Optimize HTTP2 HPack huffman decoding

.gitignore

@@ -133,6 +133,9 @@ AutoTest.Net/
 # Web workbench (sass)
 .sass-cache/
 
+# BenchmarkDotNet
+BenchmarkDotNet.Artifacts/
+
 # Installshield output folder
 [Ee]xpress/
 

src/libraries/Common/tests/Tests/System/Net/aspnetcore/Http2/HuffmanDecodingTests.cs

@@ -237,7 +237,9 @@ private static IEnumerable<byte[]> InvalidEncodingData()
 
             // Sequences that uncovered errors
             { new byte[] { 0xb6, 0xb9, 0xac, 0x1c, 0x85, 0x58, 0xd5, 0x20, 0xa4, 0xb6, 0xc2, 0xad, 0x61, 0x7b, 0x5a, 0x54, 0x25, 0x1f }, Encoding.ASCII.GetBytes("upgrade-insecure-requests") },
-            { new byte[] { 0xfe, 0x53 }, Encoding.ASCII.GetBytes("\"t") }
+            { new byte[] { 0xfe, 0x53 }, Encoding.ASCII.GetBytes("\"t") },
+            { new byte[] { 0xff, 0xff, 0xf6, 0xff, 0xff, 0xfd, 0x68 }, new byte[] { 0xcf, 0xf0, 0x73 } },
+            { new byte[] { 0xff, 0xff, 0xf9, 0xff, 0xff, 0xfd, 0x86 }, new byte[] { 0xd5, 0xc7, 0x69 } },
         };
 
         [Theory]
@@ -354,29 +356,6 @@ public void HuffmanEncode(int code, uint expectedEncoded, int expectedBitLength)
             Assert.Equal(expectedBitLength, bitLength);
         }
 
-        [Theory]
-        [MemberData(nameof(HuffmanData))]
-        public void HuffmanDecode(int code, uint encoded, int bitLength)
-        {
-            Assert.Equal(code, Huffman.DecodeValue(encoded, bitLength, out int decodedBits));
-            Assert.Equal(bitLength, decodedBits);
-        }
-
-        [Theory]
-        [MemberData(nameof(HuffmanData))]
-        public void HuffmanEncodeDecode(
-            int code,
-            // Suppresses the warning about an unused theory parameter because
-            // this test shares data with other methods
-#pragma warning disable xUnit1026
-            uint encoded,
-#pragma warning restore xUnit1026
-            int bitLength)
-        {
-            Assert.Equal(code, Huffman.DecodeValue(Huffman.Encode(code).encoded, bitLength, out int decodedBits));
-            Assert.Equal(bitLength, decodedBits);
-        }
-
         public static TheoryData<int, uint, int> HuffmanData
         {
             get

src/libraries/System.Net.Http/tests/PerformanceTests/HPackHuffmanBenchmark/HPackHuffmanBenchmark.csproj

@@ -0,0 +1,22 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net5.0</TargetFramework>
+    <StringResourcesPath>../../../src/Resources/Strings.resx</StringResourcesPath>
+    <Nullable>enable</Nullable>
+    <LangVersion>9.0</LangVersion>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <Compile Include="$(CommonPath)System\Net\Http\aspnetcore\Http2\Hpack\Huffman.cs"
+             Link="Common\System\Net\Http\aspnetcore\Http2\Hpack\Huffman.cs" />
+    <Compile Include="$(CommonPath)System\Net\Http\aspnetcore\Http2\Hpack\HuffmanDecodingException.cs"
+             Link="Common\System\Net\Http\aspnetcore\Http2\Hpack\HuffmanDecodingException.cs" />
+    <Compile Include="Program.cs" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <PackageReference Include="BenchmarkDotNet" Version="0.12.1" />
+  </ItemGroup>  
+</Project>

src/libraries/System.Net.Http/tests/PerformanceTests/HPackHuffmanBenchmark/HPackHuffmanBenchmark.sln

@@ -0,0 +1,25 @@
+
+Microsoft Visual Studio Solution File, Format Version 12.00
+# Visual Studio Version 16
+VisualStudioVersion = 16.0.30709.64
+MinimumVisualStudioVersion = 10.0.40219.1
+Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "HPackHuffmanBenchmark", "HPackHuffmanBenchmark.csproj", "{FBC03CC3-4D63-4C17-8C09-ACE6E698B3C8}"
+EndProject
+Global
+	GlobalSection(SolutionConfigurationPlatforms) = preSolution
+		Debug|Any CPU = Debug|Any CPU
+		Release|Any CPU = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(ProjectConfigurationPlatforms) = postSolution
+		{FBC03CC3-4D63-4C17-8C09-ACE6E698B3C8}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{FBC03CC3-4D63-4C17-8C09-ACE6E698B3C8}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{FBC03CC3-4D63-4C17-8C09-ACE6E698B3C8}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{FBC03CC3-4D63-4C17-8C09-ACE6E698B3C8}.Release|Any CPU.Build.0 = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(SolutionProperties) = preSolution
+		HideSolutionNode = FALSE
+	EndGlobalSection
+	GlobalSection(ExtensibilityGlobals) = postSolution
+		SolutionGuid = {1CD6E426-3019-4B48-B2DB-1A6679912054}
+	EndGlobalSection
+EndGlobal

src/libraries/System.Net.Http/tests/PerformanceTests/HPackHuffmanBenchmark/Program.cs

@@ -0,0 +1,47 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System;
+using System.Collections.Generic;
+using System.Net.Http.HPack;
+using BenchmarkDotNet.Attributes;
+using BenchmarkDotNet.Running;
+
+namespace System.Net.Http.Tests.Performance
+{ 
+    public class HPackHuffmanBenchmark
+    {
+        private List<byte[]> _data;
+        private byte[] _buffer;
+
+        public HPackHuffmanBenchmark()
+        {
+            _data = new List<byte[]> {
+
+                    // www.example.com
+                    new byte[] { 0xf1, 0xe3, 0xc2, 0xe5, 0xf2, 0x3a, 0x6b, 0xa0, 0xab, 0x90, 0xf4, 0xff },
+                    // no-cache
+                    new byte[] { 0xa8, 0xeb, 0x10, 0x64, 0x9c, 0xbf },
+                    // upgrade-insecure-requests
+                    new byte[] { 0xb6, 0xb9, 0xac, 0x1c, 0x85, 0x58, 0xd5, 0x20, 0xa4, 0xb6, 0xc2, 0xad, 0x61, 0x7b, 0x5a, 0x54, 0x25, 0x1f },
+                    // mEO7bfwFStBMwJWfW4pmg2XL25AswjrVlfcfYbxkcS2ssduZmiKoipMH9XwoTGkb+Qnq9bcjwWbwDQzsea/vMQ==
+                    Convert.FromBase64String("pwanY5fGHcm7o8ZeUvJqumYX5nE3Cjx0s40Skl5x+epNwkIkt/aTZjmr0Y3/zwffi6x/72Vdn4ydPHKPxf2e0FGx30bIIA=="),
+                };
+            _buffer = new byte[10000];
+        }
+
+        [Params(0, 1, 2, 3)]
+        public int DataIndex { get; set; }
+
+        [Benchmark]
+        public void Decode() => Huffman.Decode(_data[DataIndex], ref _buffer);
+    }
+
+    public class Program
+    {
+        public static void Main(string[] args)
+        {
+            var summary = BenchmarkRunner.Run(typeof(Program).Assembly);
+        }
+    }
+}