CODEWITHSUNDEEP
pythonpython-3.xcachingscope
gdw2
gdw2

Reputation: 8016

Access lru_cache's cache

General problem: How can I access a variable in a function's closure?

Specific problem: How can I access the raw cache from a python function wrapped with functools.lru_cache()?

If I memoize a function (example taken from the docs)...

@lru_cache(maxsize=None)
def fib(n):
    if n < 2:
        return n
    return fib(n-1) + fib(n-2)

>>> [fib(n) for n in range(16)]
[0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, 233, 377, 610]

>>> fib.cache_info()
CacheInfo(hits=28, misses=16, maxsize=None, currsize=16)

Here is where cache is defined: https://github.com/python/cpython/blob/f0851910eb8e711bf8f22165cb0df33bb27b09d6/Lib/functools.py#L491

When fib() is memoized, lru_cache adds a cache_info() and cache_clear() function to the wrapper. cache_clear() has access to cache and I have access to cache_clear() so can I somehow use that to access cache directly?

Upvotes: 12

Views: 5730

Answers (1)

Sumner Evans
Sumner Evans

Reputation: 9157

You can use cachier by Shay Palachy. You can tell it to cache to a pickle file.

Alternatively, look at persistent_lru_cache developed by Andrew Barnert.

Upvotes: 1

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