Kestrel code tidyups (#11896)

src/Servers/Kestrel/Core/src/Internal/Http/BufferExtensions.cs

@@ -255,7 +255,6 @@ namespace System.Buffers
                 {
                     char ch = *(input + i);
                     *(output + i) = (byte)ch; // Cast convert
-                    i = length;
                 }
             }
         }

src/Servers/Kestrel/Core/src/Internal/Http/Http1ChunkedEncodingMessageBody.cs

@@ -27,7 +27,7 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
         private Mode _mode = Mode.Prefix;
         private volatile bool _canceled;
         private Task _pumpTask;
-        private Pipe _requestBodyPipe;
+        private readonly Pipe _requestBodyPipe;
         private ReadResult _readResult;
 
         public Http1ChunkedEncodingMessageBody(bool keepAlive, Http1Connection context)

src/Servers/Kestrel/Core/src/Internal/Http/Http1Connection.cs

@@ -287,13 +287,13 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
                 // origin-form.
                 // The most common form of request-target.
                 // https://tools.ietf.org/html/rfc7230#section-5.3.1
-                OnOriginFormTarget(method, version, target, path, query, customMethod, pathEncoded);
+                OnOriginFormTarget(pathEncoded, target, path, query);
             }
             else if (ch == ByteAsterisk && target.Length == 1)
             {
                 OnAsteriskFormTarget(method);
             }
-            else if (target.GetKnownHttpScheme(out var scheme))
+            else if (target.GetKnownHttpScheme(out _))
             {
                 OnAbsoluteFormTarget(target, query);
             }
@@ -321,7 +321,7 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
         }
 
         // Compare with Http2Stream.TryValidatePseudoHeaders
-        private void OnOriginFormTarget(HttpMethod method, HttpVersion version, Span<byte> target, Span<byte> path, Span<byte> query, Span<byte> customMethod, bool pathEncoded)
+        private void OnOriginFormTarget(bool pathEncoded, Span<byte> target, Span<byte> path, Span<byte> query)
         {
             Debug.Assert(target[0] == ByteForwardSlash, "Should only be called when path starts with /");
 

src/Servers/Kestrel/Core/src/Internal/Http/Http1OutputProducer.cs

@@ -171,7 +171,7 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
                 return _flusher.FlushAsync(_minResponseDataRateFeature.MinDataRate, bytesWritten, this, cancellationToken);
             }
 
-            ValueTask<FlushResult> FlushAsyncChunked(Http1OutputProducer producer, CancellationToken token)
+            static ValueTask<FlushResult> FlushAsyncChunked(Http1OutputProducer producer, CancellationToken token)
             {
                 // Local function so in the common-path the stack space for BufferWriter isn't reserved and cleared when it isn't used.
 

src/Servers/Kestrel/Core/src/Internal/Http/HttpHeaders.Generated.cs

@@ -5,6 +5,7 @@ using System;
 using System.Collections.Generic;
 using System.Buffers;
 using System.IO.Pipelines;
+using System.Numerics;
 using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
 using Microsoft.Extensions.Primitives;
@@ -875,7 +876,7 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
 
         protected override int GetCountFast()
         {
-            return (_contentLength.HasValue ? 1 : 0 ) + BitCount(_bits) + (MaybeUnknown?.Count ?? 0);
+            return (_contentLength.HasValue ? 1 : 0 ) + BitOperations.PopCount((ulong)_bits) + (MaybeUnknown?.Count ?? 0);
         }
 
         protected override bool TryGetValueFast(string key, out StringValues value)
@@ -7310,7 +7311,7 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
         }
         protected override int GetCountFast()
         {
-            return (_contentLength.HasValue ? 1 : 0 ) + BitCount(_bits) + (MaybeUnknown?.Count ?? 0);
+            return (_contentLength.HasValue ? 1 : 0 ) + BitOperations.PopCount((ulong)_bits) + (MaybeUnknown?.Count ?? 0);
         }
 
         protected override bool TryGetValueFast(string key, out StringValues value)
@@ -10275,7 +10276,7 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
             _contentLength = null;
             var tempBits = _bits;
             _bits = 0;
-            if(HttpHeaders.BitCount(tempBits) > 12)
+            if(BitOperations.PopCount((ulong)tempBits) > 12)
             {
                 _headers = default(HeaderReferences);
                 return;
@@ -11848,7 +11849,7 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
 
         protected override int GetCountFast()
         {
-            return (_contentLength.HasValue ? 1 : 0 ) + BitCount(_bits) + (MaybeUnknown?.Count ?? 0);
+            return (_contentLength.HasValue ? 1 : 0 ) + BitOperations.PopCount((ulong)_bits) + (MaybeUnknown?.Count ?? 0);
         }
 
         protected override bool TryGetValueFast(string key, out StringValues value)
@@ -11985,7 +11986,7 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
             _contentLength = null;
             var tempBits = _bits;
             _bits = 0;
-            if(HttpHeaders.BitCount(tempBits) > 12)
+            if(BitOperations.PopCount((ulong)tempBits) > 12)
             {
                 _headers = default(HeaderReferences);
                 return;

src/Servers/Kestrel/Core/src/Internal/Http/HttpHeaders.cs

@@ -133,31 +133,6 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
         [MethodImpl(MethodImplOptions.NoInlining)]
         protected bool RemoveUnknown(string key) => MaybeUnknown?.Remove(key) ?? false;
 
