non-blocking redis pub/sub in sinatra

app.rb

require "fiber"
require "rack/fiber_pool"
require "sinatra/base"

require "redis"
require "redis/connection/synchrony"

class App < Sinatra::Base
  use Rack::FiberPool

  get "/:channel" do |channel|
    redis = Redis.connect
    redis.subscribe(channel) do |on|
      on.message do |channel, message|
        redis.unsubscribe
        body "#{channel}: #{message}"
      end
    end
  end
end

# rackup -s thin app.rb
#
# curl http://localhost:9292/foo
# curl http://localhost:9292/bar
#
# redis-cli publish foo "hello"
# redis-cli publish bar "hola"