| /* |
| * Copyright (c) 2010-2012 Eike Stepper (Berlin, Germany) and others. |
| * All rights reserved. This program and the accompanying materials |
| * are made available under the terms of the Eclipse Public License v1.0 |
| * which accompanies this distribution, and is available at |
| * http://www.eclipse.org/legal/epl-v10.html |
| * |
| * Contributors: |
| * Eike Stepper - initial API and implementation |
| */ |
| package org.eclipse.net4j.util.collection; |
| |
| import org.eclipse.net4j.util.ObjectUtil; |
| |
| import java.util.ArrayList; |
| import java.util.Collection; |
| import java.util.Iterator; |
| import java.util.List; |
| import java.util.concurrent.BlockingQueue; |
| import java.util.concurrent.LinkedBlockingQueue; |
| import java.util.concurrent.TimeUnit; |
| |
| /** |
| * @author Eike Stepper |
| * @since 3.1 |
| */ |
| public class RoundRobinBlockingQueue<E> implements BlockingQueue<E> |
| { |
| private BlockingQueue<Entry<E>> list = new LinkedBlockingQueue<Entry<E>>(); |
| |
| public RoundRobinBlockingQueue() |
| { |
| } |
| |
| public int remainingCapacity() |
| { |
| return Integer.MAX_VALUE; |
| } |
| |
| public int size() |
| { |
| int size = 0; |
| synchronized (list) |
| { |
| for (Entry<E> entry : list) |
| { |
| size += entry.getCount(); |
| } |
| } |
| |
| return size; |
| } |
| |
| public boolean isEmpty() |
| { |
| synchronized (list) |
| { |
| return list.isEmpty(); |
| } |
| } |
| |
| public boolean offer(E e) |
| { |
| synchronized (list) |
| { |
| for (Entry<E> entry : list) |
| { |
| if (ObjectUtil.equals(entry.getElement(), e)) |
| { |
| entry.increaseCount(); |
| return true; |
| } |
| } |
| |
| return list.add(new Entry<E>(e)); |
| } |
| } |
| |
| public boolean offer(E o, long timeout, TimeUnit unit) throws InterruptedException |
| { |
| return offer(o); |
| } |
| |
| public void put(E o) throws InterruptedException |
| { |
| offer(o); |
| } |
| |
| public boolean add(E o) |
| { |
| return offer(o); |
| } |
| |
| public E poll(long timeout, TimeUnit unit) throws InterruptedException |
| { |
| synchronized (list) |
| { |
| Entry<E> entry = list.poll(timeout, unit); |
| if (entry == null) |
| { |
| return null; |
| } |
| |
| if (entry.decreaseCount() > 0) |
| { |
| list.add(entry); |
| } |
| |
| return entry.getElement(); |
| } |
| } |
| |
| public E poll() |
| { |
| synchronized (list) |
| { |
| Entry<E> entry = list.poll(); |
| if (entry == null) |
| { |
| return null; |
| } |
| |
| if (entry.decreaseCount() > 0) |
| { |
| list.add(entry); |
| } |
| |
| return entry.getElement(); |
| } |
| } |
| |
| public E take() throws InterruptedException |
| { |
| synchronized (list) |
| { |
| Entry<E> entry = list.take(); |
| if (entry.decreaseCount() > 0) |
| { |
| list.add(entry); |
| } |
| |
| return entry.getElement(); |
| } |
| } |
| |
| public E peek() |
| { |
| synchronized (list) |
| { |
| Entry<E> entry = list.peek(); |
| if (entry == null) |
| { |
| return null; |
| } |
| |
| return entry.getElement(); |
| } |
| } |
| |
| public E element() |
| { |
| synchronized (list) |
| { |
| Entry<E> entry = list.element(); |
| if (entry == null) |
| { |
| return null; |
| } |
| |
| return entry.getElement(); |
| } |
| } |
| |
| public E remove() |
| { |
| synchronized (list) |
| { |
| Entry<E> entry = list.remove(); |
