Allow Constructor-overload for MemoryOwner<T>

[CodingMadness]

Hey I would love to see that MemoryOwner can accept a "Stream" variable as input parameter, i am currently in need of that and cant use your awesome pool sadly :/

[CodingMadness]

Compared with "CommunityToolkit" I wonder why you made the span readonly and not writeable because the version of toolkit makes more sense to me tbh to allow writing to it, so u can do for instance: "stream.ReadAtleast(memoryOwner.Span)" which right now you cant do with your MemoryOwner version.

[sakno]

What's the purpose of the Stream as input parameter? How does it should work? The stream cannot expose the buffer.

[CodingMadness]

What's the purpose of the Stream as input parameter? How does it should work? The stream cannot expose the buffer.

I wanted to fill the underlying buffer with a data-stream which already contains the bytes.

so instead it could be only those lines here:

    private Span<byte> GetEmbeddedResourceAsBytes(string relativePath)
    {
        var resourcePath = GetResourcePath();
        var fullPath = $"{resourcePath}.{relativePath}";

        using var content = EmbeddedResources.GetManifestResourceStream(fullPath) ??
                           throw new FileNotFoundException("Cannot find resource file.", fullPath);

        return new MemoryOwner<byte>(content).Span;  // the .Span should contain  ALL the data from 'content'
    }

[CodingMadness]

and internally you could just simpl use ArrayPool.Shared if only the stream variable is passed and nothning else, this is than extra nickpick how many and how exactly the ctors() should look like if you allow this.

[sakno]

1. This leads to memory leak, you loose the ownership of MemoryOwner<byte> instance, so the caller cannot dispose it
2. You don't know the length of the stream in general case, Stream.Length could throw NotSupportedException
3. You don't know the nature of the stream in general case: sync vs async. What if the stream have the async method for general use and sync methods with sync-over-async just for compatibility

[sakno]

If the length is known (which is true in the context of manifest resources), you can do simply the following:

private static MemoryOwner<byte> ToBytes(Stream stream)
    {
        var length = checked((int)stream.Length);
        var buffer = Memory.AllocateExactly<byte>(length);
        stream.ReadExactly(buffer.Span);
        return buffer;
    }