sg101: gpp/forums/stats.py comparison

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.

comparison

equal deleted inserted replaced

-:2cb0cc334c50
+:e10fa0d8e7ad
+"""
+This module is responsible for managing various forum statistics.
+"""
+from django.core.cache import cache
+from django.contrib.auth.models import User
+from forums.models import Post
+CACHE_KEY = 'forums-stats'
+CACHE_TIMEOUT = 4 * 60 * 60         # seconds
+def calc_stats():
+"""
+This function is responsible for computing the forum statistics.
+A tuple is returned: (forums post count, active user count, latest username)
+"""
+post_count = Post.objects.all().count()
+user_count = User.objects.all().count()
+if user_count > 0:
+latest_user = User.objects.filter(is_active=True).values_list(
+'username', flat=True).order_by('-date_joined')[0]
+else:
+latest_user = None
+return post_count, user_count, latest_user
+def update_stats():
+"""
+This function is responsible for computing the forum statistics and
+inserting them into the cache. The stats are returned.
+This function should be run periodically, preferably outside of the
+request/response cycle. On MySQL under InnoDb it is expensive to retrieve
+the total post count.
+"""
+stats = calc_stats()
+cache.set(CACHE_KEY, stats, CACHE_TIMEOUT)
+return stats
+def retrieve_stats():
+"""
+This function retrieves the forum stats from the cache if they are
+available. If there is a cache-miss, the stats are calcuated, the cache is
+updated, and the stats returned.
+"""
+stats = cache.get(CACHE_KEY)
+if stats is None:
+stats = update_stats()
+return stats

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