From e37eb49065abfda70abdfcf5f70ddd748f49aa74 Mon Sep 17 00:00:00 2001
From: David Ormsbee <dormsbee@mitx.mit.edu>
Date: Thu, 15 Mar 2012 14:45:27 -0400
Subject: [PATCH 1/3] Shift wiki and course.xml caching to use newly defined
 'general' cache, separate from sessions left in 'default'

--HG--
branch : cache_separation
---
 courseware/content_parser.py |  3 ++-
 simplewiki/models.py         |  3 ++-
 util/cache.py                | 16 ++++++++++++++++
 3 files changed, 20 insertions(+), 2 deletions(-)
 create mode 100644 util/cache.py

diff --git a/courseware/content_parser.py b/courseware/content_parser.py
index cc02597cb3..2c6a515c63 100644
--- a/courseware/content_parser.py
+++ b/courseware/content_parser.py
@@ -11,10 +11,11 @@ from lxml import etree
 
 try: # This lets us do __name__ == ='__main__'
     from django.conf import settings
-    from django.core.cache import cache
+
     from student.models import UserProfile
     from student.models import UserTestGroup
     from mitxmako.shortcuts import render_to_response, render_to_string
+    from util.cache import cache
 except: 
     settings = None 
 
diff --git a/simplewiki/models.py b/simplewiki/models.py
index 58173e0ca0..33c9b0403e 100644
--- a/simplewiki/models.py
+++ b/simplewiki/models.py
@@ -3,7 +3,6 @@ import os
 
 from django import forms
 from django.contrib.auth.models import User
-from django.core.cache import cache
 from django.core.urlresolvers import reverse
 from django.db import models
 from django.db.models import signals
@@ -11,6 +10,8 @@ from django.utils.translation import ugettext_lazy as _
 from markdown import markdown
 
 from settings import *
+from util.cache import cache
+
 
 class ShouldHaveExactlyOneRootSlug(Exception):
     pass
diff --git a/util/cache.py b/util/cache.py
new file mode 100644
index 0000000000..b0c370a035
--- /dev/null
+++ b/util/cache.py
@@ -0,0 +1,16 @@
+"""
+This module aims to give a little more fine-tuned control of caching and cache
+invalidation. Import these instead of django.core.cache.
+
+Note that 'default' is being preserved for user session caching, which we're 
+not migrating so as not to inconvenience users by logging them all out.
+"""
+from django.core import cache
+
+# If we can't find a 'general' CACHE defined in settings.py, we simply fall back
+# to returning the default cache. This will happen with dev machines.
+try:
+    cache = cache.get_cache('general')
+except ValueError:
+    cache = cache.cache
+

From f4625003a79a2a2d47c521d0eb3d45dca0c92725 Mon Sep 17 00:00:00 2001
From: David Ormsbee <dormsbee@mitx.mit.edu>
Date: Thu, 15 Mar 2012 15:21:39 -0400
Subject: [PATCH 2/3] change config to not cache by default, unless overridden
 by server-specific settings.py

--HG--
branch : cache_separation
---
 courseware/content_parser.py | 5 +----
 settings.py                  | 7 +++++++
 util/cache.py                | 1 +
 3 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/courseware/content_parser.py b/courseware/content_parser.py
index 2c6a515c63..eb1678536d 100644
--- a/courseware/content_parser.py
+++ b/courseware/content_parser.py
@@ -158,10 +158,7 @@ def user_groups(user):
     cache_expiration = 60 * 60 # one hour
     
     # Kill caching on dev machines -- we switch groups a lot
-    if "dev" not in settings.DEFAULT_GROUPS:
-        group_names = cache.get(fasthash(key))
-    else: 
-        group_names = None
+    group_names = cache.get(fasthash(key))
  
     if group_names is None:
         group_names = [u.name for u in UserTestGroup.objects.filter(users=user)]
diff --git a/settings.py b/settings.py
index cce3dfad4e..561fc550af 100644
--- a/settings.py
+++ b/settings.py
@@ -163,6 +163,13 @@ MAKO_TEMPLATES = {}
 
 LOGGING_ENV = "dev" # override this in different environments
 
+# Default dev cache (i.e. no caching)
+CACHES = {
+    'default': {
+        'BACKEND': 'django.core.cache.backends.dummy.DummyCache',
+    }
+}
+
 # Make sure we execute correctly regardless of where we're called from
 execfile(os.path.join(BASE_DIR, "settings.py"))
 
diff --git a/util/cache.py b/util/cache.py
index b0c370a035..1a01b3d7fd 100644
--- a/util/cache.py
+++ b/util/cache.py
@@ -6,6 +6,7 @@ Note that 'default' is being preserved for user session caching, which we're
 not migrating so as not to inconvenience users by logging them all out.
 """
 from django.core import cache
+import settings
 
 # If we can't find a 'general' CACHE defined in settings.py, we simply fall back
 # to returning the default cache. This will happen with dev machines.

From d9253a0c0fcc11088c0c0208721fb0f7cbef59bf Mon Sep 17 00:00:00 2001
From: David Ormsbee <dormsbee@mitx.mit.edu>
Date: Thu, 15 Mar 2012 15:25:39 -0400
Subject: [PATCH 3/3] remove unnecessary settings import

--HG--
branch : cache_separation
---
 util/cache.py | 1 -
 1 file changed, 1 deletion(-)

diff --git a/util/cache.py b/util/cache.py
index 1a01b3d7fd..b0c370a035 100644
--- a/util/cache.py
+++ b/util/cache.py
@@ -6,7 +6,6 @@ Note that 'default' is being preserved for user session caching, which we're
 not migrating so as not to inconvenience users by logging them all out.
 """
 from django.core import cache
-import settings
 
 # If we can't find a 'general' CACHE defined in settings.py, we simply fall back
 # to returning the default cache. This will happen with dev machines.