import pickle
from typing import Any, Union, Optional
from privex.helpers.common import empty
from privex.helpers import plugin
from privex.helpers.cache.CacheAdapter import CacheAdapter
from privex.helpers.exceptions import CacheNotFound
from privex.helpers.settings import DEFAULT_CACHE_TIMEOUT
import logging
log = logging.getLogger(__name__)
if plugin.HAS_REDIS:
from privex.helpers.plugin import get_redis, close_redis
from redis import Redis
import redis
[docs] class RedisCache(CacheAdapter):
"""
A Redis backed implementation of :class:`.CacheAdapter`. Uses the global Redis instance from
:py:mod:`privex.helpers.plugin` by default, however custom Redis instances can be passed in via
the constructor argument ``redis_instance``.
To allow for a wide variety of Python objects to be safely stored and retrieved from Redis, this class
uses the :py:mod:`pickle` module for serialising + un-serialising values to/from Redis.
**Basic Usage**::
>>> from privex.helpers import RedisCache
>>> rc = RedisCache()
>>> rc.set('hello', 'world')
>>> rc['hello']
'world'
**Disabling Pickling**
In some cases, you may need interoperable caching with other languages. The :py:mod:`pickle` serialisation
technique is extremely specific to Python and is largely unsupported outside of Python. Thus if you need
to share Redis cache data with applications in other languages, then you must disable pickling.
**WARNING:** If you disable pickling, then you must perform your own serialisation + de-serialization on
complex objects such as ``dict``, ``list``, ``Decimal``, or arbitrary classes/functions after getting
or setting cache keys.
**Disabling Pickle per instance**
Pass ``use_pickle=False`` to the constructor, or access the attribute directly to disable pickling for a
single instance of RedisCache (not globally)::
>>> rc = RedisCache(use_pickle=False) # Opt 1. Disable pickle in constructor
>>> rc.use_pickle = False # Opt 2. Disable pickle on an existing instance
**Disabling Pickle by default on any new instances**
Change the static attribute :py:attr:`.pickle_default` to ``False`` to disable the use of pickle by default
across any new instances of RedisCache::
>>> RedisCache.pickle_default = False
"""
pickle_default: bool = True
"""
Change this to ``False`` to disable the use of :py:mod:`pickle` by default for any new instances
of this class.
"""
use_pickle: bool
"""If ``True``, will use :py:mod:`pickle` for serializing objects before inserting into Redis, and
un-serialising objects retrieved from Redis. This attribute is set in :py:meth:`.__init__`.
Change this to ``False`` to disable the use of :py:mod:`pickle` - instead values will be passed to / returned
from Redis as-is, with no serialisation (this may require you to manually serialize complex types such
as ``dict`` and ``Decimal`` before insertion, and un-serialise after retrieval).
"""
_redis: Optional[Redis]
[docs] def __init__(self, use_pickle: bool = None, redis_instance: Redis = None, *args, **kwargs):
"""
RedisCache by default uses the global Redis instance from :py:mod:`privex.helpers.plugin`.
It's recommended to use :py:func:`privex.helpers.plugin.configure_redis` if you need to change any
Redis settings, as this will adjust the global settings and re-instantiate the global instance if required.
Alternatively, you may pass an instance of :class:`redis.Redis` as ``redis_instance``, then that will
be used instead of the global instance from :py:func:`.get_redis`
:param bool use_pickle: (Default: ``True``) Use the built-in ``pickle`` to serialise values before
storing in Redis, and un-serialise when loading from Redis
:param redis.Redis redis_instance: If this isn't ``None`` / ``False``, then this Redis instance will be
used instead of the global one from :py:func:`.get_redis`
"""
super().__init__(*args, **kwargs)
self._redis = get_redis() if not redis_instance else redis_instance
self.use_pickle = self.pickle_default if use_pickle is None else use_pickle
@property
def redis(self) -> Redis:
return self.connect()
[docs] def get(self, key: str, default: Any = None, fail: bool = False) -> Any:
key = str(key)
res = self.redis.get(key)
if empty(res):
if fail: raise CacheNotFound(f'Cache key "{key}" was not found.')
return default
return pickle.loads(res) if self.use_pickle else res
[docs] def set(self, key: str, value: Any, timeout: Optional[int] = DEFAULT_CACHE_TIMEOUT):
v = pickle.dumps(value) if self.use_pickle else value
return self.redis.set(str(key), v, ex=timeout)
[docs] def remove(self, *key: str) -> bool:
removed = 0
for k in key:
k = str(k)
try:
self.get(k, fail=True)
self.redis.delete(k)
removed += 1
except CacheNotFound:
pass
return removed == len(key)
[docs] def update_timeout(self, key: str, timeout: int = DEFAULT_CACHE_TIMEOUT) -> Any:
key, timeout = str(key), int(timeout)
v = self.get(key=key, fail=True)
self.set(key=key, value=v, timeout=timeout)
return v
def connect(self, *args, **kwargs) -> Redis:
if not self._redis:
self._redis = get_redis()
return self._redis
def close(self):
if self._redis is not None:
log.debug("Closing Synchronous Redis instance %s._redis", self.__class__.__name__)
self._redis.close()
self._redis = None
return close_redis()
# def __enter__(self):
# if not self.redis:
# self._redis = get_redis()
# return self
#
# def __exit__(self, exc_type, exc_val, exc_tb):
# close_redis()
# self._redis = None
# return None