improve SSDP a bit... send out multiple notifies... first is

sometime between .5 and 1 seconds, and the second is between 1 and
5 seconds later...

Also, schedule a resend of the notify for sometime between a third
and a half of the max-age of it all...

send out two byebye notifications just incase...

Yes, this increases traffic, but it's required per the spec.. and
w/ 100Mbit it's not too big of a deal..

[git-p4: depot-paths = "//depot/": change = 1088]

SSDP.py

@@ -37,18 +37,11 @@ class SSDPServer(DatagramProtocol):
 	stdheaders = [ ('Server', 'Twisted, UPnP/1.0, python-upnp'), ]
 	elements = {}
 	known = {}
-	tasks = []
+	maxage = 7 * 24 * 60 * 60
 
 	def doStop(self):
 		'''Make sure we send out the byebye notifications.'''
 
-		while True:
-			try:
-				t = self.tasks.pop()
-				t.stop()
-			except IndexError:
-				break
-
 		for st in self.known.keys():
 			self.doByebye(st)
 			del self.known[st]
@@ -120,12 +113,16 @@ class SSDPServer(DatagramProtocol):
 		self.known[st]['ST'] = st
 		self.known[st]['EXT'] = ''
 		self.known[st]['SERVER'] = 'Twisted, UPnP/1.0, python-upnp'
-		self.known[st]['CACHE-CONTROL'] = 'max-age=1800'
-		self.doNotify(st)
+		self.known[st]['CACHE-CONTROL'] = 'max-age=%d' % self.maxage
+		self.doNotifySchedule(st)
 
-		t = task.LoopingCall(lambda: self.doNotify(st))
-		t.start(7 * 60)
-		self.tasks.append(t)
+		reactor.callLater(random.uniform(.5, 1), lambda: self.doNotify(st))
+		reactor.callLater(random.uniform(1, 5), lambda: self.doNotify(st))
+
+	def doNotifySchedule(self, st):
+		self.doNotify(st)
+		reactor.callLater(random.uniform(self.maxage / 3,
+		    self.maxage / 2), lambda: self.doNotifySchedule(st))
 
 	def doByebye(self, st):
 		"""Do byebye"""
@@ -141,7 +138,9 @@ class SSDPServer(DatagramProtocol):
 		del stcpy['ST']
 		resp.extend(map(lambda x: ': '.join(x), stcpy.iteritems()))
 		resp.extend(('', ''))
-		self.transport.write('\r\n'.join(resp), (SSDP_ADDR, SSDP_PORT))
+		resp = '\r\n'.join(resp)
+		self.transport.write(resp, (SSDP_ADDR, SSDP_PORT))
+		self.transport.write(resp, (SSDP_ADDR, SSDP_PORT))
 
 	def doNotify(self, st):
 		"""Do notification"""