Specialized struct generics rather than interface (#1640)

Changed the IHttpParser interface to be generic. This lets use a struct to 
get better code generation and also should allow us to inline calls back into
the handler from the parser.

src/Microsoft.AspNetCore.Server.Kestrel.Core/Adapter/Internal/StreamSocketOutput.cs

@@ -83,7 +83,7 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Adapter.Internal
             return WriteAsync(default(ArraySegment<byte>), chunk: false, cancellationToken: cancellationToken);
         }
 
-        public void Write<T>(Action<WritableBuffer, T> callback, T state)
+        public void Write<T>(Action<WritableBuffer, T> callback, T state) where T : struct
         {
             lock (_sync)
             {

src/Microsoft.AspNetCore.Server.Kestrel.Core/Internal/Http/Frame.cs

@@ -26,7 +26,7 @@ using Microsoft.Extensions.Primitives;
 
 namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
 {
-    public abstract partial class Frame : IFrameControl, IHttpRequestLineHandler, IHttpHeadersHandler
+    public abstract partial class Frame : IFrameControl
     {
         private const byte ByteAsterisk = (byte)'*';
         private const byte ByteForwardSlash = (byte)'/';
@@ -34,7 +34,7 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
 
         private static readonly ArraySegment<byte> _endChunkedResponseBytes = CreateAsciiByteArraySegment("0\r\n\r\n");
         private static readonly ArraySegment<byte> _continueBytes = CreateAsciiByteArraySegment("HTTP/1.1 100 Continue\r\n\r\n");
-        private static readonly Action<WritableBuffer, Frame> _writeHeaders = WriteResponseHeaders;
+        private static readonly Action<WritableBuffer, FrameAdapter> _writeHeaders = WriteResponseHeaders;
 
         private static readonly byte[] _bytesConnectionClose = Encoding.ASCII.GetBytes("\r\nConnection: close");
         private static readonly byte[] _bytesConnectionKeepAlive = Encoding.ASCII.GetBytes("\r\nConnection: keep-alive");
@@ -80,7 +80,7 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
         protected long _responseBytesWritten;
 
         private readonly FrameContext _frameContext;
-        private readonly IHttpParser _parser;
+        private readonly IHttpParser<FrameAdapter> _parser;
 
         public Frame(FrameContext frameContext)
         {
@@ -88,7 +88,7 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
 
             ServerOptions = ServiceContext.ServerOptions;
 
-            _parser = ServiceContext.HttpParserFactory(this);
+            _parser = ServiceContext.HttpParserFactory(new FrameAdapter(this));
 
             FrameControl = this;
             _keepAliveMilliseconds = (long)ServerOptions.Limits.KeepAliveTimeout.TotalMilliseconds;
@@ -988,11 +988,12 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
                 responseHeaders.SetRawDate(dateHeaderValues.String, dateHeaderValues.Bytes);
             }
 
-            Output.Write(_writeHeaders, this);
+            Output.Write(_writeHeaders, new FrameAdapter(this));
         }
 
-        private static void WriteResponseHeaders(WritableBuffer writableBuffer, Frame frame)
+        private static void WriteResponseHeaders(WritableBuffer writableBuffer, FrameAdapter frameAdapter)
         {
+            var frame = frameAdapter.Frame;
             var writer = new WritableBufferWriter(writableBuffer);
 
             var responseHeaders = frame.FrameResponseHeaders;
@@ -1050,7 +1051,7 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
                 overLength = true;
             }
 
-            var result = _parser.ParseRequestLine(this, buffer, out consumed, out examined);
+            var result = _parser.ParseRequestLine(new FrameAdapter(this), buffer, out consumed, out examined);
             if (!result && overLength)
             {
                 RejectRequest(RequestRejectionReason.RequestLineTooLong);
@@ -1072,7 +1073,7 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
                 overLength = true;
             }
 
