Redis cache backend for Django

rediscache.py

#   Copyright (c) 2015, Alban Gruin <[email protected]>
#
#   Permission to use, copy, modify, and/or distribute this software for any
#   purpose with or without fee is hereby granted, provided that the above
#   copyright notice and this permission notice appear in all copies.
#
#   THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
#   WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
#   MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
#   ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
#   WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
#   ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
#   OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

"Redis cache backend"

from django.core.cache.backends.base import DEFAULT_TIMEOUT, BaseCache
import redis


class RedisCache(BaseCache):
    def __init__(self, server, params):
        super(RedisCache, self).__init__(params)

        self._server = params.get('LOCATION', 'localhost')
        self._port = params.get('PORT', 6379)
        self._db = params.get('DB', 0)
        self._password = params.get('PASSWORD', None)
        self._unixSocket = self._server.startswith('unix:/')

        if self._unixSocket:
            self._server = self._server[5:]

    def __contains__(self, key):
        return self.has_key(key)

    @property
    def _cache(self):
        if not hasattr(self, '_client'):
            if self._unixSocket:
                self._client = redis.StrictRedis(unix_socket_path=self._server,
                                                 db=self._db,
                                                 password=self._password)
            else:
                self._client = redis.StrictRedis(host=self._server,
                                                 port=self._port, db=self._db,
                                                 password=self._password)
        return self._client

    def add(self, key, value, timeout=DEFAULT_TIMEOUT, *args, **kwargs):
        if hasattr(value, '__len__') and len(value) <= 0:
            return True

        pipe = self._cache.pipeline()
        if isinstance(value, list):
            pipe.rpush(key, *value)
        elif isinstance(value, dict):
            pipe.hmset(key, value)
        else:
            pipe.set(key, value)

        pipe.expire(key, timeout)
        if pipe.execute() == [True, True]:
            return True
        else:
            return False

    def clear(self):
        self._cache.flushdb()

    def close(self):
        if getattr(self, '_client', None) is not None:
            del self._client

    def decr(self, key, delta=1, *args, **kwargs):
        return self._cache.decrby(key, -delta)

    def delete(self, key, *args, **kwargs):
        self._cache.delete(key)

    def delete_many(self, keys, *args, **kwargs):
        for key in keys:
            self.delete(key, *args, **kwargs)

    def get(self, key, default=None):
        if self._cache.exists(key): 
            if self._cache.type(key) == 'string':
                return self._cache.get(key)
            elif self._cache.type(key) == 'list':
                return self._cache.lrange(key, 0, -1)
            elif self._cache.type(key) == 'hash':
                return self._cache.hgetall(key)
        else:
            return default

    def get_many(self, keys, *args, **kwargs):
        return dict(zip(keys, [self.get(key) for key in keys]))

    def get_or_set(self, key, default=None, timeout=DEFAULT_TIMEOUT, *args,
                   **kwargs):
        if default is None:
            raise ValueError('You need to specify a value.')

        if self.has_key(key):
            return self.get(key)
        else:
            if callable(default):
                default = default()
            if self.add(key, default, timeout, *args, **kwargs):
                return self.get(key, *args, **kwargs)
            return False

    def has_key(self, key, *args, **kwargs):
        return self._cache.exists(key)

    def incr(self, key, delta=1, *args, **kwargs):
        return self._cache.incrby(key, delta)

    def set(self, key, value, timeout=DEFAULT_TIMEOUT, *args, **kwargs):
        return self.add(key, value, timeout)

    def set_many(self, data, timeout=DEFAULT_TIMEOUT, *args, **kwargs):
        for key, value in data.items():
            self.set(key, value, timeout, *args, **kwargs)