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Eliminate HTTP2 HPack enumerator allocations (#19393)

This commit is contained in:
James Newton-King 2020-03-03 12:37:34 +13:00 committed by GitHub
parent 4902672a3e
commit f34e8128c7
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GPG Key ID: 4AEE18F83AFDEB23
9 changed files with 323 additions and 36 deletions
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20
src/Servers/Kestrel/Core/src/Internal/Http2/Http2FrameWriter.cs
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@ -28,6 +28,7 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http2
private readonly object _writeLock = new object();
private readonly Http2Frame _outgoingFrame;
private readonly HPackEncoder _hpackEncoder = new HPackEncoder();
private readonly Http2HeadersEnumerator _headersEnumerator = new Http2HeadersEnumerator();
private readonly ConcurrentPipeWriter _outputWriter;
private readonly ConnectionContext _connectionContext;
private readonly Http2Connection _http2Connection;
@ -160,7 +161,7 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http2
| Padding (*) ...
+---------------------------------------------------------------+
*/
public void WriteResponseHeaders(int streamId, int statusCode, Http2HeadersFrameFlags headerFrameFlags, IHeaderDictionary headers)
public void WriteResponseHeaders(int streamId, int statusCode, Http2HeadersFrameFlags headerFrameFlags, HttpResponseHeaders headers)
{
lock (_writeLock)
{
@ -171,9 +172,10 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http2
try
{
_headersEnumerator.Initialize(headers);
_outgoingFrame.PrepareHeaders(headerFrameFlags, streamId);
var buffer = _headerEncodingBuffer.AsSpan();
var done = _hpackEncoder.BeginEncode(statusCode, EnumerateHeaders(headers), buffer, out var payloadLength);
var done = _hpackEncoder.BeginEncode(statusCode, _headersEnumerator, buffer, out var payloadLength);
FinishWritingHeaders(streamId, payloadLength, done);
}
catch (HPackEncodingException hex)
@ -196,9 +198,10 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http2
try
{
_headersEnumerator.Initialize(headers);
_outgoingFrame.PrepareHeaders(Http2HeadersFrameFlags.END_STREAM, streamId);
var buffer = _headerEncodingBuffer.AsSpan();
var done = _hpackEncoder.BeginEncode(EnumerateHeaders(headers), buffer, out var payloadLength);
var done = _hpackEncoder.BeginEncode(_headersEnumerator, buffer, out var payloadLength);
FinishWritingHeaders(streamId, payloadLength, done);
}
catch (HPackEncodingException hex)
@ -662,16 +665,5 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http2
flowControl.Abort();
}
}
private static IEnumerable<KeyValuePair<string, string>> EnumerateHeaders(IHeaderDictionary headers)
{
foreach (var header in headers)
{
foreach (var value in header.Value)
{
yield return new KeyValuePair<string, string>(header.Key, value);
}
}
}
}
}

