Merge pull request !1 from Ulric Qin/judge_prom_bugfix

2. add slowLogRecordSecond to  log slow query
3. Create a slice with a specified length to avoid dynamic expansion
4. slow query print fetch series time took and the result series num

2. upgrade snappy to v0.0.3 to avoid the following failure on Go 1.16

Bumps [github.com/gin-gonic/gin](https://github.com/gin-gonic/gin) from 1.6.3 to 1.7.0.
- [Release notes](https://github.com/gin-gonic/gin/releases)
- [Changelog](https://github.com/gin-gonic/gin/blob/master/CHANGELOG.md)
- [Commits](https://github.com/gin-gonic/gin/compare/v1.6.3...v1.7.0)

---
updated-dependencies:
- dependency-name: github.com/gin-gonic/gin
  dependency-type: direct:production
...

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