About dealing with the broken ActionController::Live and Devise/Warden handling and other discussions

Hi, I'd like to discuss a few things regarding streaming support in Rails and in Rack apps in general as well as suggesting a new Rails API to better handle the integration between ActionController::Live and Devise/Warden authentication failures.

I've detailed the subject in this project's README which suggests a new API:

https://github.com/rosenfeld/devise-and-streaming

I've also published that content in my site in case you'd prefer to discuss it on Disqus:

http://rosenfeld.herokuapp.com/en/articles/ruby-rails/2016-07-02-the-sad-state-of-streaming-in-ruby-web-applications

Or we could discuss it in this thread as well.

Here is the TLDR version:

In order for Rails (or other Rack based solutions) to handle streaming it has to spawn a new thread for the block requiring streaming.

Warden is a middleware that runs the next middleware in a catch(:warden){} block and this is how it handles authentication failures.

Devise is probably the de facto authentication solution for Rails and uses warden, so it faces the same issue:

https://github.com/plataformatec/devise/issues/2332

I'd like to propose Rails to add a new API that wouldn't process the entire request with its filters in a spawn thread but only in the block involving streaming, like this:

def my_action

   # optionally call authenticate_user! here if it's not handled by a before_action filter

   chunked do |stream| # thread spawning would happen here

      3.times{stream.write 'chunked text'; sleep 1}

   end

end

This would allow the authentication part to work just fine.

There's also a broad discussion around Rack's design and future in that README. I'd love to move that discussion forward if you agree the situation should be improved.

Thanks for reading and considering my proposal,

Rodrigo.

I've updated the project's README (and the article) and the code to add an example on how it can work with Rack hijacking instead of spawning a new thread.

Shouldn't this approach be preferred rather than spawning the thread?

I'm having a hard time to find an updated discussion around this subject. Please let me know if you have more resources I can look at.

Best,
Rodrigo.