--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/wiki/receivers.py	Tue Apr 07 20:30:25 2015 -0500
@@ -0,0 +1,46 @@
+"""Signal handlers for wiki integration.
+
+We are interested in hearing about users logging in and out, so we can create
+and destroy an external cookie to allow access to the wiki.
+
+"""
+import logging
+
+from django.contrib.auth.signals import user_logged_in, user_logged_out
+
+from wiki.constants import SESSION_SET_MEMBER
+
+logger = logging.getLogger(__name__)
+
+
+def login_callback(sender, request, user, **kwargs):
+    """Signal callback function for a user logging in.
+
+    Sets a flag for the middleware to create an external cookie.
+
+    """
+    logger.info('User login: %s', user.username)
+
+    request.wiki_set_cookie = True
+
+
+def logout_callback(sender, request, user, **kwargs):
+    """Signal callback function for a user logging in.
+
+    Sets a flag for the middleware to delete the external cookie.
+
+    Since the user is about to logout, her session will be wiped out after
+    this function returns. This forces us to set an attribute on the request
+    object so that the response middleware can delete the wiki's cookie.
+
+    """
+    if user:
+        logger.info('User logout: %s', user.username)
+
+        # Remember what Redis set member to delete by adding an attribute to the
+        # request object:
+        request.wiki_delete_cookie = request.session.get(SESSION_SET_MEMBER)
+
+
+user_logged_in.connect(login_callback, dispatch_uid='wiki.receivers.login')
+user_logged_out.connect(logout_callback, dispatch_uid='wiki.receivers.logout')