Making a result of transaction visible to everyone, saving the ability for a rollback

I need to execute a rather complex plpgsql function on a production
server, the result of which is hard to test by myself.

I want to make the result of a transaction, in which this function is
executed, visible to the outer clients, but to have the ability of
making a rollback in case one of the clients says something went wrong.
Is it possible to do that?