lvmdbusd: Use timeout_add instead

The function timeout_add_seconds has quite a bit of variability.  Using
timeout_add which specifies the timeout in ms instead of seconds.  Testing
shows that this is much more consistent which should improve clients that
are using shorter timeouts for the API and the connection.

daemons/lvmdbusd/request.py

@@ -19,7 +19,6 @@ from .utils import log_error, mt_async_result
 class RequestEntry(object):
 	def __init__(self, tmo, method, arguments, cb, cb_error,
 			return_tuple=True, job_state=None):
-		self.tmo = tmo
 		self.method = method
 		self.arguments = arguments
 		self.cb = cb
@@ -35,23 +34,27 @@ class RequestEntry(object):
 		self._return_tuple = return_tuple
 		self._job_state = job_state
 
-		if self.tmo < 0:
+		if tmo < 0:
 			# Client is willing to block forever
 			pass
 		elif tmo == 0:
 			self._return_job()
 		else:
-			self.timer_id = GLib.timeout_add_seconds(
-				tmo, RequestEntry._request_timeout, self)
+			# Note: using 990 instead of 1000 for second to ms conversion to
+			# account for overhead.  Goal is to return just before the
+			# timeout amount has expired.  Better to be a little early than
+			# late.
+			self.timer_id = GLib.timeout_add(
+				tmo * 990, RequestEntry._request_timeout, self)
 
 	@staticmethod
 	def _request_timeout(r):
 		"""
 		Method which gets called when the timer runs out!
 		:param r:  RequestEntry which timed out
-		:return: Nothing
+		:return: Result of timer_expired
 		"""
-		r.timer_expired()
+		return r.timer_expired()
 
 	def _return_job(self):
 		# Return job is only called when we create a request object or when