tuned: improved error handling of switch_profile

Now the D-Bus method "switch_profile" returns record
(bool, string), where in case of error, the string
describes the error. The string is also displayed
by tuned-adm, so the user has better overview what's
going there.

Related: rhbz#1068699

Signed-off-by: Jaroslav Škarvada <jskarvad@redhat.com>

tuned/admin/admin.py

@@ -42,7 +42,7 @@ class Admin(object):
 		if profile_name == "":
 			return False
 		try:
-			ret = self._controller.switch_profile(profile_name)
+			(ret, msg) = self._controller.switch_profile(profile_name)
 		except TunedAdminDBusException as e:
 			self._error(e)
 			if profile_name in profiles_locator(consts.LOAD_DIRECTORIES).get_known_names():
@@ -60,7 +60,7 @@ class Admin(object):
 				self._error("Cannot enable the tuning.")
 				ret = False
 		else:
-			self._error("Cannot switch the profile.")
+			self._error(msg)
 
 		return ret
 

tuned/admin/dbus_controller.py

@@ -49,7 +49,7 @@ class DBusController(object):
 
 	def switch_profile(self, new_profile):
 		if new_profile == "":
-			return False
+			return (False, "No profile specified")
 		return self._call("switch_profile", new_profile)
 
 	def recommend_profile(self):

tuned/daemon/controller.py

@@ -61,21 +61,23 @@ class Controller(tuned.exports.interfaces.ExportableInterface):
 		else:
 			return self.stop() and self.start()
 
-	@exports.export("s", "b")
+	@exports.export("s", "(bs)")
 	def switch_profile(self, profile_name):
 		was_running = self._daemon.is_running()
+		msg = "OK"
 		success = True
 		try:
 			if was_running:
 				self._daemon.stop()
 			self._daemon.set_profile(profile_name)
-		except tuned.exceptions.TunedException:
+		except tuned.exceptions.TunedException as e:
 			success = False
+			msg = str(e)
 		finally:
 			if was_running:
 				self._daemon.start()
 
-		return success
+		return (success, msg)
 
 	@exports.export("", "s")
 	def active_profile(self):

tuned/daemon/daemon.py

@@ -57,6 +57,8 @@ class Daemon(object):
 
 		if profile_name == "" or profile_name is None:
 			self._profile = None
+		elif profile_name not in self.profile_loader.profile_locator.get_known_names():
+			raise TunedException("Requested profile '%s' doesn't exist." % profile_name)
 		else:
 			try:
 				self._profile = self._profile_loader.load(profile_name)