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        protected static int BitCount(long value)
-        {
-            int SoftwareFallback(ulong v)
-            {
-                // see https://github.com/dotnet/corefx/blob/5965fd3756bc9dd9c89a27621eb10c6931126de2/src/System.Reflection.Metadata/src/System/Reflection/Internal/Utilities/BitArithmetic.cs
-
-                const ulong Mask01010101 = 0x5555555555555555UL;
-                const ulong Mask00110011 = 0x3333333333333333UL;
-                const ulong Mask00001111 = 0x0F0F0F0F0F0F0F0FUL;
-                const ulong Mask00000001 = 0x0101010101010101UL;
-
-                v = v - ((v >> 1) & Mask01010101);
-                v = (v & Mask00110011) + ((v >> 2) & Mask00110011);
-                return (int)(unchecked(((v + (v >> 4)) & Mask00001111) * Mask00000001) >> 56);
-            }
-
-            if (Popcnt.X64.IsSupported)
-            {
-                return (int)Popcnt.X64.PopCount((ulong)value);
-            }
-
-            return SoftwareFallback((ulong)value);
-        }
-
         protected virtual int GetCountFast()
         { throw new NotImplementedException(); }
 
@@ -222,8 +197,7 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
 
         bool IDictionary<string, StringValues>.ContainsKey(string key)
         {
-            StringValues value;
+            return TryGetValueFast(key, out _);
-            return TryGetValueFast(key, out value);
         }
 
         void ICollection<KeyValuePair<string, StringValues>>.CopyTo(KeyValuePair<string, StringValues>[] array, int arrayIndex)

src/Servers/Kestrel/Core/src/Internal/Http/HttpParser.cs

@@ -12,7 +12,7 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
 {
     public class HttpParser<TRequestHandler> : IHttpParser<TRequestHandler> where TRequestHandler : IHttpHeadersHandler, IHttpRequestLineHandler
     {
-        private bool _showErrorDetails;
+        private readonly bool _showErrorDetails;
 
         public HttpParser() : this(showErrorDetails: true)
         {

src/Servers/Kestrel/Core/src/Internal/Http/HttpProtocol.cs

@@ -36,7 +36,7 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
         private Stack<KeyValuePair<Func<object, Task>, object>> _onStarting;
         private Stack<KeyValuePair<Func<object, Task>, object>> _onCompleted;
 
-        private object _abortLock = new object();
+        private readonly object _abortLock = new object();
         private volatile bool _connectionAborted;
         private bool _preventRequestAbortedCancellation;
         private CancellationTokenSource _abortedCts;
@@ -839,12 +839,6 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
             }
         }
 
-        [MethodImpl(MethodImplOptions.NoInlining)]
-        private Task FlushAsyncInternal()
-        {
-            return Output.FlushAsync(default).GetAsTask();
-        }
-
         private void VerifyAndUpdateWrite(int count)
         {
             var responseHeaders = HttpResponseHeaders;
@@ -1554,7 +1548,7 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
             return await Output.FlushAsync(cancellationToken);
         }
 
-        public Task WriteAsync(ReadOnlyMemory<byte> data, CancellationToken cancellationToken = default(CancellationToken))
+        public Task WriteAsync(ReadOnlyMemory<byte> data, CancellationToken cancellationToken = default)
         {
             return WritePipeAsync(data, cancellationToken).GetAsTask();
         }

src/Servers/Kestrel/Core/src/Internal/Http/HttpRequestHeaders.cs

@@ -132,11 +132,11 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
                 _collection = collection;
                 _bits = collection._bits;
                 _next = 0;
-                _current = default(KeyValuePair<string, StringValues>);
+                _current = default;
                 _hasUnknown = collection.MaybeUnknown != null;
                 _unknownEnumerator = _hasUnknown
                     ? collection.MaybeUnknown.GetEnumerator()
-                    : default(Dictionary<string, StringValues>.Enumerator);
+                    : default;
             }
 
             public KeyValuePair<string, StringValues> Current => _current;

src/Servers/Kestrel/Core/src/Internal/Http/HttpRequestPipeReader.cs

@@ -123,8 +123,8 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
                 }
             }
 
-            void ThrowObjectDisposedException() => throw new ObjectDisposedException(nameof(HttpRequestStream));
+            static void ThrowObjectDisposedException() => throw new ObjectDisposedException(nameof(HttpRequestStream));
-            void ThrowTaskCanceledException() => throw new TaskCanceledException();
+            static void ThrowTaskCanceledException() => throw new TaskCanceledException();
         }
     }
 }

src/Servers/Kestrel/Core/src/Internal/Http/HttpRequestStream.cs

@@ -4,7 +4,6 @@
 using System;
 using System.Buffers;
 using System.IO;
-using System.IO.Pipelines;
 using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Connections;
@@ -14,7 +13,7 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
 {
     internal sealed class HttpRequestStream : Stream
     {
-        private HttpRequestPipeReader _pipeReader;
+        private readonly HttpRequestPipeReader _pipeReader;
         private readonly IHttpBodyControlFeature _bodyControl;
 
         public HttpRequestStream(IHttpBodyControlFeature bodyControl, HttpRequestPipeReader pipeReader)
@@ -155,12 +154,11 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
                 var readableBufferLength = readableBuffer.Length;
 
                 var consumed = readableBuffer.End;
-                var actual = 0;
                 try
                 {
                     if (readableBufferLength != 0)
                     {
-                        actual = (int)Math.Min(readableBufferLength, buffer.Length);
+                        var actual = (int)Math.Min(readableBufferLength, buffer.Length);
 
