YangWX/MQTTnet
1
0
Fork 0
mirror of https://github.com/dotnet/MQTTnet.git synced 2026-10-20 19:58:57 +08:00
Code Issues Packages Projects Releases Wiki Activity

Avoid copying buffer from ReadOnlySequence as ReceivedMqttPacket body (#1596)

Browse Source 
* Avoid copying buffer from ReadOnlySequence as  ReceivedMqttPacket body

* Use ReadOnlySequence.FirstSpan if possible.

* add ReaderExtensionsBenchmark

* update benchmark

* fix fixedHeader incorrect read

Co-authored-by: Christian <6939810+chkr1011@users.noreply.github.com>
This commit is contained in:
老九
2022-12-03 13:18:30 +01:00
committed by GitHub
co-authored by Christian
parent 862d76471b
commit 3d32faa8f9
2 changed files with 291 additions and 23 deletions
Download Patch File Download Diff File Expand all files Collapse all files
Source/MQTTnet.AspnetCore/ReaderExtensions.cs
+50 -23
View File
@@ -2,21 +2,23 @@
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
using System;
using System.Buffers;
using MQTTnet.Adapter;
using MQTTnet.Exceptions;
using MQTTnet.Formatter;
using MQTTnet.Packets;
using System;
using System.Buffers;
using System.Linq;
using System.Runtime.InteropServices;
namespace MQTTnet.AspNetCore
{
public static class ReaderExtensions
{
public static bool TryDecode(this MqttPacketFormatterAdapter formatter,
in ReadOnlySequence<byte> input,
out MqttPacket packet,
out SequencePosition consumed,
public static bool TryDecode(this MqttPacketFormatterAdapter formatter,
in ReadOnlySequence<byte> input,
out MqttPacket packet,
out SequencePosition consumed,
out SequencePosition observed,
out int bytesRead)
{
@@ -33,22 +35,22 @@ namespace MQTTnet.AspNetCore
return false;
}
var fixedHeader = copy.First.Span[0];
if (!TryReadBodyLength(ref copy, out int headerLength, out var bodyLength))
if (!TryReadBodyLength(ref copy, out var headerLength, out var bodyLength))
{
return false;
}
var fixedHeader = copy.First.Span[0];
copy = copy.Slice(headerLength);
if (copy.Length < bodyLength)
{
return false;
}
var bodySlice = copy.Slice(0, bodyLength);
var buffer = bodySlice.GetMemory().ToArray();
var receivedMqttPacket = new ReceivedMqttPacket(fixedHeader, new ArraySegment<byte>(buffer, 0, buffer.Length), buffer.Length + 2);
var bodySegment = GetArraySegment(ref bodySlice);
var receivedMqttPacket = new ReceivedMqttPacket(fixedHeader, bodySegment, headerLength + bodyLength);
if (formatter.ProtocolVersion == MqttProtocolVersion.Unknown)
{
formatter.DetectProtocolVersion(receivedMqttPacket);
@@ -61,18 +63,41 @@ namespace MQTTnet.AspNetCore
return true;
}
static ReadOnlyMemory<byte> GetMemory(this in ReadOnlySequence<byte> input)
static ArraySegment<byte> GetArraySegment(ref ReadOnlySequence<byte> input)
{
if (input.IsSingleSegment)
if (input.IsSingleSegment && MemoryMarshal.TryGetArray(input.First, out var segment))
{
return input.First;
return segment;
}
// Should be rare
return input.ToArray();
var array = input.ToArray();
return new ArraySegment<byte>(array);
}
static bool TryReadBodyLength(ref ReadOnlySequence<byte> input, out int headerLength, out int bodyLength)
{
var valueSequence = input.Slice(0, Math.Min(5, input.Length));
if (valueSequence.IsSingleSegment)
{
var valueSpan =
#if NET5_0_OR_GREATER
valueSequence.FirstSpan;
#else
valueSequence.First.Span;
#endif
return TryReadBodyLength(valueSpan, out headerLength, out bodyLength);
}
else
{
Span<byte> valueSpan = stackalloc byte[8];
valueSequence.CopyTo(valueSpan);
valueSpan = valueSpan.Slice(0, (int)valueSequence.Length);
return TryReadBodyLength(valueSpan, out headerLength, out bodyLength);
}
}
static bool TryReadBodyLength(ReadOnlySpan<byte> span, out int headerLength, out int bodyLength)
{
// Alorithm taken from https://docs.oasis-open.org/mqtt/mqtt/v3.1.1/errata01/os/mqtt-v3.1.1-errata01-os-complete.html.
var multiplier = 1;
@@ -81,33 +106,35 @@ namespace MQTTnet.AspNetCore
var index = 1;
headerLength = 0;
bodyLength = 0;
var temp = input.Slice(0, Math.Min(5, input.Length)).GetMemory().Span;
do
{
if (index == temp.Length)
if (index == span.Length)
{
return false;
}
encodedByte = temp[index];
encodedByte = span[index];
index++;
value += (byte)(encodedByte & 127) * multiplier;
if (multiplier > 128 * 128 * 128)
{
throw new MqttProtocolViolationException($"Remaining length is invalid (Data={string.Join(",", temp.Slice(1, index).ToArray())}).");
ThrowProtocolViolationException(span, index);
}
multiplier *= 128;
} while ((encodedByte & 128) != 0);
input = input.Slice(index);
headerLength = index;
bodyLength = value;
return true;
}
static void ThrowProtocolViolationException(ReadOnlySpan<byte> valueSpan, int index)
{
throw new MqttProtocolViolationException($"Remaining length is invalid (Data={string.Join(",", valueSpan.Slice(1, index).ToArray())}).");
}
}
}