-            var result = _parser.ParseHeaders(this, buffer, out consumed, out examined, out var consumedBytes);
+            var result = _parser.ParseHeaders(new FrameAdapter(this), buffer, out consumed, out examined, out var consumedBytes);
             _remainingRequestHeadersBytesAllowed -= consumedBytes;
 
             if (!result && overLength)

src/Microsoft.AspNetCore.Server.Kestrel.Core/Internal/Http/FrameAdapter.cs

@@ -0,0 +1,23 @@
+// 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 Microsoft.AspNetCore.Server.Kestrel.Internal.System;
+
+namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
+{
+    public struct FrameAdapter : IHttpRequestLineHandler, IHttpHeadersHandler
+    {
+        public Frame Frame;
+
+        public FrameAdapter(Frame frame)
+        {
+            Frame = frame;
+        }
+
+        public void OnHeader(Span<byte> name, Span<byte> value)
+            => Frame.OnHeader(name, value);
+
+        public void OnStartLine(HttpMethod method, HttpVersion version, Span<byte> target, Span<byte> path, Span<byte> query, Span<byte> customMethod, bool pathEncoded)
+            => Frame.OnStartLine(method, version, target, path, query, customMethod, pathEncoded);
+    }
+}

src/Microsoft.AspNetCore.Server.Kestrel.Core/Internal/Http/HttpParser.cs

@@ -9,7 +9,7 @@ using Microsoft.Extensions.Logging;
 
 namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
 {
-    public class HttpParser : IHttpParser
+    public class HttpParser<TRequestHandler> : IHttpParser<TRequestHandler> where TRequestHandler : IHttpHeadersHandler, IHttpRequestLineHandler
     {
         public HttpParser(IKestrelTrace log)
         {
@@ -27,7 +27,7 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
         private const byte ByteQuestionMark = (byte)'?';
         private const byte BytePercentage = (byte)'%';
 
-        public unsafe bool ParseRequestLine(IHttpRequestLineHandler handler, ReadableBuffer buffer, out ReadCursor consumed, out ReadCursor examined)
+        public unsafe bool ParseRequestLine(TRequestHandler handler, ReadableBuffer buffer, out ReadCursor consumed, out ReadCursor examined)
         {
             consumed = buffer.Start;
             examined = buffer.End;
@@ -66,7 +66,7 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
             return true;
         }
 
-        private unsafe void ParseRequestLine(IHttpRequestLineHandler handler, byte* data, int length)
+        private unsafe void ParseRequestLine(TRequestHandler handler, byte* data, int length)
         {
             int offset;
             Span<byte> customMethod = default(Span<byte>);
@@ -183,7 +183,7 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
             handler.OnStartLine(method, httpVersion, targetBuffer, pathBuffer, query, customMethod, pathEncoded);
         }
 
-        public unsafe bool ParseHeaders(IHttpHeadersHandler handler, ReadableBuffer buffer, out ReadCursor consumed, out ReadCursor examined, out int consumedBytes)
+        public unsafe bool ParseHeaders(TRequestHandler handler, ReadableBuffer buffer, out ReadCursor consumed, out ReadCursor examined, out int consumedBytes)
         {
             consumed = buffer.Start;
             examined = buffer.End;
@@ -346,7 +346,7 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
         }
 
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        private unsafe void TakeSingleHeader(byte* headerLine, int length, IHttpHeadersHandler handler)
+        private unsafe void TakeSingleHeader(byte* headerLine, int length, TRequestHandler handler)
         {
             // Skip CR, LF from end position
             var valueEnd = length - 3;

src/Microsoft.AspNetCore.Server.Kestrel.Core/Internal/Http/IHttpParser.cs

@@ -5,11 +5,11 @@ using Microsoft.AspNetCore.Server.Kestrel.Internal.System.IO.Pipelines;
 
 namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
 {
-    public interface IHttpParser
+    public interface IHttpParser<TRequestHandler> where TRequestHandler : IHttpHeadersHandler, IHttpRequestLineHandler
     {
-        bool ParseRequestLine(IHttpRequestLineHandler handler, ReadableBuffer buffer, out ReadCursor consumed, out ReadCursor examined);
+        bool ParseRequestLine(TRequestHandler handler, ReadableBuffer buffer, out ReadCursor consumed, out ReadCursor examined);
 
