class Concurrent::Delay

def value(timeout = nil)
  if @executor # TODO (pitr 12-Sep-2015): broken unsafe read?
    super
  else
    # this function has been optimized for performance and
    # should not be modified without running new benchmarks
    synchronize do
      execute = @evaluation_started = true unless @evaluation_started
      if execute
        begin
          set_state(true, @task.call, nil)
        rescue => ex
          set_state(false, nil, ex)
        end
      elsif incomplete?
        raise IllegalOperationError, 'Recursive call to #value during evaluation of the Delay'
      end
    end
    if @do_nothing_on_deref
      @value
    else
      apply_deref_options(@value)
    end
  end
end