Ruby timer thread

timer.rb

require 'thread'

class Clock
  def self.timestamp
    Process.clock_gettime(Process::CLOCK_MONOTONIC, :millisecond)
  end

  class Timer
    def initialize(timeout)
      @expires_at = Clock.timestamp + timeout
      @done_queue = Queue.new
    end

    def done?
      !@done_queue.empty?
    end

    def update!(timestamp)
      if timestamp >= @expires_at
        @done_queue << true
      end
    end
  end

  def initialize
    @new_timers = Queue.new
    @worker = start_worker
  end

  def new_timer(timeout)
    timer = Timer.new(timeout)
    @new_timers << timer
    timer
  end

  private

  def start_worker
    t = Thread.new do
      timers = []

      loop do
        until @new_timers.empty? do
          timers << @new_timers.pop
        end

        if timers.empty?
          timers << @new_timers.pop
        else
          timestamp = Clock.timestamp
          timers.reject! do |t|
            t.update!(timestamp)
            t.done?
          end
          sleep 0.01
        end
      end
    end
    t.abort_on_exception = true
    t
  end
end

# Usage -----------------

start = Clock.timestamp

clock = Clock.new
timers = (1..4).map { |s| clock.new_timer(s * 1000) }

while true
  states = timers.map(&:done?)
  puts states.map { |b| b ? 'y' : 'n' }.join(' | ')
  break if states.all?
  sleep 0.5
end

puts "Done in #{Clock.timestamp - start}ms"

Output:

n | n | n | n
n | n | n | n
n | n | n | n
y | n | n | n
y | y | n | n
y | y | n | n
y | y | n | n
y | y | y | n
y | y | y | y
Done in 4007ms