public SmartQueue() 
{

}

 public  void add(SmartEntry entry) 
{
        /*
         * make sure we are within a synchronized block since we are dealing
         * with two unsync collections
         */
        synchronized (mutex) {
            /* check to see if this object has already been queued */
            SmartEntry current = (SmartEntry) queueMap.get(entry.getKey());
            if (current == null) {
                /* the object has not been queued, at it to the end of the queue */
                if (log.isDebugEnabled())
                    log.debug("[" + Thread.currentThread().getName()
                            + "][SmartQueue] Adding new object=" + entry);
                queue.addLast(entry);
                queueMap.put(entry.getKey(), entry);
            } else {
                /* the object has been queued, replace the value */
                if (log.isDebugEnabled())
                    log.debug("[" + Thread.currentThread().getName()
                            + "][SmartQueue] Replacing old object=" + current);
                current.setValue(entry.getValue());
                if (log.isDebugEnabled())
                    log.debug("with new object=" + current);
            }
            /*
             * wake up all the threads that are waiting for the lock to be
             * released
             */
            mutex.notifyAll();
        }
}

Add an object to the queue

 public SmartEntry remove() 
{
        return remove(0);
}

Blocks forever until an element has been added to the queue

 public SmartEntry remove(long timeout) 
{
        SmartEntry result = null;
        long startEntry = System.currentTimeMillis();
        synchronized (mutex) {
            while (size() == 0) {
                try {
                    if (log.isDebugEnabled())
                        log
                                .debug("["
                                        + Thread.currentThread().getName()
                                        + "][SmartQueue] Queue sleeping until object added size="
                                        + size() + ".");
                    if ((timeout != 0)
                            && ((System.currentTimeMillis() - startEntry)  > timeout)) {
                        return null;
                    }
                    mutex.wait(timeout);
                    if (log.isDebugEnabled())
                        log
                                .debug("["
                                        + Thread.currentThread().getName()
                                        + "][SmartQueue] Queue woke up or interrupted size="
                                        + size() + ".");
                } catch (IllegalMonitorStateException ex) {
                    throw ex;
                } catch (InterruptedException ex) {
                }//catch
            }//while
            /* guaranteed that we are not empty by now */
            result = (SmartEntry) queue.removeFirst();
            queueMap.remove(result.getKey());
            if (log.isDebugEnabled())
                log.debug("[" + Thread.currentThread().getName()
                        + "][SmartQueue] Returning=" + result);
        }
        return result;
}

 public int size() 
{
        synchronized (mutex) {
            return queue.size();
        }
}