# -*- coding: utf-8 -*-
import os
import re
import tempfile
from time import time
from .basecache import BaseCache
from .posixemulation import rename, _items
try:
import cPickle as pickle
except ImportError:
import pickle
try:
from hashlib import md5
except ImportError:
from md5 import new as md5
class RedisCache(BaseCache):
"""Uses the Redis key-value store as a cache backend.
The first argument can be either a string denoting address of the Redis
server or an object resembling an instance of a redis.Redis class.
Note: Python Redis API already takes care of encoding unicode strings on
the fly.
.. versionadded:: 0.7
.. versionadded:: 0.8
`key_prefix` was added.
.. versionchanged:: 0.8
This cache backend now properly serializes objects.
.. versionchanged:: 0.8.3
This cache backend now supports password authentication.
:param host: address of the Redis server or an object which API is
compatible with the official Python Redis client (redis-py).
:param port: port number on which Redis server listens for connections.
:param password: password authentication for the Redis server.
:param default_timeout: the default timeout that is used if no timeout is
specified on :meth:`~BaseCache.set`.
:param key_prefix: A prefix that should be added to all keys.
"""
def __init__(self, host='localhost', port=6379, password=None,
default_timeout=300, key_prefix=None):
BaseCache.__init__(self, default_timeout)
if isinstance(host, basestring):
try:
import redis
except ImportError:
raise RuntimeError('no redis module found')
self._client = redis.Redis(host=host, port=port, password=password)
else:
self._client = host
self.key_prefix = key_prefix or ''
def dump_object(self, value):
"""Dumps an object into a string for redis. By default it serializes
integers as regular string and pickle dumps everything else.
"""
t = type(value)
if t is int or t is long:
return str(value)
return '!' + pickle.dumps(value)
def load_object(self, value):
"""The reversal of :meth:`dump_object`. This might be callde with
None.
"""
if value is None:
return None
if value.startswith('!'):
return pickle.loads(value[1:])
try:
return int(value)
except ValueError:
# before 0.8 we did not have serialization. Still support that.
return value
def get(self, key):
return self.load_object(self._client.get(self.key_prefix + key))
def get_many(self, *keys):
if self.key_prefix:
keys = [self.key_prefix + key for key in keys]
return [self.load_object(x) for x in self._client.mget(keys)]
def set(self, key, value, timeout=None):
if timeout is None:
timeout = self.default_timeout
dump = self.dump_object(value)
self._client.setex(self.key_prefix + key, dump, timeout)
def add(self, key, value, timeout=None):
if timeout is None:
timeout = self.default_timeout
dump = self.dump_object(value)
added = self._client.setnx(self.key_prefix + key, dump)
if added:
self._client.expire(self.key_prefix + key, timeout)
def set_many(self, mapping, timeout=None):
if timeout is None:
timeout = self.default_timeout
pipe = self._client.pipeline()
for key, value in _items(mapping):
dump = self.dump_object(value)
pipe.setex(self.key_prefix + key, dump, timeout)
pipe.execute()
def delete(self, key):
self._client.delete(self.key_prefix + key)
def delete_many(self, *keys):
if not keys:
return
if self.key_prefix:
keys = [self.key_prefix + key for key in keys]
self._client.delete(*keys)
def clear(self):
if self.key_prefix:
keys = self._client.keys(self.key_prefix + '*')
if keys:
self._client.delete(*keys)
else:
self._client.flushdb()
def inc(self, key, delta=1):
return self._client.incr(self.key_prefix + key, delta)
def dec(self, key, delta=1):
return self._client.decr(self.key_prefix + key, delta)
