| /* |
| * 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 weinre.server; |
| |
| import java.util.LinkedList; |
| import java.util.List; |
| import java.util.concurrent.BlockingQueue; |
| import java.util.concurrent.LinkedBlockingQueue; |
| import java.util.concurrent.TimeUnit; |
| |
| /** |
| * A type of blocking queue. |
| * |
| * - can be shutdown; subsequent add() or getAll() calls throw ISE |
| * - getAll() takes all items off the queue |
| * - if there are simultaneous getAll() calls, queued items may be split between them |
| * - current use case calls for one reader, so previous item not relevant |
| */ |
| public class MessageQueue<E> { |
| |
| private BlockingQueue<E> queue; |
| private boolean closed; |
| private Object closeLock; |
| |
| //--------------------------------------------------------------- |
| public MessageQueue() { |
| super(); |
| |
| queue = new LinkedBlockingQueue<E>(); |
| closed = false; |
| closeLock = new Object(); |
| } |
| |
| //--------------------------------------------------------------- |
| public void shutdown() { |
| synchronized(closeLock) { |
| if (closed) return; |
| |
| closed = true; |
| queue.clear(); |
| } |
| } |
| |
| //--------------------------------------------------------------- |
| public void add(E item) { |
| synchronized(closeLock) { |
| if (closed) throw new IllegalStateException("the blocking queue is closed"); |
| } |
| |
| queue.add(item); |
| } |
| |
| //--------------------------------------------------------------- |
| public List<E> getAll(int timeout, TimeUnit timeUnit) throws InterruptedException { |
| synchronized(closeLock) { |
| if (closed) throw new IllegalStateException("the blocking queue is closed"); |
| } |
| |
| // create our result list |
| List<E> result = new LinkedList<E>(); |
| |
| // wait for the first item |
| E item = queue.poll(timeout, timeUnit); |
| |
| // nothing there? return empty list |
| if (null == item) return result; |
| |
| // add the first item to the list |
| result.add(item); |
| |
| // get anything else on the queue |
| // - not appropriate for simultaneous calls to this method |
| while ((item = queue.poll()) != null) { |
| result.add(item); |
| } |
| |
| // return list |
| return result; |
| } |
| |
| //--------------------------------------------------------------- |
| public String toString() { |
| return getClass().getName() + "{" + queue.size() + "}"; |
| } |
| } |