                         var slice = actual == readableBufferLength ? readableBuffer : readableBuffer.Slice(0, actual);
                         consumed = slice.End;

src/Servers/Kestrel/Core/src/Internal/Http/HttpResponseHeaders.cs

@@ -14,8 +14,8 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
 {
     internal sealed partial class HttpResponseHeaders : HttpHeaders
     {
-        private static ReadOnlySpan<byte> _CrLf => new[] { (byte)'\r', (byte)'\n' };
+        private static ReadOnlySpan<byte> CrLf => new[] { (byte)'\r', (byte)'\n' };
-        private static ReadOnlySpan<byte> _colonSpace => new[] { (byte)':', (byte)' ' };
+        private static ReadOnlySpan<byte> ColonSpace => new[] { (byte)':', (byte)' ' };
 
         public Enumerator GetEnumerator()
         {
@@ -46,9 +46,9 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
                     {
                         if (value != null)
                         {
-                            buffer.Write(_CrLf);
+                            buffer.Write(CrLf);
                             buffer.WriteAsciiNoValidation(kv.Key);
-                            buffer.Write(_colonSpace);
+                            buffer.Write(ColonSpace);
                             buffer.WriteAsciiNoValidation(value);
                         }
                     }

src/Servers/Kestrel/Core/src/Internal/Http/HttpResponsePipeWriter.cs

@@ -104,7 +104,7 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
                 ThrowObjectDisposedException();
             }
 
-            void ThrowObjectDisposedException()
+            static void ThrowObjectDisposedException()
             {
                 throw new ObjectDisposedException(nameof(HttpResponseStream), CoreStrings.WritingToResponseBodyAfterResponseCompleted);
             }

src/Servers/Kestrel/Core/src/Internal/Http/PathNormalizer.cs

@@ -187,8 +187,6 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
         public static unsafe bool ContainsDotSegments(byte* start, byte* end)
         {
             var src = start;
-            var dst = start;
-
             while (src < end)
             {
                 var ch1 = *src;

src/Servers/Kestrel/Core/src/Internal/Http/ZeroContentLengthMessageBody.cs

@@ -18,7 +18,7 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
 
         public override bool IsEmpty => true;
 
-        public override ValueTask<ReadResult> ReadAsync(CancellationToken cancellationToken = default(CancellationToken)) => new ValueTask<ReadResult>(new ReadResult(default, isCanceled: false, isCompleted: true));
+        public override ValueTask<ReadResult> ReadAsync(CancellationToken cancellationToken = default) => new ValueTask<ReadResult>(new ReadResult(default, isCanceled: false, isCompleted: true));
 
         public override Task ConsumeAsync() => Task.CompletedTask;
 

src/Servers/Kestrel/Core/src/Internal/Http2/HPack/IntegerEncoder.cs

@@ -36,17 +36,18 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http2.HPack
                     return false;
                 }
 
-                i = i - ((1 << n) - 1);
+                i -= ((1 << n) - 1);
                 while (i >= 128)
                 {
-                    buffer[j++] = (byte)(i % 128 + 128);
+                    var ui = (uint)i; // Use unsigned for optimizations
+                    buffer[j++] = (byte)((ui % 128) + 128);
 
                     if (j >= buffer.Length)
                     {
                         return false;
                     }
 
-                    i = i / 128;
+                    i = (int)(ui / 128); // Jit converts unsigned divide by power-of-2 constant to clean shift
                 }
                 buffer[j++] = (byte)i;
             }

src/Servers/Kestrel/Core/src/Internal/Http2/HPack/StatusCodes.cs

@@ -82,141 +82,77 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http2.HPack
 
         public static byte[] ToStatusBytes(int statusCode)
         {
-            switch (statusCode)
+            return statusCode switch
             {
-                case Microsoft.AspNetCore.Http.StatusCodes.Status100Continue:
+                Microsoft.AspNetCore.Http.StatusCodes.Status100Continue => _bytesStatus100,
-                    return _bytesStatus100;
+                Microsoft.AspNetCore.Http.StatusCodes.Status101SwitchingProtocols => _bytesStatus101,
-                case Microsoft.AspNetCore.Http.StatusCodes.Status101SwitchingProtocols:
+                Microsoft.AspNetCore.Http.StatusCodes.Status102Processing => _bytesStatus102,
-                    return _bytesStatus101;
-                case Microsoft.AspNetCore.Http.StatusCodes.Status102Processing:
-                    return _bytesStatus102;
 
