class Async::Reactor

def timeout(duration, exception = TimeoutError)
	backtrace = caller
	fiber = Fiber.current
	
	timer = self.after(duration) do
		if fiber.alive?
			error = exception.new("execution expired")
			error.set_backtrace backtrace
			fiber.resume error
		end
	end
	
	yield
ensure
	timer.cancel if timer
end