public class ThrottledRegion_ {
    private class ThrottledRegionForKey {
        public AtomicInteger countInside;
        public ConcurrentLinkedQueue<Boolean> waitingQueue ;
        public ReentrantLock _reentrantLock = new ReentrantLock();

        public ThrottledRegionForKey() {
            waitingQueue = new ConcurrentLinkedQueue<Boolean>();
            countInside = new AtomicInteger(0);
        }

        public boolean tryEnter() throws InterruptedException {
            do{
                int countInsideAux = countInside.get();
                if(countInsideAux < maxInside){
                    if(countInside.compareAndSet(countInsideAux, countInsideAux+1)){
                        return true;
                    }
                    continue;
                }
                if(waitTimeout == 0){
                    return false;
                }
                if (waitingQueue.size() > maxWaiting)
                {
                    return false;
                }
                TimeoutHolder th = new TimeoutHolder(waitTimeout);
                Boolean node = new Boolean(false);
                waitingQueue.add(node);
                do{
                    if(th.value() == waitTimeout ){
                        waitingQueue.remove(node);
                        return false;
                    }
                    try{
                        _reentrantLock.wait(waitTimeout);
                    }catch(InterruptedException tre){
                        waitingQueue.remove(node);
                        Thread.currentThread().interrupt();

                        throw tre;
                    }
                }while(node.booleanValue() == false);

                return true;
            }while(true);

        }

        public void leave() {
            do{
                int countInsideAux = countInside.get();
                if(countInsideAux > 0){
                    if(countInside.compareAndSet(countInsideAux, countInsideAux-1)){
                        if(waitingQueue.size() > 0){
                            Boolean n = waitingQueue.poll();
                            n = true;
                            _reentrantLock.notifyAll();
                            break;
                        }
                    }
                }else{
                    break;
                }
            }while(true);
        }
    }
}