public class PersonSessionCache {

    private static final String FORMAT_PERSON_KEY = '{0}_Person_Id';

    public static Id getPersonId(){

        if (Cache.Session.contains(getPersonCacheKey())){
            return (Id)Cache.Session.get(getPersonCacheKey());
        }
        return null;
    }

    public static void setPersonId(Id personId){
        Cache.Session.put(getPersonCacheKey(), personId)
    }

    public static void clearCache(){
        Cache.Session.remove(getPersonCacheKey());
    }

    private static String getPersonCacheKey(){
        List<String> arguments = new List<String> {UserInfo.getProfileId()};
        return String.format(FORMAT_PERSON_KEY, arguments);
    }
}