Our new configuration system needs to handle options_act_reversible too. But on further examination, there are only two actual "reversible" pieces of options_act_reversible: * Adjusting the logs. * Adjusting the listeners. The remainder of the function is all about handling "irreversible", immutable options that need to be handled before we can mess with the logs or listeners. I think this means that we want to split this function into two pieces: one part that handles startup-only initialization, and one that handles truly reversible option changes. I think that the callback for the startup-only initialization should be called options_set_init(), options_set_onece(), options_set_early(), or something like that. The callbacks for truly reversible options should look something like this: ``` int act_reversible(const void *old_options, void *new_options, void **transaction_state_out); int commit(const void *old_options, void *new_options, void *transaction_state); int rollback(const void *old_options, void *rejected_options, void *transaction_state); ```