-        bool ParseHeaders(IHttpHeadersHandler handler, ReadableBuffer buffer, out ReadCursor consumed, out ReadCursor examined, out int consumedBytes);
+        bool ParseHeaders(TRequestHandler handler, ReadableBuffer buffer, out ReadCursor consumed, out ReadCursor examined, out int consumedBytes);
 
         void Reset();
     }

src/Microsoft.AspNetCore.Server.Kestrel.Core/Internal/Http/ISocketOutput.cs

@@ -17,6 +17,6 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
         Task WriteAsync(ArraySegment<byte> buffer, bool chunk = false, CancellationToken cancellationToken = default(CancellationToken));
         void Flush();
         Task FlushAsync(CancellationToken cancellationToken = default(CancellationToken));
-        void Write<T>(Action<WritableBuffer, T> write, T state);
+        void Write<T>(Action<WritableBuffer, T> write, T state) where T : struct;
     }
 }

src/Microsoft.AspNetCore.Server.Kestrel.Core/Internal/ServiceContext.cs

@@ -13,7 +13,7 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal
 
         public IThreadPool ThreadPool { get; set; }
 
-        public Func<Frame, IHttpParser> HttpParserFactory { get; set; }
+        public Func<FrameAdapter, IHttpParser<FrameAdapter>> HttpParserFactory { get; set; }
 
         public DateHeaderValueManager DateHeaderValueManager { get; set; }
 

src/Microsoft.AspNetCore.Server.Kestrel.Core/KestrelServer.cs

@@ -101,7 +101,7 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core
                 var serviceContext = new ServiceContext
                 {
                     Log = trace,
-                    HttpParserFactory = frame => new HttpParser(frame.ServiceContext.Log),
+                    HttpParserFactory = frameParser => new HttpParser<FrameAdapter>(frameParser.Frame.ServiceContext.Log),
                     ThreadPool = threadPool,
                     DateHeaderValueManager = _dateHeaderValueManager,
                     ServerOptions = Options

test/Microsoft.AspNetCore.Server.Kestrel.Core.Tests/FrameResponseHeadersTests.cs

@@ -256,28 +256,5 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Tests
             "42,000",
             "42.000",
         };
-
-        private class NoopHttpParser : IHttpParser
-        {
-            public bool ParseHeaders(IHttpHeadersHandler handler, ReadableBuffer buffer, out ReadCursor consumed, out ReadCursor examined, out int consumedBytes)
-            {
-                consumed = buffer.Start;
-                examined = buffer.End;
-                consumedBytes = 0;
-                return false;
-            }
-
-            public bool ParseRequestLine(IHttpRequestLineHandler handler, ReadableBuffer buffer, out ReadCursor consumed, out ReadCursor examined)
-            {
-                consumed = buffer.Start;
-                examined = buffer.End;
-                return false;
-            }
-
-            public void Reset()
-            {
-
-            }
-        }
     }
 }

test/Microsoft.AspNetCore.Server.Kestrel.Core.Tests/HttpParserTests.cs

@@ -5,7 +5,6 @@ using System.Collections.Generic;
 using System.Linq;
 using System.Text;
 using Microsoft.AspNetCore.Http;
-using Microsoft.AspNetCore.Server.Kestrel.Core;
 using Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http;
 using Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Infrastructure;
 using Microsoft.AspNetCore.Server.Kestrel.Internal.System;
@@ -418,7 +417,7 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Tests
             Assert.Equal(buffer.End, examined);
         }
 
-        private IHttpParser CreateParser(IKestrelTrace log) => new HttpParser(log);
+        private IHttpParser<RequestHandler> CreateParser(IKestrelTrace log) => new HttpParser<RequestHandler>(log);
 
         public static IEnumerable<string[]> RequestLineValidData => HttpParsingData.RequestLineValidData;
 

test/Microsoft.AspNetCore.Server.Kestrel.Core.Tests/OutputProducerTests.cs

@@ -38,11 +38,11 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Tests
 
                 var called = false;
 
-                ((ISocketOutput)socketOutput).Write<object>((buffer, state) =>
+                ((ISocketOutput)socketOutput).Write((buffer, state) =>
                 {
                     called = true;
                 },
-                null);
+                0);
 
