pylibmcd.py

"""
Thread-safe Django cache backend for pylibmc.
Tested on Python 2.6, should work on 2.5 as well.

Use it by setting CACHE_BACKEND in settings.py, e.g.:

    CACHE_BACKEND = 'projdir.utils.pylibmcd://127.0.0.1:11211/'

And here's how to properly install pylibmcd in Ubuntu for mod_wsgi:

---

VENV_PATH=/some/path/venv
virtualenv --no-site-packages $VENV_PATH

wget -O - http://launchpad.net/libmemcached/1.0/0.41/+download/libmemcached-0.41.tar.gz | tar zxf -
cd libmemcached-0.41
BASE_LIBPATH=$VENV_PATH/lib/share
./configure --prefix $BASE_LIBPATH
make install

export CPATH=$BASE_LIBPATH/include/
export LIBRARY_PATH=$BASE_LIBPATH/lib/
export LD_RUN_PATH=$LIBRARY_PATH
pip --environment=$VENV_PATH install pylibmc

---

The trick lies in setting LD_RUN_PATH so that mod_wsgi can find the shared libs.
"""
from __future__ import with_statement
from django.core.cache.backends.base import BaseCache
from django.utils.encoding import smart_unicode, smart_str

import pylibmc

class CacheClass(BaseCache):
    def __init__(self, server, params):
        super(CacheClass, self).__init__(params)
        mc = pylibmc.Client(server.split(';'))
        mc.behaviors = {"tcp_nodelay": True}
        self._pool = pylibmc.ThreadMappedPool(mc)

    def _call(self, method, *params):
        with self._pool.reserve() as mc:
            return getattr(mc, method)(*params)

    def add(self, key, value, timeout=None):
        if isinstance(value, unicode):
            value = value.encode('utf-8')
        return self._call('add', smart_str(key), value,
                self.default_timeout if timeout is None else timeout)

    def get(self, key, default=None):
        val = self._call('get', smart_str(key))
        if val is None:
            return default
        else:
            if isinstance(val, basestring):
                return smart_unicode(val)
            else:
                return val

    def set(self, key, value, timeout=None):
        if isinstance(value, unicode):
            value = value.encode('utf-8')
        self._call('set', smart_str(key), value,
                self.default_timeout if timeout is None else timeout)

    def delete(self, key):
        self._call('delete', smart_str(key))

    def get_many(self, keys):
        return self._call('get_multi', map(smart_str, keys))

    def set_many(self, mapping, timeout=None):
        return self._call('set_multi',
                dict((smart_str(key), val) for key, val in mapping.iteritems()),
                self.default_timeout if timeout is None else timeout)

    def close(self, **kwargs):
        self._pool.master.disconnect_all()

    def incr(self, key, delta=1):
        return self._call('incr', smart_str(key), delta)

    def decr(self, key, delta=1):
        return self._call('decr', smart_str(key), delta)

Neat.

Thanks :).

Perhaps this should go into some package or something, or should it simply stay as a Gist until the Django ticket is fixed?

I'd rather say let it stay as a Gist till then. After all, it's properly documented, no :)?