Python in-memory cache with time to live

Question

I have multiple threads running the same process that need to be able to to notify each other that something should not be worked on for the next n seconds its not the end of the world if they do however.

My aim is to be able to pass a string and a TTL to the cache and be able to fetch all the strings that are in the cache as a list. The cache can live in memory and the TTL's will be no more than 20 seconds.

Does anyone have a any suggestions for how this can be accomplished?

Answer 1

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