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annotate gpp/forums/stats.py @ 395:e10fa0d8e7ad

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Fixing #192; cache some forum stats and have them be computed outside of the request/response cycle. Update the template tag to just read the cache.
author Brian Neal <bgneal@gmail.com>
date Fri, 25 Mar 2011 00:27:10 +0000
parents
children e94570675664
rev   line source
bgneal@395 1 """
bgneal@395 2 This module is responsible for managing various forum statistics.
bgneal@395 3
bgneal@395 4 """
bgneal@395 5 from django.core.cache import cache
bgneal@395 6 from django.contrib.auth.models import User
bgneal@395 7
bgneal@395 8 from forums.models import Post
bgneal@395 9
bgneal@395 10
bgneal@395 11 CACHE_KEY = 'forums-stats'
bgneal@395 12 CACHE_TIMEOUT = 4 * 60 * 60 # seconds
bgneal@395 13
bgneal@395 14
bgneal@395 15 def calc_stats():
bgneal@395 16 """
bgneal@395 17 This function is responsible for computing the forum statistics.
bgneal@395 18 A tuple is returned: (forums post count, active user count, latest username)
bgneal@395 19
bgneal@395 20 """
bgneal@395 21 post_count = Post.objects.all().count()
bgneal@395 22 user_count = User.objects.all().count()
bgneal@395 23
bgneal@395 24 if user_count > 0:
bgneal@395 25 latest_user = User.objects.filter(is_active=True).values_list(
bgneal@395 26 'username', flat=True).order_by('-date_joined')[0]
bgneal@395 27 else:
bgneal@395 28 latest_user = None
bgneal@395 29
bgneal@395 30 return post_count, user_count, latest_user
bgneal@395 31
bgneal@395 32
bgneal@395 33 def update_stats():
bgneal@395 34 """
bgneal@395 35 This function is responsible for computing the forum statistics and
bgneal@395 36 inserting them into the cache. The stats are returned.
bgneal@395 37
bgneal@395 38 This function should be run periodically, preferably outside of the
bgneal@395 39 request/response cycle. On MySQL under InnoDb it is expensive to retrieve
bgneal@395 40 the total post count.
bgneal@395 41
bgneal@395 42 """
bgneal@395 43 stats = calc_stats()
bgneal@395 44 cache.set(CACHE_KEY, stats, CACHE_TIMEOUT)
bgneal@395 45 return stats
bgneal@395 46
bgneal@395 47
bgneal@395 48 def retrieve_stats():
bgneal@395 49 """
bgneal@395 50 This function retrieves the forum stats from the cache if they are
bgneal@395 51 available. If there is a cache-miss, the stats are calcuated, the cache is
bgneal@395 52 updated, and the stats returned.
bgneal@395 53
bgneal@395 54 """
bgneal@395 55 stats = cache.get(CACHE_KEY)
bgneal@395 56 if stats is None:
bgneal@395 57 stats = update_stats()
bgneal@395 58
bgneal@395 59 return stats