-                case Microsoft.AspNetCore.Http.StatusCodes.Status200OK:
+                Microsoft.AspNetCore.Http.StatusCodes.Status200OK => _bytesStatus200,
-                    return _bytesStatus200;
+                Microsoft.AspNetCore.Http.StatusCodes.Status201Created => _bytesStatus201,
-                case Microsoft.AspNetCore.Http.StatusCodes.Status201Created:
+                Microsoft.AspNetCore.Http.StatusCodes.Status202Accepted => _bytesStatus202,
-                    return _bytesStatus201;
+                Microsoft.AspNetCore.Http.StatusCodes.Status203NonAuthoritative => _bytesStatus203,
-                case Microsoft.AspNetCore.Http.StatusCodes.Status202Accepted:
+                Microsoft.AspNetCore.Http.StatusCodes.Status204NoContent => _bytesStatus204,
-                    return _bytesStatus202;
+                Microsoft.AspNetCore.Http.StatusCodes.Status205ResetContent => _bytesStatus205,
-                case Microsoft.AspNetCore.Http.StatusCodes.Status203NonAuthoritative:
+                Microsoft.AspNetCore.Http.StatusCodes.Status206PartialContent => _bytesStatus206,
-                    return _bytesStatus203;
+                Microsoft.AspNetCore.Http.StatusCodes.Status207MultiStatus => _bytesStatus207,
-                case Microsoft.AspNetCore.Http.StatusCodes.Status204NoContent:
+                Microsoft.AspNetCore.Http.StatusCodes.Status208AlreadyReported => _bytesStatus208,
-                    return _bytesStatus204;
+                Microsoft.AspNetCore.Http.StatusCodes.Status226IMUsed => _bytesStatus226,
-                case Microsoft.AspNetCore.Http.StatusCodes.Status205ResetContent:
-                    return _bytesStatus205;
-                case Microsoft.AspNetCore.Http.StatusCodes.Status206PartialContent:
-                    return _bytesStatus206;
-                case Microsoft.AspNetCore.Http.StatusCodes.Status207MultiStatus:
-                    return _bytesStatus207;
-                case Microsoft.AspNetCore.Http.StatusCodes.Status208AlreadyReported:
-                    return _bytesStatus208;
-                case Microsoft.AspNetCore.Http.StatusCodes.Status226IMUsed:
-                    return _bytesStatus226;
 
-                case Microsoft.AspNetCore.Http.StatusCodes.Status300MultipleChoices:
+                Microsoft.AspNetCore.Http.StatusCodes.Status300MultipleChoices => _bytesStatus300,
-                    return _bytesStatus300;
+                Microsoft.AspNetCore.Http.StatusCodes.Status301MovedPermanently => _bytesStatus301,
-                case Microsoft.AspNetCore.Http.StatusCodes.Status301MovedPermanently:
+                Microsoft.AspNetCore.Http.StatusCodes.Status302Found => _bytesStatus302,
-                    return _bytesStatus301;
+                Microsoft.AspNetCore.Http.StatusCodes.Status303SeeOther => _bytesStatus303,
-                case Microsoft.AspNetCore.Http.StatusCodes.Status302Found:
+                Microsoft.AspNetCore.Http.StatusCodes.Status304NotModified => _bytesStatus304,
-                    return _bytesStatus302;
+                Microsoft.AspNetCore.Http.StatusCodes.Status305UseProxy => _bytesStatus305,
-                case Microsoft.AspNetCore.Http.StatusCodes.Status303SeeOther:
+                Microsoft.AspNetCore.Http.StatusCodes.Status306SwitchProxy => _bytesStatus306,
-                    return _bytesStatus303;
+                Microsoft.AspNetCore.Http.StatusCodes.Status307TemporaryRedirect => _bytesStatus307,
-                case Microsoft.AspNetCore.Http.StatusCodes.Status304NotModified:
+                Microsoft.AspNetCore.Http.StatusCodes.Status308PermanentRedirect => _bytesStatus308,
-                    return _bytesStatus304;
-                case Microsoft.AspNetCore.Http.StatusCodes.Status305UseProxy:
-                    return _bytesStatus305;
-                case Microsoft.AspNetCore.Http.StatusCodes.Status306SwitchProxy:
-                    return _bytesStatus306;
-                case Microsoft.AspNetCore.Http.StatusCodes.Status307TemporaryRedirect:
-                    return _bytesStatus307;
-                case Microsoft.AspNetCore.Http.StatusCodes.Status308PermanentRedirect:
-                    return _bytesStatus308;
 
