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.NET-Community-Toolkit/CommunityToolkit.HighPerformance/Streams/Sources/MemoryManagerOwner.cs
2022-06-12 10:46:34 +03:00

72 lines
2.5 KiB
C#

// Licensed to the .NET Foundation under one or more agreements.
// 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 System.Runtime.CompilerServices;
namespace CommunityToolkit.HighPerformance.Streams;
/// <summary>
/// An <see cref="ISpanOwner"/> implementation wrapping a <see cref="MemoryManager{T}"/> of <see cref="byte"/> instance.
/// </summary>
internal readonly struct MemoryManagerOwner : ISpanOwner
{
/// <summary>
/// The wrapped <see cref="MemoryManager{T}"/> instance.
/// </summary>
private readonly MemoryManager<byte> memoryManager;
/// <summary>
/// The starting offset within <see cref="memoryManager"/>.
/// </summary>
private readonly int offset;
/// <summary>
/// The usable length within <see cref="memoryManager"/>.
/// </summary>
private readonly int length;
/// <summary>
/// Initializes a new instance of the <see cref="MemoryManagerOwner"/> struct.
/// </summary>
/// <param name="memoryManager">The wrapped <see cref="MemoryManager{T}"/> instance.</param>
/// <param name="offset">The starting offset within <paramref name="memoryManager"/>.</param>
/// <param name="length">The usable length within <paramref name="memoryManager"/>.</param>
public MemoryManagerOwner(MemoryManager<byte> memoryManager, int offset, int length)
{
this.memoryManager = memoryManager;
this.offset = offset;
this.length = length;
}
/// <inheritdoc/>
public int Length
{
[MethodImpl(MethodImplOptions.AggressiveInlining)]
get => this.length;
}
/// <inheritdoc/>
public Span<byte> Span
{
[MethodImpl(MethodImplOptions.AggressiveInlining)]
get
{
// We can't use the same trick we use for arrays to optimize the creation of
// the offset span, as otherwise a bugged MemoryManager<T> instance returning
// a span of an incorrect size could cause an access violation. Instead, we just
// get the span and then slice it, which will validate both offset and length.
return this.memoryManager.GetSpan().Slice(this.offset, this.length);
}
}
/// <inheritdoc/>
public Memory<byte> Memory
{
[MethodImpl(MethodImplOptions.AggressiveInlining)]
get => this.memoryManager.Memory.Slice(this.offset, this.length);
}
}