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Avoiding serializing to MemoryStream

This commit is contained in:
Pawel Kadluczka 2017-11-15 16:31:40 -08:00
parent 0255979a73
commit 046553cfe4
5 changed files with 67 additions and 99 deletions
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30
src/Microsoft.AspNetCore.SignalR.Common/Internal/Encoders/Base64Encoder.cs
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@ -5,7 +5,6 @@ using System;
using System.Buffers;
using System.Buffers.Text;
using System.Diagnostics;
using System.IO;
namespace Microsoft.AspNetCore.SignalR.Internal.Encoders
{
@ -23,18 +22,37 @@ namespace Microsoft.AspNetCore.SignalR.Internal.Encoders
return decoded.Slice(0, written);
}
private const int Int32OverflowLength = 10;
public byte[] Encode(byte[] payload)
{
Span<byte> buffer = new byte[Base64.GetMaxEncodedToUtf8Length(payload.Length)];
var maxEncodedLength = Base64.GetMaxEncodedToUtf8Length(payload.Length);
var status = Base64.EncodeToUtf8(payload, buffer, out _, out var written);
// Int32OverflowLength + length of separator (':') + length of terminator (';')
if (int.MaxValue - maxEncodedLength < Int32OverflowLength + 2)
{
throw new FormatException("The encoded message exceeds the maximum supported size.");
}
//The format is: [{length}:{message};] so allocate enough to be able to write the entire message
Span<byte> buffer = new byte[Int32OverflowLength + 1 + maxEncodedLength + 1];
buffer[Int32OverflowLength] = (byte)':';
var status = Base64.EncodeToUtf8(payload, buffer.Slice(Int32OverflowLength + 1), out _, out var written);
Debug.Assert(status == OperationStatus.Done);
using (var stream = new MemoryStream())
buffer[Int32OverflowLength + 1 + written] = (byte)';';
var prefixLength = 0;
var prefix = written;
do
{
LengthPrefixedTextMessageWriter.WriteMessage(buffer.Slice(0, written), stream);
return stream.ToArray();
buffer[Int32OverflowLength - 1 - prefixLength] = (byte)('0' + prefix % 10);
prefix /= 10;
prefixLength++;
}
while (prefix > 0);
return buffer.Slice(Int32OverflowLength - prefixLength, prefixLength + 1 + written + 1).ToArray();
}
}
}

8
src/Microsoft.AspNetCore.SignalR.Common/Internal/Encoders/LengthPrefixedTextMessageParser.cs
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@ -9,6 +9,8 @@ namespace Microsoft.AspNetCore.SignalR.Internal.Encoders
public static class LengthPrefixedTextMessageParser
{
private const int Int32OverflowLength = 10;
private const char FieldDelimiter = ':';
private const char MessageDelimiter = ';';
/// <summary>
/// Attempts to parse a message from the buffer. Returns 'false' if there is not enough data to complete a message. Throws an
@ -25,7 +27,7 @@ namespace Microsoft.AspNetCore.SignalR.Internal.Encoders
var remaining = buffer.Slice(index);
if (!TryReadDelimiter(remaining, LengthPrefixedTextMessageWriter.FieldDelimiter, "length"))
if (!TryReadDelimiter(remaining, FieldDelimiter, "length"))
{
return false;
}
@ -42,7 +44,7 @@ namespace Microsoft.AspNetCore.SignalR.Internal.Encoders
remaining = remaining.Slice(length);
if (!TryReadDelimiter(remaining, LengthPrefixedTextMessageWriter.MessageDelimiter, "payload"))
if (!TryReadDelimiter(remaining, MessageDelimiter, "payload"))
{
return false;
}
@ -56,7 +58,7 @@ namespace Microsoft.AspNetCore.SignalR.Internal.Encoders
{
length = 0;
// Read until the first ':' to find the length
index = buffer.IndexOf((byte)LengthPrefixedTextMessageWriter.FieldDelimiter);
index = buffer.IndexOf((byte)FieldDelimiter);
if (index == -1)
{