-                case Microsoft.AspNetCore.Http.StatusCodes.Status400BadRequest:
+                Microsoft.AspNetCore.Http.StatusCodes.Status400BadRequest => _bytesStatus400,
-                    return _bytesStatus400;
+                Microsoft.AspNetCore.Http.StatusCodes.Status401Unauthorized => _bytesStatus401,
-                case Microsoft.AspNetCore.Http.StatusCodes.Status401Unauthorized:
+                Microsoft.AspNetCore.Http.StatusCodes.Status402PaymentRequired => _bytesStatus402,
-                    return _bytesStatus401;
+                Microsoft.AspNetCore.Http.StatusCodes.Status403Forbidden => _bytesStatus403,
-                case Microsoft.AspNetCore.Http.StatusCodes.Status402PaymentRequired:
+                Microsoft.AspNetCore.Http.StatusCodes.Status404NotFound => _bytesStatus404,
-                    return _bytesStatus402;
+                Microsoft.AspNetCore.Http.StatusCodes.Status405MethodNotAllowed => _bytesStatus405,
-                case Microsoft.AspNetCore.Http.StatusCodes.Status403Forbidden:
+                Microsoft.AspNetCore.Http.StatusCodes.Status406NotAcceptable => _bytesStatus406,
-                    return _bytesStatus403;
+                Microsoft.AspNetCore.Http.StatusCodes.Status407ProxyAuthenticationRequired => _bytesStatus407,
-                case Microsoft.AspNetCore.Http.StatusCodes.Status404NotFound:
+                Microsoft.AspNetCore.Http.StatusCodes.Status408RequestTimeout => _bytesStatus408,
-                    return _bytesStatus404;
+                Microsoft.AspNetCore.Http.StatusCodes.Status409Conflict => _bytesStatus409,
-                case Microsoft.AspNetCore.Http.StatusCodes.Status405MethodNotAllowed:
+                Microsoft.AspNetCore.Http.StatusCodes.Status410Gone => _bytesStatus410,
-                    return _bytesStatus405;
+                Microsoft.AspNetCore.Http.StatusCodes.Status411LengthRequired => _bytesStatus411,
-                case Microsoft.AspNetCore.Http.StatusCodes.Status406NotAcceptable:
+                Microsoft.AspNetCore.Http.StatusCodes.Status412PreconditionFailed => _bytesStatus412,
-                    return _bytesStatus406;
+                Microsoft.AspNetCore.Http.StatusCodes.Status413PayloadTooLarge => _bytesStatus413,
-                case Microsoft.AspNetCore.Http.StatusCodes.Status407ProxyAuthenticationRequired:
+                Microsoft.AspNetCore.Http.StatusCodes.Status414UriTooLong => _bytesStatus414,
-                    return _bytesStatus407;
+                Microsoft.AspNetCore.Http.StatusCodes.Status415UnsupportedMediaType => _bytesStatus415,
-                case Microsoft.AspNetCore.Http.StatusCodes.Status408RequestTimeout:
+                Microsoft.AspNetCore.Http.StatusCodes.Status416RangeNotSatisfiable => _bytesStatus416,
-                    return _bytesStatus408;
+                Microsoft.AspNetCore.Http.StatusCodes.Status417ExpectationFailed => _bytesStatus417,
-                case Microsoft.AspNetCore.Http.StatusCodes.Status409Conflict:
+                Microsoft.AspNetCore.Http.StatusCodes.Status418ImATeapot => _bytesStatus418,
-                    return _bytesStatus409;
+                Microsoft.AspNetCore.Http.StatusCodes.Status419AuthenticationTimeout => _bytesStatus419,
-                case Microsoft.AspNetCore.Http.StatusCodes.Status410Gone:
+                Microsoft.AspNetCore.Http.StatusCodes.Status421MisdirectedRequest => _bytesStatus421,
-                    return _bytesStatus410;
+                Microsoft.AspNetCore.Http.StatusCodes.Status422UnprocessableEntity => _bytesStatus422,
-                case Microsoft.AspNetCore.Http.StatusCodes.Status411LengthRequired:
+                Microsoft.AspNetCore.Http.StatusCodes.Status423Locked => _bytesStatus423,
-                    return _bytesStatus411;
+                Microsoft.AspNetCore.Http.StatusCodes.Status424FailedDependency => _bytesStatus424,
-                case Microsoft.AspNetCore.Http.StatusCodes.Status412PreconditionFailed:
+                Microsoft.AspNetCore.Http.StatusCodes.Status426UpgradeRequired => _bytesStatus426,
-                    return _bytesStatus412;
+                Microsoft.AspNetCore.Http.StatusCodes.Status428PreconditionRequired => _bytesStatus428,
-                case Microsoft.AspNetCore.Http.StatusCodes.Status413PayloadTooLarge:
+                Microsoft.AspNetCore.Http.StatusCodes.Status429TooManyRequests => _bytesStatus429,
-                    return _bytesStatus413;
+                Microsoft.AspNetCore.Http.StatusCodes.Status431RequestHeaderFieldsTooLarge => _bytesStatus431,
-                case Microsoft.AspNetCore.Http.StatusCodes.Status414UriTooLong:
+                Microsoft.AspNetCore.Http.StatusCodes.Status451UnavailableForLegalReasons => _bytesStatus451,
-                    return _bytesStatus414;
-                case Microsoft.AspNetCore.Http.StatusCodes.Status415UnsupportedMediaType:
-                    return _bytesStatus415;
-                case Microsoft.AspNetCore.Http.StatusCodes.Status416RangeNotSatisfiable:
-                    return _bytesStatus416;
-                case Microsoft.AspNetCore.Http.StatusCodes.Status417ExpectationFailed:
-                    return _bytesStatus417;
-                case Microsoft.AspNetCore.Http.StatusCodes.Status418ImATeapot:
-                    return _bytesStatus418;
-                case Microsoft.AspNetCore.Http.StatusCodes.Status419AuthenticationTimeout:
-                    return _bytesStatus419;
-                case Microsoft.AspNetCore.Http.StatusCodes.Status421MisdirectedRequest:
-                    return _bytesStatus421;
-                case Microsoft.AspNetCore.Http.StatusCodes.Status422UnprocessableEntity:
-                    return _bytesStatus422;
-                case Microsoft.AspNetCore.Http.StatusCodes.Status423Locked:
-                    return _bytesStatus423;
-                case Microsoft.AspNetCore.Http.StatusCodes.Status424FailedDependency:
-                    return _bytesStatus424;
-                case Microsoft.AspNetCore.Http.StatusCodes.Status426UpgradeRequired:
-                    return _bytesStatus426;
-                case Microsoft.AspNetCore.Http.StatusCodes.Status428PreconditionRequired:
-                    return _bytesStatus428;
-                case Microsoft.AspNetCore.Http.StatusCodes.Status429TooManyRequests:
-                    return _bytesStatus429;
-                case Microsoft.AspNetCore.Http.StatusCodes.Status431RequestHeaderFieldsTooLarge:
-                    return _bytesStatus431;
-                case Microsoft.AspNetCore.Http.StatusCodes.Status451UnavailableForLegalReasons:
-                    return _bytesStatus451;
 
