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312 lines
11 KiB
312 lines
11 KiB
"""
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Redis Backends
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------------------
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Provides backends for talking to `Redis <http://redis.io>`_.
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"""
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from __future__ import absolute_import
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import typing
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import warnings
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from ..api import BytesBackend
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from ..api import NO_VALUE
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if typing.TYPE_CHECKING:
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import redis
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else:
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# delayed import
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redis = None # noqa F811
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__all__ = ("RedisBackend", "RedisSentinelBackend")
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class RedisBackend(BytesBackend):
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"""A `Redis <http://redis.io/>`_ backend, using the
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`redis-py <http://pypi.python.org/pypi/redis/>`_ backend.
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Example configuration::
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from dogpile.cache import make_region
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region = make_region().configure(
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'dogpile.cache.redis',
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arguments = {
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'host': 'localhost',
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'port': 6379,
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'db': 0,
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'redis_expiration_time': 60*60*2, # 2 hours
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'distributed_lock': True,
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'thread_local_lock': False
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}
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)
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Arguments accepted in the arguments dictionary:
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:param url: string. If provided, will override separate host/port/db
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params. The format is that accepted by ``StrictRedis.from_url()``.
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:param host: string, default is ``localhost``.
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:param password: string, default is no password.
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:param port: integer, default is ``6379``.
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:param db: integer, default is ``0``.
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:param redis_expiration_time: integer, number of seconds after setting
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a value that Redis should expire it. This should be larger than dogpile's
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cache expiration. By default no expiration is set.
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:param distributed_lock: boolean, when True, will use a
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redis-lock as the dogpile lock. Use this when multiple processes will be
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talking to the same redis instance. When left at False, dogpile will
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coordinate on a regular threading mutex.
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:param lock_timeout: integer, number of seconds after acquiring a lock that
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Redis should expire it. This argument is only valid when
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``distributed_lock`` is ``True``.
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:param socket_timeout: float, seconds for socket timeout.
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Default is None (no timeout).
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:param lock_sleep: integer, number of seconds to sleep when failed to
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acquire a lock. This argument is only valid when
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``distributed_lock`` is ``True``.
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:param connection_pool: ``redis.ConnectionPool`` object. If provided,
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this object supersedes other connection arguments passed to the
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``redis.StrictRedis`` instance, including url and/or host as well as
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socket_timeout, and will be passed to ``redis.StrictRedis`` as the
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source of connectivity.
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:param thread_local_lock: bool, whether a thread-local Redis lock object
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should be used. This is the default, but is not compatible with
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asynchronous runners, as they run in a different thread than the one
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used to create the lock.
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"""
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def __init__(self, arguments):
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arguments = arguments.copy()
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self._imports()
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self.url = arguments.pop("url", None)
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self.host = arguments.pop("host", "localhost")
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self.password = arguments.pop("password", None)
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self.port = arguments.pop("port", 6379)
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self.db = arguments.pop("db", 0)
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self.distributed_lock = arguments.get("distributed_lock", False)
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self.socket_timeout = arguments.pop("socket_timeout", None)
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self.lock_timeout = arguments.get("lock_timeout", None)
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self.lock_sleep = arguments.get("lock_sleep", 0.1)
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self.thread_local_lock = arguments.get("thread_local_lock", True)
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if self.distributed_lock and self.thread_local_lock:
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warnings.warn(
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"The Redis backend thread_local_lock parameter should be "
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"set to False when distributed_lock is True"
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)
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self.redis_expiration_time = arguments.pop("redis_expiration_time", 0)
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self.connection_pool = arguments.get("connection_pool", None)
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self._create_client()
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def _imports(self):
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# defer imports until backend is used
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global redis
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import redis # noqa
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def _create_client(self):
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if self.connection_pool is not None:
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# the connection pool already has all other connection
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# options present within, so here we disregard socket_timeout
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# and others.
