Cache

caching.py

# coding: utf-8

from datetime import datetime
import threading

__all__ = ['get', 'clear']


class Cache(dict):

    def __getattr__(self, name):
        if name in self:
            return self[name]
        return super(Cache, self).__getattr__(name)


_Expire = 15 * 60
_Lock = threading.Lock()
_Cache = {}


def get(name, func, *args, **kwargs):
    global _Cache
    if _is_enable(name):
        return _Cache[name].data
    return _set_and_get(name, func, *args, **kwargs)


def clear(name=None):
    global _Cache
    global _Lock
    with _Lock:
        if name is None:
            _Cache = {}
        else:
            try:
                del _Cache[name]
            except:
                pass


def _is_enable(name):
    global _Cache
    global _Expire
    now = datetime.now()
    c = _Cache.get(name)
    if c is None:
        return False
    if c.latest_datetime is None:
        return False
    if c.data is None:
        return False
    if c.latest_datetime.hour != now.hour:
        return False
    if (now - c.latest_datetime).seconds >= _Expire:
        return False
    return True


def _set_and_get(name, func, *args, **kwargs):
    global _Cache
    global _Lock
    with _Lock:
        result = func(*args, **kwargs)
        _Cache[name] = Cache(latest_datetime=datetime.now(), data=result)
    return result