Unify expiry condition in getWithInfo() and onEvict()

[chen-zhuohan]

Closes: #318

[janisz]

@chen-zhuohan it looks like we have race now

[chen-zhuohan]

it seems be some problem about uint64(out of the uint64 limits).

func (s *cacheShard) isExpired(oldestEntry []byte, currentTimestamp uint64) bool {
	oldestTimestamp := readTimestampFromEntry(oldestEntry)
	fmt.Println(time.Unix(int64(currentTimestamp), 0), time.Unix(int64(oldestTimestamp), 0), currentTimestamp-oldestTimestamp, s.lifeWindow, currentTimestamp-oldestTimestamp > s.lifeWindow)
	return currentTimestamp-oldestTimestamp > s.lifeWindow
}

I get this print:
2022-05-30 16:02:56 +0800 CST 2022-05-30 16:02:57 +0800 CST 18446744073709551615 600 true

see 18446744073709551615, and the problem will be clean.

I add another check to fix it.

[chen-zhuohan]

how long will the change merged QAQ @janisz

[janisz]

@chen-zhuohan I'm sorry, I missed this. It's merged, thanks!
I wish we couldn't had meet when I worked at @bytedance