Add status the 103 Early Hints as Not content for action_dispatch

[roramirez]

The status is defined in RFC 8297 https://tools.ietf.org/html/rfc8297

[eugeneius]

How can this be used in practice? If I understand correctly, an Early Hints response should be followed by another full response over the same connection, but ActionDispatch::Response manages a single response that's eventually sent by Rack.

[eugeneius]

Although I guess that argument applies to anything in the 1xx range.

Recent versions of Rack support sending this status: rack/rack#1332

I'll merge, thanks!

[roramirez]

Hi @eugeneius

Maybe should we'll try prepare a test case using a response and reply for the 103 Early Hints, as more a behavior for the case, not just a unit test case.

What do you think?, I'll could try figure out how to match to this point with a test

[eugeneius]

I don't doubt that Rails is capable of serving a properly formed 103 Early Hints response, I just can't see how that would be a useful thing to do in a real application.

From a quick test: if I call head :early_hints in a controller, Chrome receives the response, waits 20 more seconds, and then displays an error page with the code ERR_EMPTY_RESPONSE.

This also happens when using head :switching_protocols, for example, which is why I merged this: I think the HTTP protocol is an area where it makes sense for Rails to aim for completeness even if there isn't an immediately obvious benefit of doing so.

If you had a particular use case in mind for this though, please do tell me about it. 🙂

[eugeneius]

Incidentally, Puma supports sending early hints before the main response: puma/puma#1403