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1. Cache any function (with its arguments)

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   original snippet from http://www.djangosnippets.org/snippets/109/

    1 import cPickle as pickle
    2 import md5
    3 
    4 def cache_function(length):
    5     """
    6     A variant of the snippet posted by Jeff Wheeler at
    7     http://www.djangosnippets.org/snippets/109/
    8     
    9     Caches a function, using the function and its arguments as the key, and the return
   10     value as the value saved. It passes all arguments on to the function, as
   11     it should.
   12     
   13     The decorator itself takes a length argument, which is the number of
   14     seconds the cache will keep the result around.
   15     
   16     It will put in a MethodNotFinishedError in the cache while the function is
   17     processing. This should not matter in most cases, but if the app is using
   18     threads, you won't be able to get the previous value, and will need to
   19     wait until the function finishes. If this is not desired behavior, you can
   20     remove the first two lines after the ``else``.
   21     """
   22     def decorator(func):
   23         def inner_func(*args, **kwargs):
   24             from django.core.cache import cache
   25             
   26             raw = [func.__name__, func.__module__, args, kwargs]
   27             pickled = pickle.dumps(raw, protocol=pickle.HIGHEST_PROTOCOL)
   28             key = md5.new(pickled).hexdigest()
   29             value = cache.get(key)
   30             if cache.has_key(key):
   31                 return value
   32             else:
   33                 # This will set a temporary value while ``func`` is being
   34                 # processed. When using threads, this is vital, as otherwise
   35                 # the function can be called several times before it finishes
   36                 # and is put into the cache.
   37                 class MethodNotFinishedError(Exception): pass
   38                 cache.set(key, MethodNotFinishedError(
   39                     'The function %s has not finished processing yet. This \
   40 value will be replaced when it finishes.' % (func.__name__)
   41                 ), length)
   42                 result = func(*args, **kwargs)
   43                 cache.set(key, result, length)
   44                 return result
   45         return inner_func
   46     return decorator
   

   Posted by benoitc to python cache django ... saved by 3 persons ... 0 comments ... 1 year

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