Implement new SmallCapacityDictionary for dictionaries with a small amount of values.

src/Http/Http.Abstractions/src/Routing/RouteValueDictionary.cs

@@ -19,7 +19,7 @@ namespace Microsoft.AspNetCore.Routing
     public class RouteValueDictionary : IDictionary<string, object?>, IReadOnlyDictionary<string, object?>
     {
         // 4 is a good default capacity here because that leaves enough space for area/controller/action/id
-        private const int DefaultCapacity = 4;
+        private readonly int DefaultCapacity = 4;
 
         internal KeyValuePair<string, object?>[] _arrayStorage;
         internal PropertyStorage? _propertyStorage;

src/Http/Http/perf/Microbenchmarks/Microsoft.AspNetCore.Http.Microbenchmarks.csproj

@@ -11,7 +11,6 @@
   <ItemGroup>
     <Reference Include="BenchmarkDotNet" />
     <Reference Include="Microsoft.AspNetCore.Http" />
-
     <Compile Include="$(SharedSourceRoot)BenchmarkRunner\*.cs" />
   </ItemGroup>
 

src/Http/Http/perf/Microbenchmarks/SmallCapacityDictionaryBenchmark.cs

@@ -0,0 +1,150 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
+using System.Collections.Generic;
+using BenchmarkDotNet.Attributes;
+using Microsoft.AspNetCore.Internal.Dictionary;
+
+namespace Microsoft.AspNetCore.Http
+{
+    public class SmallCapacityDictionaryBenchmark
+    {
+        private SmallCapacityDictionary<string, string> _smallCapDict;
+        private SmallCapacityDictionary<string, string> _smallCapDictFour;
+        private SmallCapacityDictionary<string, string> _smallCapDictTen;
+        private Dictionary<string, string> _dict;
+        private Dictionary<string, string> _dictFour;
+        private Dictionary<string, string> _dictTen;
+
+        private KeyValuePair<string, string> _oneValue;
+        private List<KeyValuePair<string, string>> _fourValues;
+        private List<KeyValuePair<string, string>> _tenValues;
+
+        [IterationSetup]
+        public void Setup()
+        {
+            _oneValue = new KeyValuePair<string, string>("a", "b");
+
+            _fourValues = new List<KeyValuePair<string, string>>()
+            {
+                new KeyValuePair<string, string>("a", "b"),
+                new KeyValuePair<string, string>("c", "d"),
+                new KeyValuePair<string, string>("e", "f"),
+                new KeyValuePair<string, string>("g", "h"),
+            };
+
+            _tenValues = new List<KeyValuePair<string, string>>()
+            {
+                new KeyValuePair<string, string>("a", "b"),
+                new KeyValuePair<string, string>("c", "d"),
+                new KeyValuePair<string, string>("e", "f"),
+                new KeyValuePair<string, string>("g", "h"),
+                new KeyValuePair<string, string>("i", "j"),
+                new KeyValuePair<string, string>("k", "l"),
+                new KeyValuePair<string, string>("m", "n"),
+                new KeyValuePair<string, string>("o", "p"),
+                new KeyValuePair<string, string>("q", "r"),
+                new KeyValuePair<string, string>("s", "t"),
+            };
+
+            _smallCapDict = new SmallCapacityDictionary<string, string>(capacity: 1, StringComparer.OrdinalIgnoreCase);
+            _smallCapDictFour = new SmallCapacityDictionary<string, string>(capacity: 4, StringComparer.OrdinalIgnoreCase);
+            _smallCapDictTen = new SmallCapacityDictionary<string, string>(capacity: 10, StringComparer.OrdinalIgnoreCase);
+            _dict = new Dictionary<string, string>(1, StringComparer.OrdinalIgnoreCase);
+            _dictFour = new Dictionary<string, string>(4, StringComparer.OrdinalIgnoreCase);
+            _dictTen = new Dictionary<string, string>(10, StringComparer.OrdinalIgnoreCase);
+        }
+
+        [Benchmark]
+        public void OneValue_SmallDict()
+        {
+            _smallCapDict[_oneValue.Key] = _oneValue.Value;
+            _ = _smallCapDict[_oneValue.Key];
+        }
+
+        [Benchmark]
+        public void OneValue_Dict()
+        {
+            _dict[_oneValue.Key] = _oneValue.Value;
+            _ = _dict[_oneValue.Key];
+        }
+
+        [Benchmark]
+        public void FourValues_SmallDict()
+        {
+            foreach (var val in _fourValues)
+            {
+                _smallCapDictFour[val.Key] = val.Value;
+                _ = _smallCapDictFour[val.Key];
+            }
+        }
+
+        [Benchmark]
+        public void FourValues_Dict()
+        {
+            foreach (var val in _fourValues)
+            {
+                _dictFour[val.Key] = val.Value;
+                _ = _dictFour[val.Key];
+            }
+        }
+
+        [Benchmark]
+        public void TenValues_SmallDict()
+        {
+            foreach (var val in _tenValues)
+            {
+                _smallCapDictTen[val.Key] = val.Value;
+                _ = _smallCapDictTen[val.Key];
+            }
+        }
+
+        [Benchmark]
+        public void TenValues_Dict()
+        {
+            foreach (var val in _tenValues)
+            {
+                _dictTen[val.Key] = val.Value;
+                _ = _dictTen[val.Key];
+            }
+        }
+
+        [Benchmark]
+        public void SmallDict()
+        {
+            _ = new SmallCapacityDictionary<string, string>(capacity: 1);
+        }
+
+        [Benchmark]
+        public void Dict()
+        {
+            _ = new Dictionary<string, string>(capacity: 1);
+        }
+
+
+        [Benchmark]
+        public void SmallDictFour()
+        {
+            _ = new SmallCapacityDictionary<string, string>(capacity: 4);
+        }
+
+        [Benchmark]
+        public void DictFour()
+        {
+            _ = new Dictionary<string, string>(capacity: 4);
+        }
+
+        [Benchmark]
+        public void SmallDictTen()
+        {
+            _ = new SmallCapacityDictionary<string, string>(capacity: 10);
+        }
+
+        [Benchmark]
+        public void DictTen()
+        {
+            _ = new Dictionary<string, string>(capacity: 10);
+        }
+    }
+}