-                case Microsoft.AspNetCore.Http.StatusCodes.Status500InternalServerError:
+                Microsoft.AspNetCore.Http.StatusCodes.Status500InternalServerError => _bytesStatus500,
-                    return _bytesStatus500;
+                Microsoft.AspNetCore.Http.StatusCodes.Status501NotImplemented => _bytesStatus501,
-                case Microsoft.AspNetCore.Http.StatusCodes.Status501NotImplemented:
+                Microsoft.AspNetCore.Http.StatusCodes.Status502BadGateway => _bytesStatus502,
-                    return _bytesStatus501;
+                Microsoft.AspNetCore.Http.StatusCodes.Status503ServiceUnavailable => _bytesStatus503,
-                case Microsoft.AspNetCore.Http.StatusCodes.Status502BadGateway:
+                Microsoft.AspNetCore.Http.StatusCodes.Status504GatewayTimeout => _bytesStatus504,
-                    return _bytesStatus502;
+                Microsoft.AspNetCore.Http.StatusCodes.Status505HttpVersionNotsupported => _bytesStatus505,
-                case Microsoft.AspNetCore.Http.StatusCodes.Status503ServiceUnavailable:
+                Microsoft.AspNetCore.Http.StatusCodes.Status506VariantAlsoNegotiates => _bytesStatus506,
-                    return _bytesStatus503;
+                Microsoft.AspNetCore.Http.StatusCodes.Status507InsufficientStorage => _bytesStatus507,
-                case Microsoft.AspNetCore.Http.StatusCodes.Status504GatewayTimeout:
+                Microsoft.AspNetCore.Http.StatusCodes.Status508LoopDetected => _bytesStatus508,
-                    return _bytesStatus504;
+                Microsoft.AspNetCore.Http.StatusCodes.Status510NotExtended => _bytesStatus510,
-                case Microsoft.AspNetCore.Http.StatusCodes.Status505HttpVersionNotsupported:
+                Microsoft.AspNetCore.Http.StatusCodes.Status511NetworkAuthenticationRequired => _bytesStatus511,
-                    return _bytesStatus505;
-                case Microsoft.AspNetCore.Http.StatusCodes.Status506VariantAlsoNegotiates:
-                    return _bytesStatus506;
-                case Microsoft.AspNetCore.Http.StatusCodes.Status507InsufficientStorage:
-                    return _bytesStatus507;
-                case Microsoft.AspNetCore.Http.StatusCodes.Status508LoopDetected:
-                    return _bytesStatus508;
-                case Microsoft.AspNetCore.Http.StatusCodes.Status510NotExtended:
-                    return _bytesStatus510;
-                case Microsoft.AspNetCore.Http.StatusCodes.Status511NetworkAuthenticationRequired:
-                    return _bytesStatus511;
 
-                default:
+                _ => CreateStatusBytes(statusCode)
-                    return Encoding.ASCII.GetBytes(statusCode.ToString(CultureInfo.InvariantCulture));
+            };
-
-            }
         }
     }
 }

src/Servers/Kestrel/Core/src/Internal/Http2/Http2Connection.cs

@@ -396,31 +396,20 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http2
                 throw new Http2ConnectionErrorException(CoreStrings.FormatHttp2ErrorStreamIdEven(_incomingFrame.Type, _incomingFrame.StreamId), Http2ErrorCode.PROTOCOL_ERROR);
             }
 
