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from django.conf import settings
from django.core.cache import cache
from django.contrib.auth.models import User
from django.utils.deprecation import MiddlewareMixin
from django.contrib.auth import user_logged_out
from django.dispatch import receiver
ONLINE_THRESHOLD = getattr(settings, 'ONLINE_THRESHOLD', 60 * 15)
ONLINE_MAX = getattr(settings, 'ONLINE_MAX', 50)
def get_online_now(self):
return User.objects.filter(id__in=self.online_now_ids or [])
@receiver(user_logged_out)
def logout(sender, **kwargs):
try:
cache.delete('online-%s' % kwargs['user'].id)
except AttributeError:
pass
class OnlineNowMiddleware(MiddlewareMixin):
"""Maintains a list of users who have interacted with the website recently.
Their user IDs are available as ``online_now_ids`` on the request
object, and their corresponding users are available (lazily) as the
``online_now`` property on the request object.
"""
def process_request(self, request):
# First get the index
uids = cache.get('online-now', [])
# Perform the multiget on the individual online uid keys
online_keys = ['online-%s' % (u,) for u in uids]
fresh = cache.get_many(online_keys).keys()
online_now_ids = [int(k.replace('online-', '')) for k in fresh]
# If the user is authenticated, add their id to the list
if request.user.is_authenticated:
uid = request.user.id
# If their uid is already in the list, we want to bump it
# to the top, so we remove the earlier entry.
if uid in online_now_ids:
online_now_ids.remove(uid)
online_now_ids.append(uid)
if len(online_now_ids) > ONLINE_MAX:
del online_now_ids[0]
# Attach our modifications to the request object
request.__class__.online_now_ids = online_now_ids
request.__class__.online_now = property(get_online_now)
# Set the new cache
cache.set('online-%s' % (request.user.pk,), True, ONLINE_THRESHOLD)
cache.set('online-now', online_now_ids, ONLINE_THRESHOLD)
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