Remove allocations in BaseUriHelper, improve resource resolution performance

src/Microsoft.DotNet.Wpf/src/PresentationCore/MS/internal/FontCache/FontResourceCache.cs

@@ -1,4 +1,4 @@
-// Licensed to the .NET Foundation under one or more agreements.
+// 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.
 
@@ -59,19 +59,15 @@ internal static List<string> LookupFolder(Uri uri)
             // Perform a sanity check to make sure the assumption stays the same.
             Debug.Assert(uri.IsAbsoluteUri && uri.Scheme == PackUriHelper.UriSchemePack && BaseUriHelper.IsPackApplicationUri(uri));
 
-            Assembly uriAssembly;
-            string escapedPath;
-
-            BaseUriHelper.GetAssemblyAndPartNameFromPackAppUri(uri, out uriAssembly, out escapedPath);
-
+            BaseUriHelper.GetAssemblyAndPartNameFromPackAppUri(uri, out Assembly uriAssembly, out ReadOnlySpan<char> escapedPath);
             if (uriAssembly == null)
                 return null;
 
             // If we added a fake filename to the uri, remove it from the escaped path.
             if (isFolder)
             {
                 Debug.Assert(escapedPath.EndsWith(FakeFileName, StringComparison.OrdinalIgnoreCase));
-                escapedPath = escapedPath.Substring(0, escapedPath.Length - FakeFileName.Length);
+                escapedPath = escapedPath.Slice(0, escapedPath.Length - FakeFileName.Length);
             }
 
             Dictionary<string, List<string>> folderResourceMap;
@@ -86,8 +82,7 @@ internal static List<string> LookupFolder(Uri uri)
                 }
             }
 
-            List<string> ret;
-            folderResourceMap.TryGetValue(escapedPath, out ret);
+            folderResourceMap.GetAlternateLookup<ReadOnlySpan<char>>().TryGetValue(escapedPath, out List<string> ret);
             return ret;
         }
 
@@ -143,9 +138,8 @@ private static void AddResourceToFolderMap(Dictionary<string, List<string>> fold
             folderResourceMap[resourceFullName].Add(String.Empty);
         }
 
-        private static Dictionary<Assembly, Dictionary<string, List<string>>> _assemblyCaches
-            = new Dictionary<Assembly, Dictionary<string, List<string>>>(1);
         // Set the initial capacity to 1 because a single entry assembly is the most common case.
+        private static readonly Dictionary<Assembly, Dictionary<string, List<string>>> _assemblyCaches = new(1);
     }
 }
 

src/Microsoft.DotNet.Wpf/src/PresentationCore/MS/internal/Resources/ContentFileHelper.cs

@@ -17,16 +17,12 @@ namespace MS.Internal.Resources
     // </summary>
     internal static class ContentFileHelper
     {
-        internal static bool IsContentFile(string partName)
+        internal static bool IsContentFile(ReadOnlySpan<char> partName)
         {
-            if (_contentFiles == null)
+            s_contentFiles ??= GetContentFiles(BaseUriHelper.ResourceAssembly);
+            if (s_contentFiles is not null && s_contentFiles.Count > 0)
             {
-                _contentFiles = GetContentFiles(BaseUriHelper.ResourceAssembly);
-            }
-
-            if (_contentFiles != null && _contentFiles.Count > 0)
-            {                
-                if (_contentFiles.Contains(partName))
+                if (s_contentFiles.GetAlternateLookup<ReadOnlySpan<char>>().Contains(partName))
                 {
                     return true;
                 }
@@ -75,6 +71,6 @@ static internal HashSet<string> GetContentFiles(Assembly asm)
             return contentFiles;
         }
 
-        private static HashSet<string> _contentFiles;
+        private static HashSet<string> s_contentFiles;
     }
 }

src/Microsoft.DotNet.Wpf/src/PresentationCore/PresentationCore.csproj

@@ -344,6 +344,7 @@
     <Compile Include="System\Windows\BinaryFormat\ListConverterHelper.cs" />
     <Compile Include="System\Windows\BinaryFormat\FormatterConverterStub.cs" />
     <Compile Include="System\Windows\BinaryFormat\SerializationExtensions.cs" />
+    <Compile Include="System\Windows\Navigation\AssemblyPackageInfo.cs" />
     <Compile Include="System\Windows\Nrbf\SerializationRecordExtensions.cs" />
     <Compile Include="System\Windows\BinaryFormat\MessageEnd.cs" />
     <Compile Include="System\Windows\BinaryFormat\Record.cs" />

src/Microsoft.DotNet.Wpf/src/PresentationCore/System/Windows/Media/Effects/PixelShader.cs

@@ -76,7 +76,7 @@ private void UriSourcePropertyChangedHook(DependencyPropertyChangedEventArgs e)
                 {
                     if (!newUri.IsAbsoluteUri)
                     {
-                         newUri = BaseUriHelper.GetResolvedUri(BaseUriHelper.BaseUri, newUri);
+                         newUri = BaseUriHelper.GetResolvedUri(BaseUriHelper.PackAppBaseUri, newUri);
                     }
 
                     Debug.Assert(newUri.IsAbsoluteUri);

src/Microsoft.DotNet.Wpf/src/PresentationCore/System/Windows/Media/FontFamilyConverter.cs

@@ -91,14 +91,14 @@ public override object ConvertFrom(ITypeDescriptorContext context, CultureInfo c
 
                             if (!baseUri.IsAbsoluteUri)
                             {
-                                baseUri = new Uri(BaseUriHelper.BaseUri, baseUri);
+                                baseUri = new Uri(BaseUriHelper.PackAppBaseUri, baseUri);
                             }
                         }
                         else
                         {
                             // If we reach here, the base uri we got from IUriContext is "".
                             // Here we resolve it to application's base
-                            baseUri = BaseUriHelper.BaseUri;
+                            baseUri = BaseUriHelper.PackAppBaseUri;
                         }
                     }
                 }

src/Microsoft.DotNet.Wpf/src/PresentationCore/System/Windows/Navigation/AssemblyPackageInfo.cs

@@ -0,0 +1,34 @@
+// 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.
+
+namespace System.Windows.Navigation
+{
+    /// <summary>
+    /// Holds slices of pack/application URIs and exposes each slice through a property.
+    /// </summary>
+    /// <remarks>This should be dissected from relative URIs in format /AssemblyShortName{;Version]{;PublicKey];component/PackagePartName</remarks>
+    internal ref struct AssemblyPackageInfo
+    {
+        /// <summary>
+        /// Specifies the name of the package/resource.
+        /// </summary>
+        internal ReadOnlySpan<char> PackagePartName { get; set; }
+
+        /// <summary>
+        /// Holds Assembly.Name-like slice if specified, may be empty.
+        /// </summary>
+        /// <remarks>The slice is without leading forward slash ('/').</remarks>
+        internal ReadOnlySpan<char> AssemblyName { get; set; }
+        /// <summary>
+        /// Holds Assembly.Version if specified, may be empty.
+        /// </summary>
+        /// <remarks>The slice is without 'v' prefix.</remarks>
+        internal ReadOnlySpan<char> AssemblyVersion { get; set; }
+        /// <summary>
+        /// Holds Assembly.PublicKeyToken if specified, often is empty.
+        /// </summary>
+        internal ReadOnlySpan<char> AssemblyToken { get; set; }
+
+    }
+}