EventMachine.crank

cranking.rb

require 'thread'

module EventMachine
  module Test
    module Utils
      module Cranking

        # Stolen from MenTaLguYs Omnibus
        class Waiter
          def initialize
            @lock = Mutex.new
            @condition = ConditionVariable.new
            @set = false
          end

          def wait
            @lock.synchronize do
              @condition.wait(@lock) unless @set
              @set = false
            end
            self
          end

          def wakeup
            @lock.synchronize do
              @set = true
              @condition.signal
            end
            self
          end
        end

        def setup
          raise 'EventMachine already running' if EM.reactor_running?
          @em_waiter = Waiter.new
          @th_waiter = Waiter.new
          @cranking = true
          @cranker = lambda {
            @th_waiter.wakeup
            @em_waiter.wait
            EM.next_tick &@cranker if @cranking
          }
          @crank_thread = Thread.new { EM.run { EM.next_tick &@cranker } }
          @th_waiter.wait
        end

        def teardown
          @cranking = false
          @em_waiter.wakeup # free reactor
          EM.stop
          @crank_thread.join
        end

        def crank!
          @em_waiter.wakeup
          @th_waiter.wait
        end
      end
    end
  end
end

BEGIN { require 'rubygems' if __FILE__ == $0 }
if __FILE__ == $0
  require 'eventmachine'

  require 'minitest/unit'


  class TestEventMachineTestUtilsCranking < MiniTest::Unit::TestCase
    Thread.abort_on_exception = true

    include EventMachine::Test::Utils::Cranking

    def test_crank_counter
      count = 0
      counter = lambda { count += 1; EM.next_tick &counter }
      EM.next_tick &counter

      1000.times { |n|
        assert_equal n, count
        crank!
      }
    end
  end

  MiniTest::Unit.autorun

end