation>> FindReferencesInDocumentAsync(
             ISymbol symbol, Document document, SemanticModel semanticModel,
             FindReferencesSearchOptions options, CancellationToken cancellationToken)
         {
             return symbol is TSymbol typedSymbol && CanFind(typedSymbol)
                 ? FindReferencesInDocumentAsync(typedSymbol, document, semanticModel, options, cancellationToken)
-                : SpecializedTasks.EmptyImmutableArray<FinderLocation>();
+                : new ValueTask<ImmutableArray<FinderLocation>>(ImmutableArray<FinderLocation>.Empty);
         }
 
         public override Task<ImmutableArray<ISymbol>> DetermineCascadedSymbolsAsync(
@@ -959,7 +960,7 @@ protected virtual Task<ImmutableArray<ISymbol>> DetermineCascadedSymbolsAsync(
             return SpecializedTasks.EmptyImmutableArray<ISymbol>();
         }
 
-        protected static Task<ImmutableArray<FinderLocation>> FindReferencesInDocumentUsingSymbolNameAsync(
+        protected static ValueTask<ImmutableArray<FinderLocation>> FindReferencesInDocumentUsingSymbolNameAsync(
             TSymbol symbol,
             Document document,
             SemanticModel semanticModel,
@@ -1002,7 +1003,7 @@ protected static ValueTask<ImmutableArray<FinderLocation>> FindReferencesInToken
                 cancellationToken);
         }
 
-        protected static Task<ImmutableArray<FinderLocation>> FindReferencesInDocumentAsync(
+        protected static ValueTask<ImmutableArray<FinderLocation>> FindReferencesInDocumentAsync(
             TSymbol symbol,
             Document document,
             SemanticModel semanticModel,
@@ -1014,7 +1015,7 @@ protected static Task<ImmutableArray<FinderLocation>> FindReferencesInDocumentAs
                 findParentNode: null, cancellationToken: cancellationToken);
         }
 
-        protected static Task<ImmutableArray<FinderLocation>> FindReferencesInDocumentAsync(
+        protected static ValueTask<ImmutableArray<FinderLocation>> FindReferencesInDocumentAsync(
             TSymbol symbol,
             Document document,
             SemanticModel semanticModel,
@@ -1028,7 +1029,7 @@ protected static Task<ImmutableArray<FinderLocation>> FindReferencesInDocumentAs
                 symbolsMatchAsync, docCommentId, findInGlobalSuppressions, cancellationToken);
         }
 
-        protected static async Task<ImmutableArray<FinderLocation>> FindReferencesInDocumentAsync(
+        protected static async ValueTask<ImmutableArray<FinderLocation>> FindReferencesInDocumentAsync(
             Document document,
             SemanticModel semanticModel,
             Func<SyntaxToken, bool> tokensMatch,