-            switch (_incomingFrame.Type)
+            return _incomingFrame.Type switch
             {
-                case Http2FrameType.DATA:
+                Http2FrameType.DATA => ProcessDataFrameAsync(payload),
-                    return ProcessDataFrameAsync(payload);
+                Http2FrameType.HEADERS => ProcessHeadersFrameAsync(application, payload),
-                case Http2FrameType.HEADERS:
+                Http2FrameType.PRIORITY => ProcessPriorityFrameAsync(),
-                    return ProcessHeadersFrameAsync(application, payload);
+                Http2FrameType.RST_STREAM => ProcessRstStreamFrameAsync(),
-                case Http2FrameType.PRIORITY:
+                Http2FrameType.SETTINGS => ProcessSettingsFrameAsync(payload),
-                    return ProcessPriorityFrameAsync();
+                Http2FrameType.PUSH_PROMISE => throw new Http2ConnectionErrorException(CoreStrings.Http2ErrorPushPromiseReceived, Http2ErrorCode.PROTOCOL_ERROR),
-                case Http2FrameType.RST_STREAM:
+                Http2FrameType.PING => ProcessPingFrameAsync(payload),
-                    return ProcessRstStreamFrameAsync();
+                Http2FrameType.GOAWAY => ProcessGoAwayFrameAsync(),
-                case Http2FrameType.SETTINGS:
+                Http2FrameType.WINDOW_UPDATE => ProcessWindowUpdateFrameAsync(),
-                    return ProcessSettingsFrameAsync(payload);
+                Http2FrameType.CONTINUATION => ProcessContinuationFrameAsync(payload),
-                case Http2FrameType.PUSH_PROMISE:
+                _ => ProcessUnknownFrameAsync(),
-                    throw new Http2ConnectionErrorException(CoreStrings.Http2ErrorPushPromiseReceived, Http2ErrorCode.PROTOCOL_ERROR);
+            };
-                case Http2FrameType.PING:
-                    return ProcessPingFrameAsync(payload);
-                case Http2FrameType.GOAWAY:
-                    return ProcessGoAwayFrameAsync();
-                case Http2FrameType.WINDOW_UPDATE:
-                    return ProcessWindowUpdateFrameAsync();
-                case Http2FrameType.CONTINUATION:
-                    return ProcessContinuationFrameAsync(payload);
-                default:
-                    return ProcessUnknownFrameAsync();
-            }
         }
 
         private Task ProcessDataFrameAsync(in ReadOnlySequence<byte> payload)

src/Servers/Kestrel/Core/src/Internal/Http2/Http2FrameWriter.cs

@@ -22,7 +22,7 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http2
     internal class Http2FrameWriter
     {
         // Literal Header Field without Indexing - Indexed Name (Index 8 - :status)
-        private static ReadOnlySpan<byte> _continueBytes => new byte[] { 0x08, 0x03, (byte)'1', (byte)'0', (byte)'0' };
+        private static ReadOnlySpan<byte> ContinueBytes => new byte[] { 0x08, 0x03, (byte)'1', (byte)'0', (byte)'0' };
 
         private readonly object _writeLock = new object();
         private readonly Http2Frame _outgoingFrame;
@@ -138,9 +138,9 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http2
                 }
 
                 _outgoingFrame.PrepareHeaders(Http2HeadersFrameFlags.END_HEADERS, streamId);
-                _outgoingFrame.PayloadLength = _continueBytes.Length;
+                _outgoingFrame.PayloadLength = ContinueBytes.Length;
                 WriteHeaderUnsynchronized();
-                _outputWriter.Write(_continueBytes);
+                _outputWriter.Write(ContinueBytes);
                 return TimeFlushUnsynchronizedAsync();
             }
         }
@@ -545,7 +545,7 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http2
                     return default;
                 }
 
-                _outgoingFrame.PreparePing(Http2PingFrameFlags.ACK);
+                _outgoingFrame.PreparePing(flags);
                 Debug.Assert(payload.Length == _outgoingFrame.PayloadLength); // 8
                 WriteHeaderUnsynchronized();
                 foreach (var segment in payload)

src/Servers/Kestrel/Core/src/Internal/Http2/Http2OutputProducer.cs

@@ -95,11 +95,6 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http2
             _stream.ResetAndAbort(abortReason, Http2ErrorCode.INTERNAL_ERROR);
         }
 
-        public Task WriteChunkAsync(ReadOnlySpan<byte> span, CancellationToken cancellationToken)
-        {
-            throw new NotImplementedException();
-        }
-
         public ValueTask<FlushResult> FlushAsync(CancellationToken cancellationToken)
         {
             if (cancellationToken.IsCancellationRequested)

src/Servers/Kestrel/Core/src/Internal/Http2/Http2Stream.cs

@@ -94,8 +94,8 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http2
                 {
                     Log.RequestBodyNotEntirelyRead(ConnectionIdFeature, TraceIdentifier);
 
-                    var states = ApplyCompletionFlag(StreamCompletionFlags.Aborted);
+                    var (oldState, newState) = ApplyCompletionFlag(StreamCompletionFlags.Aborted);
-                    if (states.OldState != states.NewState)
+                    if (oldState != newState)
                     {
                         // Don't block on IO. This never faults.
                         _ = _http2Output.WriteRstStreamAsync(Http2ErrorCode.NO_ERROR);
@@ -425,9 +425,9 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http2
 
         public void Abort(IOException abortReason)
         {
-            var states = ApplyCompletionFlag(StreamCompletionFlags.Aborted);
+            var (oldState, newState) = ApplyCompletionFlag(StreamCompletionFlags.Aborted);
 
