I am building a simple caching class and I want to use this class to cache queries. My initial thinking was to create a Query class and use this to handle all queries, meaning the Query class would use my Cache class to check if there is a saved query, otherwise it would run WP_query or $wpdb and cache the results.

So far so good and I want to take this one step further. What about the queries that wordpress runs by default ? Wordpress core functions won't use my class, so my question is this: Is there a way to hook into wordpress on query execution level ? The only hooks I was able to find were hooks about modifying the query, but what I want is a hook that handles the query execution itself (so that I can stop the query execution and retrieve the data that the query would search for from the cache).

For example, with wordpress structure I would guess that all queries would get executed at the end by $wpdb->query('FINAL BUILT QUERY HERE');. I don't know if this is true, but it is something that would make sense. So if this was the case, I would be looking for an action filter that receives the final query as a string or as an array of arguments and expects query results as a return (sounds like an insecure hook, but you get the idea). By default that hook would run $wpdb->query on the input data and that's where I come in to override this behaviour and add a detour for a cached query check before the actual execution.

I hope my example makes sense to understand what I am looking for, anyone knows a way to go about it ?