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self.writer_client = redis.StrictRedis(
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connection_pool=self.connection_pool
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)
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self.reader_client = self.writer_client
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else:
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args = {}
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if self.socket_timeout:
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args["socket_timeout"] = self.socket_timeout
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if self.url is not None:
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args.update(url=self.url)
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self.writer_client = redis.StrictRedis.from_url(**args)
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self.reader_client = self.writer_client
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else:
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args.update(
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host=self.host,
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password=self.password,
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port=self.port,
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db=self.db,
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)
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self.writer_client = redis.StrictRedis(**args)
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self.reader_client = self.writer_client
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def get_mutex(self, key):
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if self.distributed_lock:
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return self.writer_client.lock(
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"_lock{0}".format(key),
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timeout=self.lock_timeout,
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sleep=self.lock_sleep,
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thread_local=self.thread_local_lock,
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)
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else:
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return None
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def get_serialized(self, key):
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value = self.reader_client.get(key)
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if value is None:
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return NO_VALUE
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return value
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def get_serialized_multi(self, keys):
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if not keys:
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return []
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values = self.reader_client.mget(keys)
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return [v if v is not None else NO_VALUE for v in values]
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def set_serialized(self, key, value):
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if self.redis_expiration_time:
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self.writer_client.setex(key, self.redis_expiration_time, value)
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else:
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self.writer_client.set(key, value)
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def set_serialized_multi(self, mapping):
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if not self.redis_expiration_time:
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self.writer_client.mset(mapping)
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else:
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pipe = self.writer_client.pipeline()
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for key, value in mapping.items():
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pipe.setex(key, self.redis_expiration_time, value)
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pipe.execute()
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def delete(self, key):
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self.writer_client.delete(key)
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def delete_multi(self, keys):
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self.writer_client.delete(*keys)
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class RedisSentinelBackend(RedisBackend):
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"""A `Redis <http://redis.io/>`_ backend, using the
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`redis-py <http://pypi.python.org/pypi/redis/>`_ backend.
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It will use the Sentinel of a Redis cluster.
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.. versionadded:: 1.0.0
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Example configuration::
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from dogpile.cache import make_region
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region = make_region().configure(
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'dogpile.cache.redis_sentinel',
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arguments = {
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'sentinels': [
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['redis_sentinel_1', 26379],
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['redis_sentinel_2', 26379]
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],
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'db': 0,
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'redis_expiration_time': 60*60*2, # 2 hours
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'distributed_lock': True,
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'thread_local_lock': False
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}
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)
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Arguments accepted in the arguments dictionary:
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:param db: integer, default is ``0``.
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:param redis_expiration_time: integer, number of seconds after setting
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a value that Redis should expire it. This should be larger than dogpile's
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cache expiration. By default no expiration is set.
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:param distributed_lock: boolean, when True, will use a
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redis-lock as the dogpile lock. Use this when multiple processes will be
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talking to the same redis instance. When False, dogpile will
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coordinate on a regular threading mutex, Default is True.
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:param lock_timeout: integer, number of seconds after acquiring a lock that
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Redis should expire it. This argument is only valid when
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``distributed_lock`` is ``True``.
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:param socket_timeout: float, seconds for socket timeout.
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Default is None (no timeout).
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:param sentinels: is a list of sentinel nodes. Each node is represented by
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a pair (hostname, port).
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Default is None (not in sentinel mode).
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:param service_name: str, the service name.
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Default is 'mymaster'.
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:param sentinel_kwargs: is a dictionary of connection arguments used when
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connecting to sentinel instances. Any argument that can be passed to
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a normal Redis connection can be specified here.
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Default is {}.
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:param connection_kwargs: dict, are keyword arguments that will be used
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when establishing a connection to a Redis server.
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Default is {}.
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:param lock_sleep: integer, number of seconds to sleep when failed to
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acquire a lock. This argument is only valid when
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``distributed_lock`` is ``True``.
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:param thread_local_lock: bool, whether a thread-local Redis lock object
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should be used. This is the default, but is not compatible with
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asynchronous runners, as they run in a different thread than the one
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used to create the lock.
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"""
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def __init__(self, arguments):
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arguments = arguments.copy()
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self.sentinels = arguments.pop("sentinels", None)
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self.service_name = arguments.pop("service_name", "mymaster")
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self.sentinel_kwargs = arguments.pop("sentinel_kwargs", {})
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self.connection_kwargs = arguments.pop("connection_kwargs", {})
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super().__init__(
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arguments={
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"distributed_lock": True,
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"thread_local_lock": False,
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**arguments,
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}
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)
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def _imports(self):
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# defer imports until backend is used
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global redis
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import redis.sentinel # noqa
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def _create_client(self):
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sentinel_kwargs = {}
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sentinel_kwargs.update(self.sentinel_kwargs)
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sentinel_kwargs.setdefault("password", self.password)
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connection_kwargs = {}
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connection_kwargs.update(self.connection_kwargs)
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connection_kwargs.setdefault("password", self.password)
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if self.db is not None:
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connection_kwargs.setdefault("db", self.db)
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sentinel_kwargs.setdefault("db", self.db)
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if self.socket_timeout is not None:
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connection_kwargs.setdefault("socket_timeout", self.socket_timeout)
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sentinel = redis.sentinel.Sentinel(
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self.sentinels,
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sentinel_kwargs=sentinel_kwargs,
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**connection_kwargs,
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)
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self.writer_client = sentinel.master_for(self.service_name)
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self.reader_client = sentinel.slave_for(self.service_name)
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