| /* |
| * weinre is available under *either* the terms of the modified BSD license *or* the |
| * MIT License (2008). See http://opensource.org/licenses/alphabetical for full text. |
| * |
| * Copyright (c) 2010, 2011 IBM Corporation |
| */ |
| |
| 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() + "}"; |
| } |
| } |