                 Assert.False(called);
             }

test/Microsoft.AspNetCore.Server.Kestrel.Performance/FrameFeatureCollection.cs

@@ -78,7 +78,7 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Performance
         {
             var serviceContext = new ServiceContext
             {
-                HttpParserFactory = _ => NullParser.Instance,
+                HttpParserFactory = _ => NullParser<FrameAdapter>.Instance,
                 ServerOptions = new KestrelServerOptions()
             };
             var frameContext = new FrameContext

test/Microsoft.AspNetCore.Server.Kestrel.Performance/FrameParsingOverheadBenchmark.cs

@@ -22,7 +22,7 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Performance
         {
             var serviceContext = new ServiceContext
             {
-                HttpParserFactory = _ => NullParser.Instance,
+                HttpParserFactory = _ => NullParser<FrameAdapter>.Instance,
                 ServerOptions = new KestrelServerOptions()
             };
             var frameContext = new FrameContext

test/Microsoft.AspNetCore.Server.Kestrel.Performance/FrameWritingBenchmark.cs

@@ -94,7 +94,7 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Performance
                 DateHeaderValueManager = new DateHeaderValueManager(),
                 ServerOptions = new KestrelServerOptions(),
                 Log = new MockTrace(),
-                HttpParserFactory = f => new HttpParser(log: null)
+                HttpParserFactory = f => new HttpParser<FrameAdapter>(log: null)
             };
             var frameContext = new FrameContext
             {

test/Microsoft.AspNetCore.Server.Kestrel.Performance/KestrelHttpParserBenchmark.cs

@@ -12,7 +12,7 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Performance
 
     public class KestrelHttpParserBenchmark : IHttpRequestLineHandler, IHttpHeadersHandler
     {
-        private readonly HttpParser _parser = new HttpParser(log: null);
+        private readonly HttpParser<Adapter> _parser = new HttpParser<Adapter>(log: null);
 
         private ReadableBuffer _buffer;
 
@@ -53,14 +53,14 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Performance
 
         private void ParseData()
         {
-            if (!_parser.ParseRequestLine(this, _buffer, out var consumed, out var examined))
+            if (!_parser.ParseRequestLine(new Adapter(this), _buffer, out var consumed, out var examined))
             {
                 ErrorUtilities.ThrowInvalidRequestHeaders();
             }
 
             _buffer = _buffer.Slice(consumed, _buffer.End);
 
-            if (!_parser.ParseHeaders(this, _buffer, out consumed, out examined, out var consumedBytes))
+            if (!_parser.ParseHeaders(new Adapter(this), _buffer, out consumed, out examined, out var consumedBytes))
             {
                 ErrorUtilities.ThrowInvalidRequestHeaders();
             }
@@ -73,5 +73,21 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Performance
         public void OnHeader(Span<byte> name, Span<byte> value)
         {
         }
+
+        private struct Adapter : IHttpRequestLineHandler, IHttpHeadersHandler
+        {
+            public KestrelHttpParserBenchmark RequestHandler;
+
+            public Adapter(KestrelHttpParserBenchmark requestHandler)
+            {
+                RequestHandler = requestHandler;
+            }
+
+            public void OnHeader(Span<byte> name, Span<byte> value)
+                => RequestHandler.OnHeader(name, value);
+
+            public void OnStartLine(HttpMethod method, HttpVersion version, Span<byte> target, Span<byte> path, Span<byte> query, Span<byte> customMethod, bool pathEncoded)
+                => RequestHandler.OnStartLine(method, version, target, path, query, customMethod, pathEncoded);
+        }
     }
 }

test/Microsoft.AspNetCore.Server.Kestrel.Performance/Mocks/NullParser.cs

@@ -8,7 +8,7 @@ using Microsoft.AspNetCore.Server.Kestrel.Internal.System.IO.Pipelines;
 
 namespace Microsoft.AspNetCore.Server.Kestrel.Performance
 {
-    public class NullParser : IHttpParser
+    public class NullParser<TRequestHandler> : IHttpParser<TRequestHandler> where TRequestHandler : struct, IHttpHeadersHandler, IHttpRequestLineHandler
     {
         private readonly byte[] _startLine = Encoding.ASCII.GetBytes("GET /plaintext HTTP/1.1\r\n");
         private readonly byte[] _target = Encoding.ASCII.GetBytes("/plaintext");
@@ -19,9 +19,9 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Performance
         private readonly byte[] _connectionHeaderName = Encoding.ASCII.GetBytes("Connection");
         private readonly byte[] _connectionHeaderValue = Encoding.ASCII.GetBytes("keep-alive");
 
