Reduce allocations in SolutionParser by 80-90% and cut CPU time 40-70%

src/Build.UnitTests/Construction/ProjectInSolution_Tests.cs

@@ -0,0 +1,30 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using Xunit;
+
+namespace Microsoft.Build.Construction;
+
+public sealed class ProjectInSolution_Tests
+{
+    [Theory]
+    [InlineData("", "")]
+    [InlineData("Hello", "Hello")]
+    [InlineData("Hello.world", "Hello_world")]
+    [InlineData("Hello_world", "Hello_world")]
+    [InlineData("Hello (world)", "Hello _world_")]
+    [InlineData("It's 99.9% bug free", "It_s 99_9_ bug free")]
+    [InlineData("%$@;.()'", "________")]
+    public void CleanseProjectName(string input, string expected)
+    {
+        // Disallowed characters are: %$@;.()'
+        string actual = ProjectInSolution.CleanseProjectName(input);
+
+        Assert.Equal(expected, actual);
+
+        if (input == expected)
+        {
+            Assert.Same(input, actual);
+        }
+    }
+}

src/Build.UnitTests/Microsoft.Build.Engine.UnitTests.csproj

@@ -19,7 +19,7 @@
     <PackageReference Include="Shouldly" />
     <PackageReference Include="System.Net.Http" />
     <PackageReference Include="Microsoft.CodeAnalysis.Build.Tasks" />
-    <PackageReference Include="NuGet.Frameworks" >
+    <PackageReference Include="NuGet.Frameworks">
       <PrivateAssets>all</PrivateAssets>
     </PackageReference>
 
@@ -80,9 +80,6 @@
     <Compile Include="..\UnitTests.Shared\RunnerUtilities.cs">
       <ExcludeFromStyleCop>true</ExcludeFromStyleCop>
     </Compile>
-    <Compile Include="..\Shared\UnitTests\StreamHelpers.cs">
-      <ExcludeFromStyleCop>true</ExcludeFromStyleCop>
-    </Compile>
     <Compile Include="..\Shared\UnitTests\EngineTestEnvironment.cs">
       <Link>EngineTestEnvironment.cs</Link>
     </Compile>

src/Build/BackEnd/Components/ProjectCache/ProjectCacheService.cs

@@ -21,6 +21,7 @@
 using Microsoft.Build.Graph;
 using Microsoft.Build.Internal;
 using Microsoft.Build.Shared;
+using Microsoft.NET.StringTools;
 
 namespace Microsoft.Build.Experimental.ProjectCache
 {
@@ -549,6 +550,8 @@ static IReadOnlyCollection<ProjectGraphEntryPoint> GenerateGraphEntryPointsFromS
                     return Array.Empty<ProjectGraphEntryPoint>();
                 }
 
+                StringPool pool = new();
+
                 var graphEntryPoints = new List<ProjectGraphEntryPoint>(projectConfigurations.Count);
 
                 foreach (XmlElement projectConfiguration in projectConfigurations)
@@ -569,7 +572,7 @@ static IReadOnlyCollection<ProjectGraphEntryPoint> GenerateGraphEntryPointsFromS
 
                     string projectPath = projectPathAttribute!.Value;
 
-                    (string configuration, string platform) = SolutionFile.ParseConfigurationName(projectConfiguration.InnerText, definingProjectPath, 0, solutionConfigurationXml);
+                    (string configuration, string platform) = SolutionFile.ParseConfigurationName(projectConfiguration.InnerText.AsSpan(), definingProjectPath, 0, solutionConfigurationXml.AsSpan(), pool);
 
                     // Take the defining project global properties and override the configuration and platform.
                     // It's sufficient to only set Configuration and Platform.

src/Build/Construction/Solution/ProjectConfigurationInSolution.cs

@@ -3,24 +3,23 @@
 
 using System;
 
-#nullable disable
-
 namespace Microsoft.Build.Construction
 {
     /// <summary>
     /// This class represents an entry for a project configuration in a solution configuration.
     /// </summary>
     public sealed class ProjectConfigurationInSolution
     {
+        private string? _fullName;
+
         /// <summary>
-        /// Constructor
+        /// Initializes a new instance of the <see cref="ProjectConfigurationInSolution"/> class.
         /// </summary>
         internal ProjectConfigurationInSolution(string configurationName, string platformName, bool includeInBuild)
         {
             ConfigurationName = configurationName;
             PlatformName = RemoveSpaceFromAnyCpuPlatform(platformName);
             IncludeInBuild = includeInBuild;
-            FullName = SolutionConfigurationInSolution.ComputeFullName(ConfigurationName, PlatformName);
         }
 
