I have a function f1 in tezos contract that can be invoked by a node but after 30 min of the invocation if no other function f' has been invoked the f1 has to continue its process normally otherwise it stop invoking another function f2.
I'll just pust @FFF answer from Twitter here for reference:
You cannot trigger automatically the contract after 30 minutes. You need someone to do it (typically an oracle). What you can do is simply check inside your contract that at least 30 minutes have elapsed. You should avoid putting too small upper bounds as they can be gamed.