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Make all write operations atomic #562

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halter73 merged 4 commits into from
Jan 12, 2016
Merged

Make all write operations atomic #562

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e90b61e
Move call to CopyFrom in SocketOutput.WriteAsync inside lock to make …
halter73 Jan 7, 2016
df695ac
Use TryEnter to acquire SocketOutput._contextLock on the libuv event …
halter73 Jan 7, 2016
daa2b7e
Remove _tasksCompleted from SocketOutput
halter73 Jan 8, 2016
ab5ef54
Make chunked writes atomic
halter73 Jan 8, 2016
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26 changes: 22 additions & 4 deletions src/Microsoft.AspNet.Server.Kestrel/Filter/StreamSocketOutput.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,7 @@

using System;
using System.IO;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.AspNet.Server.Kestrel.Http;
Expand All @@ -12,27 +13,44 @@ namespace Microsoft.AspNet.Server.Kestrel.Filter
{
public class StreamSocketOutput : ISocketOutput
{
private static readonly byte[] _endChunkBytes = Encoding.ASCII.GetBytes("\r\n");
private static readonly byte[] _nullBuffer = new byte[0];

private readonly Stream _outputStream;
private readonly MemoryPool2 _memory;
private MemoryPoolBlock2 _producingBlock;

private object _writeLock = new object();

public StreamSocketOutput(Stream outputStream, MemoryPool2 memory)
{
_outputStream = outputStream;
_memory = memory;
}

void ISocketOutput.Write(ArraySegment<byte> buffer, bool immediate)
public void Write(ArraySegment<byte> buffer, bool immediate, bool chunk)
{
_outputStream.Write(buffer.Array ?? _nullBuffer, buffer.Offset, buffer.Count);
lock (_writeLock)
{
if (chunk && buffer.Array != null)
{
var beginChunkBytes = ChunkWriter.BeginChunkBytes(buffer.Count);
_outputStream.Write(beginChunkBytes.Array, beginChunkBytes.Offset, beginChunkBytes.Count);
}

_outputStream.Write(buffer.Array ?? _nullBuffer, buffer.Offset, buffer.Count);

if (chunk && buffer.Array != null)
{
_outputStream.Write(_endChunkBytes, 0, _endChunkBytes.Length);
}
}
}

Task ISocketOutput.WriteAsync(ArraySegment<byte> buffer, bool immediate, CancellationToken cancellationToken)
public Task WriteAsync(ArraySegment<byte> buffer, bool immediate, bool chunk, CancellationToken cancellationToken)
{
// TODO: Use _outputStream.WriteAsync
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@cesarblum cesarblum Jan 8, 2016

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Remove TODO?

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@halter73 halter73 Jan 8, 2016

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This is still a todo though. Someday...

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@cesarblum cesarblum Jan 8, 2016

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What's preventing us from addressing it?

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@halter73 halter73 Jan 8, 2016

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Debugging. All I know is calling WriteAsync on SslStream didn't work when last I tried it. I think the call never completed, but I'm not 100% on that. You are definitely right that I should have left a better comment when I first wrote this code.

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@benaadams benaadams Jan 10, 2016

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Can you retest post #567 ? Ran into issue #565 with Ssl WriteAsync as its sync.

On the upside; I think I fixed the issue :)

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@benaadams benaadams Jan 11, 2016

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K, so tests fail changing this to async. Will dig in and do a different PR if I get a resolution. Added issue #569

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@halter73 halter73 Jan 11, 2016

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@benaadams Thanks for looking into this.

_outputStream.Write(buffer.Array ?? _nullBuffer, buffer.Offset, buffer.Count);
Write(buffer, immediate, chunk);
return TaskUtilities.CompletedTask;
}

Expand Down
62 changes: 62 additions & 0 deletions src/Microsoft.AspNet.Server.Kestrel/Http/ChunkWriter.cs
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Original file line number Diff line number Diff line change
@@ -0,0 +1,62 @@
// 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.Text;
using Microsoft.AspNet.Server.Kestrel.Infrastructure;

namespace Microsoft.AspNet.Server.Kestrel.Http
{
public static class ChunkWriter
{
private static readonly ArraySegment<byte> _endChunkBytes = CreateAsciiByteArraySegment("\r\n");
private static readonly byte[] _hex = Encoding.ASCII.GetBytes("0123456789abcdef");

private static ArraySegment<byte> CreateAsciiByteArraySegment(string text)
{
var bytes = Encoding.ASCII.GetBytes(text);
return new ArraySegment<byte>(bytes);
}

public static ArraySegment<byte> BeginChunkBytes(int dataCount)
{
var bytes = new byte[10]
{
_hex[((dataCount >> 0x1c) & 0x0f)],
_hex[((dataCount >> 0x18) & 0x0f)],
_hex[((dataCount >> 0x14) & 0x0f)],
_hex[((dataCount >> 0x10) & 0x0f)],
_hex[((dataCount >> 0x0c) & 0x0f)],
_hex[((dataCount >> 0x08) & 0x0f)],
_hex[((dataCount >> 0x04) & 0x0f)],
_hex[((dataCount >> 0x00) & 0x0f)],
(byte)'\r',
(byte)'\n',
};

