Make Prefetching (Opportunistic caching) more Transparent & Configurable & Powerful

[gspannu]

Currently AGH does prefetching (opportunistic caching) with its own algorithm.

Can the settings be exposed be exposed/ made configurable through the yaml file?

As an example:
If any DNS query is requested x times within y timeframe, it should always be available cached for z duration from the last datetime of the query.

E.g. Requesting google.com 3 times within 60 minutes, keep google.com cached for 12 hours.

So, if AGH receives 2 queries within 60 minutes, it works as today.
However, if it receives 3 queries within 60 minutes, it should work to always prefetch the query as soon as the TTL is about to expire until 12 hours have passed, and reset the 12 hours each time another query is made.

This will allow fine control of the opportunistic cache.

If a user wanted to always have every query available cached (at all times), it just needs to set x=1, y=0, z=0.
If a user wanted to have every query available cached (for at least a week), it just needs to set x=1, y=0, z=7d.
If a user wanted to have every query used at least twice an hour, available cached (at all times), it just needs to set x=2, y=60m, z=0.
If a user wanted to have queries used at least 5times in 2 hours, available cached (for next 10 days), it just needs to set x=5, y=2h, z=10d.

… and so forth.

I think this (along with the ability to se minTTL and maxTTL) would make AGH a very powerful configurable DNS tool.

As a sid note: Blocky DNS supports this feature; and this feature does help in managing/ fine tuning its prefetch features.