Basic rate limiter using Celluloid

rate_limiter.rb

class RateLimiter
  include Celluloid

  def initialize(actions_per, seconds)
    @bucket, @nice = actions_per, seconds
  end

  def request
    wait :bucket_increment unless @bucket > 0
    @bucket -= 1
    after(@nice) { @bucket += 1; signal :bucket_increment }
  end
end

usage.rb

r = RateLimiter.new(5, 10) # 5 actions allowed within any 10 second period
# make 6 requests in rapid fire:
r.request # => #<Timers::Timer:de353c fires in 9.999746148 seconds>
r.request # => #<Timers::Timer:dedaf0 fires in 9.999815019 seconds>
r.request # => #<Timers::Timer:df2dac fires in 9.999770345 seconds>
r.request # => #<Timers::Timer:e02a40 fires in 9.999726619 seconds>
r.request # => #<Timers::Timer:56dc04 fires in 9.999643746 seconds>
# the next one blocks for ~10s:
r.request # => #<Timers::Timer:68b8ac fires in 9.999792257 seconds>