src/Http/Http/src/Internal/RequestCookieCollection.cs

@@ -6,7 +6,9 @@
 using System.Collections.Generic;
 using System.Diagnostics.CodeAnalysis;
 using Microsoft.Extensions.Primitives;
+using Microsoft.AspNetCore.Internal.Dictionary;
 using Microsoft.Net.Http.Headers;
+using System.Linq;
 
 namespace Microsoft.AspNetCore.Http
 {
@@ -19,20 +21,21 @@ internal class RequestCookieCollection : IRequestCookieCollection
         private static readonly IEnumerator<KeyValuePair<string, string>> EmptyIEnumeratorType = EmptyEnumerator;
         private static readonly IEnumerator EmptyIEnumerator = EmptyEnumerator;
 
-        private Dictionary<string, string>? Store { get; set; }
+        private SmallCapacityDictionary<string, string> Store { get; set; }
 
         public RequestCookieCollection()
         {
+            Store = new SmallCapacityDictionary<string, string>(StringComparer.OrdinalIgnoreCase);
         }
 
-        public RequestCookieCollection(Dictionary<string, string> store)
+        public RequestCookieCollection(int capacity)
         {
-            Store = store;
+            Store = new SmallCapacityDictionary<string, string>(capacity, StringComparer.OrdinalIgnoreCase);
         }
 
-        public RequestCookieCollection(int capacity)
+        public RequestCookieCollection(Dictionary<string, string> store)
         {
-            Store = new Dictionary<string, string>(capacity, StringComparer.OrdinalIgnoreCase);
+            Store = new SmallCapacityDictionary<string, string>(store.ToList(), capacity: store.Count, StringComparer.OrdinalIgnoreCase);
         }
 
         public string? this[string key]
@@ -121,7 +124,9 @@ public bool TryGetValue(string key, [MaybeNullWhen(false)] out string? value)
                 value = null;
                 return false;
             }
-            return Store.TryGetValue(key, out value);
+            var res = Store.TryGetValue(key, out var objValue);
+            value = objValue as string;
+            return res;
         }
 
         /// <summary>
@@ -172,10 +177,10 @@ IEnumerator IEnumerable.GetEnumerator()
         public struct Enumerator : IEnumerator<KeyValuePair<string, string>>
         {
             // Do NOT make this readonly, or MoveNext will not work
-            private Dictionary<string, string>.Enumerator _dictionaryEnumerator;
+            private SmallCapacityDictionary<string, string>.Enumerator _dictionaryEnumerator;
             private bool _notEmpty;
 
