class Async::Task

def defer_stop

@public Since `stable-v1`.
@yields {} The block of code to execute.

If stop is invoked a second time, it will be immediately executed.

You can nest calls to defer_stop, but the stop will only be deferred until the outermost block exits.

Defer the handling of stop. During the execution of the given block, if a stop is requested, it will be deferred until the block exits. This is useful for ensuring graceful shutdown of servers and other long-running tasks. You should wrap the response handling code in a defer_stop block to ensure that the task is stopped when the response is complete but not before. 
def defer_stop
	# Tri-state variable for controlling stop:
	# - nil: defer_stop has not been called.
	# - false: defer_stop has been called and we are not stopping.
	# - true: defer_stop has been called and we will stop when exiting the block.
	if @defer_stop.nil?
		# If we are not deferring stop already, we can defer it now:
		@defer_stop = false
		
		begin
			yield
		rescue Stop
			# If we are exiting due to a stop, we shouldn't try to invoke stop again:
			@defer_stop = nil
			raise
		ensure
			# If we were asked to stop, we should do so now:
			if @defer_stop
				@defer_stop = nil
				raise Stop, "Stopping current task (was deferred)!"
			end
		end
	else
		# If we are deferring stop already, entering it again is a no-op.
		yield
	end
end