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from django.core.cache.backends.base import DEFAULT_TIMEOUT |
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from django_redis.cache import RedisCache as PlainRedisCache |
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from redis_lock import Lock |
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from redis_lock import reset_all |
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class RedisCache(PlainRedisCache): |
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@property |
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def __client(self): |
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try: |
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return self.client.get_client() |
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except Exception as exc: |
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raise NotImplementedError( |
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"RedisCache doesn't have a raw client: %r. " |
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"Use 'redis_cache.client.DefaultClient' as the CLIENT_CLASS !" % exc |
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) |
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def lock(self, key, expire=None, id=None): |
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return Lock(self.__client, key, expire=expire, id=id) |
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def locked_get_or_set(self, key, value_creator, version=None, |
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expire=None, id=None, lock_key=None, |
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timeout=DEFAULT_TIMEOUT): |
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""" |
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Fetch a given key from the cache. If the key does not exist, the key is added and |
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set to the value returned when calling `value_creator`. The creator function |
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is invoked inside of a lock. |
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""" |
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if lock_key is None: |
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lock_key = 'get_or_set:' + key |
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val = self.get(key, version=version) |
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if val is not None: |
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return val |
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with self.lock(lock_key, expire=expire, id=id): |
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# Was the value set while we were trying to acquire the lock? |
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val = self.get(key, version=version) |
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if val is not None: |
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return val |
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# Nope, create value now. |
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val = value_creator() |
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if val is None: |
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raise ValueError('`value_creator` must return a value') |
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self.set(key, val, timeout=timeout, version=version) |
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return val |
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def reset_all(self): |
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""" |
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Forcibly deletes all locks if its remains (like a crash reason). Use this with care. |
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""" |
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reset_all(self.__client) |
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ionelmc /
python-redis-lock