161
src/Servers/Kestrel/Core/src/Internal/Http2/Http2HeaderEnumerator.cs Normal file
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@ -0,0 +1,161 @@
// 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.Collections;
using System.Collections.Generic;
using Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http;
using Microsoft.Extensions.Primitives;
namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http2
{
internal sealed class Http2HeadersEnumerator : IEnumerator<KeyValuePair<string, string>>
{
private bool _isTrailers;
private HttpResponseHeaders.Enumerator _headersEnumerator;
private HttpResponseTrailers.Enumerator _trailersEnumerator;
private IEnumerator<KeyValuePair<string, StringValues>> _genericEnumerator;
private StringValues.Enumerator _stringValuesEnumerator;
public KeyValuePair<string, string> Current { get; private set; }
object IEnumerator.Current => Current;
public Http2HeadersEnumerator()
{
}
public void Initialize(HttpResponseHeaders headers)
{
_headersEnumerator = headers.GetEnumerator();
_trailersEnumerator = default;
_genericEnumerator = null;
_isTrailers = false;
_stringValuesEnumerator = default;
Current = default;
}
public void Initialize(HttpResponseTrailers headers)
{
_headersEnumerator = default;
_trailersEnumerator = headers.GetEnumerator();
_genericEnumerator = null;
_isTrailers = true;
_stringValuesEnumerator = default;
Current = default;
}
public void Initialize(IDictionary<string, StringValues> headers)
{
_headersEnumerator = default;
_trailersEnumerator = default;
_genericEnumerator = headers.GetEnumerator();
_isTrailers = false;
_stringValuesEnumerator = default;
Current = default;
}
public bool MoveNext()
{
if (MoveNextOnStringEnumerator())
{
return true;
}
if (!TryGetNextStringEnumerator(out _stringValuesEnumerator))
{
return false;
}
return MoveNextOnStringEnumerator();
}
private string GetCurrentKey()
{
if (_genericEnumerator != null)
{
return _genericEnumerator.Current.Key;
}
else if (_isTrailers)
{
return _trailersEnumerator.Current.Key;
}
else
{
return _headersEnumerator.Current.Key;
}
}
private bool MoveNextOnStringEnumerator()
{
var result = _stringValuesEnumerator.MoveNext();
Current = result ? new KeyValuePair<string, string>(GetCurrentKey(), _stringValuesEnumerator.Current) : default;
return result;
}
private bool TryGetNextStringEnumerator(out StringValues.Enumerator enumerator)
{
if (_genericEnumerator != null)
{
if (!_genericEnumerator.MoveNext())
{
enumerator = default;
return false;
}
else
{
enumerator = _genericEnumerator.Current.Value.GetEnumerator();
return true;
}
}
else if (_isTrailers)
{
if (!_trailersEnumerator.MoveNext())
{
enumerator = default;
return false;
}
else
{
enumerator = _trailersEnumerator.Current.Value.GetEnumerator();
return true;
}
}
else
{
if (!_headersEnumerator.MoveNext())
{
enumerator = default;
return false;
}
else
{
enumerator = _headersEnumerator.Current.Value.GetEnumerator();
return true;
}
}
}
public void Reset()
{
if (_genericEnumerator != null)
{
_genericEnumerator.Reset();
}
else if (_isTrailers)
{
_trailersEnumerator.Reset();
}
else
{
_headersEnumerator.Reset();
}
_stringValuesEnumerator = default;
}
public void Dispose()
{
}
}
}

22
src/Servers/Kestrel/Core/test/HPackEncoderTests.cs
View File

@ -3,7 +3,12 @@
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Net.Http.HPack;
using Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http;
using Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http2;
using Microsoft.Extensions.Primitives;
using Xunit;
namespace Microsoft.AspNetCore.Server.Kestrel.Core.Tests
@ -94,11 +99,11 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Tests
var length = 0;
if (statusCode.HasValue)
{
Assert.True(encoder.BeginEncode(statusCode.Value, headers, payload, out length));
Assert.True(encoder.BeginEncode(statusCode.Value, GetHeadersEnumerator(headers), payload, out length));
}
else
{
Assert.True(encoder.BeginEncode(headers, payload, out length));
Assert.True(encoder.BeginEncode(GetHeadersEnumerator(headers), payload, out length));
}
Assert.Equal(expectedPayload.Length, length);
@ -159,7 +164,7 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Tests
// When !exactSize, slices are one byte short of fitting the next header
var sliceLength = expectedStatusCodePayload.Length + (exactSize ? 0 : expectedDateHeaderPayload.Length - 1);
Assert.False(encoder.BeginEncode(statusCode, headers, payload.Slice(offset, sliceLength), out var length));
Assert.False(encoder.BeginEncode(statusCode, GetHeadersEnumerator(headers), payload.Slice(offset, sliceLength), out var length));
Assert.Equal(expectedStatusCodePayload.Length, length);
Assert.Equal(expectedStatusCodePayload, payload.Slice(0, length).ToArray());
@ -184,5 +189,16 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Tests
Assert.Equal(expectedServerHeaderPayload.Length, length);
Assert.Equal(expectedServerHeaderPayload, payload.Slice(offset, length).ToArray());
}
private static Http2HeadersEnumerator GetHeadersEnumerator(IEnumerable<KeyValuePair<string, string>> headers)
{
var groupedHeaders = headers
.GroupBy(k => k.Key)
.ToDictionary(g => g.Key, g => new StringValues(g.Select(gg => gg.Value).ToArray()));
var enumerator = new Http2HeadersEnumerator();
enumerator.Initialize(groupedHeaders);
return enumerator;
}
}
}

