Avoid repetitive GCHandles in IIS WebSocket operations

[BrennanConroy]

Make the AsyncIOEngine in IIS disposable so we can avoid creating a new GCHandle for every WebSocket read and write operation.

[Tratcher]

What's the impact? Is it just allocations, or is there some perf cost to making the GC handle over and over?

[davidfowl]

There’s a performance cost yes. This is from an internal customer

[davidfowl]

Do the uncached operations get disposed?

[BrennanConroy]

Do the uncached operations get disposed?

It shouldn't be possible to get uncached ones right?
The read and write are in single loops
https://source.dot.net/#Microsoft.AspNetCore.Server.IIS/Core/IISHttpContext.IO.cs,105

[davidfowl]

It shouldn't be possible to get uncached ones right?
The read and write are in single loops
https://source.dot.net/#Microsoft.AspNetCore.Server.IIS/Core/IISHttpContext.IO.cs,105

That's technically true, but the code isn't written that way.

[BrennanConroy]

Would removing the Get*Operation() and ReturnOperation() methods make that clearer?

[davidfowl]

I think so?

[BrennanConroy]

Thoughts on new changes?

[davidfowl]

This looks much easier to follow!

[BrennanConroy]

@Tratcher Want to re-review? Or does your current approval still stand?