Performance improvement in MemoryStream

[Sergio0694]

PR type:

What kind of change does this PR introduce?

• Performance improvement

What is the current behavior?

The MemoryStream type wraps a Memory<byte> instance, so every time a read/write operation needs to be performed, it will need to use Memory<T>.Span, which is relatively expensive to invoke, as it needs to handle multiple possible sources of data. We can use generic types and the value delegate trick (constrained generic struct + interface) to optimize this away.

What is the new behavior?

We now use a MemoryStream<TSource> type (which is internal anyway) and have a bunch of IMemorySource types specifically supporting byte[] and MemoryManager<byte> sources with additional optimizations wherever possible. Also, just using this already removes all the overhead of dynamically creating a Span<T> from the wrapped Memory<T> instance.

Here's a benchmark I put together to show the before/after:

The benchmark consists of writing 1024 times a 1024 bytes buffer to a target Stream instance.
The new MemoryStream<TSource> version is almost 25% faster just thanks to this change 🚀

PR Checklist

Please check if your PR fulfills the following requirements:

• Tested code with current supported SDKs
• Pull Request has been submitted to the documentation repository instructions.
• Sample in sample app has been added / updated (for bug fixes / features)
  • Icon has been created (if new sample) following the Thumbnail Style Guide and templates
• Tests for the changes have been added (for bug fixes / features) (if applicable)
• Header has been added to all new source files (run build/UpdateHeaders.bat)
• Contains NO breaking changes

[ghost]

Thanks Sergio0694 for opening a Pull Request! The reviewers will test the PR and highlight if there is any conflict or changes required. If the PR is approved we will proceed to merge the pull request 🙌

[ghost]

Hello @michael-hawker!

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