有没有办法为 Django 缓存锁设置过期时间？

Posted 2023-03-25

【中文标题】有没有办法为 Django 缓存锁设置过期时间？

【英文标题】：Is there a way to set an expiration time for a Django cache lock?

【发布时间】：2021-04-02 10:35:49

【问题描述】：

我有一个 Django 3.1.3 服务器，它通过 django-redis 4.12.1 使用 Redis 作为其缓存。我知道缓存锁一般可以通过以下方式设置：

with cache.lock('my_cache_lock_key'):
    # Execute some logic here, such as:
    cache.set('some_key', 'Hello world', 3000)

通常，当with 块完成执行时，缓存锁会释放。但是，我的代码中有一些自定义逻辑，有时不会释放缓存锁（出于我自己的原因，这很好）。

我的问题：有没有办法为 Django 缓存锁设置超时值，就像设置缓存值的超时值 (cache.set('some_key', 'Hello world', 3000)) 一样？

【参考方案1】：

我已经回答了我自己的问题。 following arguments 可用于cache.lock()：

    def lock(
        self,
        key,
        version=None,
        timeout=None,
        sleep=0.1,
        blocking_timeout=None,
        client=None,
        thread_local=True,
    ):

使用来自 Python Redis source 的 cmets 交叉引用它，它使用相同的参数：

   ``timeout`` indicates a maximum life for the lock.
    By default, it will remain locked until release() is called.
    ``timeout`` can be specified as a float or integer, both representing
    the number of seconds to wait.
    ``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.

因此，要设置缓存锁定生效的最大时间段为 2 秒，请执行以下操作：

with cache.lock(key='my_cache_lock_key', timeout=2):
    # Execute some logic here, such as:
    cache.set('some_key', 'Hello world', 3000)