database.py 文件源码

def do_open(self, flags):
        # If we already loaded the data, don't bother loading it again
        if self.loaded:
            self.flags = flags
            return

        cache = self.cache
        result = sa.select([cache.c.data], 
                           cache.c.namespace==self.namespace
                          ).execute().fetchone()
        if not result:
            self._is_new = True
            self.hash = {}
        else:
            self._is_new = False
            try:
                self.hash = result['data']
            except (IOError, OSError, EOFError, cPickle.PickleError,
                    pickle.PickleError):
                log.debug("Couln't load pickle data, creating new storage")
                self.hash = {}
                self._is_new = True
        self.flags = flags
        self.loaded = True