django-redis: lock
djanog-redis: cache.lock lock https://github.com/jazzband/django-redis/blob/d94a7f9644b96cc37743914fce899cca942c032a/django_redis/cache.py#L177 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 class RedisCache(BaseCache): ... @omit_exception def lock(self, *args, **kwargs): return self.client.lock(*args, **kwargs) def __init__(self, server: str, params: Dict[str, Any]) -> None: ... self._client_cls = options.get( "CLIENT_CLASS", "django_redis.client.DefaultClient" ) self._client_cls = import_string(self._client_cls) self._client = None ... DefaultClient https://github.com/jazzband/django-redis/blob/d94a7f9644b96cc37743914fce899cca942c032a/django_redis/client/default.py#L29 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 from redis import Redis class DefaultClient: def __init__(self, server, params: Dict[str, Any], backend: BaseCache) -> None: ... self._clients: List[Optional[Redis]] = [None] * len(self._server) ... def lock( self, key: KeyT, version: Optional[int] = None, timeout: Optional[float] = None, sleep: float = 0.1, blocking_timeout: Optional[float] = None, client: Optional[Redis] = None, thread_local: bool = True, ): if client is None: client = self.get_client(write=True) key = self.make_key(key, version=version) return client.lock( key, timeout=timeout, sleep=sleep, blocking_timeout=blocking_timeout, thread_local=thread_local, ) def get_client( self, write: bool = True, tried: Optional[List[int]] = None, ) -> Redis: """ Method used for obtain a raw redis client. This function is used by almost all cache backend operations for obtain a native redis client/connection instance. """ index = self.get_next_client_index(write=write, tried=tried) if self._clients[index] is None: self._clients[index] = self.connect(index) return self._clients[index] # type:ignore Redis https://github.com/redis/redis-py/blob/6d77c6d715430c30f22147f8c572659d77380a9f/redis/client.py#L88 lock: https://github.com/redis/redis-py/blob/6d77c6d715430c30f22147f8c572659d77380a9f/redis/client.py#L439C1-L511C10 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 class Redis(RedisModuleCommands, CoreCommands, SentinelCommands): def lock( self, name: str, timeout: Optional[float] = None, sleep: float = 0.1, blocking: bool = True, blocking_timeout: Optional[float] = None, lock_class: Union[None, Any] = None, thread_local: bool = True, ): """ Return a new Lock object using key ``name`` that mimics the behavior of threading.Lock. If specified, ``timeout`` indicates a maximum life for the lock. By default, it will remain locked until release() is called. ``sleep`` indicates the amount of time to sleep per loop iteration when the lock is in blocking mode and another client is currently holding the lock. ``blocking`` indicates whether calling ``acquire`` should block until the lock has been acquired or to fail immediately, causing ``acquire`` to return False and the lock not being acquired. Defaults to True. Note this value can be overridden by passing a ``blocking`` argument to ``acquire``. ``blocking_timeout`` indicates the maximum amount of time in seconds to spend trying to acquire the lock. A value of ``None`` indicates continue trying forever. ``blocking_timeout`` can be specified as a float or integer, both representing the number of seconds to wait. ``lock_class`` forces the specified lock implementation. Note that as of redis-py 3.0, the only lock class we implement is ``Lock`` (which is a Lua-based lock). So, it's unlikely you'll need this parameter, unless you have created your own custom lock class. ``thread_local`` indicates whether the lock token is placed in thread-local storage. By default, the token is placed in thread local storage so that a thread only sees its token, not a token set by another thread. Consider the following timeline: time: 0, thread-1 acquires `my-lock`, with a timeout of 5 seconds. thread-1 sets the token to "abc" time: 1, thread-2 blocks trying to acquire `my-lock` using the Lock instance. time: 5, thread-1 has not yet completed. redis expires the lock key. time: 5, thread-2 acquired `my-lock` now that it's available. thread-2 sets the token to "xyz" time: 6, thread-1 finishes its work and calls release(). if the token is *not* stored in thread local storage, then thread-1 would see the token value as "xyz" and would be able to successfully release the thread-2's lock. In some use cases it's necessary to disable thread local storage. For example, if you have code where one thread acquires a lock and passes that lock instance to a worker thread to release later. If thread local storage isn't disabled in this case, the worker thread won't see the token set by the thread that acquired the lock. Our assumption is that these cases aren't common and as such default to using thread local storage.""" if lock_class is None: lock_class = Lock return lock_class( self, name, timeout=timeout, sleep=sleep, blocking=blocking, blocking_timeout=blocking_timeout, thread_local=thread_local, )