class Async::Reactor

def run(*args, &block)
	raise RuntimeError, 'Reactor has been closed' if @selector.nil?
	
	@stopped = false
	
	# Allow the user to kick of the initial async tasks.
	initial_task = async(*args, &block) if block_given?
	
	@timers.wait do |interval|
		# running used to correctly answer on `finished?`, and to reuse Array object.
		@running, @ready = @ready, @running
		if @running.any?
			@running.each do |fiber|
				fiber.resume if fiber.alive?
			end
			@running.clear
			# if there are tasks ready to execute, don't sleep.
			if @ready.any?
				interval = 0
			else
				# The above tasks may schedule, cancel or affect timers in some way. We need to compute a new wait interval for the blocking selector call below:
				interval = @timers.wait_interval
			end
		end
		
		# - nil: no timers
		# - -ve: timers expired already
		# -   0: timers ready to fire
		# - +ve: timers waiting to fire
		if interval && interval < 0
			interval = 0
		end
		
		# Async.logger.debug(self) {"Updating #{@children.count} children..."}
		# As timeouts may have been updated, and caused fibers to complete, we should check this.
		
		# If there is nothing to do, then finish:
		if !interval && self.finished?
			return initial_task
		end
		
		# Async.logger.debug(self) {"Selecting with #{@children.count} fibers interval = #{interval.inspect}..."}
		if monitors = @selector.select(interval)
			monitors.each do |monitor|
				monitor.value.resume
			end
		end
	end until @stopped
	
	return initial_task
ensure
	Async.logger.debug(self) {"Exiting run-loop because #{$! ? $!.inspect : 'finished'}."}
	@stopped = true
end