Python in-memory cache with time to live

In case you don’t want to use any 3rd libraries, you can add one more parameter to your expensive function: ttl_hash=None. This new parameter is so-called “time sensitive hash”, its the only purpose is to affect lru_cache.

For example:

from functools import lru_cache
import time


@lru_cache()
def my_expensive_function(a, b, ttl_hash=None):
    del ttl_hash  # to emphasize we don't use it and to shut pylint up
    return a + b  # horrible CPU load...


def get_ttl_hash(seconds=3600):
    """Return the same value withing `seconds` time period"""
    return round(time.time() / seconds)


# somewhere in your code...
res = my_expensive_function(2, 2, ttl_hash=get_ttl_hash())
# cache will be updated once in an hour