This sample is a bit out of date now. For something more current and mucu more fleshed out, see here.

Rust/CSharp Interop

C# is capable of interopping with native C code. It's a common feature that projects like Kestrel use this heavily to communicate with libuv for efficient asynchronous io.

I'm not so keen on the idea of writing C though, I'd much rather write Rust. This repo is a playground for interop between Rust and C#, which can be done in the same way.

These samples use cargo-nuget for building and packaging the Rust libraries.

What would be nice

• Share byte arrays between Rust and C#
• Poll a C# Task from Rust as a Future
• await a Rust Future in C#

What to do

Work out conventions between the Rust and C# ends

Who owns the memory? If it's allocated in Rust then it's freed in Rust, but who initiates that call? In Rust it's possible to invalidate a structure by moving it into a new shape (from Vec<u8> to Buf). So you simply require exclusive ownership of that instance. In C# we can't really do that, and once a buf has been sliced around it's not safe to dispose in Rust so long as those slices are still active.

So maybe we can look at the same ref-counting pattern used by OwnedBuffer in corefxlab and require that drops to 0 before returning ownership of the buffer to Rust. Or alternatively we can use Rust ref counting for all things and once that count drops to 0 from borrows in Rust or C# the buffer is dropped. That means a p/invoke call for each new reference though.