Sinatra + EventMachine + Puma – Heroku workaround for 30 seconds timeout

my_controller.rb

module Application
  module Controllers
    class MyController < Sinatra::Base
      helpers Sinatra::Streaming

      class << self
        def stream(method, path, opts = {}, &block)
          send(method, path, opts) do
            stream do |out|
              timer = EventMachine::PeriodicTimer.new(10) { out << "\0" }
              out << instance_eval(&block)
              timer.cancel
            end
          end
        end
      end
      
      stream :get, '/test_stream' do
        # do the long-running stuff here
        sleep 40
        'done'
      end
    end
  end
end

puma.rb

# puma.rb
require 'eventmachine'

on_worker_boot do
  # start EM for each worker
  Thread.new { EventMachine.run } unless EventMachine.reactor_running? && EventMachine.reactor_thread.alive?
end

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