59
src/Servers/Kestrel/perf/Kestrel.Performance/Http2FrameWriterBenchmark.cs Normal file
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@ -0,0 +1,59 @@
// 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.Buffers;
using System.IO.Pipelines;
using BenchmarkDotNet.Attributes;
using Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http;
using Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http2;
using Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http2.FlowControl;
using Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Infrastructure;
using Microsoft.Extensions.Logging.Abstractions;
namespace Microsoft.AspNetCore.Server.Kestrel.Performance
{
public class Http2FrameWriterBenchmark
{
private MemoryPool<byte> _memoryPool;
private Pipe _pipe;
private Http2FrameWriter _frameWriter;
private HttpResponseHeaders _responseHeaders;
[GlobalSetup]
public void GlobalSetup()
{
_memoryPool = SlabMemoryPoolFactory.Create();
var options = new PipeOptions(_memoryPool, readerScheduler: PipeScheduler.Inline, writerScheduler: PipeScheduler.Inline, useSynchronizationContext: false);
_pipe = new Pipe(options);
_frameWriter = new Http2FrameWriter(
new NullPipeWriter(),
connectionContext: null,
http2Connection: null,
new OutputFlowControl(initialWindowSize: uint.MaxValue),
timeoutControl: null,
minResponseDataRate: null,
"TestConnectionId",
_memoryPool,
new KestrelTrace(NullLogger.Instance));
_responseHeaders = new HttpResponseHeaders();
_responseHeaders.HeaderContentType = "application/json";
_responseHeaders.HeaderContentLength = "1024";
}
[Benchmark]
public void WriteResponseHeaders()
{
_frameWriter.WriteResponseHeaders(0, 200, Http2HeadersFrameFlags.END_HEADERS, _responseHeaders);
}
[GlobalCleanup]
public void Dispose()
{
_pipe.Writer.Complete();
_memoryPool?.Dispose();
}
}
}

42
src/Servers/Kestrel/perf/Kestrel.Performance/Mocks/NullPipeWriter.cs Normal file
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@ -0,0 +1,42 @@
// 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.IO.Pipelines;
using System.Threading;
using System.Threading.Tasks;
namespace Microsoft.AspNetCore.Server.Kestrel.Performance
{
internal class NullPipeWriter : PipeWriter
{
private byte[] _buffer = new byte[1024 * 128];
public override void Advance(int bytes)
{
}
public override void CancelPendingFlush()
{
}
public override void Complete(Exception exception = null)
{
}
public override ValueTask<FlushResult> FlushAsync(CancellationToken cancellationToken = default)
{
return new ValueTask<FlushResult>(new FlushResult(false, true));
}
public override Memory<byte> GetMemory(int sizeHint = 0)
{
return _buffer;
}
public override Span<byte> GetSpan(int sizeHint = 0)
{
return _buffer;
}
}
}

2
src/Servers/Kestrel/samples/http2cat/http2cat.csproj
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@ -38,4 +38,4 @@
</ItemGroup>
</Project>

