Timer example

timer.rb

require 'monitor'

class Timer
  # include MonitorMixin

  def self.repeat_every(interval_sec, &code)
    t = Timer.new(interval_sec, code)
    t.start
    t
  end

  def initialize(interval, code)
    extend MonitorMixin
    @interval = interval
    @code = code
  end

  def start
    synchronize do
      raise "Already running" if @thread

      @stop = false

      @thread = Thread.new do
        intv = synchronize { @interval }

        until synchronize { @stop }
          t = Time.now
          @code.call
          sleep(t + intv - Time.now)
        end

        synchronize { @thread = nil }
      end
    end

    self
  end

  def stop
    synchronize do
      @stop = true
    end

    self
  end

  def shutdown
    th = synchronize do
      @stop = true
      @thread
    end

    th.join if th

    self
  end
end

t = Timer.repeat_every 1 do
  puts "foo"
end

sleep 20

t.stop