Source code for requests_cache.backends.redis

"""
.. 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, and 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 logging import getLogger
from typing import Iterable

from redis import Redis, StrictRedis

from .._utils import get_valid_kwargs
from ..cache_keys import decode, encode
from . import BaseCache, BaseStorage

logger = getLogger(__name__)


[docs]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, connection=connection, **kwargs) self.redirects = RedisHashDict( namespace, 'redirects', connection=self.responses.connection, **kwargs )
[docs]class RedisDict(BaseStorage): """A dictionary-like interface for Redis operations. **Notes:** * All keys will be encoded as bytes, and all values will be serialized * Supports TTL """ def __init__(self, namespace: str, collection_name: str = None, connection=None, **kwargs): super().__init__(**kwargs) connection_kwargs = get_valid_kwargs(Redis, kwargs) self.connection = connection or StrictRedis(**connection_kwargs) self.namespace = namespace def _bkey(self, key: str) -> bytes: """Get a full hash key as bytes""" return encode(f'{self.namespace}:{key}') def _bkeys(self, keys: Iterable[str]): return [self._bkey(key) for key in keys] def __contains__(self, key) -> bool: return bool(self.connection.exists(self._bkey(key))) def __getitem__(self, key): result = self.connection.get(self._bkey(key)) if result is None: raise KeyError return self.serializer.loads(result) def __setitem__(self, key, item): """Save an item to the cache, optionally with TTL""" if getattr(item, 'ttl', None): self.connection.setex(self._bkey(key), item.ttl, self.serializer.dumps(item)) else: self.connection.set(self._bkey(key), self.serializer.dumps(item)) def __delitem__(self, key): if not self.connection.delete(self._bkey(key)): raise KeyError def __iter__(self): yield from self.keys() def __len__(self): return len(list(self.keys()))
[docs] def bulk_delete(self, keys: Iterable[str]): """Delete multiple keys from the cache, without raising errors for missing keys""" if keys: self.connection.delete(*self._bkeys(keys))
[docs] def clear(self): self.bulk_delete(self.keys())
[docs] def keys(self): return [ decode(key).replace(f'{self.namespace}:', '') for key in self.connection.keys(f'{self.namespace}:*') ]
[docs] def items(self): return [(k, self[k]) for k in self.keys()]
[docs] def values(self): return [self.serializer.loads(v) for v in self.connection.mget(*self._bkeys(self.keys()))]
[docs]class RedisHashDict(BaseStorage): """A dictionary-like interface for operations on a single Redis hash **Notes:** * All keys will be encoded as bytes, and all values will be serialized * Items will be stored in a hash named ``namespace:collection_name`` """ def __init__( self, namespace: str = 'http_cache', collection_name: str = None, connection=None, **kwargs ): super().__init__(**kwargs) connection_kwargs = get_valid_kwargs(Redis, kwargs) self.connection = connection or StrictRedis(**connection_kwargs) self._hash_key = f'{namespace}-{collection_name}' def __contains__(self, key): return self.connection.hexists(self._hash_key, encode(key)) def __getitem__(self, key): result = self.connection.hget(self._hash_key, encode(key)) if result is None: raise KeyError return self.serializer.loads(result) def __setitem__(self, key, item): self.connection.hset(self._hash_key, encode(key), self.serializer.dumps(item)) def __delitem__(self, key): if not self.connection.hdel(self._hash_key, encode(key)): raise KeyError def __iter__(self): yield from self.keys() def __len__(self): return self.connection.hlen(self._hash_key)
[docs] def bulk_delete(self, keys: Iterable[str]): """Delete multiple keys from the cache, without raising errors for missing keys""" if keys: self.connection.hdel(self._hash_key, *[encode(key) for key in keys])
[docs] def clear(self): self.connection.delete(self._hash_key)
[docs] def keys(self): return [decode(key) for key in self.connection.hkeys(self._hash_key)]
[docs] def items(self): """Get all ``(key, value)`` pairs in the hash""" return [ (decode(k), self.serializer.loads(v)) for k, v in self.connection.hgetall(self._hash_key).items() ]
[docs] def values(self): """Get all values in the hash""" return [self.serializer.loads(v) for v in self.connection.hvals(self._hash_key)]