44
src/Microsoft.AspNetCore.SignalR.Common/Internal/Encoders/LengthPrefixedTextMessageWriter.cs
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@ -1,44 +0,0 @@
// 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.Buffers;
using System.Globalization;
using System.IO;
using System.Text;
namespace Microsoft.AspNetCore.SignalR.Internal.Encoders
{
public static class LengthPrefixedTextMessageWriter
{
private const int Int32OverflowLength = 10;
internal const char FieldDelimiter = ':';
internal const char MessageDelimiter = ';';
public static void WriteMessage(ReadOnlySpan<byte> payload, Stream output)
{
// Calculate the length, it's the number of characters for text messages, but number of base64 characters for binary
// Write the length as a string
// Super inefficient...
var lengthString = payload.Length.ToString(CultureInfo.InvariantCulture);
var buffer = ArrayPool<byte>.Shared.Rent(Int32OverflowLength);
var encodedLength = Encoding.UTF8.GetBytes(lengthString, 0, lengthString.Length, buffer, 0);
output.Write(buffer, 0, encodedLength);
ArrayPool<byte>.Shared.Return(buffer);
// Write the field delimiter ':'
output.WriteByte((byte)FieldDelimiter);
buffer = ArrayPool<byte>.Shared.Rent(payload.Length);
payload.CopyTo(buffer);
output.Write(buffer, 0, payload.Length);
ArrayPool<byte>.Shared.Return(buffer);
// Terminator
output.WriteByte((byte)MessageDelimiter);
}
}
}

38
test/Microsoft.AspNetCore.SignalR.Common.Tests/Internal/Encoders/Base64EncoderTests.cs Normal file
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@ -0,0 +1,38 @@
// 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.Generic;
using System.Text;
using Xunit;
namespace Microsoft.AspNetCore.SignalR.Internal.Encoders
{
public class Base64EncoderTests
{
[Theory]
[MemberData(nameof(Payloads))]
public void VerifyDecode(string payload, string encoded)
{
var message = Encoding.UTF8.GetBytes(payload);
var encodedMessage = Encoding.UTF8.GetString(new Base64Encoder().Encode(message));
Assert.Equal(encoded, encodedMessage);
}
[Theory]
[MemberData(nameof(Payloads))]
public void VerifyEncode(string payload, string encoded)
{
var encodedMessage = Encoding.UTF8.GetBytes(encoded);
var decodedMessage = Encoding.UTF8.GetString(new Base64Encoder().Decode(encodedMessage).ToArray());
Assert.Equal(payload, decodedMessage);
}
public static IEnumerable<object[]> Payloads =>
new object[][]
{
new object[] { "", "0:;" },
new object[] { "ABC", "4:QUJD;" },
new object[] { "A\nR\rC\r\n;DEF1234567890", "28:QQpSDUMNCjtERUYxMjM0NTY3ODkw;" },
};
}
}

46
test/Microsoft.AspNetCore.SignalR.Common.Tests/Internal/Encoders/LengthPrefixedTextMessageFormatterTests.cs
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@ -1,46 +0,0 @@
// 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.IO;
using System.Text;
using Microsoft.AspNetCore.SignalR.Internal.Encoders;
using Xunit;
namespace Microsoft.AspNetCore.SignalR.Tests.Internal.Encoders
{
public class LengthPrefixedTextMessageFormatterTests
{
[Fact]
public void WriteMultipleMessages()
{
const string expectedEncoding = "0:;14:Hello,\r\nWorld!;";
var messages = new[]
{
new byte[0],
Encoding.UTF8.GetBytes("Hello,\r\nWorld!")
};
var output = new MemoryStream();
foreach (var message in messages)
{
LengthPrefixedTextMessageWriter.WriteMessage(message, output);
}
Assert.Equal(expectedEncoding, Encoding.UTF8.GetString(output.ToArray()));
}
[Theory]
[InlineData("0:;", "")]
[InlineData("3:ABC;", "ABC")]
[InlineData("11:A\nR\rC\r\n;DEF;", "A\nR\rC\r\n;DEF")]
public void WriteMessage(string encoded, string payload)
{
var message = Encoding.UTF8.GetBytes(payload);
var output = new MemoryStream();
LengthPrefixedTextMessageWriter.WriteMessage(message, output);
Assert.Equal(encoded, Encoding.UTF8.GetString(output.ToArray()));
}
}
}