A resettable timeout for Ruby

killer.rb

require 'redis'

@redis = Redis.new

@redis.set('timeout', 0)

referee.rb

require 'redis'

module Referee
  class Timeout < StandardError; end

  class Timer
    def initialize(key, limit = 5, &block)
      @redis = Redis.new
      @key = key
      @limit = limit

      @redis.set(@key, @limit)

      start

      @work = Thread.new { yield self }
      @work.join

      @timer.join if @timed_out
    end

    def start
      @timer = Thread.new do
        @counter = 0

        # TODO: Use promises to make sure we have the limit from redis before
        #   incrementing the counter.
        loop do
          @limit = @redis.get(@key).to_i

          @counter += 1

          if @counter > @limit
            break
          end

          sleep(1)
        end

        @timed_out = true

        @work.kill

        raise Referee::Timeout
      end
    end

    def stop
      @timer.kill
    end

    def reset
      stop
      start
    end
  end
end

worker.rb

require_relative 'referee'

begin
  Referee::Timer.new(5) do |timer|
    sleep(1)
    puts "yup"
    sleep(5)
    puts "nope"
  end
rescue Referee::Timeout
  puts "timed out!"
end