Mix this module into your controller, and all actions in that controller will be able to stream data to the client as it's written.
class MyController < ActionController::Base
include ActionController::Live
def stream
response.headers['Content-Type'] = 'text/event-stream'
100.times {
response.stream.write "hello world\n"
sleep 1
}
ensure
response.stream.close
end
end
There are a few caveats with this module. You cannot write headers after the response has been committed (Response#committed? will return truthy). Calling write
or close
on the response stream will cause the response object to be committed. Make sure all headers are set before calling write or close on your stream.
You must call close on your stream when you're finished, otherwise the socket may be left open forever.
The final caveat is that your actions are executed in a separate thread than the main thread. Make sure your actions are thread safe, and this shouldn't be a problem (don't share state across threads, etc).
- MODULE ActionController::Live::ClassMethods
- CLASS ActionController::Live::ClientDisconnected
- CLASS ActionController::Live::SSE
Instance Public methods
process(name) Link
# File actionpack/lib/action_controller/metal/live.rb, line 244 def process(name) t1 = Thread.current locals = t1.keys.map { |key| [key, t1[key]] } error = nil # This processes the action in a child thread. It lets us return the # response code and headers back up the Rack stack, and still process # the body in parallel with sending data to the client. new_controller_thread { ActiveSupport::Dependencies.interlock.running do t2 = Thread.current # Since we're processing the view in a different thread, copy the # thread locals from the main thread to the child thread. :'( locals.each { |k, v| t2[k] = v } begin super(name) rescue => e if @_response.committed? begin @_response.stream.write(ActionView::Base.streaming_completion_on_exception) if request.format == :html @_response.stream.call_on_error rescue => exception log_error(exception) ensure log_error(e) @_response.stream.close end else error = e end ensure @_response.commit! end end } ActiveSupport::Dependencies.interlock.permit_concurrent_loads do @_response.await_commit end raise error if error end