         /// <summary>
@@ -36,7 +35,7 @@ internal ProjectConfigurationInSolution(string configurationName, string platfor
         /// <summary>
         /// The full name of this configuration - e.g. "Debug|Any CPU"
         /// </summary>
-        public string FullName { get; }
+        public string FullName => _fullName ??= SolutionConfigurationInSolution.ComputeFullName(ConfigurationName, PlatformName);
 
         /// <summary>
         /// True if this project configuration should be built as part of its parent solution configuration

src/Build/Construction/Solution/ProjectInSolution.cs

@@ -90,19 +90,18 @@ public sealed class ProjectInSolution
         /// </summary>
         internal static readonly string[] projectNamesToDisambiguate = { "Build", "Rebuild", "Clean", "Publish" };
 
-        /// <summary>
-        /// Character that will be used to replace 'unclean' ones.
-        /// </summary>
-        private const char cleanCharacter = '_';
-
         #endregion
+
         #region Member data
+
         private string _relativePath;         // Relative from .SLN file.  For example, "WindowsApplication1\WindowsApplication1.csproj"
         private string _absolutePath;         // Absolute path to the project file
         private readonly List<string> _dependencies;     // A list of strings representing the Guids of the dependent projects.
         private IReadOnlyList<string> _dependenciesAsReadonly;
+        private Hashtable _aspNetConfigurations; // Lazily allocated collection, as this is rarely populated or read
         private string _uniqueProjectName;    // For example, "MySlnFolder\MySubSlnFolder\Windows_Application1"
         private string _originalProjectName;    // For example, "MySlnFolder\MySubSlnFolder\Windows.Application1"
+        private List<string> _projectReferences;
 
         /// <summary>
         /// The project configuration in given solution configuration
@@ -130,9 +129,6 @@ internal ProjectInSolution(SolutionFile solution)
             // default to .NET Framework 3.5 if this is an old solution that doesn't explicitly say.
             TargetFrameworkMoniker = ".NETFramework,Version=v3.5";
 
-            // This hashtable stores a AspNetCompilerParameters struct for each configuration name supported.
-            AspNetConfigurations = new Hashtable(StringComparer.OrdinalIgnoreCase);
-
             _projectConfigurations = new Dictionary<string, ProjectConfigurationInSolution>(StringComparer.OrdinalIgnoreCase);
         }
 
@@ -243,12 +239,17 @@ public IReadOnlyDictionary<string, ProjectConfigurationInSolution> ProjectConfig
         /// either specified as Dependencies above, or as ProjectReferences in the
         /// project file, which the solution doesn't have insight into. 
         /// </summary>
-        internal List<string> ProjectReferences { get; } = new List<string>();
+        internal List<string> ProjectReferences => _projectReferences ??= new();
 
         internal SolutionFile ParentSolution { get; set; }
 
         // Key is configuration name, value is [struct] AspNetCompilerParameters
-        internal Hashtable AspNetConfigurations { get; set; }
+        // This hashtable stores a AspNetCompilerParameters struct for each configuration name supported.
+        internal Hashtable AspNetConfigurations
+        {
+            get => _aspNetConfigurations ??= new Hashtable(StringComparer.OrdinalIgnoreCase);
+            set => _aspNetConfigurations = value;
+        }
 
