Summary
Replace the following methods:
namespace WindowsRuntime.InteropServices;
public static class WindowsRuntimeBufferMarshal
{
- public static bool TryGetDataUnsafe([NotNullWhen(true)] IMemoryBufferReference? buffer, out byte* data, out uint capacity);
+ public static bool TryGetDataUnsafe([NotNullWhen(true)] IMemoryBufferReference? buffer, out Span<byte> data);
- public static bool TryGetDataUnsafe([NotNullWhen(true)] IBuffer? buffer, out byte* data);
+ public static bool TryGetDataUnsafe([NotNullWhen(true)] IBuffer? buffer, out Span<byte> data);
}Rationale
With the theme of unsafe evolution, the .NET runtime team is reducing the usages of raw pointers and replacing with safe equivalents like Span<T>. Span<T> and Memory<T> can hold unmanaged memory, and users who need raw pointers can use fixed or System.Runtime.CompilerServices.Unsafe to get it back.
Important Notes
It's important to decide the safeness of span-returning method under the new rule (RequiresUnsafe). Since it requires manual KeepAlive for the object, it should be considered unsafe (similar to CollectionsMarshal.AsSpan(List<T>)). Since most things under xxMarshal would be unsafe, this shouldn't be a problem.
Alternatively, returning a IMemoryOwner<byte> can achieve completely safe lifetime for the caller, but with more overhead and unnatural usage patterns.
Open Questions
Should the IBuffer case use Capacity or Length? Capacity is natural for writing and Length is natural for reading, should it be split into two overloads returning Span and ReadOnlySpan respectively?
Should the name be change to drop the Unsafe suffix to match BCL naming convention? The term "marshal" already implies unsafeness.
Summary
Replace the following methods:
namespace WindowsRuntime.InteropServices; public static class WindowsRuntimeBufferMarshal { - public static bool TryGetDataUnsafe([NotNullWhen(true)] IMemoryBufferReference? buffer, out byte* data, out uint capacity); + public static bool TryGetDataUnsafe([NotNullWhen(true)] IMemoryBufferReference? buffer, out Span<byte> data); - public static bool TryGetDataUnsafe([NotNullWhen(true)] IBuffer? buffer, out byte* data); + public static bool TryGetDataUnsafe([NotNullWhen(true)] IBuffer? buffer, out Span<byte> data); }Rationale
With the theme of unsafe evolution, the .NET runtime team is reducing the usages of raw pointers and replacing with safe equivalents like
Span<T>.Span<T>andMemory<T>can hold unmanaged memory, and users who need raw pointers can usefixedorSystem.Runtime.CompilerServices.Unsafeto get it back.Important Notes
It's important to decide the safeness of span-returning method under the new rule (
RequiresUnsafe). Since it requires manualKeepAlivefor the object, it should be considered unsafe (similar toCollectionsMarshal.AsSpan(List<T>)). Since most things underxxMarshalwould be unsafe, this shouldn't be a problem.Alternatively, returning a
IMemoryOwner<byte>can achieve completely safe lifetime for the caller, but with more overhead and unnatural usage patterns.Open Questions
Should the
IBuffercase useCapacityorLength?Capacityis natural for writing andLengthis natural for reading, should it be split into two overloads returningSpanandReadOnlySpanrespectively?Should the name be change to drop the
Unsafesuffix to match BCL naming convention? The term "marshal" already implies unsafeness.