// Determine the most-significant non-zero nibble
int total, shift;
total = (dataCount > 0xffff) ? 0x10 : 0x00;
dataCount >>= total;
shift = (dataCount > 0x00ff) ? 0x08 : 0x00;
dataCount >>= shift;
total |= shift;
total |= (dataCount > 0x000f) ? 0x04 : 0x00;
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@cesarblum cesarblum Jan 8, 2016

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I like this sorcery 👍

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@cesarblum cesarblum Jan 8, 2016

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Oh now I see it's just copied from another class :P

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@halter73 halter73 Jan 8, 2016

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This was simply moved from Frame. Credit @lodejard.


var offset = 7 - (total >> 2);
return new ArraySegment<byte>(bytes, offset, 10 - offset);
}

public static int WriteBeginChunkBytes(ref MemoryPoolIterator2 start, int dataCount)
{
var chunkSegment = BeginChunkBytes(dataCount);
start.CopyFrom(chunkSegment);
return chunkSegment.Count;
}

public static void WriteEndChunkBytes(ref MemoryPoolIterator2 start)
{
start.CopyFrom(_endChunkBytes);
}
}
}
39 changes: 2 additions & 37 deletions src/Microsoft.AspNet.Server.Kestrel/Http/Frame.cs
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Expand Up @@ -23,11 +23,9 @@ namespace Microsoft.AspNet.Server.Kestrel.Http
public abstract partial class Frame : FrameContext, IFrameControl
{
private static readonly Encoding _ascii = Encoding.ASCII;
private static readonly ArraySegment<byte> _endChunkBytes = CreateAsciiByteArraySegment("\r\n");
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 ArraySegment<byte> _emptyData = new ArraySegment<byte>(new byte[0]);
private static readonly byte[] _hex = Encoding.ASCII.GetBytes("0123456789abcdef");

private static readonly byte[] _bytesConnectionClose = Encoding.ASCII.GetBytes("\r\nConnection: close");
private static readonly byte[] _bytesConnectionKeepAlive = Encoding.ASCII.GetBytes("\r\nConnection: keep-alive");
Expand Down Expand Up @@ -472,45 +470,12 @@ public async Task WriteAsyncAwaited(ArraySegment<byte> data, CancellationToken c

private void WriteChunked(ArraySegment<byte> data)
{
SocketOutput.Write(BeginChunkBytes(data.Count), immediate: false);
SocketOutput.Write(data, immediate: false);
SocketOutput.Write(_endChunkBytes, immediate: true);
SocketOutput.Write(data, immediate: false, chunk: true);
}

private async Task WriteChunkedAsync(ArraySegment<byte> data, CancellationToken cancellationToken)
{
await SocketOutput.WriteAsync(BeginChunkBytes(data.Count), immediate: false, cancellationToken: cancellationToken);
await SocketOutput.WriteAsync(data, immediate: false, cancellationToken: cancellationToken);
await SocketOutput.WriteAsync(_endChunkBytes, immediate: true, cancellationToken: cancellationToken);
}

public static ArraySegment<byte> BeginChunkBytes(int dataCount)
{
var bytes = new byte[10]
{
_hex[((dataCount >> 0x1c) & 0x0f)],
_hex[((dataCount >> 0x18) & 0x0f)],
_hex[((dataCount >> 0x14) & 0x0f)],
_hex[((dataCount >> 0x10) & 0x0f)],
_hex[((dataCount >> 0x0c) & 0x0f)],
_hex[((dataCount >> 0x08) & 0x0f)],
_hex[((dataCount >> 0x04) & 0x0f)],
_hex[((dataCount >> 0x00) & 0x0f)],
(byte)'\r',
(byte)'\n',
};

// Determine the most-significant non-zero nibble
int total, shift;
total = (dataCount > 0xffff) ? 0x10 : 0x00;
dataCount >>= total;
shift = (dataCount > 0x00ff) ? 0x08 : 0x00;
dataCount >>= shift;
total |= shift;
total |= (dataCount > 0x000f) ? 0x04 : 0x00;

var offset = 7 - (total >> 2);
return new ArraySegment<byte>(bytes, offset, 10 - offset);
await SocketOutput.WriteAsync(data, immediate: false, chunk: true, cancellationToken: cancellationToken);
}

private void WriteChunkedResponseSuffix()
Expand Down
4 changes: 2 additions & 2 deletions src/Microsoft.AspNet.Server.Kestrel/Http/ISocketOutput.cs
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Expand Up @@ -13,8 +13,8 @@ namespace Microsoft.AspNet.Server.Kestrel.Http
/// </summary>
public interface ISocketOutput
{
void Write(ArraySegment<byte> buffer, bool immediate = true);
Task WriteAsync(ArraySegment<byte> buffer, bool immediate = true, CancellationToken cancellationToken = default(CancellationToken));
void Write(ArraySegment<byte> buffer, bool immediate = true, bool chunk = false);
Task WriteAsync(ArraySegment<byte> buffer, bool immediate = true, bool chunk = false, CancellationToken cancellationToken = default(CancellationToken));

/// <summary>
/// Returns an iterator pointing to the tail of the response buffer. Response data can be appended
Expand Down
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