#!/usr/bin/python import functoolsfrom threading import RLockimport logging  LOGGER = logging.getLogger(__name__)class CacheNullValue(object):    pass _Null = CacheNullValue() class Cache(object):     def __init__(self, cache_limit=1000):        self._cache = {}        self._queue = []        self.cache_limit = cache_limit        self._lock = RLock()     def __getitem__(self, name):        with self._lock:            return self._cache.get(name, _Null)    get = __getitem__     def __setitem__(self, name, value):        with self._lock:            if len(self._queue) >= self.cache_limit:                del self._cache[self._queue.pop()]            self._queue.append(name)            self._cache[name] = value    set = __setitem__  def cache(cache_limit):    """A function decorator for method cache store    """        def cached(f):        @functools.wraps(f)        def _cached(*args, **kwargs):            cid = repr((args, kwargs))            data = _cached.cache.get(cid)            if data != _Null:                LOGGER.debug(‘hit cached `‘ + _cached.__name__ + ‘` for ‘ + cid)                return data            data = _cached.f(*args, **kwargs)            _cached.cache.set(cid, data)            return data         _cached.f = f        _cached.cache = Cache(cache_limit)         return _cached     return cached  def setup(cache_limit):    """ A global thread safe key-value store    """    global _cache_object    _cache_object = Cache(cache_limit)  def set(cid, data):     _cache_object.set(cid, data)  def get(cid):    return _cache_object.get(cid)  if __name__ == ‘__main__‘:     logging.basicConfig(level=logging.DEBUG,                        format=‘%(asctime)s %(levelname)-8s %(message)s‘,                        datefmt=‘%Y-%m-%d %H:%M:%S‘, filemode=‘a+‘)     class T(object):         @cache(100)        def c(self, t):            return t     @cache(100)    def cc(t):        return t     t = T()    print t.c(‘hello‘)    print t.c(‘hello‘)    print t.c(‘h‘)    print t.c(‘hello‘)    print cc(‘he‘)    print cc(‘he‘)