Ticket #6791: cached_db_docs_and_tests.diff

django/conf/global_settings.py

@@ -279 +279 @@
 # SESSIONS #
 ############
 
-SESSION_COOKIE_NAME = 'sessionid'                       # Cookie name. This can be whatever you want.
-SESSION_COOKIE_AGE = 60 * 60 * 24 * 7 * 2               # Age of cookie, in seconds (default: 2 weeks).
-SESSION_COOKIE_DOMAIN = None                            # A string like ".lawrence.com", or None for standard domain cookie.
-SESSION_COOKIE_SECURE = False                           # Whether the session cookie should be secure (https:// only).
-SESSION_COOKIE_PATH = '/'                               # The path of the session cookie.
-SESSION_SAVE_EVERY_REQUEST = False                      # Whether to save the session data on every request.
-SESSION_EXPIRE_AT_BROWSER_CLOSE = False                 # Whether sessions expire when a user closes his browser.
-SESSION_ENGINE = 'django.contrib.sessions.backends.db'  # The module to store session data
-SESSION_FILE_PATH = '/tmp/'                             # Directory to store session files if using the file session module
+SESSION_COOKIE_NAME = 'sessionid'                              # Cookie name. This can be whatever you want.
+SESSION_COOKIE_AGE = 60 * 60 * 24 * 7 * 2                      # Age of cookie, in seconds (default: 2 weeks).
+SESSION_COOKIE_DOMAIN = None                                   # A string like ".lawrence.com", or None for standard domain cookie.
+SESSION_COOKIE_SECURE = False                                  # Whether the session cookie should be secure (https:// only).
+SESSION_COOKIE_PATH = '/'                                      # The path of the session cookie.
+SESSION_SAVE_EVERY_REQUEST = False                             # Whether to save the session data on every request.
+SESSION_EXPIRE_AT_BROWSER_CLOSE = False                        # Whether sessions expire when a user closes his browser.
+SESSION_ENGINE = 'django.contrib.sessions.backends.cached_db'  # The module to store session data
+SESSION_FILE_PATH = '/tmp/'                                    # Directory to store session files if using the file session module
 
 #########
 # CACHE #

django/contrib/sessions/tests.py

@@ -3 +3 @@
 >>> from django.conf import settings
 >>> from django.contrib.sessions.backends.db import SessionStore as DatabaseSession
 >>> from django.contrib.sessions.backends.cache import SessionStore as CacheSession
+>>> from django.contrib.sessions.backends.cached_db import SessionStore as CacheDBSession
 >>> from django.contrib.sessions.backends.file import SessionStore as FileSession
 >>> from django.contrib.sessions.backends.base import SessionBase
 
@@ -23 +24 @@
 >>> db_session.exists(db_session.session_key)
 False
 
+>>> cdb_session = CacheDBSession()
+>>> cdb_session.modified
+False
+>>> cdb_session['cat'] = "dog"
+>>> cdb_session.modified
+True
+>>> cdb_session.pop('cat')
+'dog'
+>>> cdb_session.pop('some key', 'does not exist')
+'does not exist'
+>>> cdb_session.save()
+>>> cdb_session.exists(cdb_session.session_key)
+True
+>>> cdb_session.delete(cdb_session.session_key)
+>>> cdb_session.exists(cdb_session.session_key)
+False
+
 >>> file_session = FileSession()
 >>> file_session.modified
 False

docs/sessions.txt

@@ -53 +53 @@
 sure to check that your Web server has permissions to read and write to
 this location.
 
-Using cache-based sessions
---------------------------
+Using cached sessions
+---------------------
 
-To store session data using Django's cache system, set ``SESSION_ENGINE``
-to ``"django.contrib.sessions.backends.cache"``. You'll want to make sure
-you've configured your cache; see the `cache documentation`_ for details.
+There are two cache backends for Django.  Setting ``SESSION_ENGINE`` to 
+``"django.contrib.sessions.backends.cache"`` uses a simple caching session 
+store, while ``"django.contrib.sessions.backends.cached_db"`` uses a 
+write-through cache.  In a write-through cache, every write to the cache 
+causes a write to the backing store, while reads only use the backing store
+on a cache miss.  Both session stores offer high performance, but the simple
+cache store trades more performance for persistence.
 
+You'll want to make sure you've configured your cache; see the 
+`cache documentation`_ for details.
+
 .. _cache documentation: ../cache/
 
 .. note::
+    If you decide to use the ``cache`` session store, you should 
+    probably only use the memcached cache backend. The local memory and simple 
+    cache backends don't retain data long enough to be good choices; It'll be 
+    faster to use file or database sessions directly instead of sending 
+    everything through the file or database cache backends.
 
-    You should probably only use cache-based sessions if you're using the
-    memcached cache backend. The local memory and simple cache backends
-    don't retain data long enough to be good choices, and it'll be faster
-    to use file or database sessions directly instead of sending everything
-    through the file or database cache backends.
 
+
 Using sessions in views
 =======================