Fiber Sleep

fiber_sleep.rb

require 'fiber'
require 'concurrent' # gem install concurrent-ruby
Thread.abort_on_exception = true

class Async
  def self.perform(&block)
    instance = new
    instance.instance_eval(&block)
    until instance.dispatched.value.zero? do
      unless instance.yields.empty?
        fiber = instance.yields.pop
        instance.dispatched.decrement
        fiber.resume
      end
    end
  end

  attr_reader :dispatched, :yields

  def initialize
    @dispatched = Concurrent::AtomicFixnum.new
    @yields = Queue.new
  end

  def job(&block)
    fiber = Fiber.new do
      Block.new(self).instance_eval &block
    end.resume
  end

  class Block < Struct.new(:parent)
    def sleepx(duration)
      current = Fiber.current
      parent.dispatched.increment
      Thread.new do
        sleep(duration)
        parent.yields.push current
      end
      Fiber.yield
    end
  end
end

Async.perform do
  job do
    sleepx(5)
    puts 'slept 5'
  end
  job do
    sleepx(4)
    puts 'slept 4'
  end
  job do
    sleepx(2)
    puts 'slept 2'
  end
  job do
    sleepx(6)
    puts 'slept 6'
  end
  job do
    sleepx(3)
    puts 'slept 3'
  end
  job do
    sleepx(1)
    puts 'slept 1'
  end
end