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Implement #45, add a who's online feature for the forums. Created middleware that caches usernames and guest session ids in the cache. Added a tag that displays this info.
author Brian Neal <bgneal@gmail.com>
date Tue, 22 Dec 2009 02:08:05 +0000
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159:416353def4ca 160:2eb3984ccb15
1 """
2 Middleware for the forums application.
3 """
4 import datetime
5
6 from django.core.cache import cache
7 from django.conf import settings
8
9
10 USER_ONLINE_TIMEOUT = datetime.timedelta(minutes=15)
11 USERS_ONLINE_KEY = 'users_online'
12 GUESTS_ONLINE_KEY = 'guests_online'
13 USERS_CACHE_TIMEOUT = 60 * 60 * 24 # units are seconds
14
15
16 class WhosOnline(object):
17 """
18 This middleware class keeps track of which registered users have
19 been seen recently, and the number of unique unregistered users.
20 We use the Django cache system to store this information.
21 This middleware should come after the authentication middleware,
22 as we count on the user attribute being attached to the request.
23 """
24
25 def process_request(self, request):
26 """
27 Keep track of who is online.
28 """
29 now = datetime.datetime.now()
30 cutoff = now - USER_ONLINE_TIMEOUT
31 users_online = cache.get(USERS_ONLINE_KEY, {})
32 guests_online = cache.get(GUESTS_ONLINE_KEY, {})
33
34 # update timestamp for user
35 if request.user.is_authenticated():
36 users_online[request.user.username] = now
37 else:
38 sid = request.COOKIES.get(settings.SESSION_COOKIE_NAME, '')
39 guests_online[sid] = now
40
41 # expire old records
42 for username, timestamp in users_online.items():
43 if timestamp < cutoff:
44 del users_online[username]
45
46 for sid, timestamp in guests_online.items():
47 if timestamp < cutoff:
48 del guests_online[sid]
49
50 cache.set(USERS_ONLINE_KEY, users_online, USERS_CACHE_TIMEOUT)
51 cache.set(GUESTS_ONLINE_KEY, guests_online, USERS_CACHE_TIMEOUT)