24
src/Servers/Kestrel/test/InMemory.FunctionalTests/Http2/Http2TestBase.cs
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@ -26,6 +26,7 @@ using Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http2.FlowControl;
using Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Infrastructure;
using Microsoft.AspNetCore.Testing;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Primitives;
using Microsoft.Net.Http.Headers;
using Moq;
using Xunit;
@ -504,7 +505,7 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Tests
frame.PrepareHeaders(Http2HeadersFrameFlags.NONE, streamId);
var buffer = _headerEncodingBuffer.AsSpan();
var done = _hpackEncoder.BeginEncode(headers, buffer, out var length);
var done = _hpackEncoder.BeginEncode(GetHeadersEnumerator(headers), buffer, out var length);
frame.PayloadLength = length;
if (done)
@ -539,6 +540,17 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Tests
return FlushAsync(writableBuffer);
}
private static Http2HeadersEnumerator GetHeadersEnumerator(IEnumerable<KeyValuePair<string, string>> headers)
{
var groupedHeaders = headers
.GroupBy(k => k.Key)
.ToDictionary(g => g.Key, g => new StringValues(g.Select(gg => gg.Value).ToArray()));
var enumerator = new Http2HeadersEnumerator();
enumerator.Initialize(groupedHeaders);
return enumerator;
}
/* https://tools.ietf.org/html/rfc7540#section-6.2
+---------------+
|Pad Length? (8)|
@ -565,7 +577,7 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Tests
extendedHeader[0] = padLength;
var payload = buffer.Slice(extendedHeaderLength, buffer.Length - padLength - extendedHeaderLength);
_hpackEncoder.BeginEncode(headers, payload, out var length);
_hpackEncoder.BeginEncode(GetHeadersEnumerator(headers), payload, out var length);
var padding = buffer.Slice(extendedHeaderLength + length, padLength);
padding.Fill(0);
@ -608,7 +620,7 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Tests
extendedHeader[4] = priority;
var payload = buffer.Slice(extendedHeaderLength);
_hpackEncoder.BeginEncode(headers, payload, out var length);
_hpackEncoder.BeginEncode(GetHeadersEnumerator(headers), payload, out var length);
frame.PayloadLength = extendedHeaderLength + length;
@ -655,7 +667,7 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Tests
extendedHeader[5] = priority;
var payload = buffer.Slice(extendedHeaderLength, buffer.Length - padLength - extendedHeaderLength);
_hpackEncoder.BeginEncode(headers, payload, out var length);
_hpackEncoder.BeginEncode(GetHeadersEnumerator(headers), payload, out var length);
var padding = buffer.Slice(extendedHeaderLength + length, padLength);
padding.Fill(0);
@ -776,7 +788,7 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Tests
frame.PrepareHeaders(flags, streamId);
var buffer = _headerEncodingBuffer.AsMemory();
var done = _hpackEncoder.BeginEncode(headers, buffer.Span, out var length);
var done = _hpackEncoder.BeginEncode(GetHeadersEnumerator(headers), buffer.Span, out var length);
frame.PayloadLength = length;
Http2FrameWriter.WriteHeader(frame, outputWriter);
@ -869,7 +881,7 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Tests
frame.PrepareContinuation(flags, streamId);
var buffer = _headerEncodingBuffer.AsMemory();
var done = _hpackEncoder.BeginEncode(headers, buffer.Span, out var length);
var done = _hpackEncoder.BeginEncode(GetHeadersEnumerator(headers), buffer.Span, out var length);
frame.PayloadLength = length;
Http2FrameWriter.WriteHeader(frame, outputWriter);

