class ReferenceCountedACLCache {

    public synchronized void addUsage(Long acl) {
        if (acl == OPEN_UNSAFE_ACL_ID) {
            return;
        }

        if (!longKeyMap.containsKey(acl)) {
            LOG.info("Ignoring acl " + acl + " as it does not exist in the cache");
            return;
        }

        AtomicLong count = referenceCounter.get(acl);
        if (count == null) {
            referenceCounter.put(acl, new AtomicLongWithEquals(1));
        } else {
            count.incrementAndGet();
        }
    }

}