Optimized the cached_db session backend to check if a key exists in t…

…he cache first. git-svn-id: http://code.djangoproject.com/svn/django/trunk@17156 bcc190cf-cafb-0310-a4f2-bffc1f526a37
django · Nov 27, 2011 · c11f9c3 · c11f9c3
1 parent bda21e2
commit c11f9c3
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diff --git a/django/contrib/sessions/backends/cached_db.py b/django/contrib/sessions/backends/cached_db.py
@@ -28,6 +28,8 @@ def load(self):
         return data
 
     def exists(self, session_key):
+        if (KEY_PREFIX + session_key) in cache:
+            return True
         return super(SessionStore, self).exists(session_key)
 
     def save(self, must_create=False):

diff --git a/django/contrib/sessions/tests.py b/django/contrib/sessions/tests.py
@@ -293,6 +293,11 @@ class CacheDBSessionTests(SessionTestsMixin, TestCase):
 
     backend = CacheDBSession
 
+    def test_exists_searches_cache_first(self):
+        self.session.save()
+        with self.assertNumQueries(0):
+            self.assertTrue(self.session.exists(self.session.session_key))
+
 
 CacheDBSessionWithTimeZoneTests = override_settings(USE_TZ=True)(CacheDBSessionTests)