openmedialibrary/oml/cache.py

import time

class Cache(dict):

    def __init__(self, ttl=10):
        self._ttl = ttl
        self._added = {}

    def get(self, key):
        now = time.time()
        for k, value in list(self._added.items()):
            if value < now:
                del self._added[k]
                del self[k]
        return dict.get(self, key)

    def set(self, key, value, ttl=None):
        ttl = ttl or self._ttl
        self._added[key] = time.time() + ttl
        dict.__setitem__(self, key, value)

    def delete(self, key):
        if key in self._added:
            del self._added[key]
            del self[key]

    def clear(self, prefix):
        for key in list(self):
            if key.startswith(prefix):
                self.delete(key)