custom_cache.py

import datetime


class CustomCache:
    def __init__(self, max_size=100):
        """Constructor"""
        self.cache = {}
        self.max_cache_size = max_size

    def __call__(self, function):
        def wrapper(*args, **kwargs):
            key = str(args) + str(kwargs)
            if key in self.cache:
                return self.cache[key]['value']

            value = function(*args, **kwargs)
            if value:
                self.update(key, value)
            return value
        return wrapper

    def __contains__(self, key):
        """
        Returns True or False depending on whether or not the key is in the cache
        """
        return key in self.cache

    def update(self, key, value):
        """
        Update the cache dictionary and optionally remove the oldest item
        """

        if key not in self.cache and len(self.cache) >= self.max_cache_size:
            self.remove_oldest()
        self.cache[key] = {'date_accessed': datetime.datetime.now(), 'value': value}

    def update_key(self, value, *args, **kwargs):
        """
        Update specific key in cache just in case
        """
        key = str(args) + str(kwargs)
        if key in self.cache:
            self.cache[key] = {'date_accessed': datetime.datetime.now(), 'value': value}

    def remove_oldest(self):
        """
        Remove the entry that has the oldest accessed date
        """

        oldest_entry = None
        for key in self.cache:
            if oldest_entry is None:
                oldest_entry = key
            elif self.cache[key]['date_accessed'] < self.cache[oldest_entry]['date_accessed']:
                oldest_entry = key
        self.cache.pop(oldest_entry)

    def cache_clear(self):
        """
        Clear entire cache
        """
        self.cache = {}

    @property
    def size(self):
        """
        Return the size of the cache
        """

        return len(self.cache)