net.timewalker.ffmq4.remote.session.RemoteQueueBrowserEnumeration.java Source code

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Here is the source code for net.timewalker.ffmq4.remote.session.RemoteQueueBrowserEnumeration.java

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/*
 * This file is part of FFMQ.
 *
 * FFMQ is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * FFMQ 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 Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public License
 * along with FFMQ; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */
package net.timewalker.ffmq4.remote.session;

import java.util.NoSuchElementException;

import javax.jms.JMSException;
import javax.jms.Message;

import net.timewalker.ffmq4.common.message.AbstractMessage;
import net.timewalker.ffmq4.common.session.AbstractQueueBrowserEnumeration;
import net.timewalker.ffmq4.storage.message.MessageSerializationLevel;
import net.timewalker.ffmq4.transport.PacketTransportEndpoint;
import net.timewalker.ffmq4.transport.packet.query.CloseBrowserEnumerationQuery;
import net.timewalker.ffmq4.transport.packet.query.QueueBrowserFetchElementQuery;
import net.timewalker.ffmq4.transport.packet.query.QueueBrowserGetEnumerationQuery;
import net.timewalker.ffmq4.transport.packet.response.QueueBrowserFetchElementResponse;
import net.timewalker.ffmq4.transport.packet.response.QueueBrowserGetEnumerationResponse;
import net.timewalker.ffmq4.utils.ErrorTools;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
 * RemoteQueueBrowserEnumeration
 */
public final class RemoteQueueBrowserEnumeration extends AbstractQueueBrowserEnumeration {
    private static final Log log = LogFactory.getLog(RemoteQueueBrowserEnumeration.class);

    // Parent connection
    private PacketTransportEndpoint transportEndpoint;
    // Parent session
    private RemoteSession session;

    // Attributes
    private AbstractMessage nextMessage;
    private boolean endOfQueueReached;

    /**
     * Constructor
     */
    public RemoteQueueBrowserEnumeration(RemoteSession session, RemoteQueueBrowser browser) {
        super(browser, null);
        this.transportEndpoint = session.getTransportEndpoint();
        this.session = session;
    }

    /**
      * Initialize the remote endpoint for this session
      */
    protected void remoteInit() throws JMSException {
        QueueBrowserGetEnumerationQuery query = new QueueBrowserGetEnumerationQuery();
        query.setSessionId(session.getId());
        query.setBrowserId(browser.getId());
        QueueBrowserGetEnumerationResponse response = (QueueBrowserGetEnumerationResponse) transportEndpoint
                .blockingRequest(query);
        this.id = response.getEnumId();
        log.debug("Remote queue browser enumeration ID is " + id);
    }

    private AbstractMessage fetchNext() throws JMSException {
        if (nextMessage != null) // Already fetched ?
            return nextMessage;

        // Lookup next candidate
        QueueBrowserFetchElementQuery query = new QueueBrowserFetchElementQuery();
        query.setSessionId(session.getId());
        query.setBrowserId(browser.getId());
        query.setEnumId(id);
        QueueBrowserFetchElementResponse response = (QueueBrowserFetchElementResponse) transportEndpoint
                .blockingRequest(query);
        nextMessage = response.getMessage();

        if (nextMessage == null) {
            endOfQueueReached = true;
            close(); // Auto-close enumeration at end of queue
        }

        return nextMessage;
    }

    /* (non-Javadoc)
     * @see java.util.Enumeration#hasMoreElements()
     */
    @Override
    public boolean hasMoreElements() {
        if (endOfQueueReached)
            return false;
        try {
            checkNotClosed();
            Message msg = fetchNext();
            return msg != null;
        } catch (JMSException e) {
            throw new IllegalStateException(e.toString());
        }
    }

    /* (non-Javadoc)
     * @see java.util.Enumeration#nextElement()
     */
    @Override
    public AbstractMessage nextElement() {
        if (endOfQueueReached)
            throw new NoSuchElementException();

        try {
            checkNotClosed();
            AbstractMessage msg = fetchNext();
            if (msg != null) {
                nextMessage = null; // Consume fetched message

                // Make sure the message is fully deserialized and marked as read-only
                msg.ensureDeserializationLevel(MessageSerializationLevel.FULL);
                msg.markAsReadOnly();

                return msg;
            }

            throw new NoSuchElementException();
        } catch (NoSuchElementException e) {
            throw e;
        } catch (JMSException e) {
            throw new IllegalStateException(e.toString());
        }
    }

    /* (non-Javadoc)
     * @see net.timewalker.ffmq4.common.session.AbstractQueueBrowserEnumeration#onQueueBrowserEnumerationClose()
     */
    @Override
    protected void onQueueBrowserEnumerationClose() {
        try {
            CloseBrowserEnumerationQuery query = new CloseBrowserEnumerationQuery();
            query.setSessionId(session.getId());
            query.setBrowserId(browser.getId());
            query.setEnumId(id);
            transportEndpoint.blockingRequest(query);
        } catch (JMSException e) {
            ErrorTools.log(e, log);
        }
    }
}