"""

Cached, database-backed sessions.

"""

from django.conf import settings

from django.contrib.sessions.backends.db import SessionStore as DBStore

from django.core.cache import cache

class SessionStore(DBStore):

    """

    Implements cached, database backed sessions.

    """

    def __init__(self, session_key=None):

        super(SessionStore, self).__init__(session_key)

    def load(self):

        data = cache.get(self.session_key, None)

        if data is None:

            data = super(SessionStore, self).load()

            cache.set(self.session_key, data, settings.SESSION_COOKIE_AGE)

        return data

    def exists(self, session_key):

        return super(SessionStore, self).exists(session_key)

    def save(self, must_create=False):

        super(SessionStore, self).save(must_create)

        cache.set(self.session_key, self._session, settings.SESSION_COOKIE_AGE)

    def delete(self, session_key=None):

        super(SessionStore, self).delete(session_key)

        cache.delete(session_key or self.session_key)

    def flush(self):

        """

        Removes the current session data from the database and regenerates the

        key.

        """

        self.clear()

        self.delete(self.session_key)

        self.create()