bazarr/libs/dogpile/cache/backends/redis.py

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"""
Redis Backends
------------------
Provides backends for talking to `Redis <http://redis.io>`_.
"""
from __future__ import absolute_import
from ..api import CacheBackend, NO_VALUE
from ...util.compat import pickle, u
redis = None
__all__ = 'RedisBackend',
class RedisBackend(CacheBackend):
"""A `Redis <http://redis.io/>`_ backend, using the
`redis-py <http://pypi.python.org/pypi/redis/>`_ backend.
Example configuration::
from dogpile.cache import make_region
region = make_region().configure(
'dogpile.cache.redis',
arguments = {
'host': 'localhost',
'port': 6379,
'db': 0,
'redis_expiration_time': 60*60*2, # 2 hours
'distributed_lock': True
}
)
Arguments accepted in the arguments dictionary:
:param url: string. If provided, will override separate host/port/db
params. The format is that accepted by ``StrictRedis.from_url()``.
.. versionadded:: 0.4.1
:param host: string, default is ``localhost``.
:param password: string, default is no password.
.. versionadded:: 0.4.1
:param port: integer, default is ``6379``.
:param db: integer, default is ``0``.
:param redis_expiration_time: integer, number of seconds after setting
a value that Redis should expire it. This should be larger than dogpile's
cache expiration. By default no expiration is set.
:param distributed_lock: boolean, when True, will use a
redis-lock as the dogpile lock.
Use this when multiple
processes will be talking to the same redis instance.
When left at False, dogpile will coordinate on a regular
threading mutex.
:param lock_timeout: integer, number of seconds after acquiring a lock that
Redis should expire it. This argument is only valid when
``distributed_lock`` is ``True``.
.. versionadded:: 0.5.0
:param socket_timeout: float, seconds for socket timeout.
Default is None (no timeout).
.. versionadded:: 0.5.4
:param lock_sleep: integer, number of seconds to sleep when failed to
acquire a lock. This argument is only valid when
``distributed_lock`` is ``True``.
.. versionadded:: 0.5.0
:param connection_pool: ``redis.ConnectionPool`` object. If provided,
this object supersedes other connection arguments passed to the
``redis.StrictRedis`` instance, including url and/or host as well as
socket_timeout, and will be passed to ``redis.StrictRedis`` as the
source of connectivity.
.. versionadded:: 0.5.4
"""
def __init__(self, arguments):
arguments = arguments.copy()
self._imports()
self.url = arguments.pop('url', None)
self.host = arguments.pop('host', 'localhost')
self.password = arguments.pop('password', None)
self.port = arguments.pop('port', 6379)
self.db = arguments.pop('db', 0)
self.distributed_lock = arguments.get('distributed_lock', False)
self.socket_timeout = arguments.pop('socket_timeout', None)
self.lock_timeout = arguments.get('lock_timeout', None)
self.lock_sleep = arguments.get('lock_sleep', 0.1)
self.redis_expiration_time = arguments.pop('redis_expiration_time', 0)
self.connection_pool = arguments.get('connection_pool', None)
self.client = self._create_client()
def _imports(self):
# defer imports until backend is used
global redis
import redis # noqa
def _create_client(self):
if self.connection_pool is not None:
# the connection pool already has all other connection
# options present within, so here we disregard socket_timeout
# and others.
return redis.StrictRedis(connection_pool=self.connection_pool)
args = {}
if self.socket_timeout:
args['socket_timeout'] = self.socket_timeout
if self.url is not None:
args.update(url=self.url)
return redis.StrictRedis.from_url(**args)
else:
args.update(
host=self.host, password=self.password,
port=self.port, db=self.db
)
return redis.StrictRedis(**args)
def get_mutex(self, key):
if self.distributed_lock:
return self.client.lock(u('_lock{0}').format(key),
self.lock_timeout, self.lock_sleep)
else:
return None
def get(self, key):
value = self.client.get(key)
if value is None:
return NO_VALUE
return pickle.loads(value)
def get_multi(self, keys):
if not keys:
return []
values = self.client.mget(keys)
return [
pickle.loads(v) if v is not None else NO_VALUE
for v in values]
def set(self, key, value):
if self.redis_expiration_time:
self.client.setex(key, self.redis_expiration_time,
pickle.dumps(value, pickle.HIGHEST_PROTOCOL))
else:
self.client.set(key, pickle.dumps(value, pickle.HIGHEST_PROTOCOL))
def set_multi(self, mapping):
mapping = dict(
(k, pickle.dumps(v, pickle.HIGHEST_PROTOCOL))
for k, v in mapping.items()
)
if not self.redis_expiration_time:
self.client.mset(mapping)
else:
pipe = self.client.pipeline()
for key, value in mapping.items():
pipe.setex(key, self.redis_expiration_time, value)
pipe.execute()
def delete(self, key):
self.client.delete(key)
def delete_multi(self, keys):
self.client.delete(*keys)