Webware for Python

Am 15.03.2010 19:38 schrieb Steve Schwarz:
> I don't recall if I've already submitted this enhancement...
> I've written a memcached based Session that others might find useful.

Thanks, Steve. I'll have a look and probably include it with the next 
Webware release (yes it got postponed but is not abandoned...)

-- Christoph

Am 15.03.2010 19:38 schrieb Steve Schwarz:
> I've written a memcached based Session that others might find useful.
> Feel free to use as you wish.

I had some time today to try it out. Works nicely. I have added some 
improvements (namespaces, clear() and some more methods) and tests.
Committed to the 1.1. branch now.

Only one thing was not quite clear: Why do you inherit the store from 
threading.local? As far as I see, this should not be necessary.

-- Christoph

On Sun, Apr 11, 2010 at 4:23 PM, Christoph Zwerschke <cito@...> wrote:

> Am 15.03.2010 19:38 schrieb Steve Schwarz:
> > I've written a memcached based Session that others might find useful.
> > Feel free to use as you wish.
>
> I had some time today to try it out. Works nicely. I have added some
> improvements (namespaces, clear() and some more methods) and tests.
> Committed to the 1.1. branch now.
>
> Only one thing was not quite clear: Why do you inherit the store from
> threading.local? As far as I see, this should not be necessary.
>
> Christoph,
Must have been a cut/paste error from the Session subclass on which I based
this implementation; there is no need for threading.local.
I'll take a look at your version.
Steve

On Sun, Apr 11, 2010 at 4:32 PM, Steve Schwarz <steve@...:

> On Sun, Apr 11, 2010 at 4:23 PM, Christoph Zwerschke <cito@...:
>
>> Am 15.03.2010 19:38 schrieb Steve Schwarz:
>> > I've written a memcached based Session that others might find useful.
>> > Feel free to use as you wish.
>>
>> I had some time today to try it out. Works nicely. I have added some
>> improvements (namespaces, clear() and some more methods) and tests.
>> Committed to the 1.1. branch now.
>>
> Christoph,
I took a look at the commit and I think the namespace idea is a good
enhancement. We use separate memcached servers only for session data so it
hasn't been an issue for us.

However I'm concerned by the added code/complexity required to support
clear(). In our usage of the memcached session store users are moved between
servers based on load. So if the sessions are cleared on one appserver what
mechanism is used to trigger the other servers to call getCounter() and
reset their notion of the session counter? Similarly if an appserver
restarts it will get the latest session namespace key but appservers that
didn't call clear() won't have the latest session namespace key.

I'd much rather the session store fail early and raise an exception if you
try to clear(). The less code in the session implementation the safer I'd
feel.

Best Regards,
Steve

Am 12.04.2010 00:59 schrieb Steve Schwarz:
> However I'm concerned by the added code/complexity required to support
> clear(). In our usage of the memcached session store users are moved
> between servers based on load. So if the sessions are cleared on one
> appserver what mechanism is used to trigger the other servers to call
> getCounter() and reset their notion of the session counter?

Ok, I see the problem. It happens if you are using more than one Webware 
app server connecting to the same memcache, right? In that case we need 
to fetch the counter every time from memcache (which is currently not 
done) because the other appservers could have updated it, and that would 
be indeed a lot of overhead.

I'll see if I can come up with a solution, but probably I will just 
remove the counter mechanism again.

-- Christoph

Am 12.04.2010 00:59 schrieb Steve Schwarz:
> I'd much rather the session store fail early and raise an exception if
> you try to clear(). The less code in the session implementation the
> safer I'd feel.

Ok, I have changed that now. You can configure whether you want an 
error, warning or ignore things unsupported by Memcached. The default is 
printing a warning.

-- Christoph