         internal string TargetFrameworkMoniker { get; set; }
 
@@ -391,7 +392,7 @@ internal string GetUniqueProjectName()
             if (_uniqueProjectName == null)
             {
                 // EtpSubProject and Venus projects have names that are already unique.  No need to prepend the SLN folder.
-                if ((ProjectType == SolutionProjectType.WebProject) || (ProjectType == SolutionProjectType.EtpSubProject))
+                if (ProjectType is SolutionProjectType.WebProject or SolutionProjectType.EtpSubProject)
                 {
                     _uniqueProjectName = CleanseProjectName(ProjectName);
                 }
@@ -430,7 +431,7 @@ internal string GetOriginalProjectName()
             if (_originalProjectName == null)
             {
                 // EtpSubProject and Venus projects have names that are already unique.  No need to prepend the SLN folder.
-                if ((ProjectType == SolutionProjectType.WebProject) || (ProjectType == SolutionProjectType.EtpSubProject))
+                if (ProjectType is SolutionProjectType.WebProject or SolutionProjectType.EtpSubProject)
                 {
                     _originalProjectName = ProjectName;
                 }
@@ -486,25 +487,28 @@ internal void UpdateUniqueProjectName(string newUniqueName)
         /// </summary>
         /// <param name="projectName">The name to be cleansed</param>
         /// <returns>string</returns>
-        private static string CleanseProjectName(string projectName)
+        internal static string CleanseProjectName(string projectName)
         {
             ErrorUtilities.VerifyThrow(projectName != null, "Null strings not allowed.");
 
             // If there are no special chars, just return the original string immediately.
             // Don't even instantiate the StringBuilder.
             int indexOfChar = projectName.IndexOfAny(s_charsToCleanse);
+
             if (indexOfChar == -1)
             {
+                // No illegal character exists in the name, so return the input unchanged.
                 return projectName;
             }
 
             // This is where we're going to work on the final string to return to the caller.
-            var cleanProjectName = new StringBuilder(projectName);
+            StringBuilder cleanProjectName = new(projectName);
 
-            // Replace each unclean character with a clean one            
-            foreach (char uncleanChar in s_charsToCleanse)
+            while (indexOfChar != -1)
             {
-                cleanProjectName.Replace(uncleanChar, cleanCharacter);
+                cleanProjectName[indexOfChar] = '_';
+
+                indexOfChar = projectName.IndexOfAny(s_charsToCleanse, indexOfChar + 1);
             }
 
             return cleanProjectName.ToString();

src/Build/Construction/Solution/SolutionConfigurationInSolution.cs

@@ -1,7 +1,7 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
-#nullable disable
+using System.Collections.Immutable;
 
 namespace Microsoft.Build.Construction
 {
@@ -10,13 +10,9 @@ namespace Microsoft.Build.Construction
     /// </summary>
     public sealed class SolutionConfigurationInSolution
     {
-        /// <summary>
-        /// Default separator between configuration and platform in configuration
-        /// full names
-        /// </summary>
-        internal const char ConfigurationPlatformSeparator = '|';
+        private static ImmutableDictionary<Key, string> _fullNameByKey = ImmutableDictionary<Key, string>.Empty;
 
-        internal static readonly char[] ConfigurationPlatformSeparatorArray = { '|' };
+        private string? _fullName;
 
         /// <summary>
         /// Constructor
@@ -25,7 +21,6 @@ internal SolutionConfigurationInSolution(string configurationName, string platfo
         {
             ConfigurationName = configurationName;
             PlatformName = platformName;
-            FullName = ComputeFullName(configurationName, platformName);
         }
 
         /// <summary>
@@ -41,20 +36,26 @@ internal SolutionConfigurationInSolution(string configurationName, string platfo
         /// <summary>
         /// The full name of this configuration - e.g. "Debug|Any CPU"
         /// </summary>
-        public string FullName { get; }
+        public string FullName => _fullName ??= ComputeFullName(ConfigurationName, PlatformName);
 
         /// <summary>
-        /// Given a configuration name and a platform name, compute the full name 
-        /// of this configuration
+        /// Given a configuration name and a platform name, compute the full name
+        /// of this configuration.
         /// </summary>
         internal static string ComputeFullName(string configurationName, string platformName)
         {
             // Some configurations don't have the platform part
-            if (!string.IsNullOrEmpty(platformName))
+            if (string.IsNullOrEmpty(platformName))
             {
-                return $"{configurationName}{ConfigurationPlatformSeparator}{platformName}";
+                return configurationName;
             }
-            return configurationName;
+
+            return ImmutableInterlocked.GetOrAdd(
+                ref _fullNameByKey,
+                new Key(configurationName, platformName),
+                static key => $"{key.Configuration}|{key.Platform}");
         }
+
+        private record struct Key(string Configuration, string Platform);
     }
 }