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"""
.. image::
../_static/redis.png
`Redis <https://redis.io>`_ is an in-memory data store with on-disk persistence. It offers a
high-performace cache that scales exceptionally well, making it an ideal choice for larger
applications.
Persistence
^^^^^^^^^^^
Redis operates on data in memory, and by default also persists data to snapshots on disk. This is
optimized for performance with a minor risk of data loss, which is usually the best configuration
for a cache. If you need different behavior, the frequency and type of persistence can be customized
or disabled entirely. See `Redis Persistence <https://redis.io/topics/persistence>`_ for details.
Connection Options
^^^^^^^^^^^^^^^^^^
The Redis backend accepts any keyword arguments for :py:class:`redis.client.Redis`. These can be passed
via :py:class:`.CachedSession`:
>>> session = CachedSession('http_cache', backend='redis', host='192.168.1.63', port=6379)
Or via :py:class:`.RedisCache`:
>>> backend = RedisCache(host='192.168.1.63', port=6379)
>>> session = CachedSession('http_cache', backend=backend)
API Reference
^^^^^^^^^^^^^
.. automodsumm:: requests_cache.backends.redis
:classes-only:
:nosignatures:
"""
from typing import Iterable
from redis import Redis, StrictRedis
from ..cache_keys import decode, encode
from . import BaseCache, BaseStorage, get_valid_kwargs
class RedisCache(BaseCache):
"""Redis cache backend
Args:
namespace: Redis namespace
connection: Redis connection instance to use instead of creating a new one
kwargs: Additional keyword arguments for :py:class:`redis.client.Redis`
"""
def __init__(self, namespace='http_cache', connection: Redis = None, **kwargs):
super().__init__(**kwargs)
self.responses = RedisDict(namespace, 'responses', connection=connection, **kwargs)
self.redirects = RedisDict(
namespace, 'redirects', connection=self.responses.connection, **kwargs
)
class RedisDict(BaseStorage):
"""A dictionary-like interface for Redis operations
**Notes:**
* In order to deal with how Redis stores data, all keys will be encoded and all values will
be serialized.
* The full hash name will be ``namespace:collection_name``
"""
def __init__(self, namespace, collection_name='http_cache', connection=None, **kwargs):
super().__init__(**kwargs)
connection_kwargs = get_valid_kwargs(Redis, kwargs)
self.connection = connection or StrictRedis(**connection_kwargs)
self._self_key = f'{namespace}:{collection_name}'
def __getitem__(self, key):
result = self.connection.hget(self._self_key, encode(key))
if result is None:
raise KeyError
return self.serializer.loads(result)
def __setitem__(self, key, item):
self.connection.hset(self._self_key, encode(key), self.serializer.dumps(item))
def __delitem__(self, key):
if not self.connection.hdel(self._self_key, encode(key)):
raise KeyError
def __len__(self):
return self.connection.hlen(self._self_key)
def __iter__(self):
for key in self.connection.hkeys(self._self_key):
yield decode(key)
def bulk_delete(self, keys: Iterable[str]):
"""Delete multiple keys from the cache. Does not raise errors for missing keys."""
if keys:
self.connection.hdel(self._self_key, *[encode(key) for key in keys])
def clear(self):
self.connection.delete(self._self_key)
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