Sessions support

[hartror]

A common usage of dogpile.cache like its predecessor beaker is to store session information such as with the pyramid_beaker library. What are thoughts on having a similar implementation for pyramid_dogpile_cache2?

Thanks

[wosc]

In one of our projects we indeed use a pyramid session implementation that uses a dogpile.cache region to store the information. Unfortunately, the pyramid session code is not factored very friendly for extending, so this involved quite a bit of copy&paste. The basic idea looked something like below, but note, that's not fully working code, just a rough draft of the main structure. I'm definitely open to a pull request if you want to flesh this out, but I won't have time to work on this myself.

SESSION_CACHE = pyramid_dogpile_cache2.get_region('session')

@zope.interface.implementer(pyramid.interfaces.ISession)
class CacheSession(dict):

    def __init__(self, request):
        self.request = request

        stored = SESSION_CACHE.get(
            self.session_id) if self.session_id else NO_VALUE
        if stored is not NO_VALUE:
            super(CacheSession, self).__init__(stored)
        else:
            now = int(time.time())
            self.created = now
            self.accessed = now
            self.renewed = now

    @property
    def session_id(self):
        return self.request.cookies.get('my_session_cookie')

    def persist(self):
        if not self.session_id:
            return
        SESSION_CACHE.set(self.session_id, dict(self))

    def changed(self):
        if not self._dirty:
            self._dirty = True
            self.renewed = time_now()

            def store_session(request, response):
                self.persist()
                self._set_cookie(response)
                self.request = None  # explicitly break cycle for GC
            self.request.add_response_callback(store_session)

# in your pyramid setup
config.set_session_factory(CacheSession)

[hartror]

Thanks @wosc I am indeed happy to have a crack at a PR in the near future.