-            internal Enumerator(Dictionary<string, string>.Enumerator dictionaryEnumerator)
+            internal Enumerator(SmallCapacityDictionary<string, string>.Enumerator dictionaryEnumerator)
             {
                 _dictionaryEnumerator = dictionaryEnumerator;
                 _notEmpty = true;
@@ -197,7 +202,7 @@ public KeyValuePair<string, string> Current
                     if (_notEmpty)
                     {
                         var current = _dictionaryEnumerator.Current;
-                        return new KeyValuePair<string, string>(current.Key, current.Value);
+                        return new KeyValuePair<string, string>(current.Key, (string)current.Value!);
                     }
                     return default(KeyValuePair<string, string>);
                 }

src/Http/Http/src/Microsoft.AspNetCore.Http.csproj

@@ -19,6 +19,7 @@
     <Compile Include="..\..\Shared\HttpRuleParser.cs" LinkBase="Internal" />
     <Compile Include="..\..\Shared\HttpParseResult.cs" LinkBase="Internal" />
     <Compile Include="..\..\WebUtilities\src\AspNetCoreTempDirectory.cs" LinkBase="Internal" />
+    <Compile Include="..\..\..\Shared\Dictionary\SmallCapacityDictionary.cs" LinkBase="Internal" />
   </ItemGroup>
 
   <ItemGroup>

src/Http/Shared/CookieHeaderParserShared.cs

@@ -11,7 +11,7 @@ namespace Microsoft.Net.Http.Headers
 {
     internal static class CookieHeaderParserShared
     {
-        public static bool TryParseValues(StringValues values, Dictionary<string, string> store, bool enableCookieNameEncoding, bool supportsMultipleValues)
+        public static bool TryParseValues(StringValues values, IDictionary<string, string> store, bool enableCookieNameEncoding, bool supportsMultipleValues)
         {
             // If a parser returns an empty list, it means there was no value, but that's valid (e.g. "Accept: "). The caller
             // can ignore the value.

src/Security/Authentication/Cookies/samples/CookieSample/Startup.cs

@@ -14,31 +14,34 @@ public class Startup
         public void ConfigureServices(IServiceCollection services)
         {
             // This can be removed after https://github.com/aspnet/IISIntegration/issues/371
-            services.AddAuthentication(options =>
-            {
-                options.DefaultAuthenticateScheme = CookieAuthenticationDefaults.AuthenticationScheme;
-                options.DefaultChallengeScheme = CookieAuthenticationDefaults.AuthenticationScheme;
-            }).AddCookie();
+            //services.AddAuthentication(options =>
+            //{
+            //    options.DefaultAuthenticateScheme = CookieAuthenticationDefaults.AuthenticationScheme;
+            //    options.DefaultChallengeScheme = CookieAuthenticationDefaults.AuthenticationScheme;
+            //}).AddCookie();
         }
 
         public void Configure(IApplicationBuilder app)
         {
-            app.UseAuthentication();
+            //app.UseAuthentication();
 
             app.Run(async context =>
             {
-                if (!context.User.Identities.Any(identity => identity.IsAuthenticated))
-                {
-                    var user = new ClaimsPrincipal(new ClaimsIdentity(new[] { new Claim(ClaimTypes.Name, "bob") }, CookieAuthenticationDefaults.AuthenticationScheme));
-                    await context.SignInAsync(CookieAuthenticationDefaults.AuthenticationScheme, user);
+                var cookie = context.Request.Cookies[".AspNetCore.Cookies"];
+
+                await context.Response.WriteAsync($"Hello World {cookie}");
+                //if (!context.User.Identities.Any(identity => identity.IsAuthenticated))
+                //{
+                //    var user = new ClaimsPrincipal(new ClaimsIdentity(new[] { new Claim(ClaimTypes.Name, "bob") }, CookieAuthenticationDefaults.AuthenticationScheme));
+                //    await context.SignInAsync(CookieAuthenticationDefaults.AuthenticationScheme, user);
 
-                    context.Response.ContentType = "text/plain";
-                    await context.Response.WriteAsync("Hello First timer");
-                    return;
-                }
+                //    context.Response.ContentType = "text/plain";
+                //    await context.Response.WriteAsync("Hello First timer");
+                //    return;
+                //}
 
-                context.Response.ContentType = "text/plain";
-                await context.Response.WriteAsync("Hello old timer");
+                //context.Response.ContentType = "text/plain";
+                //await context.Response.WriteAsync("Hello old timer");
             });
         }
     }