13
src/Shared/Http2cat/Http2Utilities.cs
View File

@ -20,6 +20,7 @@ using Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http2;
using Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Infrastructure;
using Microsoft.Extensions.Logging;
using Microsoft.Net.Http.Headers;
using IHttpHeadersHandler = System.Net.Http.IHttpHeadersHandler;
namespace Microsoft.AspNetCore.Http2Cat
{
@ -235,7 +236,7 @@ namespace Microsoft.AspNetCore.Http2Cat
frame.PrepareHeaders(Http2HeadersFrameFlags.NONE, streamId);
var buffer = _headerEncodingBuffer.AsSpan();
var done = _hpackEncoder.BeginEncode(headers, buffer, out var length);
var done = _hpackEncoder.BeginEncode(headers.GetEnumerator(), buffer, out var length);
frame.PayloadLength = length;
if (done)
@ -334,7 +335,7 @@ namespace Microsoft.AspNetCore.Http2Cat
extendedHeader[0] = padLength;
var payload = buffer.Slice(extendedHeaderLength, buffer.Length - padLength - extendedHeaderLength);
_hpackEncoder.BeginEncode(headers, payload, out var length);
_hpackEncoder.BeginEncode(headers.GetEnumerator(), payload, out var length);
var padding = buffer.Slice(extendedHeaderLength + length, padLength);
padding.Fill(0);
@ -376,7 +377,7 @@ namespace Microsoft.AspNetCore.Http2Cat
extendedHeader[4] = priority;
var payload = buffer.Slice(extendedHeaderLength);
_hpackEncoder.BeginEncode(headers, payload, out var length);
_hpackEncoder.BeginEncode(headers.GetEnumerator(), payload, out var length);
frame.PayloadLength = extendedHeaderLength + length;
@ -422,7 +423,7 @@ namespace Microsoft.AspNetCore.Http2Cat
extendedHeader[5] = priority;
var payload = buffer.Slice(extendedHeaderLength, buffer.Length - padLength - extendedHeaderLength);
_hpackEncoder.BeginEncode(headers, payload, out var length);
_hpackEncoder.BeginEncode(headers.GetEnumerator(), payload, out var length);
var padding = buffer.Slice(extendedHeaderLength + length, padLength);
padding.Fill(0);
@ -548,7 +549,7 @@ namespace Microsoft.AspNetCore.Http2Cat
frame.PrepareHeaders(flags, streamId);
var buffer = _headerEncodingBuffer.AsMemory();
var done = _hpackEncoder.BeginEncode(headers, buffer.Span, out var length);
var done = _hpackEncoder.BeginEncode(headers.GetEnumerator(), buffer.Span, out var length);
frame.PayloadLength = length;
WriteHeader(frame, outputWriter);
@ -641,7 +642,7 @@ namespace Microsoft.AspNetCore.Http2Cat
frame.PrepareContinuation(flags, streamId);
var buffer = _headerEncodingBuffer.AsMemory();
var done = _hpackEncoder.BeginEncode(headers, buffer.Span, out var length);
var done = _hpackEncoder.BeginEncode(headers.GetEnumerator(), buffer.Span, out var length);
frame.PayloadLength = length;
WriteHeader(frame, outputWriter);

16
src/Shared/runtime/Http2/Hpack/HPackEncoder.cs
View File

@ -2,26 +2,30 @@
// Licensed under the Apache License, Version 2.0.
// See THIRD-PARTY-NOTICES.TXT in the project root for license information.
using System.Collections.Generic;
using System.Diagnostics;
#if KESTREL
using HeadersEnumerator = Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http2.Http2HeadersEnumerator;
#else
using HeadersEnumerator = System.Collections.Generic.IEnumerator<System.Collections.Generic.KeyValuePair<string, string>>;
#endif
namespace System.Net.Http.HPack
{
internal class HPackEncoder
{
private IEnumerator<KeyValuePair<string, string>> _enumerator;
private HeadersEnumerator _enumerator;
public bool BeginEncode(IEnumerable<KeyValuePair<string, string>> headers, Span<byte> buffer, out int length)
public bool BeginEncode(HeadersEnumerator enumerator, Span<byte> buffer, out int length)
{
_enumerator = headers.GetEnumerator();
_enumerator = enumerator;
_enumerator.MoveNext();
return Encode(buffer, out length);
}
public bool BeginEncode(int statusCode, IEnumerable<KeyValuePair<string, string>> headers, Span<byte> buffer, out int length)
public bool BeginEncode(int statusCode, HeadersEnumerator enumerator, Span<byte> buffer, out int length)
{
_enumerator = headers.GetEnumerator();
_enumerator = enumerator;
_enumerator.MoveNext();
int statusCodeLength = EncodeStatusCode(statusCode, buffer);