| if (entry.decreaseCount() > 0) |
| { |
| list.add(entry); |
| } |
| |
| return entry.getElement(); |
| } |
| } |
| |
| public boolean remove(Object o) |
| { |
| synchronized (list) |
| { |
| for (Iterator<Entry<E>> it = list.iterator(); it.hasNext();) |
| { |
| Entry<E> entry = it.next(); |
| if (ObjectUtil.equals(entry.getElement(), o)) |
| { |
| if (entry.decreaseCount() > 0) |
| { |
| it.remove(); |
| } |
| |
| return true; |
| } |
| } |
| } |
| |
| return false; |
| } |
| |
| public void clear() |
| { |
| synchronized (list) |
| { |
| list.clear(); |
| } |
| } |
| |
| public Iterator<E> iterator() |
| { |
| List<E> copy = new ArrayList<E>(); |
| |
| synchronized (list) |
| { |
| int round = 0; |
| boolean again; |
| |
| do |
| { |
| again = false; |
| for (Entry<E> entry : list) |
| { |
| int rest = entry.getCount() - round; |
| if (rest > 0) |
| { |
| copy.add(entry.getElement()); |
| if (rest > 1) |
| { |
| again = true; |
| } |
| } |
| } |
| |
| ++round; |
| } while (again); |
| } |
| |
| return copy.iterator(); |
| } |
| |
| public boolean contains(Object o) |
| { |
| synchronized (list) |
| { |
| for (Entry<E> entry : list) |
| { |
| if (ObjectUtil.equals(entry.getElement(), o)) |
| { |
| return true; |
| } |
| } |
| } |
| |
| return false; |
| } |
| |
| public Object[] toArray() |
| { |
| synchronized (list) |
| { |
| return list.toArray(); |
| } |
| } |
| |
| public <T> T[] toArray(T[] array) |
| { |
| synchronized (list) |
| { |
| return list.toArray(array); |
| } |
| } |
| |
| public boolean containsAll(Collection<?> c) |
| { |
| // TODO: implement RoundRobinBlockingQueue.containsAll(c) |
| throw new UnsupportedOperationException(); |
| } |
| |
| public boolean addAll(Collection<? extends E> c) |
| { |
| // TODO: implement RoundRobinBlockingQueue.addAll(c) |
| throw new UnsupportedOperationException(); |
| } |
| |
| public boolean removeAll(Collection<?> c) |
| { |
| // TODO: implement RoundRobinBlockingQueue.removeAll(c) |
| throw new UnsupportedOperationException(); |
| } |
| |
| public boolean retainAll(Collection<?> c) |
| { |
| // TODO: implement RoundRobinBlockingQueue.retainAll(c) |
| throw new UnsupportedOperationException(); |
| } |
| |
| public int drainTo(Collection<? super E> c) |
| { |
| // TODO: implement RoundRobinBlockingQueue.drainTo(c) |
| throw new UnsupportedOperationException(); |
| } |
| |
| public int drainTo(Collection<? super E> c, int maxElements) |
| { |
| // TODO: implement RoundRobinBlockingQueue.drainTo(c, maxElements) |
| throw new UnsupportedOperationException(); |
| } |
| |
| @Override |
| public String toString() |
| { |
| synchronized (list) |
| { |
| return list.toString(); |
| } |
| } |
| |
| /** |
| * @author Eike Stepper |
| */ |
| private static final class Entry<E> |
| { |
| private E element; |
| |
| private int count; |
| |
| public Entry(E element) |
| { |
| this.element = element; |
| count = 1; |
| } |
| |
| public E getElement() |
| { |
| return element; |
| } |
| |
| public int getCount() |
| { |
| return count; |
| } |
| |
| public int increaseCount() |
| { |
| return ++count; |
| } |
| |
| public int decreaseCount() |
| { |
| return --count; |
| } |
| |
| @Override |
| public String toString() |
| { |
| return element.toString() + "(" + count + ")"; |
| } |
| } |
| } |