org.jcurl.demo.tactics.HFBlockingQueue.java Source code

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Here is the source code for org.jcurl.demo.tactics.HFBlockingQueue.java

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/*
 * jcurl java curling software framework http://www.jcurl.org Copyright (C)
 * 2005-2009 M. Rohrmoser
 * 
 * This program is free software; you can redistribute it and/or modify it under
 * the terms of the GNU General Public License as published by the Free Software
 * Foundation; either version 2 of the License, or (at your option) any later
 * version.
 * 
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 * FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
 * details.
 * 
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
 * Place, Suite 330, Boston, MA 02111-1307 USA
 */

package org.jcurl.demo.tactics;

import java.util.Collection;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.TimeUnit;

import org.apache.commons.logging.Log;
import org.jcurl.core.log.JCLoggerFactory;

/**
 * @author <a href="mailto:m@jcurl.org">M. Rohrmoser </a>
 * @version $Id$
 */
public class HFBlockingQueue<E> extends LinkedBlockingQueue<E> {

    private static final Log log = JCLoggerFactory.getLogger(HFBlockingQueue.class);
    private static final long serialVersionUID = 8529261423710640827L;

    private final Map<Class<?>, E> recent = new HashMap<Class<?>, E>();

    public HFBlockingQueue() {
    }

    @Override
    synchronized public boolean add(final E o) {
        recent.put(o.getClass(), o);
        return super.add(o);
    }

    @Override
    public boolean addAll(final Collection<? extends E> c) {
        throw new UnsupportedOperationException();
    }

    @Override
    public boolean contains(final Object o) {
        return super.contains(o) && recent.get(o.getClass()) == o;
    }

    @Override
    public boolean containsAll(final Collection<?> c) {
        throw new UnsupportedOperationException();
    }

    @Override
    public int drainTo(final Collection<? super E> c) {
        throw new UnsupportedOperationException();
    }

    @Override
    public int drainTo(final Collection<? super E> c, final int maxElements) {
        throw new UnsupportedOperationException();
    }

    @Override
    public E element() {
        for (;;) {
            final E o = super.element();
            if (o == null || recent.get(o.getClass()) == o)
                return o;
            log.debug("discarded");
        }
    }

    @Override
    public Iterator<E> iterator() {
        throw new UnsupportedOperationException();
    }

    @Override
    synchronized public boolean offer(final E o) {
        recent.put(o.getClass(), o);
        return super.offer(o);
    }

    @Override
    synchronized public boolean offer(final E o, final long timeout, final TimeUnit unit)
            throws InterruptedException {
        recent.put(o.getClass(), o);
        return super.offer(o, timeout, unit);
    }

    @Override
    public E peek() {
        throw new UnsupportedOperationException();
    }

    @Override
    public E poll() {
        for (;;) {
            final E o = super.poll();
            if (o == null || recent.get(o.getClass()) == o)
                return o;
            log.debug("discarded");
        }
    }

    @Override
    public E poll(final long timeout, final TimeUnit unit) throws InterruptedException {
        for (;;) {
            final E o = super.poll(timeout, unit);
            if (o == null || recent.get(o.getClass()) == o)
                return o;
            log.debug("discarded");
        }
    }

    @Override
    synchronized public void put(final E o) throws InterruptedException {
        recent.put(o.getClass(), o);
        super.put(o);
    }

    @Override
    public boolean remove(final Object o) {
        throw new UnsupportedOperationException();
    }

    @Override
    public boolean removeAll(final Collection<?> c) {
        throw new UnsupportedOperationException();
    }

    @Override
    public boolean retainAll(final Collection<?> c) {
        throw new UnsupportedOperationException();
    }

    @Override
    public E take() throws InterruptedException {
        for (;;) {
            final E o = super.take();
            if (o == null || recent.get(o.getClass()) == o)
                return o;
            log.debug("discarded");
        }
    }
}