lock.py 文件源码

def do_extend(self, additional_time):
        pipe = self.redis.pipeline()
        pipe.watch(self.name)
        lock_value = pipe.get(self.name)
        if lock_value != self.local.token:
            raise LockError("Cannot extend a lock that's no longer owned")
        expiration = pipe.pttl(self.name)
        if expiration is None or expiration < 0:
            # Redis evicted the lock key between the previous get() and now
            # we'll handle this when we call pexpire()
            expiration = 0
        pipe.multi()
        pipe.pexpire(self.name, expiration + int(additional_time * 1000))

        try:
            response = pipe.execute()
        except WatchError:
            # someone else acquired the lock
            raise LockError("Cannot extend a lock that's no longer owned")
        if not response[0]:
            # pexpire returns False if the key doesn't exist
            raise LockError("Cannot extend a lock that's no longer owned")
        return True