Persons who have served as district attorneys in Etowah County and who are in all manner and respects entitled to status as supernumerary district attorneys under the general law of the state and who have elected to become supernumerary district attorneys pursuant to such general law shall be entitled to receive total compensation in such amounts as shall be set from time to time for supernumerary circuit judges. Each such supernumerary district attorney shall be paid as a supplement from the general funds of the county in addition to all sums received from state funds such funds, if any, as shall be necessary so that his or her total compensation for services as a supernumerary district attorney shall be in amount equal to that received by persons who have elected to become supernumerary circuit judges under the general law of the state.