Confluent 面經

gintau 发表于 2019-10-28 06:51
Use map for get() and ring buffer for avg(). When retrieve from map need to check if the entry exp ...

如果是ring buffer的话会有size限制吧，超过size的话，怎么办啊

swimmingfish96 发表于 2019-10-28 07:52
如果是ring buffer的话会有size限制吧，超过size的话，怎么办啊

avg() only requires value in fixed window. Just need to memorize sum in the smallest granularity. I assumed accuracy in millis and clarify with interviewer this assumption. They were okay with it. The idea is similar to web page view count question. You should be able to find it.

gintau 发表于 2019-10-28 10:15
avg() only requires value in fixed window. Just need to memorize sum in the smallest granularity.  ...

求问楼主avg是指所有key对应val的avg还是目前时间窗口里还没过期的val的msg，因为考虑到同一个时间窗口可能有两个相同的key对应不同的val

多谢分享！请教一下楼主，第二题，允许直接用java的ScheduledExecutorService吗？还是要自己实现？

swimmingfish96 发表于 2019-10-29 08:23
求问楼主avg是指所有key对应val的avg还是目前时间窗口里还没过期的val的msg，因为考虑到同一个时间窗口可 ...

所有窗口的val, 包含重複的key

put(K1, 2), put(K1, 4), put(K2, 6),  avg() => (2 + 4 + 6) / 3 = 4

longvision 发表于 2019-11-13 13:08
多谢分享！请教一下楼主，第二题，允许直接用java的ScheduledExecutorService吗？还是要自己实现？

自己實現

gintau 发表于 2019-10-28 06:51
Use map for get() and ring buffer for avg(). When retrieve from map need to check if the entry exp ...

ring buffer 是定长的。而题目是按时间expire的。怎么做呢？

想来想去tinyurl还是得redis+lua脚本吧。好像没有其他更合适的做法了。