__init__.py 文件源码

def add(self, data):
        assert isinstance(data, numbers.Number)
        if self.last_update is None:
            self._avg = data
            self.last_update = time.time()
            self.last_data_decay = 1
        else:
            now = time.time()
            delta = now - self.last_update
            if delta < 0:
                # Time is allowed to go a little backwards (NTP update, etc)
                logger.warn("Backwards delta value: {}".format(delta))
                # Treat this entry as if it happened with 0 delta
                delta = 0
            if delta != 0:
                self.last_data_decay = (1 - self.decay**delta) * 1/delta
                self._avg = self.decay**delta * self._avg + self.last_data_decay * data
            else:
                # Don't divide by zero; just reuse the last delta. Should stack well
                self._avg += self.last_data_decay * data
            self.last_update = now