Support rack 3.0.0

[lucaskanashiro]

rack version 3.0.0 was released a couple of months ago, it'd be great if thin could also support that.

[ioquatix]

Feel free to submit a PR. There is a conformance test suite here: https://github.com/socketry/rack-conform. Thin is already supported Rack v2 as you'd probably expect.

[ioquatix]

I've tested it with rack-conform (socketry/rack-conform#26), and there is only one issue:

2025-03-01 20:17:00 +1300 Unexpected error while processing request: not opened for reading
	/Users/samuel/.gem/ruby/3.4.2/bundler/gems/thin-de6b6188f1f1/lib/thin/response.rb:12:in 'Thin::Response::Stream#read'
	/Users/samuel/.gem/ruby/3.4.2/gems/protocol-websocket-0.20.1/lib/protocol/websocket/framer.rb:67:in 'Protocol::WebSocket::Framer#read_header'
	/Users/samuel/.gem/ruby/3.4.2/gems/protocol-websocket-0.20.1/lib/protocol/websocket/framer.rb:51:in 'Protocol::WebSocket::Framer#read_frame'
	/Users/samuel/.gem/ruby/3.4.2/gems/protocol-websocket-0.20.1/lib/protocol/websocket/connection.rb:123:in 'Protocol::WebSocket::Connection#read_frame'
	/Users/samuel/.gem/ruby/3.4.2/gems/protocol-websocket-0.20.1/lib/protocol/websocket/connection.rb:295:in 'Protocol::WebSocket::Connection#read'
	/Users/samuel/Developer/socketry/rack-conform/lib/rack/conform/application.rb:103:in 'block in Rack::Conform::Application#test_websocket_echo'
	/Users/samuel/.gem/ruby/3.4.2/gems/async-websocket-0.30.0/lib/async/websocket/adapters/http.rb:41:in 'block in Async::WebSocket::Adapters::HTTP.open'
	/Users/samuel/.gem/ruby/3.4.2/gems/async-http-0.87.0/lib/async/http/body/hijack.rb:39:in 'Async::HTTP::Body::Hijack#call'
	/Users/samuel/.gem/ruby/3.4.2/bundler/gems/thin-de6b6188f1f1/lib/thin/response.rb:144:in 'Method#call'
	/Users/samuel/.gem/ruby/3.4.2/bundler/gems/thin-de6b6188f1f1/lib/thin/response.rb:144:in 'Thin::Response#each'
	/Users/samuel/.gem/ruby/3.4.2/bundler/gems/thin-de6b6188f1f1/lib/thin/connection.rb:118:in 'Thin::Connection#post_process'
	/Users/samuel/.gem/ruby/3.4.2/bundler/gems/thin-de6b6188f1f1/lib/thin/connection.rb:53:in 'Thin::Connection#process'
	/Users/samuel/.gem/ruby/3.4.2/bundler/gems/thin-de6b6188f1f1/lib/thin/connection.rb:39:in 'Thin::Connection#receive_data'
	/Users/samuel/.gem/ruby/3.4.2/gems/eventmachine-1.2.7/lib/eventmachine.rb:195:in 'EventMachine.run_machine'
	/Users/samuel/.gem/ruby/3.4.2/gems/eventmachine-1.2.7/lib/eventmachine.rb:195:in 'EventMachine.run'
	/Users/samuel/.gem/ruby/3.4.2/bundler/gems/thin-de6b6188f1f1/lib/thin/backends/base.rb:75:in 'Thin::Backends::Base#start'
	/Users/samuel/.gem/ruby/3.4.2/bundler/gems/thin-de6b6188f1f1/lib/thin/server.rb:162:in 'Thin::Server#start'
	/Users/samuel/.gem/ruby/3.4.2/bundler/gems/thin-de6b6188f1f1/lib/thin/controllers/controller.rb:87:in 'Thin::Controllers::Controller#start'
	/Users/samuel/.gem/ruby/3.4.2/bundler/gems/thin-de6b6188f1f1/lib/thin/runner.rb:203:in 'Thin::Runner#run_command'
	/Users/samuel/.gem/ruby/3.4.2/bundler/gems/thin-de6b6188f1f1/lib/thin/runner.rb:159:in 'Thin::Runner#run!'
	/Users/samuel/.gem/ruby/3.4.2/bundler/gems/thin-de6b6188f1f1/bin/thin:6:in '<top (required)>'
	/Users/samuel/.gem/ruby/3.4.2/bin/thin:25:in 'Kernel#load'
	/Users/samuel/.gem/ruby/3.4.2/bin/thin:25:in '<main>'

[womblep]

@ioquatix Can you please put a version of the latest Thin on Rubygems?
I have tested my production app with Thin master branch, Sinatra 4.1.1, Rack 3.1.12 and everything is working correctly.

I also did a performance test with SSE on a docker container on my desktop and was able to easily pump 3000 events a second (approx 300 bytes per event) through 300 connections.

[petracihalova]

hi, please just wondering if there are any plans for a new release of thin? thank you ❤

@ioquatix Please, please please, could we get a release for Thin 2.0 and Rack 3?
If it helps, I will be willing to do admin work and triage issues.

[womblep]

@ioquatix sorry this account would be the one to do admin work and triage

[womblep]

@macournoyer any chance of a new release?

[ioquatix]

I am a maintainer of Thin but I don't have time right now to actually fix the compatibility issues with Rack. I may have time in the future.

We can make a release, but it won't be fully compliant with Rack 3. Therefore, I think it's better we fix the last remaining issue before cutting a 2.0 release. At least, that's my preference, and I think @macournoyer will probably support this position.

We value your feedback (stuff like @womblep above) and it's really helpful to know that it's working in many scenarios.

So the two options going forward are:

1. Someone steps up to fix the last remaining issue(s).
2. We wait until myself or another maintainer has motivation and time to fix the issue.

[womblep]

@ioquatix @macournoyer I understand the desire to have full functionality but as has been discussed before, Thin never supported the only feature that it isn't compliant with. It didn't support it with Rack 2 and so I don't see the issue with not supporting it with Rack 3.
There are many other useful projects that dont support all the features of a standard and as long as that is documented there should be no issue.
However I do see an issue with not releasing a Rack 3 mostly compliant version when it has been outstanding for over 2 years, other people are asking for it, and there are other tickets suggesting that downstream projects are impacted by not having it.
I personally have a number of outstanding Rack 2 CVEs I need to keep explaining to auditors.
Perfection is the enemy of good and I would hate to see a useful (not perfect) ruby webserver (the 3rd most popular according to https://www.ruby-toolbox.com/categories/web_servers) suffer from bit-rot due to one feature it has never supported.
No one would be forced to upgrade but there isn't even an option at the moment.
As I said I would be happy to triage any tickets raised by people who were perhaps looking for that feature and I would suggest a ticket is opened for that feature so that a patch could be solicited.

[ioquatix]

Okay, I have a little time today, let me take a look.

[womblep]

@ioquatix I had a look too.
The big problem I can see (which I am not smart enough to solve) is that client facing data is coming via Connection.receive_data and the server side is being requested via Thin::Response::Stream.read. These need some sort of buffer to be handling the data between.
However the read needs to be blocking otherwise the server websocket side is erroring with a frame header issue because there is no data in the buffer yet.
What I cant figure out with my limited EventMachine experience is how to block the read until there is data to be read without stopping the writes from going out so the handshake completes. All the ways I have tried either have the websocket frame header read happen with no data in the buffer which fails and exits before the handshake has completed or blocks the event loop.