cache.py 文件源码

def open(self):
        if self.opened:
            return

        self.lock = open(SETTINGS.CACHE_PATH + '.lock', 'ab')
        try:
            fcntl.flock(self.lock, fcntl.LOCK_EX | fcntl.LOCK_NB)
            mode = 'c'
        except IOError:
            logger.warn("Cache locked, using read-only")
            mode = 'r'
            self.lock.close()
            self.lock = None

        try:
            self.storage = shelve.open(SETTINGS.CACHE_PATH, mode)
        except Exception as e:
            if mode != 'c':
                raise
            logger.warn("Dropping corrupted cache on %s", e)
            self.lock.truncate(0)
            self.storage = shelve.open(SETTINGS.CACHE_PATH, mode)
        self.opened = True