-            if (states.OldState == states.NewState)
+            if (oldState == newState)
             {
                 return;
             }
@@ -451,9 +451,9 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http2
         internal void ResetAndAbort(ConnectionAbortedException abortReason, Http2ErrorCode error)
         {
             // Future incoming frames will drain for a default grace period to avoid destabilizing the connection.
-            var states = ApplyCompletionFlag(StreamCompletionFlags.Aborted);
+            var (oldState, newState) = ApplyCompletionFlag(StreamCompletionFlags.Aborted);
 
-            if (states.OldState == states.NewState)
+            if (oldState == newState)
             {
                 return;
             }

src/Servers/Kestrel/Core/src/Internal/Infrastructure/HttpUtilities.cs

@@ -422,15 +422,12 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Infrastructure
 
         public static string VersionToString(HttpVersion httpVersion)
         {
-            switch (httpVersion)
+            return httpVersion switch
             {
-                case HttpVersion.Http10:
+                HttpVersion.Http10 => Http10Version,
-                    return Http10Version;
+                HttpVersion.Http11 => Http11Version,
-                case HttpVersion.Http11:
+                _ => null,
-                    return Http11Version;
+            };
-                default:
-                    return null;
-            }
         }
         public static string MethodToString(HttpMethod method)
         {
@@ -445,15 +442,12 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Infrastructure
 
         public static string SchemeToString(HttpScheme scheme)
         {
-            switch (scheme)
+            return scheme switch
             {
-                case HttpScheme.Http:
+                HttpScheme.Http => HttpUriScheme,
-                    return HttpUriScheme;
+                HttpScheme.Https => HttpsUriScheme,
-                case HttpScheme.Https:
+                _ => null,
-                    return HttpsUriScheme;
+            };
-                default:
-                    return null;
-            }
         }
 
         public static bool IsHostHeaderValid(string hostText)

src/Servers/Kestrel/Core/src/Internal/Infrastructure/PipeWriterHelpers/TimingPipeFlusher.cs

@@ -60,10 +60,10 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Infrastructure.PipeW
                 return new ValueTask<FlushResult>(pipeFlushTask.Result);
             }
 
-            return TimeFlushAsyncAwaited(pipeFlushTask, minRate, count, outputAborter, cancellationToken);
+            return TimeFlushAsyncAwaited(pipeFlushTask, minRate, outputAborter, cancellationToken);
         }
 
-        private async ValueTask<FlushResult> TimeFlushAsyncAwaited(ValueTask<FlushResult> pipeFlushTask, MinDataRate minRate, long count, IHttpOutputAborter outputAborter, CancellationToken cancellationToken)
+        private async ValueTask<FlushResult> TimeFlushAsyncAwaited(ValueTask<FlushResult> pipeFlushTask, MinDataRate minRate, IHttpOutputAborter outputAborter, CancellationToken cancellationToken)
         {
             if (minRate != null)
             {

src/Servers/Kestrel/Core/src/Middleware/Internal/DuplexPipeStream.cs

@@ -152,7 +152,7 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal
 
         public override IAsyncResult BeginRead(byte[] buffer, int offset, int count, AsyncCallback callback, object state)
         {
-            var task = ReadAsync(buffer, offset, count, default(CancellationToken), state);
+            var task = ReadAsync(buffer, offset, count, default, state);
             if (callback != null)
             {
                 task.ContinueWith(t => callback.Invoke(t));
@@ -190,7 +190,7 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal
 
         public override IAsyncResult BeginWrite(byte[] buffer, int offset, int count, AsyncCallback callback, object state)
         {
-            var task = WriteAsync(buffer, offset, count, default(CancellationToken), state);
+            var task = WriteAsync(buffer, offset, count, default, state);
             if (callback != null)
             {
                 task.ContinueWith(t => callback.Invoke(t));

src/Servers/Kestrel/Transport.Sockets/src/Internal/SocketAwaitableEventArgs.cs

@@ -40,7 +40,7 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Transport.Sockets.Internal
 
             return BytesTransferred;
 
-            void ThrowSocketException(SocketError e)
+            static void ThrowSocketException(SocketError e)
             {
                 throw new SocketException((int)e);
             }

src/Servers/Kestrel/shared/KnownHeaders.cs

@@ -579,6 +579,7 @@ using System;
 using System.Collections.Generic;
 using System.Buffers;
 using System.IO.Pipelines;
+using System.Numerics;
 using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
 using Microsoft.Extensions.Primitives;
@@ -642,7 +643,7 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
         }}")}
         protected override int GetCountFast()
         {{
-            return (_contentLength.HasValue ? 1 : 0 ) + BitCount(_bits) + (MaybeUnknown?.Count ?? 0);
+            return (_contentLength.HasValue ? 1 : 0 ) + BitOperations.PopCount((ulong)_bits) + (MaybeUnknown?.Count ?? 0);
         }}
 
         protected override bool TryGetValueFast(string key, out StringValues value)
@@ -824,7 +825,7 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
             _contentLength = null;
             var tempBits = _bits;
             _bits = 0;
-            if(HttpHeaders.BitCount(tempBits) > 12)
+            if(BitOperations.PopCount((ulong)tempBits) > 12)
             {{
                 _headers = default(HeaderReferences);
                 return;