bug: log-rotate can not rotate logs strictly hourly(or minutely)

[snowdusk]

Issue description

e.g.
Apisix start time is 15:29:23, log-rotate interval is 3600(1 hour)
Next rotate time is 16:29:23, next next rotate time is 17:29:23

I want next rotate time is 16:00:00, next next rotate time is 17:00:00

The current implement:

    if not rotate_time then
        -- first init rotate time
        rotate_time = now_time + interval
        core.log.info("first init rotate time is: ", rotate_time)
        return
    end

This is my change.

    if not rotate_time then
        -- first init rotate time
        rotate_time = now_time + interval - (now_time % interval)
        core.log.info("first init rotate time is: ", rotate_time)
        return
    end

[shuaijinchao]

What problem does this solve? Also I don't think this is a bug

[membphis]

@snowdusk I think you are right. It seems 139c397 break this feature

[membphis]

@snowdusk I think you are right. It seems 139c397 break this feature

need @shuaijinchao's help

[soulbird]

Strictly hourly rotation of logs is better

[shuaijinchao]

@snowdusk Sorry, this is a problem caused by one of my previous PRs. Aligning time avoids fragmented logs in case of restarts etc. during rotation time, so the solution you provided would be better.

Are you interested in fixing it?

[snowdusk]

@shuaijinchao OK. I will create a PR