Want to read the contents of lru_cache

Python Help
1

So I am using LRU Cache from functools

I use the decorator @lru_cache to cache certain functions.

I would like to have a way to check the contents of the cache object from a file.

I tried requesting for a function like this from the CPython github library but the issue won’t be proceeding.

So I need some help/guidance. Bottom line is I need to see the contents of the cache object.

2

You could copy the Python implementation of lru_cache from the standard library in Lib/functools.py (and include the proper license info) and add access to the cache

Simplest version of that would be to just add a line

wrapper.cache = cache

before the wrapper is returned at the end

2 Likes
3

Some ideas for you.

  1. Consider adding logging to the cached function:
@functools.lru_cache
def increment(x):
    y = x + 1
    logging.debug("Incrementing %r to %r", x, y)
    return y
  1. Make your own lru_cache replacement where the internals are visible. This is a minor edit of the examples in the collections docs.
from collections import OrderedDict

class LRU:

    def __init__(self, func):
        self.cache = OrderedDict()
        self.func = func
        self.maxsize = 128

    def __call__(self, *args):
        if args in self.cache:
            self.cache.move_to_end(args)
            return self.cache[args]
        result = self.func(*args)
        self.cache[args] = result
        if len(self.cache) > self.maxsize:
            self.cache.popitem(last=False)
        return result

@LRU
def func(x):
    return x + 1