| /** |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you 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 backtype.storm.utils; |
| |
| import java.util.ArrayList; |
| import java.util.HashMap; |
| import java.util.LinkedList; |
| import java.util.List; |
| import java.util.Map; |
| import java.util.Queue; |
| import java.util.concurrent.Semaphore; |
| |
| public class KeyedRoundRobinQueue<V> { |
| private final Object _lock = new Object(); |
| private Semaphore _size = new Semaphore(0); |
| private Map<Object, Queue<V>> _queues = new HashMap<Object, Queue<V>>(); |
| private List<Object> _keyOrder = new ArrayList<Object>(); |
| private int _currIndex = 0; |
| |
| public void add(Object key, V val) { |
| synchronized(_lock) { |
| Queue<V> queue = _queues.get(key); |
| if(queue==null) { |
| queue = new LinkedList<V>(); |
| _queues.put(key, queue); |
| _keyOrder.add(key); |
| } |
| queue.add(val); |
| } |
| _size.release(); |
| } |
| |
| public V take() throws InterruptedException { |
| _size.acquire(); |
| synchronized(_lock) { |
| Object key = _keyOrder.get(_currIndex); |
| Queue<V> queue = _queues.get(key); |
| V ret = queue.remove(); |
| if(queue.isEmpty()) { |
| _keyOrder.remove(_currIndex); |
| _queues.remove(key); |
| if(_keyOrder.size()==0) { |
| _currIndex = 0; |
| } else { |
| _currIndex = _currIndex % _keyOrder.size(); |
| } |
| } else { |
| _currIndex = (_currIndex + 1) % _keyOrder.size(); |
| } |
| return ret; |
| } |
| } |
| } |