backoff.py 文件源码

def next(self, message, backoff_exchange_name):

        total_attempts = 0
        for deadlettered in message.headers.get('x-death', ()):
            if deadlettered['exchange'] == backoff_exchange_name:
                total_attempts += int(deadlettered['count'])

        if self.limit and total_attempts >= self.limit:
            expired = Backoff.Expired(
                "Backoff aborted after '{}' retries (~{:.0f} seconds)".format(
                    self.limit, self.max_delay / 1000
                )
            )
            six.raise_from(expired, self)

        expiration = self.get_next_schedule_item(total_attempts)

        if self.random_sigma:
            randomised = int(random.gauss(expiration, self.random_sigma))
            group_size = self.random_sigma / self.random_groups_per_sigma
            expiration = round_to_nearest(randomised, interval=group_size)

        # Prevent any negative values created by randomness
        expiration = abs(expiration)

        # store calculation results on self.
        self._next_expiration = expiration
        self._total_attempts = total_attempts

        return expiration