discourse/config/initializers/200-message_bus_request_tracker.rb

# we want MesageBus in the absolute front
# this is important cause the vast majority of web requests go to it
# this allows us to avoid full middleware crawls each time
# Pending https://github.com/rails/rails/pull/27936
session_operations = Rails::Configuration::MiddlewareStackProxy.new([
   [:delete, MessageBus::Rack::Middleware],
   [:unshift, MessageBus::Rack::Middleware],
])

Rails.configuration.middleware = Rails.configuration.middleware + session_operations

# no reason to track this in development, that is 300+ redis calls saved per
# page view (we serve all assets out of thin in development)
if Rails.env != 'development' || ENV['TRACK_REQUESTS']
  require 'middleware/request_tracker'
  Rails.configuration.middleware.unshift Middleware::RequestTracker
end