Improve ranking calculation

[spolnik]

Instead of using caching and compute on demand ranking, it should be pre-computed after every event coming. But think about that in other way, if there is many changes during 1 sec, would we recalculate after each? That would kill performance ...

The other way to deal with that is with time. Let's say, on the beginning service takes snapshot of results, and stores datetime which identifies the moment where snapshot was took. Then everytime it needs to rebuild ranking, it ask for all results between now() - snapshot time - refreshing snapshot to a new one?

• how to use messages to make it more performant and consistent?