From 41dfa3e5527bc3e446d2fb2f0e15962b0ac28d2f Mon Sep 17 00:00:00 2001
From: Calen Pennington <cale@edx.org>
Date: Thu, 12 Dec 2013 21:45:22 -0500
Subject: [PATCH] Cache anonymous user id on the user object, so that queries
 aren't made many times over during module rendering

---
 common/djangoapps/student/models.py | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/common/djangoapps/student/models.py b/common/djangoapps/student/models.py
index 8f1ac09a0651..8921a078ba4f 100644
--- a/common/djangoapps/student/models.py
+++ b/common/djangoapps/student/models.py
@@ -66,6 +66,10 @@ def anonymous_id_for_user(user, course_id):
     if user.is_anonymous():
         return None
 
+    cached_id = getattr(user, '_anonymous_id', {}).get(course_id)
+    if cached_id is not None:
+        return cached_id
+
     # include the secret key as a salt, and to make the ids unique across different LMS installs.
     hasher = hashlib.md5()
     hasher.update(settings.SECRET_KEY)
@@ -94,6 +98,11 @@ def anonymous_id_for_user(user, course_id):
         # continue
         pass
 
+    if not hasattr(user, '_anonymous_id'):
+        user._anonymous_id = {}
+
+    user._anonymous_id[course_id] = digest
+
     return digest