task.rb in async-1.32.0

- old
+ new

@@ -82,10 +82,12 @@
 			@finished = finished
 			
 			@logger = logger || @parent.logger
 			
 			@fiber = make_fiber(&block)
+			
+			@defer_stop = nil
 		end
 		
 		attr :logger
 		
 		if Fiber.current.respond_to?(:backtrace)
@@ -160,10 +162,17 @@
 			if self.stopped?
 				# If we already stopped this task... don't try to stop it again:
 				return
 			end
 			
+			# If we are deferring stop...
+			if @defer_stop == false
+				# Don't stop now... but update the state so we know we need to stop later.
+				@defer_stop = true
+				return false
+			end
+			
 			if self.running?
 				if self.current?
 					if later
 						@reactor << Stop::Later.new(self)
 					else
@@ -177,9 +186,44 @@
 					end
 				end
 			else
 				# We are not running, but children might be, so transition directly into stopped state:
 				stop!
+			end
+		end
+		
+		# 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.
+		#
+		# You can nest calls to defer_stop, but the stop will only be deferred until the outermost block exits.
+		#
+		# If stop is invoked a second time, it will be immediately executed.
+		#
+		# @yields {} The block of code to execute.
+		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
+						self.stop
+					end
+				end
+			else
+				# If we are deferring stop already, entering it again is a no-op.
+				yield
 			end
 		end
 		
 		# Lookup the {Task} for the current fiber. Raise `RuntimeError` if none is available.
 		# @return [Async::Task]