in plugin/src/main/groovy/grails/plugins/redis/RedisService.groovy [270:279]
List<Long> memoizeDomainIdList(Class domainClass, String key, Map options = [:], Closure closure) {
List<Long> idList = getIdListFor(key)
if (idList) return idList
def domainList = closure()
saveIdListTo(key, domainList, options.expire)
getIdListFor(key)
}