Initialize thread pool only if there are plugins

safeeyes/Plugins.py

@@ -35,7 +35,6 @@ class Plugins:
 		"""
 		logging.info('Load all the plugins')
 		self.__plugins = []
-		self.__thread_pool = ThreadPool(4)
 
 		for plugin in config['plugins']:
 			if plugin['location'].lower() in ['left', 'right']:
@@ -50,28 +49,34 @@ class Plugins:
 			else:
 				logging.warning('Ignoring the plugin ' + str(plugin['name']) + ' due to invalid location value: ' +  plugin['location'])
 
+		print(min([4, len(self.__plugins)]))
+		if self.__plugins:
+			self.__thread_pool = ThreadPool(min([4, len(self.__plugins)]))
+
 
 	def start(self, context):
 		"""
 		Call the start function of all the plugins in separate thread.
 		"""
-		context = copy.deepcopy(context)	# If plugins change the context, it should not affect Safe Eyes
+		if self.__plugins:
-		for plugin in self.__plugins:
+			context = copy.deepcopy(context)	# If plugins change the context, it should not affect Safe Eyes
-			try:
+			for plugin in self.__plugins:
-				self.__thread_pool.apply_async(plugin['module'].start, (context,))
+				try:
-			except Exception as e:
+					self.__thread_pool.apply_async(plugin['module'].start, (context,))
-				pass
+				except Exception as e:
+					pass
 
 	def pre_notification(self, context):
 		"""
 		Call the pre_notification function of all the plugins in separate thread.
 		"""
-		context = copy.deepcopy(context)	# If plugins change the context, it should not affect Safe Eyes
+		if self.__plugins:
-		for plugin in self.__plugins:
+			context = copy.deepcopy(context)	# If plugins change the context, it should not affect Safe Eyes
-			try:
+			for plugin in self.__plugins:
-				self.__thread_pool.apply_async(plugin['module'].pre_notification, (context,))
+				try:
-			except Exception as e:
+					self.__thread_pool.apply_async(plugin['module'].pre_notification, (context,))
-				pass
+				except Exception as e:
+					pass
 
 
 	def pre_break(self, context):
@@ -81,57 +86,60 @@ class Plugins:
 
 		Returns: {'left': 'Markup of plugins to be aligned on left', 'right': 'Markup of plugins to be aligned on right' }
 		"""
-		context = copy.deepcopy(context)	# If plugins change the context, it should not affect Safe Eyes
+		if self.__plugins:
-		output = {'left': '                                                  \n', 'right': '                                                  \n'}
+			context = copy.deepcopy(context)	# If plugins change the context, it should not affect Safe Eyes
-		multiple_results = [self.__thread_pool.apply_async(plugin['module'].pre_break, (context,)) for plugin in self.__plugins]
+			output = {'left': '                                                  \n', 'right': '                                                  \n'}
-		for i in range(len(multiple_results)):
+			multiple_results = [self.__thread_pool.apply_async(plugin['module'].pre_break, (context,)) for plugin in self.__plugins]
-			try:
+			for i in range(len(multiple_results)):
-				result = multiple_results[i].get(timeout=1)
+				try:
-				if result:
+					result = multiple_results[i].get(timeout=1)
-					# Limit the line length to 50 characters
+					if result:
-					large_lines  = list(filter(lambda x: len(x) > 50, Utility.html_to_text(result).splitlines()))
+						# Limit the line length to 50 characters
-					if large_lines:
+						large_lines  = list(filter(lambda x: len(x) > 50, Utility.html_to_text(result).splitlines()))
-						logging.warning('Ignoring lengthy result from the plugin ' + self.__plugins[i]['name'])
+						if large_lines:
-						continue
+							logging.warning('Ignoring lengthy result from the plugin ' + self.__plugins[i]['name'])
-					output[self.__plugins[i]['location']] += (result + '\n\n')
+							continue
-			except Exception:
+						output[self.__plugins[i]['location']] += (result + '\n\n')
-				# Something went wrong in the plugin
+				except Exception:
-				logging.warning('Error when executing the plugin ' + self.__plugins[i]['name'])
+					# Something went wrong in the plugin
+					logging.warning('Error when executing the plugin ' + self.__plugins[i]['name'])
 
-		return output
+			return output
 
 
 	def post_break(self, context):
 		"""
 		Call the post_break function of all the plugins in separate thread.
 		"""
-		context = copy.deepcopy(context)	# If plugins change the context, it should not affect Safe Eyes
+		if self.__plugins:
-		for plugin in self.__plugins:
+			context = copy.deepcopy(context)	# If plugins change the context, it should not affect Safe Eyes
-			try:
+			for plugin in self.__plugins:
-				self.__thread_pool.apply_async(plugin['module'].post_break, (context,))
+				try:
-			except Exception as e:
+					self.__thread_pool.apply_async(plugin['module'].post_break, (context,))
-				pass
+				except Exception as e:
+					pass
 
 	def exit(self, context):
 		"""
 		Call the exit function of all the plugins in separate thread.
 		"""
-		context = copy.deepcopy(context)	# If plugins change the context, it should not affect Safe Eyes
+		if self.__plugins:
+			context = copy.deepcopy(context)	# If plugins change the context, it should not affect Safe Eyes
+
+			# Give maximum 1 sec for all plugins before terminating the thread pool
+			multiple_results = [self.__thread_pool.apply_async(plugin['module'].exit, (context,)) for plugin in self.__plugins]
+			for i in range(len(multiple_results)):
+				try:
+					multiple_results[i].get(timeout=1)
+				except Exception:
+					# Something went wrong in the plugin
+					pass
 
-		# Give maximum 1 sec for all plugins before terminating the thread pool
-		multiple_results = [self.__thread_pool.apply_async(plugin['module'].exit, (context,)) for plugin in self.__plugins]
-		for i in range(len(multiple_results)):
 			try:
-				multiple_results[i].get(timeout=1)
+				self.__thread_pool.terminate()	# Shutdown the pool
-			except Exception:
+			except Exception as e:
-				# Something went wrong in the plugin
 				pass
 
-		try:
-			self.__thread_pool.terminate()	# Shutdown the pool
-		except Exception as e:
-			pass
-
 
 	def __has_method(self, module, method_name, no_of_args = 1):
 		"""