Django, dynamic urlconfs, thread-safety

I need to dynamically generate urlpatterns based on data in the session in a thread-safe way.

I implemented this via a custom URLResolver that defers url resolving until later. I do know about setting request.urlconf from a middleware; but there are reasons I cannot do that (Django caches resolvers, and in my case would result in unbounded memory usage).

I need someone to take a look at the implementation and see if I've handled the thread-safety correctly.

Thanks!

The code:

myapp/urls.py:

urlpatterns = patterns('',
    # other urlconfs
    url(r'^/foo', include('foo.urls')),
)

foo/urls.py:

import threading
from django.core.urlresolvers import ResolverMatch

class MyResolver(RegexURLResolver):
    def __init__(self):
        self.resolver = threading.local()
        return super(MyResolver, self).__init__(r'', None)

    @property
    def urlconf_module(self):
        return self.resolver.value

    def resolve(self, path):
        def view(request):
            resolver = request.session.get('myresolver', 'default')
            resolver = getattr(import_module('foo.resolvers'), resolver)
            self.resolver.value = resolver()
            view, args, kwags = super(MyResolver, self).resolve(path)
            return view(request, *args, **kwargs)
         return ResolverMatch(view, (), {})

urlpatterns = [MyResolver()]

foo/resolvers.py:

class default(object):
    @property
    def urlpatterns(self):
        return patterns('foo.views',
           url(r'', 'error'),
        )

 class test(object):
     @property
     def urlpatterns(self):
         return dynamically_generated_urlpatterns

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