-        public static readonly NullParser Instance = new NullParser();
+        public static readonly NullParser<FrameAdapter> Instance = new NullParser<FrameAdapter>();
 
-        public bool ParseHeaders(IHttpHeadersHandler handler, ReadableBuffer buffer, out ReadCursor consumed, out ReadCursor examined, out int consumedBytes)
+        public bool ParseHeaders(TRequestHandler handler, ReadableBuffer buffer, out ReadCursor consumed, out ReadCursor examined, out int consumedBytes)
         {
             handler.OnHeader(new Span<byte>(_hostHeaderName), new Span<byte>(_hostHeaderValue));
             handler.OnHeader(new Span<byte>(_acceptHeaderName), new Span<byte>(_acceptHeaderValue));
@@ -34,7 +34,7 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Performance
             return true;
         }
 
-        public bool ParseRequestLine(IHttpRequestLineHandler handler, ReadableBuffer buffer, out ReadCursor consumed, out ReadCursor examined)
+        public bool ParseRequestLine(TRequestHandler handler, ReadableBuffer buffer, out ReadCursor consumed, out ReadCursor examined)
         {
             handler.OnStartLine(HttpMethod.Get,
                 HttpVersion.Http11,

test/Microsoft.AspNetCore.Server.Kestrel.Performance/RequestParsingBenchmark.cs

@@ -23,7 +23,7 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Performance
         {
             var serviceContext = new ServiceContext
             {
-                HttpParserFactory = f => new HttpParser(f.ServiceContext.Log),
+                HttpParserFactory = f => new HttpParser<FrameAdapter>(f.Frame.ServiceContext.Log),
                 ServerOptions = new KestrelServerOptions()
             };
             var frameContext = new FrameContext

test/Microsoft.AspNetCore.Server.Kestrel.Performance/ResponseHeaderCollectionBenchmark.cs

@@ -170,7 +170,7 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Performance
         {
             var serviceContext = new ServiceContext
             {
-                HttpParserFactory = f => new HttpParser(f.ServiceContext.Log),
+                HttpParserFactory = f => new HttpParser<FrameAdapter>(f.Frame.ServiceContext.Log),
                 ServerOptions = new KestrelServerOptions()
             };
             var frameContext = new FrameContext

test/Microsoft.AspNetCore.Server.Kestrel.Performance/ResponseHeadersWritingBenchmark.cs

@@ -120,7 +120,7 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Performance
                 DateHeaderValueManager = new DateHeaderValueManager(),
                 ServerOptions = new KestrelServerOptions(),
                 Log = new MockTrace(),
-                HttpParserFactory = f => new HttpParser(log: null)
+                HttpParserFactory = f => new HttpParser<FrameAdapter>(log: null)
             };
 
             var frameContext = new FrameContext

test/shared/MockSocketOutput.cs

@@ -34,7 +34,7 @@ namespace Microsoft.AspNetCore.Testing
             return TaskCache.CompletedTask;
         }
 
-        public void Write<T>(Action<WritableBuffer, T> write, T state)
+        public void Write<T>(Action<WritableBuffer, T> write, T state) where T : struct
         {
 
         }

test/shared/TestServiceContext.cs

@@ -18,7 +18,7 @@ namespace Microsoft.AspNetCore.Testing
             ThreadPool = new LoggingThreadPool(Log);
             DateHeaderValueManager = new DateHeaderValueManager(systemClock: new MockSystemClock());
             DateHeaderValue = DateHeaderValueManager.GetDateHeaderValues().String;
-            HttpParserFactory = frame => new HttpParser(frame.ServiceContext.Log);
+            HttpParserFactory = frameAdapter => new HttpParser<FrameAdapter>(frameAdapter.Frame.ServiceContext.Log);
             ServerOptions = new KestrelServerOptions
             {
                 AddServerHeader = false