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"Base Cache class."
from django.core.exceptions import ImproperlyConfigured
class InvalidCacheBackendError(ImproperlyConfigured):
pass
class BaseCache(object):
def __init__(self, params):
timeout = params.get('timeout', 300)
try:
timeout = int(timeout)
except (ValueError, TypeError):
timeout = 300
self.default_timeout = timeout
def get(self, key, default=None):
"""
Fetch a given key from the cache. If the key does not exist, return
default, which itself defaults to None.
"""
raise NotImplementedError
def set(self, key, value, timeout=None):
"""
Set a value in the cache. If timeout is given, that timeout will be
used for the key; otherwise the default cache timeout will be used.
"""
raise NotImplementedError
def delete(self, key):
"""
Delete a key from the cache, failing silently.
"""
raise NotImplementedError
def get_many(self, keys):
"""
Fetch a bunch of keys from the cache. For certain backends (memcached,
pgsql) this can be *much* faster when fetching multiple values.
Returns a dict mapping each key in keys to its value. If the given
key is missing, it will be missing from the response dict.
"""
d = {}
for k in keys:
val = self.get(k)
if val is not None:
d[k] = val
return d
def has_key(self, key):
"""
Returns True if the key is in the cache and has not expired.
"""
return self.get(key) is not None
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