why rocksdb::GetSnapshot frequently used in v2.7

[qiwei9743]

hi,
rocksdb::GetSnapshot() may impact performance if used frequently. I find that it's used even when get a single key. May I know the reason behind the decision?

Thanks.

[mapleFU]

Yes, I think this can be removed. In fact this is refactor to use engine::Context in latest version, which tries to share the same Snapshopt if write doesn't happens