/*
 *
 * Copyright (c) 2006 The Apache Software Foundation
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 */
package org.apache.qpid.server.exchange;

import org.apache.qpid.server.queue.AMQQueue;

import java.util.List;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.CopyOnWriteArrayList;

/**
 * An index of queues against routing key. Allows multiple queues to be stored
 * against the same key. Used in the DestNameExchange.
 */
class Index
{
    private ConcurrentMap<String, List<AMQQueue>> _index
            = new ConcurrentHashMap<String, List<AMQQueue>>();

    boolean add(String key, AMQQueue queue)
    {
        List<AMQQueue> queues = _index.get(key);
        if(queues == null)
        {
            queues = new CopyOnWriteArrayList<AMQQueue>();
            //next call is atomic, so there is no race to create the list
            List<AMQQueue> active = _index.putIfAbsent(key, queues);
            if(active != null)
            {
                //someone added the new one in faster than we did, so use theirs
                queues = active;
            }
        }
        if(queues.contains(queue))
        {
            return false;
        }
        else
        {
            return queues.add(queue);
        }
    }

    boolean remove(String key, AMQQueue queue)
    {
        List<AMQQueue> queues = _index.get(key);
        if (queues != null)
        {
            boolean removed = queues.remove(queue);
            if (queues.size() == 0)
            {
                _index.remove(key);
            }
            return removed;
        }
        return false;
    }

    List<AMQQueue> get(String key)
    {
        return _index.get(key);
    }

    Map<String, List<AMQQueue>> getBindingsMap()
    {
        return _index;
    }
}
