Fixed #13283 -- Corrected CACHE_MIDDLEWARE_ANONYMOUS_ONLY's bad habit of setting Vary: Cookie on all responses and destroying cache efficiency. Thanks to natrius for the fix.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@15381 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/middleware/cache.py

@@ -50,7 +50,7 @@ More details about how the caching works:
 
 from django.conf import settings
 from django.core.cache import get_cache, DEFAULT_CACHE_ALIAS
-from django.utils.cache import get_cache_key, learn_cache_key, patch_response_headers, get_max_age
+from django.utils.cache import get_cache_key, learn_cache_key, patch_response_headers, get_max_age, has_vary_header
 
 
 class UpdateCacheMiddleware(object):
@@ -69,9 +69,19 @@ class UpdateCacheMiddleware(object):
         self.cache_alias = settings.CACHE_MIDDLEWARE_ALIAS
         self.cache = get_cache(self.cache_alias)
 
+    def _should_update_cache(self, request, response):
+        if not hasattr(request, '_cache_update_cache') or not request._cache_update_cache:
+            return False
+        if self.cache_anonymous_only and has_vary_header(response, 'Cookie'):
+            assert hasattr(request, 'user'), "The Django cache middleware with CACHE_MIDDLEWARE_ANONYMOUS_ONLY=True requires authentication middleware to be installed. Edit your MIDDLEWARE_CLASSES setting to insert 'django.contrib.auth.middleware.AuthenticationMiddleware' before the CacheMiddleware."
+            if request.user.is_authenticated():
+                # Don't cache user-variable requests from authenticated users.
+                return False
+        return True
+
     def process_response(self, request, response):
         """Sets the cache, if needed."""
-        if not hasattr(request, '_cache_update_cache') or not request._cache_update_cache:
+        if not self._should_update_cache(request, response):
             # We don't need to update the cache, just return.
             return response
         if not response.status_code == 200:
@@ -116,17 +126,10 @@ class FetchFromCacheMiddleware(object):
         Checks whether the page is already cached and returns the cached
         version if available.
         """
-        if self.cache_anonymous_only:
-            assert hasattr(request, 'user'), "The Django cache middleware with CACHE_MIDDLEWARE_ANONYMOUS_ONLY=True requires authentication middleware to be installed. Edit your MIDDLEWARE_CLASSES setting to insert 'django.contrib.auth.middleware.AuthenticationMiddleware' before the CacheMiddleware."
-
         if not request.method in ('GET', 'HEAD') or request.GET:
             request._cache_update_cache = False
             return None # Don't bother checking the cache.
 
-        if self.cache_anonymous_only and request.user.is_authenticated():
-            request._cache_update_cache = False
-            return None # Don't cache requests from authenticated users.
-
         # try and get the cached GET response
         cache_key = get_cache_key(request, self.key_prefix, 'GET', cache=self.cache)
         if cache_key is None:

django/utils/cache.py

@@ -134,6 +134,16 @@ def patch_vary_headers(response, newheaders):
                           if newheader.lower() not in existing_headers]
     response['Vary'] = ', '.join(vary_headers + additional_headers)
 
+def has_vary_header(response, header_query):
+    """
+    Checks to see if the response has a given header name in its Vary header.
+    """
+    if not response.has_header('Vary'):
+        return False
+    vary_headers = cc_delim_re.split(response['Vary'])
+    existing_headers = set([header.lower() for header in vary_headers])
+    return header_query.lower() in existing_headers
+
 def _i18n_cache_key_suffix(request, cache_key):
     """If enabled, returns the cache key ending with a locale."""
     if settings.USE_I18N: