Smack/source/org/jivesoftware/smackx/muc/ConnectionDetachedPacketCollector.java

/**
 *
 * Copyright 2003-2006 Jive Software.
 *
 * All rights reserved. Licensed 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 org.jivesoftware.smackx.muc;

import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.TimeUnit;

import org.jivesoftware.smack.SmackConfiguration;
import org.jivesoftware.smack.packet.Packet;

/**
 * A variant of the {@link org.jivesoftware.smack.PacketCollector} class
 * that does not force attachment to a <code>Connection</code>
 * on creation and no filter is required. Used to collect message
 * packets targeted to a group chat room.
 *
 * @author Larry Kirschner
 */
class ConnectionDetachedPacketCollector {
    /**
     * Max number of packets that any one collector can hold. After the max is
     * reached, older packets will be automatically dropped from the queue as
     * new packets are added.
     */
    private int maxPackets = SmackConfiguration.getPacketCollectorSize();

    private ArrayBlockingQueue<Packet> resultQueue;

    /**
     * Creates a new packet collector. If the packet filter is <tt>null</tt>, then
     * all packets will match this collector.
     */
    public ConnectionDetachedPacketCollector() {
        this(SmackConfiguration.getPacketCollectorSize());
    }

    /**
     * Creates a new packet collector. If the packet filter is <tt>null</tt>, then
     * all packets will match this collector.
     */
    public ConnectionDetachedPacketCollector(int maxSize) {
        this.resultQueue = new ArrayBlockingQueue<Packet>(maxSize);
    }

    /**
     * Polls to see if a packet is currently available and returns it, or
     * immediately returns <tt>null</tt> if no packets are currently in the
     * result queue.
     *
     * @return the next packet result, or <tt>null</tt> if there are no more
     *      results.
     */
    public Packet pollResult() {
    	return resultQueue.poll();
    }

    /**
     * Returns the next available packet. The method call will block (not return)
     * until a packet is available.
     *
     * @return the next available packet.
     */
    public Packet nextResult() {
        try {
			return resultQueue.take();
		}
		catch (InterruptedException e) {
			throw new RuntimeException(e);
		}
    }

    /**
     * Returns the next available packet. The method call will block (not return)
     * until a packet is available or the <tt>timeout</tt> has elapased. If the
     * timeout elapses without a result, <tt>null</tt> will be returned.
     *
     * @param timeout the amount of time to wait for the next packet (in milleseconds).
     * @return the next available packet.
     */
    public Packet nextResult(long timeout) {
        try {
        	return resultQueue.poll(timeout, TimeUnit.MILLISECONDS);
		}
		catch (InterruptedException e) {
			throw new RuntimeException(e);
		}
    }

    /**
     * Processes a packet to see if it meets the criteria for this packet collector.
     * If so, the packet is added to the result queue.
     *
     * @param packet the packet to process.
     */
    protected void processPacket(Packet packet) {
        if (packet == null) {
            return;
        }
        
    	while (!resultQueue.offer(packet)) {
    		// Since we know the queue is full, this poll should never actually block.
    		resultQueue.poll();
    	}
    }
}